The development and assessment of assays for quantitation of hepatitis B virus DNA (HBV DNA) and the clinical significance of low HBV DNA level in patients with chronic hepatitis B Sum, Siu-man, Simon;

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SECTION E

REFERENCES

References

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antigen-antibody

system
Australia-antigen-positive hepatitis. Lancet 1971; ii: 1225-1227.
Besson PB. Jaundice occurring one to four months after transfusion of blood or plasma. Journal of the American Medical Association 1943; 121: 1332-1334.
Birrer RB, Birrer D, Klavins JV. Hepatocellular carcinoma and hepatitis virus. Ann Clin Lab Sci 2003; 33(1): 39-54.
Blumberg BS, Dray S, Robinson JC. Antigen polymorphism of a low-density beta-lipoprotein. Allotype in human serum. Nature 1962; 194: 656-658.
Blumberg BS, Alter HJ, Visnich S. A new antigen in leukemia sera. Journal of the American Medical Association 1965; 191: 541-546.
Bowden S. 2002. Laboratory diagnosis of hepatitis B infection in Lai CL and Locarnini S. Hepatitis B Virus. International Medical Press.
Cameron JDS. Infective hepatitis. Quarterly Journal of Medicine 1943; 12: 139-155.
Chan HLY. 2001. Viral Mutations and natural course of HBeAg. USA, UMI.
Chan HLY, Leung NWY, Lau TCM, Wong ML, Sung JJY. Comparison of three different sensitive assays for hepatitis B virus DNA in monitoring of responses to antiviral therapy. Journal of Clinical Microbiology 2000; 38(9): 3205-3208.
Chen Y, Sze J, He ML. HBV cccDNA in patients'sera as an indicator for HBV reactivation and an early signal of liver damage. World Journal of Gastroenterology 2004; 10(1): 82-85.
Chisari FV. Rous-Whipple Award Lecture. Viruses, immunity, and cancer: lessons from hepatitis B. American Journal of Pathology 2000; 156: 1117-1132.
Conjeevaram HS, Lok AS. Management of chronic hepatitis B. Journal of Hepatology 2003; 38: S90-S103.
Dane DS, Cameron CH, Briggs M. Virus-like particles in serum of patients with Australia-antigen-associated hepatitis. Lancet 1971; I: 695-698.
Evans AA, London WT. 1998. Epidemiology of hepatitis B in Zuckerman AJ and Thomas HC. Viral Hepatitis 2nd edition. London, Churchill Livingstone.
Farrell J, Dienstag J. 2002. Epidemiology and prevention of hepatitis B virus infection in Lai CL and Locarnini S. Hepatitis B Virus. International Medical Press.
Fattovich G. Natural history and prognosis of hepatitis B. Seminars in liver disease 2003; 23(1): 47-58.
Gilbert N, Corden S, Ijaz S, Grant PR, Tedder RS, Bosall EH. Comparison of commercial assays for the quantification of HBV DNA load in health care workers: calibration differences. Journal of Virological Methods 2002; 100: 37-47.
Hadziyannis SJ, Vassilopoulos D. Immunopathogenesis of hepatitis B e antigen negative chronic hepatitis B infection. Antiviral research 2001; 52: 91-98.
Heermann KH, Gerlich WH, Chudy M, Schaefer S, Thomssen R. Quantitative detection of hepatitis B virus DNA in two international reference plasma preparations. Eurohep Pathobiology Group. Journal of Clinical Microbiology 1999; 37(1): 68-73.
Ho SK, Yam WC, Leung ET, Wong LP, Lai KN, Chan TM. 2003. Rapid quantidication of hepatitis B virus DNA by real-time PCR using fluorescent hybridization probes. Journal of Medical Microbiology; 52(Pt5): 397-402.
Hollinger FB. 2002. Viral Hepatitis. Lippincott, Williams & Wilkins.
Huo TI, Wu JC, Lee PC, Chau GY, Lui WY, Tsay SH, Ting LT, Chang FY, Lee SD. Sero-clearance of hepatitis B surface antigen in chronic carriers does not necessarily imply a good prognosis. Hepatology 1998; 28(1): 231-236.

Hussain KB, Lok ASF. 2002. Hepatitis B virology in Gordon SC. Management of chronic viral hepatitis. New York, Marcel Dekker Inc.; 1-26.
Hwang SJ, Lu RH, Wood ML, Wang YJ, Chang FY, Lee SD. 1999. Comparison of the
nucleic acid-based crosslinking hybridization assay and the branched DNA signal amplification assay in the quantitative measurement of serum hepatitis B virus DNA. Journal of Clinical Laboratory Analysis ; 13: 296-300.
Ide T, Kumashiro R, Koga Y, Tanaka E, Hino T, Hisamochi A, Murashima S, Ogata K, Tanaka K, Kuwahara R, Sata M. A real time quantitative polymerase chain reaction method for hepatitis B virus in patients with chronic hepatitis B treated with lamivudine. The American Journal of Gastroenterology 2003; 98(9): 2048-2051.
Jardi R, Rodriguez F, Buti M, Costa X, Cotrina M, Valdes A, Galimany R, Esteban R. Quantitative detection of hepatitis B virus DNA in serum by a new rapid real-time fluorescence PCR assay. Journal of Viral Hepatitis 2001; 8: 465-471.
Jilbert AR, Burrell CJ, Triatni M, Kann M. 2002. Hepatitis B virus replication in Lai CL and Locarnini S. Hepatitis B Virus. International Medical Press.
Kann M, Gerlich W. 1998. Structure and molecular virology in Zuckerman AJ and Thomas HC. Viral Hepatitis 2nd edition. Churchill Livingstone.
Kann M. 2002. Structural and molecular virology in Lai CL and Locarnini S. Hepatitis B Virus. International Medical Press.
Kao JH, Chen DS. 2002. The natural history of hepatitis B virus infection in Lai CL and Locarnini S. Hepatitis B Virus. International Medical Press.
Koike K, Tsutsumi T, Fujie H, Shintani Y, Kyoji M. 2002. Molecular mechanism of viral hepatocarcinogenesis. Oncology; 62 (Supp 1): 29-37.
Krugman S, Giles JP, Hammond J. 1967. Infectious hepatitis: evidence for two distinctive clinical, epidemiological and immunological types of infection. Journal of the American Medical Association; 200: 365-373.
Lai CL. 2002. Discover and classification in Lai CL and Locarnini S. Hepatitis B Virus. International Medical Press.
Lai CL, Yuen MF, Locarnini S. 2002. Treatment of chronic hepatitis B infection in Lai CL and Locarnini S. Hepatitis B Virus. International Medical Press.
Lai CL, Chien RN, Leung NW, Chang TT, Guan R, Tai DI et al. A one-year trial of lamivudine for chronic hepatitis B. Asia Hepatitis Lamivudine Study Group. N Engl J Med 1998; 339(2):61-68.
Lai, C. L., Ratziu, V., Yuen, M. F., and Poynard, T., Lancet 20;362, 2089-2094, 2003a
Lai, C. L., Leung, N. W., Teo, E. K., Tong, M., Wong, F., Hann, H. W., Han, S., Poynard, T., Myers, M., and Brown, N. Results of a one-year international phase IIB comparative trial of telbivudine, lamivudine, and the combination, in patients with chronic hepatitis B. Hepatology 38(4 Suppl. 1), 262A. 2003b.

Lai VCH, Lai CL, Low BG, Lau JYN, Wu PC. Quantitative detection of serum HBV DNA in Chinese patients. Journal of Viral Hepatitis 1997; 4: 359-362.
Lai, VC, Guan, R., Wood, ML, Lo, SK, Yuen, MF, and Lai, CL, J.Clin.Microbiol. 37, 161-164, 1999
Lee WM. 1997. Hepatitis B virus infection. New England Journal of Medicine; 337: 1733-1745.
Lee CA, Thomas HC. Classic papers in viral hepatitis 1988; Science Press.
Lok AS, Heathcote EJ, Hoofnagle JH. Management of hepatitis B: 2000 summary of a workshop. Gastroenterology 2001; 120: 1828-1853.
Magnius LO, Espmark A. 1972. A new antigen complex co-occuring with Australia antigen. Acta Pathologica et Microbiologica Scandinavica; B(80): 335-337.
Main J, Thomas HC. 1998. Treatment of chronic hepatitis B in Zuckerman AJ and Thomas HC. Viral Hepatitis 2nd edition. Churchill Livingstone.
Manesis EK, Papatheodoridis GV, Sevastianos V, Cholongitas E, Papaioannou C, Hadziyannis SJ. Significance of hepatitis B viremia levels determined by a quantitative polymerase chain reaction assay in patients with hepatitis B e antigen-negative chronic hepatitis B virus infection. The American Journal of Gastroenterology 2003; 98(10):

2261-2267.

Martin P, Edelstein MA, Han SHB. 2002. Current treatment of chronic hepatitis B in Gordon SC. Management of chronic viral hepatitis. Marcel Dekker Inc.
Mommeja-Marin H, Mondou E, Blum MR, Rousseau F. Serum HBV DNA as a marker of efficacy during therapy for chronic HBV infection: analysis and review of the literature. Hepatology 2003; 37(6): 1309-1319.
Niesters HGM, Krajden M, Cork L, Medina M, Hill M, Fries E, Osterhaus AME. A multicenter study evaluation of the Digene Hybrid Capture II Signal amplification technique for detection of hepatitis B virus DNA in serum samples and testing of Eurohep standards. Journal of Clinical Microbiology 2000; 38(6): 2150-2155.
OBrien C, Moonka D. 1999. Antiviral chemotherapy for viral hepatitis in Specter S. Viral hepatitis. Humana Press.
Ohkubo K, Kato Y, Ichikawa T, Kajiya Y, Takeda Y, Higashi S, Hamasaki K, Nakao K,
Nakata K, Eguchi K. Viral load is a significant prognostic factor for hepatitis B virus-associated hepatocellular carcinoma. Cancer 2002; 94(10): 2663-2668.
Parakevis D, Haida C, Tassopoulos N, Raptopoulou M, Tsantoulas D, Papachristou H, Sypsa V, Hatzakis A. 2002. Development and assessment of a novel real-time PCR assay for Quantitation of HBV DNA. Journal of Virological Methods; 103(2): 201-212.
Pas, S. D., Fries, E., De Man, R. A., Osterhaus, A. D., and Niesters, H. G., J.Clin.Microbiol. 38, 2897-2901, 2000.

Pawlotsky JM. Molecular diagnosis of viral hepatitis. Gastroenterology 2002; 122: 1554-1568.
Pawlotsky JM. Hepatitis B virus (HBV) DNA assays (methods and practical use) and viral kinetics. Journal of Hepatology 2003; 39: S31-S35.
Robinson WS. DNA and DNA polymerase in the core of the Dane particle of hepatitis B. American Journal of Medical Science 1975; 270: 151-159.
Sakugawa, H., Kobashigawa, K., Nakayoshi, T., Yamashiro, T., Maeshiro, T., Tomimori, K., Kinjo, F., Saito, A., and Mukaide, M., Hepatol.Res. 26, 281-286, 2003 Seeger C, Manson WS. Hepatitis B virus biology. Microbiology and Molecular Biology Reviews 2000; 64: 51-68.
Sambrook, J., E.F. Fritsch, and T. Maniatis. Molecular Cloning, a laboratory manual, 2nd ed. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y. 1989.
Shao JB, Chen Z, Ni WQ, Fan J. A quantitative method to detect HBV cccDNA by chimeric
primer and real-time polymerase chain reaction. Journal of Virological Methods 2003; 112(1-2): 45-52.
Smith RM, Wu GY. 2002. Molecular virology of hepatitis B and C in Koff RS and Wu GY. Chronic viral hepatitis, Diagnosis and Therapeutics. New Jersey, Humana Press.
Specter S. 1999. Hepatitis B vaccines in Specter S. Viral hepatitis, Diagnosis, Therapy, and Prevention. New Jersey, Humana Press.
Vyas GN, Yen TSB. 1999. Hepatitis B virus: biology, pathogenesis, epidemiology, clinical description, and diagnosis in Specter S. Viral hepatitis, Diagnosis, Therapy, and Prevention. New Jersey, Humana Press.
Weiss, J., Wu, H., Farrenkopf, B., Schultz, T., Song, G., Shah, S., and Siegel, J., J.Clin.Virol. 30, 86-93, 2004.
Yao, J. D., Beld, M. G., Oon, L. L., Sherlock, C. H., Germer, J., Menting, S., Se Thoe, S. Y., Merrick, L., Ziermann, R., Surtihadi, J., and Hnatyszyn, H. J., J.Clin.Microbiol. 42, 800-806, 2004
Yates, S., Penning, M., Goudsmit, J., Frantzen, I., van de, W. B., van Strijp, D., and van Gemen, B., J.Clin.Microbiol. 39, 3656-3665, 2001.
Yuen MF and Lai CL 1999. Debates in Hepatitis: How to assess HBV DNA reductions in association with therapy. Viral Hepatitis Reviews 1999; 5 (3): 159-175.
Yuen MF and Lai CL 2000. Natural history chronic hepatitis B virus infection. Journal

of Gastroenterology and Hepatology 2000; May (15) Supp: E20-24. Yuen MF, Sablon E, Hui CK, Yuan HJ, Decraemer H, Lai CL. Factors associated with hepatitis B virus DNA breakthrough in patients receiving prolonged lamivudine therapy. Hepatology 2001; 34; 785-791.
Yuen MF, Lai CL. Treatment of chronic hepatitis B. Lancet Infect Dis 2001; 1(4):232-241.
Yuen MF, Sablon E, Yuan HJ, Wong DK, Hui CK, Wong BC, Chan AO, Lai CL. Significance of hepatitis B genotype in acute exacerbation, HBeAg seroconversion, cirrhosis-related complications, and hepatocellular carcinoma. Hepatology 2003; 37(3): 562-7.
Yuen MF, Wong DK, Sablon E, Tse E, Ng IO, Yuan HJ et al. HBsAg seroclearance in chronic hepatitis B in the Chinese: virological, histological, and clinical aspects. Hepatology 2004; 39(6):1694-1701
Yuen MF, Yuan HJ, Hui CK, Wong DK, Wong WM, Chan AO et al. A large population study of spontaneous HBeAg seroconversion and acute exacerbation of chronic hepatitis B infection: implications for antiviral therapy. Gut 2003; 52(3):416-419.
Zuckerman JN, Harrison TJ, Zuckerman AJ. 1998. Prevention in Zuckerman AJ and Thomas HC. Viral Hepatitis 2nd edition. Churchill Livingstone. 245-252.

THE ASTRONOMICAL JOURNAL, 118 : 785796, 1999 August
( 1999. The American Astronomical Society. All rights reserved. Printed in U.S.A.
DUST PROPERTIES OF NGC 4753 G. C. DEWANGAN,1 K. P. SINGH,2 AND P. N. BHAT3
Department of Astronomy and Astrophysics, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India Received 1999 January 7 ; accepted 1999 May 11
ABSTRACT We report on BV R surface photometry of a lenticular galaxy, NGC 4753, with prominent dust lanes. We have used the multicolor broadband photometry to study dust extinction as a function of wavelength and derived the extinction curve. We nd the extinction curve of NGC 4753 to be similar to the Galactic extinction curve in the visible region, which implies that the sizes of dust grains responsible for optical extinction are similar to those in our Galaxy. We derive the dust mass from optical extinction as well as from the far-infrared uxes observed with IRAS. The ratio of the two dust masses, /M , is 2.28 for NGC 4753, which is signicantly lower than the value of 8.4 ^ 1.3 found M d,IRAS previously d,optical large sample of elliptical galaxies. The total mass of the observed dust within NGC 4753 for a is about a factor of 10 higher than the mass of dust expected from loss of mass from red giant stars and destruction by sputtering and grain-grain collisions in low-velocity shocks and sputtering in supernovadriven blast waves. We nd evidence for the coexistence of dust and Ha-emitting gas within NGC 4753. The current star formation rate of NGC 4753, averaged over the past 2 ] 106 yr, is estimated to be less than 0.21 M yr~1. A substantial amount of dust within NGC 4753 exists in the form of cirrus. _ Key words : dust, extinction galaxies : elliptical and lenticular, cD galaxies : ISM galaxies : photometry infrared : galaxies

INTRODUCTION

It has now been well established that the presence of dust in early-type galaxies is the rule rather than an exception. Cool interstellar dust has been observed by IRAS (Jura 1986) and by means of optical extinction (Hawarden et al. 1981 ; Sadler & Gerhard 1985 ; Ebneter, Djorgovski, & Davis 1988 ; Goudfrooij et al. 1994b). Using IRAS data, Knapp et al. (1989) have shown that about 45% of the ellipticals and 68% of the S0 galaxies have been detected at the 60 and 100 km bands, whereas Goudfrooij & de Jong (1995) have reported a detection rate of 61% for their sample of Shapley-Ames elliptical galaxies. The Hubble Space T elescope (HST ) survey of ellipticals in the Virgo Cluster has revealed the presence of dust in the nuclei of almost every galaxy (Jae et al. 1994). Apart from dust, early-type galaxies also contain substantial amounts of gas at various temperatures. Cold gas (T 100 K) has been observed via its H I 21 cm line emission (Knapp, Turner, & Cunnier 1985) and CO line emission (Wiklind & Rydbeck 1986 ; Phillips et al. 1986), warm gas (T B 104 K) via optical emission lines (e.g., [O II], [O III] ; Caldwell 1984 ; Phillips et al. 1986), and hot gas via their X-ray emission (Forman, Jones, & Tucker 1985 ; Canizares, Fabbiano, & Trinchieri 1987 ; Fabbiano, Kim, & Trinchieri 1992). The interstellar medium (ISM) of earlytype galaxies thus contains many dierent phases from cold to very hot. Typically they contain an amount of cool dust of mass ^104106 M (Jura et al. 1987 ; Goudfrooij et _ al. 1994c), hot gas of mass ^1091010 M (Forman et al. _ 1985 ; Fabbiano et al. 1992), and small amounts of warm gas of mass ^103105 M (Phillips et al. 1986 ; Caldwell 1984). _
1 gulab=tifr.res.in. 2 singh=tifr.res.in. 3 pnbhat=tifr.res.in.
The study of properties of dierent phases of ISM in early-type galaxies provides important clues to the origin, nature, and fate of the interstellar matter. In particular, dusty early-type galaxies provide a suitable environment to study the nature of extragalactic dust grains, either via their far-infrared (FIR) emission or optical extinction. The data can be used to study the physical mechanism operating on them, which can determine, among other things, their size distribution, temperature, abundances, formation, and destruction. The physical properties of the dust grains are functions of time and can be used as an indicator for the time elapsed since the dust was last substantially replenished (see Goudfrooij et al. 1994c). The emission-line regions in X-raybright early-type galaxies are expected to be dust-free in view of very short lifetime (^106107 yr) of dust grains. However, Goudfrooij et al. (1994c) found that the emission-line regions in these galaxies are essentially always associated with substantial dust extinction. This dilemma can be resolved in the evaporative ow scenario (de Jong et al. 1990) in which the observed dust immersed in hot, high-pressure plasma may be replenished by the evaporation of cool clouds. The presence of cool clouds is assumed to be due to the capture of a companion dwarf galaxy rich in dust and gas. A recent study of nuclear dust in 64 elliptical galaxies imaged with HST has shown that the dust and gas are generally dynamically decoupled (Van Dokkum & Franx 1995). Moreover, the kinematics of stars and gas in ellipticals with large dust lanes are found to be decoupled (e.g., Bertola et al. 1988). These conclusions generally indicate an external origin of dust in these galaxies. Further, the dynamical state of dust and gas can be used to probe the intrinsic shape of the underlying galaxy. The dust and gas, settled in the galaxy potential, are allowed in stable closed orbits, which indicates a plane in the galaxy (Merritt & de Zeeuw 1983 ; Habe & Ikewchi 1985, 1988). 785

DEWANGAN, SINGH, & BHAT
TABLE 1 BASIC PARAMETERS OF NGC 4753 Parameter a (J2000). d (J2000). Distance. Velocity. Magnitude. FIR ux densities (mJy). Value 12h52m23s 23. [0112@00A50. 8.7 Mpc 1225 km s~1 U \ 11.26 ^ 0.10 ; B \ 10.85 ^ 0.10 ; T T V (Johnson) \ 10.30 f (12 km) \ 340 ^ 42 ; f (25 km) \ 310 ^ 71 ; f (60 km) \ 2640 ^ 60 ; f (100 km) \ 8010 ^ 176

Vol. 118

In this paper, we present a detailed study of dust properties of an early-type galaxy, NGC 4753, with very prominent dust lanes. NGC 4753 is located at a distance of 8.7 Mpc, as determined from a distance modulus of 29.7 by Buta et al. (1985) using published estimates and the light curve of supernova SN 1983g observed within the galaxy. NGC 4753 has been classied as a peculiar S0-type galaxy in the Hubble atlas (Sandage 1961) because its underlying luminosity distribution resembles an S0-type galaxy. However, the Third Reference Catalogue (RC3 ; de Vaucouleurs et al. 1991) classies it as an irregular type, I0. The complex dust lanes in NGC 4753 pass through its center. Steiman-Cameron, Kormendy, & Durisen (1992) have shown using R-band photometry that the dust lanes lie in a disk that is strongly twisted by dierential precession. We have carried out BV R surface photometry of NGC 4753 and derived its color and extinction maps. Based on these, we estimate the dust-mass from optical extinction. We have also derived the dust mass based on FIR emission. The observed optical (RC3) and IR (Knapp et al. 1989) properties of NGC 4753 are summarized in Table 1. The paper is organized as follows. In the next section we provide details of our observation. In 3 we present our method of analysis and the results obtained. In 4 we discuss our results, followed by conclusions in 5.

ANALYSIS AND RESULTS

OBSERVATIONS
NGC 4753 was observed with the Vainu Bappu Telescope (VBT) on the night of 1996 March 13. The observations were carried with a liquid nitrogencooled TEK 1024 ] 1024 CCD chip placed at the prime focus of the 2.3 m reector. The nominal value of the f-ratio is f/3.25. The pixel size of 24 km2 pixel~1 of the CCD chip gives a scale of 0A6 pixel~1 and a total eld of 10@24 ] 10@24. The obser. vations were carried out under photometric conditions. The seeing (FWHM) was in the range 2A12A6. The exposure. times were chosen not to saturate the CCD pixels because of the presence of bright stars in the neighborhood of the galaxy NGC 4753. In order to achieve a good signal-tonoise ratio, two images of NGC 4753 were taken in each of the broadband lters B, V , and R, with exposure times 300, 180, and 60 s, respectively. To correct for the bias level, bias images were taken just before and after the galaxy observation apart from many bias frames taken during the observing night. Several at-eld images in each lter were taken by exposing to the twilight and dawn sky in order to correct for the nonuniformity of response of pixels of the CCD. The standard star eld in the dipper asterism region of the open cluster M67 was observed for photometric calibration. Both NGC 4753 and M67 were observed close to the zenith.

We have used an IRAF4 software package for the basic reduction and analysis of CCD images. Examination of the bias frames showed that the mean bias level did not vary signicantly over the observation run. An average bias frame, constructed from bias frames taken very close to the galaxy observation, was subtracted from each of the object frames and at-eld frames. The bias-subtracted frames were trimmed to a size of 700 ] 850 pixels in order to avoid the eects due to vignetting at the edges. The pixel-to-pixel response variation in each of the object frames were corrected by dividing the object frames by master at frames in each band separately. The master at frame in a lter band was obtained by averaging the best at frames in the same lter and normalizing by the mean intensity level of the averaged frame. Cosmic-ray events, seen as few isolated bright pixels, were removed by replacing them by the average intensity of four nearest neighbors. The two frames of NGC 4753, obtained in each band, were combined after alignment, which increased the signal-to-noise ratio. The point-spread functions of individual and combined frames in each band were found to be similar to an accuracy better than 0.5%, which implies that the alignments were correct. The pixel coordinates in each of the object images were converted into the standard equatorial coordinates for the epoch J2000.0. The plate solutions were computed by tting a quadratic polynomial between the known celestial coordinates and pixels coordinates of stars nearby to the object after projecting the celestial coordinates onto the plane tangent to the object center. The subsequent analysis utilized the nal corrected and combined object images. The bias-corrected and at-elded B- and R-band images of NGC 4753 are shown in Figures 1 and 2, respectively, where the eect of extinction due to dust can easily be seen as the severe departure of the isophotes from the nearly elliptical shapes at the positions of dust lanes or patches. It is also clear that the extinction due to dust is larger in the B band, compared with that in the R band. 3.1. Photometric Calibration Many authors (e.g., Chevalier & Ilovaisky 1991 ; Mayya 1991 ; Anupama et al. 1994 ; Bhat et al. 1992) have emphasized the advantages of using the standard star eld in the dipper asterism region of the open cluster M67 for photometric calibration. We have determined instrumental magnitude of stars in the dipper asterism region of M67
4 IRAF is distributed by the National Optical Astronomy Observatories, which are operated by the Association of Universities for Research in Astronomy, Inc. under cooperative agreement with the National Science Foundation. The IRAF version 2.11.1 was used.

No. 2, 1999

DUST PROPERTIES OF NGC 4753

FIG. 1.Bias-subtracted, at-elded and cosmic-rayremoved B-band image of NGC 4753, superposed on which are the contours of same image. The contour levels are drawn at 4.2%, 4.5%, 5%, 6%, 7%, and 8% of the peak intensity. The outermost contour is drawn at a surface brightness 23.1 mag arcsec~2. The brighter lanes or patches represent dust-occupied regions.
by prole-tting photometry using the DAOPHOT routine within IRAF. The method is discussed in detail by Stetson (1987). To correct the instrumental magnitudes for atmospheric extinction, we have made use of extinction coefficients given by Mayya (1991), who, based on eight nights observation at VBT during 1991 JanuaryApril, has determined the average extinction coefficients for the observatory. The extinction-corrected instrumental magnitudes and colors were transformed into the standard BV R system by tting the following equations to the data : V [ v \ a ] b (B[V ) , (1) 0 v v B[V \ a ] b (b [ v) , (2) b~v b~v 0 V [R \ a ] b (v [ r) , (3) v~r v~r 0 B[R \ a ] b (b [ r) , (4) b~r b~r 0 where the uppercase letters B, V , and R are the standard magnitudes in the corresponding lters, taken from Chevalier & Ilovaisky (1991). The linear regression model chosen to t the data was an ordinary least-squares regression of y on x [OLS(Y X)], which has been recommended for the data used for calibration purposes (see Isobe et al. 1990 ;
Feigelson & Babu 1992). The derived transformation coefficients are given in Table 2. 3.2. Surface Photometry We have carried out isophotal analysis of the galaxy NGC 4753 in the B, V , and R bands. The shapes of the isophotes were analyzed using the ellipse-tting routine within the STSDAS5 software package (for details, see Jedrzejewski 1987). A proper background subtraction is crucial in the analysis. We determined the median intensity level
TABLE 2 TRANSFORMATION COEFFICIENTS Quantity V [v. 0 B[V. V [R. B[R. a 0.399 ^ 0.004 [0.473 ^ 0.015 [0.041 ^ 0.008 [0.482 ^ 0.008 b 0.021 ^ 0.006 1.416 ^ 0.018 1.001 ^ 0.017 1.248 ^ 0.006
5 STSDAS is distributed by Space Telescope Science Institute ; version 2.0.1 was used.
FIG. 2.R-band image of NGC 4753 overlapped with the contours of the same image. The contour levels are drawn at 3%, 3.3%, 4%, 5%, 6%, 7%, and 8% of the peak intensity. The outermost contour corresponds to the surface brightness 22.1 mag arcsec~2.
(and its associated dispersion) in several 25 ] 25 pixel boxes in the source-free regions of an object image. The dispersion in intensity levels in each box was found to be less than 2.4%, 2.0%, and 2.1% in the B-, V -, and R-band images, respectively ; however, the dispersion in the median intensity levels was found to be 0.26%, 0.4%, and 0.19% in the B-, V -, and R-band images, respectively. We did not nd any signicant gradient in the median intensity levels in the source-free regions across any of the object images. The sky background level was determined as the mean of the median background intensity levels in each band separately. The background level, thus determined, was subtracted from the object image in each band. The regions covered by stars and dust were masked and excluded from the isophotal analysis. The deviant pixels with intensity values 3 p below or above the mean intensity level were clipped, and the maximum accepted fraction of agged pixels in an ellipse tting was kept at 50%. The complex dust lanes and/or patches pass through the center of the galaxy, so it was not possible to determine the center very accurately. We choose the R-band image, which is the least aected by dust extinction, for detailed isophotal analysis. Starting with trial values of ellipticity (v), position angle (h), and ellipse center, an ellipse of mean intensity at a given length a

of semimajor axis was tted. The rst two harmonics of the deviations from the trial ellipse were found. The best-tted ellipses were determined after performing a minimum of 10 iterations and a maximum of 1000 iterations to minimize the deviations. The third and fourth harmonics of the residual intensity from the best-tting ellipse were then evaluated. The procedure was repeated after changing the semimajor axis length by 10%, taking annuli and using the median value of the pixels for sampling along the elliptical path. The center was then determined by averaging the centers of the best-tted ellipses. The center, thus determined, was kept xed, and the above-described ellipse tting procedure was repeated. The same center as determined for the R-band image was also used in the isophotal analysis of well-aligned images in other bands. The generated radial distribution of surface brightness and isophotal shape parameter proles are shown in Figure 3. The position angle prole reveals twisted isophotes. The ellipticity prole shows that the isophotes become progressively more elliptical in the outer regions. The parameters a3, a4 and b3, b4 are the amplitudes of sin 3h, sin 4h and cos 3h, cos 4h coefficients, respectively, of the isophotal deviation from the perfect ellipticity. It should be pointed out that in the inner regions (a 10@@) of NGC 4753, covered by
FIG. 3.Results of R-band isophotal shape analysis of NGC 4753. (a) Surface brightness prole, (b) position angle prole, (c) ellipticity prole, (d) amplitude, a3, of residual sin 3h coefficient of the isophotal deviation from perfect ellipse as a function of semimajor axis length (SMA), (e) amplitude, a4, of residual sin 4h coefficient of the isophotal deviation from perfect ellipse as a function of SMA, ( f) amplitude, b3, of residual cos 3h coefficient of the isophotal deviation from perfect ellipse as a function f SMA, (g) amplitude, b4, of residual cos 4h coefficient of the isophotal deviation from perfect ellipse as a function of SMA.
complex dust lanes and/or patches, more than 50% of the pixels are aected by dust extinction. The isophotal parameter proles in the inner region, therefore, should not be taken very seriously. It has been tried to estimate the correct dust-free intensity by decreasing the accepted fraction of pixels to t ellipses in the inner regions. This may have aected the actual shape parameters in the central regions. The core region of the galaxy of size of the order of the seeing disk was excluded from the isophotal analysis, as these are aected by the seeing. 3.3. Color Index Maps We have generated color index maps (B[R, B[V , and V [R) using the broadband images to nd out the distribution of dust. Instrumental colors were corrected for atmospheric extinction using the average extinction coefficients of Mayya (1991) and then converted into standard colors using the transformation coefficients given in Table 2. The B[R color index map is shown in Figure 4, superposed on which are the contours of the Ha image (Singh et al. 1995). The brighter regions represent the part of the galaxy that

are redder in color and hence represent cooler/dusty regions within the galaxy. The B[R color in the dust-occupied regions within the galaxy was found to vary from 1.92 to 2.68. The maximum B[R color is found to be 2.68 at the center. In the dust-free regions, the B[R color as derived from the isophotal analysis was found to vary from 1.87 ^ 0.07 at a semimajor axis length of 6A0 to 1.38 ^ 0.07. at the semimajor axis length of 246A7. In the dust-free. regions, the color gradient with respect to logarithmic Galactocentric radius r, [d(B[R)/d(log r)], was found to be [0.21 ^ 0.05 for NGC 4753. This value can be compared with the color gradients [d(B[R)/d(log r)], [0.26, [0.23, and [0.14 for the S0 galaxies NGC 3414, NGC 3607, and NGC 5866, respectively, as derived by Vader et al. (1988). Hence, the average color gradient of NGC 4753 in the dustfree regions is normal for S0 galaxies. Figure 4 also suggests the coexistence of dusty regions with the Ha-emitting gas. 3.4. Extinction Maps Several authors have studied dust properties of elliptical galaxies by an indirect method in which dust extinction is
FIG. 4.B[R color image of NGC 4753, superposed on which are the contours of Ha image. The brighter regions represent part of the galaxy that are redder in color. The maximum B[R color is found to be 2.677 at the center. The Ha ] [N II] contours are drawn at levels 5%, 7.5%, 10%, 15%, 25%, 50%, and 80% of the peak intensity. The Ha][N II] image is taken from Singh et al. (1995).
determined as a function of wavelength by comparing the actual distribution of intensity of the galaxy with that expected in the absence of dust extinction. The dust-free intensity distribution is modeled using elliptical isophotes. Sahu, Pandey, & Kambhavi (1998) have used the same method to study dust properties of an S0 galaxy, NGC 2076. The projections of three-dimensional intensity proles of bulge and disk of an S0 galaxy onto the plane of sky are elliptical bulge and elliptical disk isophotes. If the disk is inclined with respect to the plane of the sky, disk isophotes are more elliptical than bulge isophotes. In many cases, the bulge and disk isophotal parameters are dierent. In the presence of a disk, the isophotes are not perfect ellipses. The deviations of isophotes of NGC 4753 from perfect ellipses are revealed by the presence of third- and fourth-order harmonics (a3, b3, a3, and b4). Therefore, the projected intensity distribution of bulge and disk can be modeled by using the isophotal parameters and the harmonics. The dust-free model images of NGC 4753 were generated by interpolating the tted isophotal parameters (dust-free) with polynomial of order 3, including the third- and fourth-order harmonics determined above, thus incorporating the disklike structure. In order to check whether the dust-free intensity distribu-

(a 10@@) of NGC 4753, the derived extinction values in R band are not signicantly aected by the presence of line emission. To determine the ratio of total extinction to selective extinction, we tted bivariate correlated measurement errors and intrinsic scatter (BCES) least-squares regression lines between dierent extinction values. The BCES method is a direct generalization of the ordinary least-squares (OLS) regression method, modied to accommodate the measurement errors either correlated or uncorrelated and intrinsic scatter (for details, see Akritas, Bershady, & Bird 1996). In the presence of errors, the use of the OLS regression method can cause considerable bias, as it does not take into account measurement errors in the variables. Apart from the measurement errors in the derived extinction values, there is also intrinsic scatter depending on spatial distribution of dust and their properties. The measurement errors for extinction in two bands are uncorrelated. As a consequence, we must use the BCES technique, ignoring the correlated errors, to derive the linear regression lines relating extinction in two bands. We tted the BCES regression lines A y on A and A on A (x, y \ B, V , R ; x D y). The bisector x x y

TABLE 3

BCES AND OLS LINEAR REGRESSION COEFFICIENTS Fit BCES(A o A ). B V OLS(A o A ). B V BCES(A o A ). V B OLS(A o A ). V B BCES bisector. OLS bisector. BCES(A o A ). R V BCES(A o A ). V R BCES bisector. BCES(A o A ). B R BCES(A o A ). R B BCES bisector. Slope 2.61 ^ 0.476 1.20 ^ 0.046 0.747 ^ 0.113 1.323 ^ 0.054 1.32 ^ 0.0881 1.26 ^ 0.048 2.10 ^ 0.493 0.188 ^ 0.131 0.77 ^ 0.0811 4.53 ^ 2.08 0.852 ^ 0.146 1.66 ^ 0.171 Intercept [ 0.292 ^ 0.102 0.009 ^ 0.011 0.106 ^ 0.0255 [ 0.017 ^ 0.013 [ 0.0168 ^ 0.0197 [ 0.003 ^ 0.012 [ 0.315 ^ 0.110 0.112 ^ 0.0294 [ 0.0182 ^ 0.0184 [ 0.404 ^ 0.314 0.0221 ^ 0.0254 0.143 ^ 0.023
of these two regression lines was chosen as the best-t line. The bisector treats the variables symmetrically and has been recommended for scientic problems where the goal is to estimate the underlying functional relationship between the variables (see Isobe et al. 1990 ; Feigelson & Babu 1992). To compare our results and to see the eects of errors on the regression coefficients, we have also tted OLS regression lines using the method described by Isobe et al. (1990) between extinction values in dierent bands. The BCES and OLS regression coefficients are given in Table 3, and the tted straight lines are shown in Figures 6a6d. In Figure 6a, the lines marked as 1, 2, and 3 are the linear regression ts of A on A , A on A , and the bisector of the two B V V B lines, respectively, derived using the BCES technique. In

Figure 6b, lines 1, 2, and 3 are same as those in Figure 6a but derived using the OLS method. As can be seen in Table 3, the lines marked 1 in Figures 6a and 6b are signicantly dierent. It is also seen in Table 3 that the lines marked 2 in Figures 6a and 6b are signicantly dierent, but the BCES bisector and OLS bisector lines marked 3 in Figures 6a and 6b are similar. The dierence in lines 1 in Figures 6a and 6b and the dierence in lines 2 can be explained as the eect of large errors as shown in Figure 6a. The BCES bisector and OLS bisector yielded intercepts close to zero, which are within 1 standard deviation, as expected. This further suggested the validity of use of the bisector line between extinction values in dierent bands. Henceforth, we use the BCES bisector line as the best-t regression line. The linear regression t between A and A using the BCES bisector R B method is shown in Figure 6c. Similarly, the BCES bisector line of A and A is shown in Figure 6d. V R The best-tting BCES bisector slopes and their associated uncertainties were subsequently used to derive the ratio of total extinction to selective extinction, R \ (A /A j j B [ A ), and their associated uncertainties. The average V extinction curve for the areas occupied by dust in NGC 4753 is shown in Figure 7, along with the extinction curve of our Galaxy for comparison. The total extinction to selective extinction values for the Milky Way were derived in the same manner as for NGC 4753 from the ratios of extinction that, for the Galaxy, were taken from Rieke & Lebofsky (1985). Figure 7 shows that the ratio R \ A /(A [ A ) j j B V varies linearly with inverse wavelength, which is consistent with the result that for small grain size x \ 1, Q P j~1, ext where x \ (2na/j), a is the grain radius, and Q is the ext
FIG. 6.BCES and OLS regression lines between extinction values in dierent passbands. (a) BCES regression lines between extinction in V and B bands. Line 1 is the BCES regression line of A on A , line 2 is the BCES regression line of A on A , and line 3 represents the BCES bisector of lines 1 and 2. B V (b) OLS regression lines between A onV. Line 1 is the OLS line of A on A , line 2 isBthe OLS line of A on A , and line 3 is the OLS bisector of lines 1 A Vline ofB and A. (d) BCES bisector regression line of A and A. The quantities of A (j \ B, V , and R) represent the V B B V and 2. (c) BCES bisector regression A R V R B j dust extinction in the j-band.

3.7. IRAS Properties NGC 4753 was detected as a point source in the IRAS survey at all four bands : 12, 25, 60, and 100 km. We obtained IRAS ux densities from Knapp et al. (1989). The ux densities at 60 and 100 km were corrected for the contribution of circumstellar dust emission (Goudfrooij & de Jong 1995). The dust temperature was determined to be 30.4 K on the basis of the ratio of ux densities at 100 and 60 km under the assumption that the FIR emission from the dust grains within NGC 4753 is governed by an emissivity law where emissivity is proportional to j~1 at wavelengths [ 200 km (Schwartz 1982 ; Hildebrand 1983 ; Kwan & Xie 1992). Because a distribution of temperature may be more appropriate for dust, the derived dust temperature should be regarded as a representative value. We have estimated the dust mass of NGC 4753 following the method outlined in Hildebrand (1983), Thronson & Telesco (1986), and Goudfrooij & de Jong (1995), which is based on measurements of FIR ux density f (l), dust temperature T , dust d
TABLE 4 PARAMETERS USED IN THE ESTIMATION OF DUST MASS Parameter Value Reference
amax 4 na3o n(a)da ] l d d 3
n(a)da \ A n a~3.5 da i H

aa ) , max

A. 10~25.11 cm2.5/H 1 silicate A. 10~25.16 cm~2.5/H 1 graphite n. 20 cm~H o. 3.26 g cm~d,graphite o. 3.3 g cm~d,silicate REFERENCES.(1) Draine & Lee 1984 ; (2) Hoyle & Wickramasinghe 1991.
emissivity Q(l), and size of the grains. The total dust mass is given by D2f (l) (4/3)a M \ ] o , (9) d B(l, T ) Q(l) d d where o is the specic grain mass density, a is the average d grain radius weighted by the grain volume, and D is the distance of the galaxy. The derived cool dust mass is 3.46 ] 105 M. Assuming that the IR spectrum of NGC _ 4753 can be tted by a function of the form f (l) P lB(l, T ), d which is a good approximation to the total IR spectrum of most galaxies (Telesco & Harper 1980 ; Rickard & Harvey 1984), the total IR luminosity can be written as L (L ) \ 3.7 ] 10~12D2f (l)T 5 j4 IR _ d ] [exp (1.44 ] 104/jT ) [ 1] (10)
(Thronson & Telesco 1986), where D is the object distance in megaparsecs, the ux density f (l) is in janskys, and j is in micrometers. Using the above relation the total IR luminosity of NGC 4753 is estimated to be 6.6 ] 108 L. _

DISCUSSION

The surface brightness prole and isophotal shape parameters (Fig. 3) of NGC 4753 reveal some intensity features of this early-type galaxy. The parameter b4, the amplitude of the cos 4h coefficient of the isophotal deviation from the best-tting ellipse, is interpreted as being due to an embedded disk (b4 [ 0) or boxiness of isophotes (b4 \ 0 ; e.g., Peletier et al. 1990). The positive values of b4 indicate a disk component in NGC 4753. The galaxy is very attened in its outer parts. The presence of disk component is supported by large rotational velocities, v 250 km s~1, measured by Chromey (1973). The disk component and twisted isophotes as revealed by the position angle prole, Figure 3b, are supported by a model where an inclined disk twisted by dierential precession ts the observed dust lanes lying very well on the disk (Steiman-Cameron et al. 1992). We have derived the dust mass of NGC 4753 from optical extinction as well as from IRAS ux densities. The ratio of the two dust masses, M /M , is 2.28. The discrepd,IRAS d,optical ancy can be attributed to the fact that the dust mass derived from optical extinction is a lower limit because the extinction is observed only when the dust is in front of the stars. The dust is probably distributed between the stars or stellar system, and the actual dust mass is expected to be higher than the dust mass derived from optical extinction. Goudfrooij & de Jong (1995) have reported that the average ratio SM /M T to be 8.4 ^ 1.3 for a large sample of d,IRAS d,optical elliptical galaxies for which the presence of dust is revealed by both FIR emission and optical dust lanes or patches. This ratio is signicantly higher than the ratio for NGC 4753, which implies that the dust-mass discrepancy in NGC 4753 is not as severe as for an average elliptical galaxy. Sahu et al. (1998) have reported that M /M \ 1.14 for d,IRAS d,optical an S0 galaxy, NGC 2076. This indicates that the dierence in dust mass derived from FIR emission and optical extinction is not signicant for S0 galaxies, in contrast to the dust-mass discrepancy in elliptical galaxies. This is an expected result, because the dust masses derived for spiral galaxies from optical and IRAS data reveal that M > d,IRAS M (Goudfrooij 1996) and the S0 galaxies, being interd,optical mediate in the morphological sequence from ellipticals to spirals, can be expected to have intermediate properties.

TABLE 5 MASSES OF DIFFERENT COMPONENTS OF ISM IN NGC 4753 Component Dust (M )a. d,optical Dust (M )a. d,IRAS H Ib. Molecular gasa. Ha gasc. Mass (M ) _ 1.5 ] 105 3.46 ] 105 5.28 ] 108 0.22.4 ] 108 0.67 ] 105
a Derived value. b Based on 21 cm line emission observed by Knapp et al. 1985. c Taken from Singh et al. 1995.
ergs s~1 Hz~1 from the measured ux at 12 km and adopting a distance of 8.7 Mpc (see Table 1). Substituting L (12 l km) into the above equation, we estimate the total mass-loss rate from red giant stars within NGC 4753 to be 1.3 ] 10~3 M yr~1. The derived mass-loss rate is uncertain because _ stellar population within elliptical galaxies and NGC 4753 may be signicantly dierent ; however, the mass-loss rate is not expected to vary by large factors. If we assume that the gas-to-dust ratio in the circumstellar shells of red giant stars to be 100 : 1 by mass, with a factor of 23 uncertainty (see Knapp, Sandell, & Robson 1993), the total loss rate of dust mass by red giant stars within NGC 4753 is about 1.3 ] 10~5 M yr~1. The mass of dust accumulated within _ NGC 4753 can be estimated by the mass loss from stars and by the mechanisms of destruction of dust (see below). The rate at which dust mass is accumulated within NGC 4753 can be written as LM (t) LM d \ d,s [ M (t)q~1 , d Lt Lt (12)
where (LM /Lt) is the loss rate of mass in the form of dust d,s by red giant stars and q~1 is the destruction rate of dust. The second term on the right represents the rate at which mass of dust within NGC 4753 is destroyed. Assuming that the mass loss from red giant stars begins at an age D106 yr of NGC 4753 and taking q~1 D 7.14 ] 10~10 yr~1 (see below), we have solved numerically the above equation for the mass of dust accumulated as a function of time. The buildup of mass of dust within NGC 4753 is shown in Figure 8. Assuming an age of 1010 yr for NGC 4753, the total mass of dust accumulated within NGC 4753 is calculated to be 1.8 ] 104 M , which is about a factor of 10 lower than the measured_ mass of dust. This indicates that the mass-loss rate from red giant stars is probably not sufficient to account for the observed dust within NGC 4753. Based on our simplied calculation given above, the possibility of an external origin of dust within NGC 4753 cannot be ruled out. X-ray emission of varying amounts is seen in several early-type galaxies. Integrated X-ray emission from discrete sources and the presence of hot gas (D107 K) can both contribute to the overall X-ray emission. Hot plasma, if
present, can destroy the dust very efficiently (Draine & Salpeter 1979a). The ratio of total X-ray luminosity to absolute blue luminosity is a good indicator of the presence of hot gas in an early-type galaxy (Canizares et al. 1987). Therefore, to estimate the dust destruction timescale, we examine X-ray emission from NGC 4753. The quantity log (L /L ) X B (L in ergs s~1 and L in L ) for NGC 4753 is 29.42, based X B _ on which Canizares et al. (1987) would conclude that the total X-ray luminosity of NGC 4753 is consistent with that expected from the integrated X-ray luminosity of discrete sources. The galaxy NGC 4753 is a member of the lowest (L /L ) group in Kim, Fabbiano, & Trinchieri (1992), where X B it has been shown that early-type galaxies in the lowest (L /L ) group have a very soft X-ray excess that amounts to X B about half the total X-ray emission. This emission could be due either to a cooler ISM or to the integrated emission of soft stellar sources. In any case, ISM of these galaxies is not heated to high X-ray temperatures. This implies that the dust in NGC 4753 is unlikely to be embedded in a very hot plasma. In the absence of hot plasma, the most eective destruction mechanism for refractive grains (e.g., graphite and silicate) are sputtering and grain-grain collisions in lowvelocity shocks (v 60 km s~1) and sputtering in shock supernova-driven blast waves (Goudfrooij et al. 1994c). Using the model of Draine & Salpeter (1979b), appropriate for X-ray faint early-type galaxies, and a recent estimate for the rate of supernova explosions in early-type galaxies, Goudfrooij et al. (1994c) have estimated the lifetime q D 1.4 ] 109 yr for 0.1 km refractory grains. We have used this value to calculate the mass of dust accumulated within NGC 4753, given above. Ha ] [N II] emission-line regions in the center of NGC 4753 are embedded in the regions with substantial optical extinction (see Figs. 4 and 5). This association of emissionline regions and regions with substantial dust absorption points toward the coexistence of dust and warm gas (D104 K) within NGC 4753. The observed Ha line emission can be accounted by photoionization from postasymptotic giant branch stars (see Singh et al. 1994, 1995), which can also supply signicant amounts of dust. As to the fate of cool dust and gas, we examine the possibility of star formation within NGC 4753. The galaxy occupies an intermediate position but close to the lower right end in the phenomenological IRAS color-color diagram of Helou (1986), where both the cirrus component and active star-forming regions contribute to the total FIR emission. However, the FIR emission from active starforming regions is less than 50% of the total FIR luminosity, so that the total FIR emission of NGC 4753 cannot be interpreted as due to current star formation. Following Thronson & Telesco (1980), the current star formation rate averaged over past 2 ] 106 yr can be calculated using the relation \ 6.5 ] 10~10L (L ) , (13) FIR FIR _ where L is the total FIR luminosity. However, considerFIR ing the phenomenological model of Helou (1986), only the FIR luminosity due to the active star-forming regions must be used in above expression. We estimate the current star formation rate of NGC 4753, averaged over past 2 ] 106 yr, to be less than 0.21 M yr~1. As discussed above, the cirrus _ component of dust contributes more than 50% to the total FIR luminosity, hence signicant amount of dust within NGC 4753 is in the form of cirrus. This suggests that the M 0

FIG. 8.Total dust mass accumulated within NGC 4753 as a function of time.
DEWANGAN, SINGH, & BHAT within NGC 4753. The current star formation rate of NGC 4753, averaged over past 2 ] 106 yr, is derived to be less than 0.21 M yr~1 using the FIR emission arising from _ active star-forming regions. A signicant amount of dust within NGC 4753 seems to exist in the form of cirrus. We thank the director of the Indian Institute of Astrophysics and the Time Allocation Committee for allotting the dark nights for our observations. The members of the technical support sta of the VBT are gratefully acknowledged for their assistance during the observations. We thank an anonymous referee, whose critical comments and suggestions helped in improving the paper. We also thank A. D. Karnik and D. K. Ojha for helpful discussions during the analysis. This research has made use of the NASA/ IPAC Extragalactic Database, which is operated by the Jet Propulsion Laboratory, Caltech, under contract with the National Aeronautics and Space Administration.
cirrus clouds are not destroyed efficiently because of the lack of hot ISM. Also, these regions are not sufficiently dense to lead to gravitational instability to form stars.

CONCLUSIONS

Our isophotal analysis of NGC 4753 has revealed a twisted disk component in it. The dust grain properties of NGC 4753 appear to be similar to that of our Galaxy, based on comparison of the extinction curves. The derived mass of cold dust in NGC 4753 is 1.5 ] 105 M of NGC 4753 _ based on optical extinction and 3.46 ] 105 M based on _ FIR uxes. The discrepancy between the two dust masses for NGC 4753 is not as severe as the discrepancy generally found for the elliptical galaxies. The accumulated mass of dust within NGC 4753 from mass loss by red giant stars after taking into account the efficient destruction processes is D1.8 ] 104 M , which is about a factor of 10 lower than _ the measured dust mass. Dust and ionized gas coexist
REFERENCES Akritas, M. G., Bershady, M. A., & Bird, C. M. 1996, ApJ, 470, 706 Hoyle, F., & Wickramasinghe, N. C. 1991, in The Theory of Cosmic Grains Anupama, G. C., Kembhavi, A. K., Prabhu, T. P., Singh, K. P., & Bhat, (Dordrecht : Kluwer), 94 P. N. 1994, A&AS, 103, 315 Isobe, T., Feigelson, E. D., Akritas, M. G., & Babu, G. J. 1990, ApJ, 364, Bertola, F., Galleta, G., Kotanyi, C., & Zeilinger, W. W. 1988, MNRAS, 104 234, 733 Jae, W., Ford, H. C., OCornell, R. W., van den Bosch, F. C., & Ferrarese, Bhat, P. N., Singh, K. P., Prabhu, T. P., & Kembhavi, A. K. 1992, J. L. 1994, AJ, 108, 1567 Astrophys. Astron., 13, 293 Jedrzejewski, R. I. 1987, MNRAS, 226, 747 Buta, R. J., et al. 1985, PASP, 97, 229 Jura, M. 1986, ApJ, 306, 483 Caldwell, N. 1984, ApJ, 278, 96 Jura, M., Kim, D. W., Knapp, G. R., & Guhathakurta, P. 1987, ApJ, 312, Canizares, C. R., Fabbiano, G., & Trinchieri, G. 1987, ApJ, 312, 503 L11 Cappellaro, E., Turatto, M., Benetti, S., Tsvetkov, D. Yu., Bartunov, O. S., Kim, D. -W., Fabbiano, G., & Trinchieri, G. 1992, ApJ, 393, 134 & Makarova, I. N. 1993, A&A, 273, 383 Knapp, G. R., Guhathakurta, P., Kim, D. W., & Jura, M. 1989, ApJS, 70, Chevalier, C., & Ilovaisky, S. A. 1991, A&AS, 90, Chromey, F. R. 1973, A&A, 29, 77 Knapp, G. R., Sandell, G., & Robson, E. I. 1993, ApJS, 88, 173 de Jong, T., Nrgaard-Nielsen, H. U., Hansen, L., & Jrgensen, H. E. 1990, Knapp, G. R., Turner, E. L., & Cunnier, P. E. 1985, AJ, 90, 454 A&A, 232, 317 Kwan, J., & Xie, S. 1992, ApJ, 398, 105 de Vaucouleurs, G., de Vaucouleurs, A., Corwin, H. G., Jr., Buta, R. J., Mathis, J. S., Rumpl W., & Nordsieck, K. H. 1977, ApJ, 217, 45 Paturel, G., & Fouque, P. 1991, The Third Reference Catalogue of Mayya, Y. D. 1991, J. Astrophys. Astron., 12, 319 Bright Galaxies (New York : Springer) (RC3) Merritt, D., & de Zeeuw, P. T. 1983, ApJ, 267, L19 Draine, B. T., & Lee, H. M. 1984, ApJ, 285, 89 Peletier, R. F., Davies, R. L., Illingworth, G. D., Davis, L. E., & Cawson, M. Draine, B. T., & Salpeter, E. 1979a, ApJ, 231, 77 1990, AJ, 100, 1091. 1979b, ApJ, 231, 438 Phillips, M. M., Jenkins, C. R., Dopita, M. A., Sadler, E. M., & Binette, L. Dwek, E., & Scalo, J. M. 1980, ApJ, 239, 193 1986, AJ, 91, 1062 Ebneter, K., Djorgovski, S., & Davis, M. 1988, AJ, 95, 422 Rickard, L. J., & Harvey, P. M. 1984, AJ, 89, 1520 Fabbiano, G., Kim, D. W., & Trinchieri, G. 1992, ApJS, 80, 531 Rieke, G. H., & Lebofsky, M. J. 1985, ApJ, 288, 618 Fabian, A. C., & Thomas P. A. 1987, in IAU Symp. 127, Structure and Sadler, E. M., & Gerhard, O. E. 1985, MNRAS, 214, 177 Dynamics of Elliptical Galaxies, ed. P. T. de Zeeuw (Dordrecht : Reidel), Sahu, D. K., Pandey, S. K., & Kembhavi, A. 1998, A&A, 333, Sandage, A. 1961, The Hubble Atlas (Washington : Carnegie Inst. Feigelson, E. D., & Babu, G. J. 1992, ApJ, 397, 55 Washington) Forman, W., Jones, C., & Tucker, W. 1985, ApJ, 293, 102 Schwartz, P. R. 1982, ApJ, 252, 589 Goudfrooij, P. 1996, in Proc. New Extragalactic Perspectives in the New Singh, K. P., Bhat, P. N., Prabhu, T. P., & Kembhavi, A. K. 1995, A&A, South Africa : Changing Perceptions of the Morphology, Dust Content 302, 658 and Dust-Gas Ratios in Galaxies, ed. D. L. Block (Dordrecht : Kluwer), Singh, K. P., Prabhu, T. P., Kembhavi, A. K., & Bhat, P. N. 1994, ApJ, 424, in press 638 Goudfrooij, P., & de Jong, T. 1995, A&A, 298, 784 Soifer, B. T., Rice, W. L., Mould, J. R., Gillet, F. C., Rowan-Robinson, M., Goudfrooij, P., de Jong, T., Nrgaard-Nielsen, H. U., & Hansen, L. 1994c, & Habing, H. J. 1986, ApJ, 304, 651 MNRAS, 271, 833 Steiman-Cameron, T. Y., Kormendy, J., & Durisen, R. H. 1991, AJ, 104, Goudfrooij, P., Hansen, L., Jrgensen, H. E., & Nrgaard-Nielsen, H. U. 1339 1994b, A&AS, 105, 341 Stetson, P. B. 1987, PASP, 99, 191 Goudfrooij, P., Hansen, L., Jrgensen, H. E., Nrgaard-Nielsen, H. U., de Telesco, C. M., & Harper, D. A. 1980, ApJ, 235, 392 Jong, T., & van den Hock, L. B. 1994a, A&AS, 104, 179 Thronson, H., & Telesco, C. 1986, ApJ, 311, 98 Habe, A., & Ikeeuchi, S. 1985, ApJ, 289, 540 Vader, J. P., Vigroux, L., Lachieze-Rey, M., & Souviron, J. 1988, A&A, 203,. 1988, ApJ, 326, Hawarden, T. G., Elson, R. A. W., Longmore, A. J., Tritton, S. B., & Van Dokkum, P. G., & Franx, M. 1995, AJ, 110, 2027 Corwin, H. G. 1981, MNRAS, 196, 747 Wiklind, T., Combes, F., & Henkel, C. 1995, A&A, 297, 643 Helou, G. 1986, ApJ, 311, L33 Wiklind, T., & Rydbeck, G. 1986, A&A, 164, L22 Hildebrand, R. D. 1983, QJRAS, 24, 267