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M. K. Patil

Publications and source records attributed to M. K. Patil.

20 records · Page 2Linked to original sources

Multiband imaging observations of a prominent dust lane galaxy NGC 4370

In this paper we present extinction properties of interstellar dust in a prominent dust lane galaxy NGC 4370 based on the optical broad band (BVRI) imaging observations taken from the Himalaya Chandra Telescope (HCT), Hanle and the near-IR (J,H,K$_s$) images taken from the 2MASS archive. NGC 4370 belongs to the Virgo cluster (VCC 0758) and form a non-interactive pair with NGC 4365 at 10$\arcmin$. NGC 4370 hosts a prominent dust lane running parallel to its optical major axis and is extended almost up to 1\arcmin. The extinction curve derived for NGC 4370 is found to run parallel to Galactic extinction curve, implying that the properties of dust in NGC 4370 are identical to those of the canonical grains in the Milky Way. The $R_V$ value is found to be equal to 2.85$\pm$0.05 and is consitent with the values reported for the dust lane galaxies. The total dust content of NGC 4370 estimated using optical extinction and IRAS flux densities are found to be equal to $4.4\times 10^4$ \msol and $2.0\times 10^5$ \msol, respectively. As regard to the origin of dust and ISM in this galaxy, the accumulated dust by this galaxy over its life-time is insufficient to account for the detected mass by optical means, which in turn imply that the ISM might have been acquired by the NGC 4370 through a merger like event. An attempt is also made to study the apparent spatial correspondence between the multiple phases of ISM, i.e., hot gas, warm gas and dust in this galaxy by obtaining optical emission maps from narrow band imaging and diffuse X-ray emission map obtained from the analysis of \emph{Chandra} archival data. This analysis implies a physical connection between the dust and warm gas in terms of their physical co-existence and common origin too.

astro-ph.GA↗

Properties of dust in early-type galaxies

We report optical extinction properties of dust for a sample of 26 early-type galaxies based on the analysis of their multicolour CCD observations. The wavelength dependence of dust extinction for these galaxies is determined and the extinction curves are found to run parallel to the Galactic extinction curve, which implies that the properties of dust in the extragalactic environment are quite similar to those of the Milky Way. For the sample galaxies, value of the parameter $R_V$, the ratio of total extinction in $V$ band to selective extinction in $B$ & $V$ bands, lies in the range 2.03 - 3.46 with an average of 3.02, compared to its canonical value of 3.1 for the Milky Way. A dependence of $R_V$ on dust morphology of the host galaxy is also noticed in the sense that galaxies with a well defined dust lane show tendency to have smaller $R_V$ values compared to the galaxies with disturbed dust morphology. The dust content of these galaxies estimated using total optical extinction is found to lie in the range $10^4$ to $10^6 \rm M_{\sun}$, an order of magnitude smaller than those derived from IRAS flux densities, indicating that a significant fraction of dust intermixed with stars remains undetected by the optical method. We examine the relationship between dust mass derived from IRAS flux and the X-ray luminosity of the host galaxies.The issue of the origin of dust in early-type galaxies is also discussed.

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