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217 results on '"Seth, Anil C."'

201. THE ADVANCED CAMERA FOR SURVEYS NEARBY GALAXY SURVEY TREASURY. V. RADIAL STAR FORMATION HISTORY OF NGC 300

Author

Gogarten, Stephanie M., primary, Dalcanton, Julianne J., additional, Williams, Benjamin F., additional, Roškar, Rok, additional, Holtzman, Jon, additional, Seth, Anil C., additional, Dolphin, Andrew, additional, Weisz, Daniel, additional, Cole, Andrew, additional, Debattista, Victor P., additional, Gilbert, Karoline M., additional, Olsen, Knut, additional, Skillman, Evan, additional, de Jong, Roelof S., additional, Karachentsev, Igor D., additional, and Quinn, Thomas R., additional

Published
2010
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203. THE ACS NEARBY GALAXY SURVEY TREASURY

Author

Dalcanton, Julianne J., primary, Williams, Benjamin F., additional, Seth, Anil C., additional, Dolphin, Andrew, additional, Holtzman, Jon, additional, Rosema, Keith, additional, Skillman, Evan D., additional, Cole, Andrew, additional, Girardi, Léo, additional, Gogarten, Stephanie M., additional, Karachentsev, Igor D., additional, Olsen, Knut, additional, Weisz, Daniel, additional, Christensen, Charlotte, additional, Freeman, Ken, additional, Gilbert, Karoline, additional, Gallart, Carme, additional, Harris, Jason, additional, Hodge, Paul, additional, de Jong, Roelof S., additional, Karachentseva, Valentina, additional, Mateo, Mario, additional, Stetson, Peter B., additional, Tavarez, Maritza, additional, Zaritsky, Dennis, additional, Governato, Fabio, additional, and Quinn, Thomas, additional

Published
2009
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205. THE ACS NEARBY GALAXY SURVEY TREASURY. II. YOUNG STARS AND THEIR RELATION TO Hα AND UV EMISSION TIMESCALES IN THE M81 OUTER DISK

Author

Gogarten, Stephanie M., primary, Dalcanton, Julianne J., additional, Williams, Benjamin F., additional, Seth, Anil C., additional, Dolphin, Andrew, additional, Weisz, Daniel, additional, Skillman, Evan, additional, Holtzman, Jon, additional, Cole, Andrew, additional, Girardi, Leo, additional, de Jong, Roelof S., additional, Karachentsev, Igor D., additional, Olsen, Knut, additional, and Rosema, Keith, additional

Published
2009
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206. THE ACS NEARBY GALAXY SURVEY TREASURY. I. THE STAR FORMATION HISTORY OF THE M81 OUTER DISK

Author

Williams, Benjamin F., primary, Dalcanton, Julianne J., additional, Seth, Anil C., additional, Weisz, Daniel, additional, Dolphin, Andrew, additional, Skillman, Evan, additional, Harris, Jason, additional, Holtzman, Jon, additional, Girardi, Léo, additional, de Jong, Roelof S., additional, Olsen, Knut, additional, Cole, Andrew, additional, Gallart, Carme, additional, Gogarten, Stephanie M., additional, Hidalgo, Sebastian L., additional, Mateo, Mario, additional, Rosema, Keith, additional, Stetson, Peter B., additional, and Quinn, Thomas, additional

Published
2008
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212. EXTRAGALACTIC THICK DISKS.

Author

DE JONG, R. S., Dalcanton, Julianne J., Seth, Anil C., and Yoachim, Peter

Abstract

I briefly review the growing evidence that thick stellar disks surround most edgeon disk galaxies. Recent studies show that these extragalactic thick disks have old ages, low metallicities, long scale lengths, and moderately flattened axial ratios, much like the thick disk of the MilkyWay. However, the properties of thick disks change systematically with the mass of the galaxy. The thick disks of low mass galaxies are more prominent and somewhat more metal-poor than those surrounding massive disk galaxies. Given the strong evidence that thick disks are fossils from an early epoch of merging, these trends place tight constraints on the early assembly of disk galaxies. [ABSTRACT FROM AUTHOR]

Published
2007
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213. GLIMPSE-CO1: the most massive intermediate-age stellar cluster in the Galaxy.

Author

Davies, Ben, Bastian, Nate, Gieles, Mark, Seth, Anil C., Mengel, Sabine, and Konstantopoulos, Iraklis S.

Subjects
STAR clusters, GLOBULAR clusters, DISKS (Astrophysics), NEAR infrared spectroscopy, DENSITY of stars, RADIAL velocity of galaxies, ASTROPHYSICS
Abstract

The stellar cluster GLIMPSE-C01 is a dense stellar system located in the Galactic plane. Though often referred to in the literature as an old globular cluster traversing the Galactic disc, previous observations do not rule out that it is an intermediate-age (less than a few Gyr) disc-borne cluster. Here, we present high-resolution near-infrared spectroscopy of over 50 stars in the cluster. We find an average radial velocity is consistent with being part of the disc, and determine the cluster's dynamical mass to be . Analysis of the cluster's M/ L ratio, the location of the red clump and an extremely high stellar density, all suggest an age of 400-800 Myr for GLIMPSE-C01, much lower than that for a typical globular cluster. This evidence therefore leads us to conclude that GLIMPSE-C01 is a part of the disc population, and is the most massive Galactic intermediate-age cluster discovered to date. [ABSTRACT FROM AUTHOR]

Published
2011
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214. THE ADVANCED CAMERA FOR SURVEYS NEARBY GALAXY SURVEY TREASURY. IV. THE STAR FORMATION HISTORY OF NGC 2976

Author

Williams, Benjamin F., Dalcanton, Julianne J., Stilp, Adrienne, Gilbert, Karoline M., Roskar, Rok, Seth, Anil C., Weisz, Daniel, Dolphin, Andrew, Gogarten, Stephanie M., Skillman, Evan, and Holtzman, Jon

Abstract

We present resolved stellar photometry of NGC 2976 obtained with the Advanced Camera for Surveys (ACS) as part of the ACS Nearby Galaxy Survey Treasury (ANGST) program. The data cover the radial extent of the major axis of the disk out to 6 kpc, or [?]6 scale lengths. The outer disk was imaged to a depth of M F606W [?] 1, and an inner field was imaged to the crowding limit at a depth of M F606W [?] -1. Through detailed analysis and modeling of the resulting color-magnitude diagrams, we have reconstructed the star formation history (SFH) of the stellar populations currently residing in these portions of the galaxy, finding similar ancient populations at all radii but significantly different young populations at increasing radii. In particular, outside of the well-measured break in the disk surface brightness profile, the age of the youngest population increases with distance from the galaxy center, suggesting that star formation is shutting down from the outside-in. We use our measured SFH, along with H I surface density measurements, to reconstruct the surface density profile of the disk during previous epochs. Comparisons between the recovered star formation rates and reconstructed gas densities at previous epochs are consistent with star formation following the Schmidt law during the past 0.5 Gyr, but with a drop in star formation efficiency at low gas densities, as seen in local galaxies at the present day. The current rate and gas density suggest that rapid star formation in NGC 2976 is currently in the process of ceasing from the outside-in due to gas depletion. This process of outer disk gas depletion and inner disk star formation was likely triggered by an interaction with the core of the M81 group [?]1 Gyr ago that stripped the gas from the galaxy halo and/or triggered gas inflow from the outer disk toward the galaxy center.

Published
2010

215. Revealing the intermediate-mass black hole at the heart of the dwarf galaxy NGC 404 with sub-parsec resolution ALMA observations.

Author

Davis, Timothy A, Nguyen, Dieu D, Seth, Anil C, Greene, Jenny E, Nyland, Kristina, Barth, Aaron J, Bureau, Martin, Cappellari, Michele, den Brok, Mark, Iguchi, Satoru, Lelli, Federico, Liu, Lijie, Neumayer, Nadine, North, Eve V, Onishi, Kyoko, Sarzi, Marc, Smith, Mark D, and Williams, Thomas G

Subjects
*BLACK holes, *DWARF galaxies, *SUBMILLIMETER astronomy, *MOLECULAR clouds, *ELLIPTICAL galaxies, *INTERSTELLAR medium
Abstract

We estimate the mass of the intermediate-mass black hole at the heart of the dwarf elliptical galaxy NGC 404 using Atacama Large Millimetre/submillimetre Array (ALMA) observations of the molecular interstellar medium at an unprecedented linear resolution of ≈0.5 pc, in combination with existing stellar kinematic information. These ALMA observations reveal a central disc/torus of molecular gas clearly rotating around the black hole. This disc is surrounded by a morphologically and kinematically complex flocculent distribution of molecular clouds, that we resolve in detail. Continuum emission is detected from the central parts of NGC 404, likely arising from the Rayleigh–Jeans tail of emission from dust around the nucleus, and potentially from dusty massive star-forming clumps at discrete locations in the disc. Several dynamical measurements of the black hole mass in this system have been made in the past, but they do not agree. We show here that both the observed molecular gas and stellar kinematics independently require a ≈5 × 105 M⊙ black hole once we include the contribution of the molecular gas to the potential. Our best estimate comes from the high-resolution molecular gas kinematics, suggesting the black hole mass of this system is 5.5 |$^{+4.1}_{-3.8}\times 10^5$|  M⊙ (at the 99 per cent confidence level), in good agreement with our revised stellar kinematic measurement and broadly consistent with extrapolations from the black hole mass–velocity dispersion and black hole mass–bulge mass relations. This highlights the need to accurately determine the mass and distribution of each dynamically important component around intermediate-mass black holes when attempting to estimate their masses. [ABSTRACT FROM AUTHOR]

Published
2020
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