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In this paper we study the stellar populations of 356 bright, $M_{r}$ $\leq$ -19, Coma cluster members located in a 2 degree field centred on the cluster core using SDSS DR7 spectroscopy. For the quiescent galaxies we find strong…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 James Price , Steve Phillipps , Avon Huxor , Russell J Smith , John R Lucey

We use deep Hubble Space Telescope photometry of the rich, young (~20-45 Myr-old) star cluster NGC 1818 in the Large Magellanic Cloud to derive its stellar mass function (MF) down to ~0.15 Msun. This represents the deepest robust MF thus…

Solar and Stellar Astrophysics · Physics 2015-05-13 Q. Liu , R. de Grijs , L. C. Deng , Y. Hu , I. Baraffe , S. F. Beaulieu

The stellar content of the intracluster light (ICL) provides unique insight into the hierarchical assembly process of galaxy clusters.However, the ICL is difficult to study due to its low surface brightness and large physical extent. We…

The production rate of ionizing photons in young < 8 Myr, unresolved stellar clusters in the nearby irregular galaxy NGC 4214 is probed using multi-wavelength Hubble Space Telescope WFC3 data. We normalize the ionizing photon rate by the…

We demonstrate the feasibility of detecting directly low mass stars in unresolved super-star clusters with ages < 10 Myr using near-infrared spectroscopy at modest resolution (R ~ 1000). Such measurements could constrain the ratio of high…

Astrophysics · Physics 2009-11-13 Michael R. Meyer , Julia Greissl

The hypothesis of a universal initial mass function (IMF) -- motivated by observations in nearby stellar systems -- has been recently challenged by the discovery of a systematic variation of the IMF with the central velocity dispersion,…

The stellar initial mass function (IMF), which is often assumed to be universal across unresolved stellar populations, has recently been suggested to be "bottom-heavy" for massive ellipticals. In these galaxies, the prevalence of…

To fully understand the star formation process, we are compelled to study it in a variety of environments. Of particular interest are how star formation and the resulting initial mass function (IMF) vary as a function of metallicity. We…

Astrophysics of Galaxies · Physics 2025-05-20 M. Andersen , A. Brizawasi , Y. Cheng , J. C. Tan , R. Fedriani , J. J. Armstrong , M. Robberto

We present deep Hubble Space Telescope (HST) NICMOS 2 F160W band observations of the central 56*57" (14pc*14.25pc) region around R136 in the starburst cluster 30 Dor (NGC 2070) located in the Large Magellanic Cloud. Our aim is to derive the…

Astrophysics of Galaxies · Physics 2014-11-20 M. Andersen , H. Zinnecker , A. Moneti , M. J. McCaughrean , B. Brandl , W. Brandner , G. Meylan , D. Hunter

[arXiv Abridged] In this work, we explore new spatially-resolved measurements of the IMF for three edge-on lenticular galaxies in the Fornax cluster. Specifically, we utilise existing orbit-based dynamical models, which re-produce the…

We use deep $HST$ WFC3/IR imaging to study the Initial Mass Function (IMF) of the ultra faint dwarf galaxy Coma Berenices (Com Ber). Our observations reach the lowest stellar mass ever probed in a resolved galaxy, with 50\% completeness at…

We measure equivalent widths (EW) - focussing on two unique features (NaI and TiO2) of low-mass stars (<0.3M\odot) - for luminous red galaxy spectra from the the Sloan Digital Sky Survey (SDSS) and X-Shooter Lens Survey (XLENS) in order to…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 C. Spiniello , S. C. Trager , L. V. E. Koopmans , Y. Chen

Stellar population studies of massive early-type galaxies (ETGs) suggest that the stellar initial mass function may not be universal. In particular, the centres of ETGs seem to contain an excess of low-mass dwarf stars compared to our own…

Astrophysics of Galaxies · Physics 2024-02-12 Taniya Parikh , Roberto Saglia , Jens Thomas , Kianusch Mehrgan , Ralf Bender , Claudia Maraston

We present a new measurement of the stellar initial mass function (IMF) based on ultra-deep, high-resolution photometry of >5,000 stars in the outskirts of the Small Magellanic Cloud (SMC) galaxy. The Hubble Space Telescope (HST) Advanced…

The stellar initial mass function (IMF) is central to our interpretation of astronomical observables and to our understanding of most baryonic processes within galaxies. The universality of the IMF, suggested by observations in our own…

Recent observations and theories have presented a strong challenge to the universality of the stellar initial mass function (IMF) in extreme environments. A notable example has been found for starburst conditions, where evidence favours a…

Astrophysics of Galaxies · Physics 2024-05-10 Ziyi Guo , Zhi-Yu Zhang , Zhiqiang Yan , Eda Gjergo , Allison Man , R. J. Ivison , Xiaoting Fu , Yong Shi

Banerji et al. (2009) suggested that top-heavy stellar Initial Mass Functions (IMFs) in galaxies may arise when the interstellar physical conditions inhibit low-mass star formation, and they determined the physical conditions under which…

Cosmology and Nongalactic Astrophysics · Physics 2010-03-23 Manda Banerji , Serena Viti , David A. Williams

We present constraints on variations in the initial mass function (IMF) of nine local early-type galaxies based on their low mass X-ray binary (LMXB) populations. Comprised of accreting black holes and neutron stars, these LMXBs can be used…

We have investigated the properties of the stellar mass function in the globular cluster NGC6397 using a large set of HST observations that include WFPC2 images in V and I, obtained at ~4' and 10' radial distances, and a series of deep…

Astrophysics · Physics 2009-10-31 Guido De Marchi , Francesco Paresce , Luigi Pulone

The stellar initial mass function (IMF) is expressed by $\phi(m) \propto m^{-\alpha}$ with the slope $\alpha$, and known as the poorly-constrained but very important function in studies of star and galaxy formation. There are no sensible…

Astrophysics of Galaxies · Physics 2023-04-13 Shohei Aoyama , Masami Ouchi , Yuichi Harikane