Related papers: M Dwarfs from Hubble Space Telescope Star Counts. …
We describe a program of star counts in the range 19 < I < 26 made with the WFPC cameras aboard the Hubble Space Telescope. Red (V-I > 1.0) stars at these magnitudes are primarily disk and spheroid M dwarfs. The stars are found both on…
With the Wide Field Planetary Camera 2 (WFPC2) on the Hubble Space Telescope, we have discovered in M4 (NGC 6121, C 1620-264) the first extensive sequence of cooling white dwarfs seen in a globular cluster. Adopting a distance modulus of…
The stellar initial mass function (IMF) and the fraction of binary systems are fundamental ingredients that govern the formation and evolution of galaxies. Whether the IMF is universal or varies with environment remains one of the central…
At redshifts around 0.1 the CFHT Legacy Survey Deep fields contain some 6x10^4 galaxies spanning the mass range from 10^5 to 10^12 Msun. We measure the stellar mass dependence of the two point correlation using angular measurements to…
The Galactic disk is one of the main components of the Milky Way, which contributes most of the luminosity. Its structure is essential for understanding the formation and evolution of the Milky Way. Using 174,443 K-type dwarf stars observed…
We present an empirical near-infrared (NIR) spectroscopic method for estimating M dwarf metallicities, based on features in the H-band, as well as an implementation of a similar published method in the K-band. We obtained R~2000 NIR spectra…
Context. Several new techniques to determine the metallicity of M dwarfs with better precision have been developed over the last decades. However, most of these studies were based on empirical methods. In order to enable detailed abundance…
We present the first phase in our ongoing work to use Sloan Digital Sky Survey (SDSS) data to create separate white dwarf (WD) luminosity functions for two or more different mass ranges. In this paper, we determine the completeness of the…
We present preliminary results of a radial-velocity search for companions to a volume limited sample of M dwarfs. Typical accuracy range between 10m/s for the brighter stars and 70m/s at our limiting magnitude. We complement the radial…
Results of surface photometry of 50 galaxies in the Local Volume based on archived images obtained with the Hubble Space Telescope are presented. Integrated magnitudes in the V and I bands are introduced for the sample galaxies, along with…
We present a flare rate analysis of 50,130 M dwarf light curves in SDSS Stripe 82. We identified 271 flares using a customized variability index to search ~2.5 million photometric observations for flux increases in the u- and g-bands. Every…
Using WFPC2 on the Hubble Space Telescope, we have isolated a sample of 258 white dwarfs (WDs) in the Galactic globular cluster M4. Fields at three radial distances from the cluster center were observed and sizeable WD populations were…
A metal-rich environment facilitates planet formation, making metal-rich stars the most favorable targets for surveys seeking to detect new exoplanets. Using this advantage to identify likely low-mass planet hosts, however, has been…
We analyze the magnetic activity of 59,318 M dwarfs from the Sloan Digital Sky Survey (SDSS) Data Release 7. This analysis explores the spatial distribution of M dwarf activity as a function of both vertical distance from the Galactic plane…
A sample of very high resolution cosmological disk galaxy simulations is used to investigate the evolution of galaxy disk sizes back to redshift 1 within the Lambda CDM cosmology. Artificial images in the rest frame B band are generated,…
Microlensing and pixel-lensing surveys play a fundamental role in the searches for galactic dark matter and in the study of the galactic structure. Recent observations suggest the presence of a population of old white dwarfs with high…
We examine the metallicity distribution of the Galactic thick disk using F, G, and K dwarf stars selected from the Sloan Digital Sky Survey, Data Release 8. Using the large sample of dwarf stars with proper motions and spectroscopically…
Stellar mass estimates of massive galaxies are susceptible to systematic errors in their photometry, due to their extended light profiles. In this study we use data from the Dragonfly Wide Field Survey (DWFS) to accurately measure the total…
We present a model-independent method of quantifying galaxy evolution in high- resolution images, which we apply to the Hubble Deep Field (HDF). Our procedure is to k-correct the pixels belonging to the images of a complete set of bright…
We present a novel approach for measuring the two-point correlation function of galaxies in narrow pencil beam surveys with varying depths. Our methodology is utilized to expand high-redshift galaxy clustering investigations up to $z \sim…