Following an approach by Paczy´nski & Stanek we compare red clump stars with parallaxes known to better than 10% in the Hipparcos catalog with the red clump stars observed in three fields in M31 using the HST. There are ∼ 600 and ∼ 6, 300 such stars in the two data sets, respectively. The local red clump luminosity function is well represented by a Gaussian with the peak at M I 0 ,m = −0.23, an...

The LIGO gravitational wave detectors have recently reached their design sensitivity and finished a two-year science run. During this period one year of data with unprecedented sensitivity has been collected. I will briefly describe the status of the LIGO detectors and the overall quality of the most recent science run. I also will present results of a search for inspiral waveforms in gravitati...

HST has recently revealed that many among the most massive globular clusters harbor multiple stellar populations, and –most surprisingly– some of them are extremely helium rich. How these clusters managed to generate such complex stellar populations, and what processes let to so dramatic helium enrichment, is today one of the most exciting puzzles in the astrophysics of stellar systems. HST has...

We present analysis of nearly 1,000 near-infrared, integrated light spectra from APOGEE in the inner $\sim$7 kpc M31. utilize full spectrum fitting with A-LIST simple stellar population spectral templates that represent a stars same age, [M/H], and [$\alpha$/M]. With this, we determine mean kinematics, metallicities, $\alpha$ abundances, ages populations M31's bar, bulge, disk ($\sim$4-7 kpc). ...

Abstract Using the γ -ray data obtained with Large Area Telescope on board Fermi Gamma-ray Space (Fermi) for ∼14 yr, we examine high-energy emission emanating from center of Andromeda galaxy M31. Different previously reported results, which show a seemingly extended source, instead find two individual point sources, one consistent being at and 0.°4 southeast center. The former is well described...

We used radio observations of the neighbor galaxy M31 in order to put constraints on the dark matter particle mass and annihilation cross section. Dark matter annihilation in M31 halo produces highly energetic leptons, which emit synchrotron radiation on radio frequencies in the galactic magnetic field. We predicted expected radio fluxes for the two annihilation channels: ! b b and ! þ . We the...

We present a comprehensive study of star-forming (SF) regions in the nearest large spiral galaxy M31. We use GALEX far-UV (1344-1786 Å, FUV) and nearUV (1771-2831 Å, NUV) imaging to detect young massive stars and trace the recent star formation across the galaxy. The FUV and NUV flux measurements of the SF regions, combined with ground-based data for estimating the reddening by interstellar dus...

Recent progress in constraining the massive accretions (>1:10) experienced by Milky Way (MW) and Andromeda galaxy (M31) offers an opportunity to understand dwarf population of Local Group. Using zoom-in dark matter-only simulations MW-mass haloes concentrating on subhaloes that are thought be capable hosting galaxies, we demonstrate infall a progenitor is accompanied with accretion destruction ...