The stellar kinematics of the low-luminosity elliptical galaxy NGC 4486B have been measured in seeing σ∗ = 0. 22 with the Canada-France-Hawaii Telescope (CFHT) and Subarcsecond Imaging Spectrograph. Lauer and collaborators have shown that NGC 4486B is similar to M31 in having a double nucleus. Here we show that it also resembles M31 in its kinematics. Like M31, NGC 4486B rotates fairly rapidly ...

We present the results of X-ray observations of four bright transients sources detected in the July 2004 XMM-Newton observations of the central bulge of M31. Two X-ray sources, XMMU J004315.5+412440 and XMMU J004144.7+411110, were discovered for the first time. Two other sources, CXOM31 J004309.9+412332 and CXOM31 J004241.8+411635, were previously detected by Chandra. The properties of the sour...

We present an updated catalog of 1300 objects in the field of M31, including 670 likely star clusters of various types, the rest being stars or background galaxies once thought to be clusters. The coordinates in the catalog are accurate to 0.2 ̋, and are based on images from the Local Group Survey (LGS, Massey et al. 2006) or from the DSS. Archival HST images and the LGS were inspected to confir...

NGC 205, a close satellite of the M31 galaxy, is our nearest example of a dwarf elliptical galaxy. Photometric and kinematic observations strongly suggest that NGC 205 is currently undergoing tidal distortion as a result of its interaction with M31. Despite earlier attempts, the orbit and progenitor properties of NGC 205 are not well known. In this paper, we present an optimized search for thes...

The nucleus of M31 may be a thick eccentric disk, composed of stars traveling on nearly Keplerian orbits around a black hole or other dark compact object. This hypothesis reproduces most of the features seen in HST photometry of the center of M31; in particular the bright o center source P1 is the apoapsis of the disk. An eccentric disk can also explain the rotation curve and asymmetric dispers...

1 System Biology Institute, M31 6A, 6-31-15 Jingumae, Shibuya-ku, Tokyo 150-0001, Japan 2 National Institute of Agrobiological Sicences, 2-1-2 Kannondai, Tsukuba-shi, Ibaraki 305-8602, Japan 3 Graduate School of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohokuku, Yokohama 223-8522, Japan 4 Kitano Symbiotic Systems Project, ERATO, JST., M31 6A, 6-31-15 Jingumae, Shibuya-ku, Tokyo ...

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...

We analyse the quenched fractions, gas content, and star formation histories of ~1200 satellite galaxies with $M_* \geq 5 \times 10^6~{\rm M}_\odot$ around 198 Milky Way- (MW) Andromeda-like (M31) hosts in TNG50, highest-resolution simulation IllustrisTNG. Satellite fractions are larger for smaller masses, distances to their host galaxy, more massive M31-like compared MW-like hosts. As satellit...

There are two fundamentally different physical origins of faint satellite galaxies: cosmological sub-structures that contain shining baryons and the fragmentation of gas-rich tidal arms thrown out from interacting galaxies during hierarchical structure formation. The latter tidal-dwarf galaxies (TDG) may form populations with correlated orbital angular momenta about their host galaxies. The exi...

The morphology of the infrared (11?) emission and the properties of discrctc far-infrared (10 R) sources in M31 disk are studied using the high resolution (I IiRes) maps fro]n 1 RAS. Very thin and bright FIR. arm segments are shown ill tllmc maps, which have similar structure as the 111 gas but with much c]lhanccd arn]/inter-arm contrast, typically a factor of N 5 on the 60pTrL image. We identi...