ar X iv : a st ro - p h / 98 02 12 1 v 3 6 M ar 1 99 8 Distance to M 31 With the HST and Hipparcos Red Clump Stars

ar X iv : a st ro - p h / 98 02 12 1 v 1 1 0 Fe b 19 98 Distance to M 31 With the HST and Hipparcos Red Clump Stars

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...

ar X iv : a st ro - p h / 98 02 12 1 v 2 1 1 Fe b 19 98 Distance to M 31 With the HST and Hipparcos Red Clump Stars

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...

ar X iv : a st ro - p h / 98 02 08 8 v 1 7 F eb 1 99 8 to appear in the AJ The Distance to the M 31 Globular Cluster System

The distance to the centroid of the M31 globular cluster system is determined by fitting theoretical isochrones to the observed red-giant branches of fourteen globular clusters in M31. The mean true distance modulus of the M31 globular clusters is found to be µ 0 = 24.47 ± 0.07 mag. This is consistent with distance moduli for M31 that have been obtained using other distance indicators.

ar X iv : a st ro - p h / 98 02 02 8 v 1 3 F eb 1 99 8 Phase Transitions in Neutron Stars

Phase transitions in neutron stars due to formation of quark matter, kaon condensates, etc. are discussed with particular attention to the order of these transitions. Observational consequences of phase transitions in pulsar angular velocities are examined.

ar X iv : a st ro - p h / 98 02 08 2 v 1 6 F eb 1 99 8 What is the True Covering Factor of Absorbing Matter in BALQSO ’ s ?