THE SPLIT RED CLUMP OF THE GALACTIC BULGE FROM OGLE-III

The red clump (RC) is found to be split into two components along several sightlines toward the Galactic bulge. This split is detected with high significance toward the areas (−3.5 < l < 1, b < −5) and (l, b) = (0, + 5.2), i.e., along the bulge minor axis and at least 5 deg off the plane. The fainter (hereafter “main”) component is the one that more closely follows the distance–longitude relation of the bulge RC. The main component is ∼0.5 mag fainter than the secondary component and with an overall approximately equal population. For sightlines further from the plane, the difference in brightness increases, and more stars are found in the secondary component than in the main component. The two components have very nearly equal (V − I) color.

[1]  P. Ventura,et al.  TERZAN 5: AN ALTERNATIVE INTERPRETATION FOR THE SPLIT HORIZONTAL BRANCH , 2010, 1004.3426.

[2]  M. Bellazzini,et al.  The cluster Terzan 5 as a remnant of a primordial building block of the Galactic bulge , 2009, Nature.

[3]  A. Cabrera-Lavers,et al.  The long Galactic bar as seen by UKIDSS Galactic plane survey , 2008, 0809.3174.

[4]  A. Udalski,et al.  The Optical Gravitational Lensing Experiment. Final Reductions of the OGLE-III Data , 2008, 0807.3884.

[5]  S. Mao,et al.  Erratum: Modelling the Galactic bar using OGLE-II red clump giant stars , 2007, 0704.1614.

[6]  T. Mahoney,et al.  Tracing the long bar with red-clump giants , 2007, astro-ph/0702109.

[7]  L. Chomiuk,et al.  First GLIMPSE Results on the Stellar Structure of the Galaxy , 2005, astro-ph/0508325.

[8]  E. Athanassoula.  On the nature of bulges in general and of box/peanut bulges in particular: input from N-body simulations , 2005, astro-ph/0502316.

[9]  Takahiro Nagayama,et al.  A Distinct Structure inside the Galactic Bar , 2005, astro-ph/0502058.

[10]  G. Gilmore,et al.  The structure of the Galactic bar , 2005, astro-ph/0501383.

[11]  R. Indebetouw,et al.  GLIMPSE. I. An SIRTF Legacy Project to Map the Inner Galaxy , 2003, astro-ph/0306274.

[12]  P. Wozniak,et al.  The Optical Gravitational Lensing Experiment: catalogue of stellar proper motions in the OGLE-II Galactic bulge fields , 2003, astro-ph/0305315.

[13]  Liverpool John Moores University,et al.  Population effects on the red giant clump absolute magnitude: The K-band , 2002, astro-ph/0208057.

[14]  C. Alard.  Another bar in the Bulge , 2001, astro-ph/0110491.

[15]  L. Girardi,et al.  Population effects on the red giant clump absolute magnitude, and distance determinations to nearby galaxies , 2000, astro-ph/0007343.

[16]  L. Girardi,et al.  Evolutionary tracks and isochrones for low- and intermediate-mass stars: From 0.15 to 7 , and from to 0.03 , 1999, astro-ph/9910164.

[17]  C. Gallart.  Observational Discovery of the Asymptotic Giant Branch Bump in Densely Populated Color-Magnitude Diagrams of Galaxies and Star Clusters , 1997, astro-ph/9712283.

[18]  A. Udalski,et al.  MODELLING THE GALACTIC BAR USING RED CLUMP GIANTS , 1996 .

[19]  M. Irwin,et al.  Sagittarius: the nearest dwarf galaxy , 1995, astro-ph/9506071.

[20]  K. Stanek,et al.  COLOR-MAGNITUDE DIAGRAM DISTRIBUTION OF THE BULGE RED CLUMP STARS : EVIDENCE FOR THE GALACTIC BAR , 1994, astro-ph/9404026.