Beaton, Rachael L. and Majewski, Steven R. and Guhathakurta, Puragra and Skrutskie, Michael F. and Cutri, Roc M. and Good, John and Patterson, Richard J. and Athanassoula , E. and Bureau, Martin (2007) Unveiling the Boxy Bulge and Bar of the Andromeda Spiral Galaxy. Astrophysical Journal Letters, 658 (2). L91-L94. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20091014-112807918
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A new, 2.8 deg^2 J, H, Ks near-infrared (NIR) survey from the 2MASS 6X program across the extent of the optical disk of the Andromeda (M31) galaxy provides a clear view of the M31 center almost completely unfettered by dust extinction and reveals a high-contrast bulge with very boxy isophotes dominating the NIR light to a semimajor axis of ~700" (2.6 kpc). The inner bulge (≾50") isophotes are relatively circular but show some twisting. Beyond this, (1) the M31 bulge ellipticity increases, (2) its position angle is constant at ~50°, or about 10° higher than the position angle of the M31 disk, and (3) its boxiness increases to a degree (~3%-4%) comparable to other renowned examples of boxy bulges observed in the NIR. In a companion paper, self-consistent N-body simulations of a classical bulge plus a bar with a boxy bulge are shown to reproduce the observed NIR M31 features presented here. Beyond the boxy bulge region and nearly along the 40° position angle of the disk a narrow ridge of NIR flux, which can be identified with the thin part of the bar, more or less symmetrically extends into the inner disk at semimajor axis radii of 700"-1200" or more. Little variation in the morphology or relative brightnesses of these various M31 structures is seen across the NIR bands (e.g., no color gradients are seen). These new data verify that M31 is a barred spiral galaxy like the Milky Way.
|Additional Information:||© 2007 The American Astronomical Society. Received 2006 May 9; accepted 2007 February 14; published 2007 March 7. This publication uses data products from the Two Micron All Sky Survey, a joint project of the University of Massachusetts and Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration (NASA) and National Science Foundation (NSF). We appreciate support by NSF grant AST 03- 07851 (SRM), NASA/JPL contract 1228235 (S. R. Majewski), NASA/JPL contract 1234021 (M. F. Skrutskie), and NSF grants AST 03-07966 and AST 05-07483 and NASA/STScI grants GO-10265.02 and GO-10134.02 to P. Guhathakurta. R. L. Beaton was supported by a Harrison Undergraduate Research Award from the University of Virginia Center for Undergraduate Research. This work was also supported by the F. H. Levinson Fund of the Peninsular Community Foundation.|
|Subject Keywords:||galaxies : bulges; galaxies : individual (M31); galaxies : spiral; galaxies : structure; infrared : galaxies; Local Group|
|Official Citation:||Unveiling the Boxy Bulge and Bar of the Andromeda Spiral Galaxy Rachael L. Beaton, Steven R. Majewski, Puragra Guhathakurta, Michael F. Skrutskie, Roc M. Cutri, John Good, Richard J. Patterson, E. Athanassoula, and Martin Bureau 2007 ApJ 658 L91-L94 doi: 10.1086/514333|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||26 Oct 2009 18:16|
|Last Modified:||26 Dec 2012 11:28|
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