THREE-DIMENSIONAL MAPS OF THE MAGELLANIC CLOUDS USING RR LYRAE STARS AND CEPHEIDS. II. THE SMALL MAGELLANIC CLOUD

Journal Article · Mon Oct 01 04:00:00 EDT 2012 · Astronomical Journal (New York, N.Y. Online)

DOI:https://doi.org/10.1088/0004-6256/144/4/107· OSTI ID:22089858

Haschke, Raoul ^[1]; Grebel, Eva K.; Duffau, Sonia ^[2]

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1. Member of the Heidelberg Graduate School for Fundamental Physics (HGSFP) and of the International Max Planck Research School for Astronomy and Cosmic Physics at the University of Heidelberg. (Germany)
2. Astronomisches Rechen-Institut, Zentrum fuer Astronomie der Universitaet Heidelberg, Moenchhofstrasse 12-14, D-69120 Heidelberg (Germany)

We use data on variable stars from the Optical Gravitational Lensing Experiment survey to determine the three-dimensional structure of the Small Magellanic Cloud (SMC). Deriving individual distances to RR Lyrae stars and Cepheids, we investigate the distribution of these tracers of the old and young populations in the SMC. Photometrically estimated metallicities are used to determine the distances to 1494 RR Lyrae stars, which have typical ages greater than 9 Gyr. For 2522 Cepheids, with ages of a few tens to a few hundred Myr, distances are calculated using their period-luminosity relation. Individual reddening estimates from the intrinsic color of each star are used to obtain high precision three-dimensional maps. The distances of RR Lyrae stars and Cepheids are in very good agreement with each other. The median distance of the RR Lyrae stars is found to be 61.5 {+-} 3.4 kpc. For the Cepheids, a median distance of 63.1 {+-} 3.0 kpc is obtained. Both populations show an extended scale height, with 2.0 {+-} 0.4 kpc for the RR Lyrae stars and 2.7 {+-} 0.3 kpc for the Cepheids. This confirms the large depth of the SMC suggested by a number of earlier studies. The young population is very differently oriented than the old stars. While we find an inclination angle of 7 Degree-Sign {+-} 15 Degree-Sign and a position angle of 83 Degree-Sign {+-} 21 Degree-Sign for the RR Lyrae stars, for the Cepheids an inclination of 74 Degree-Sign {+-} 9 Degree-Sign and a position angle of 66 Degree-Sign {+-} 15 Degree-Sign is obtained. The RR Lyrae stars show a fairly homogeneous distribution, while the Cepheids roughly follow the distribution of the bar, with their northeastern part being closer to us than the southwestern part of the bar. Interactions between the SMC, Large Magellanic Cloud, and Milky Way are presumably responsible for the tilted, elongated structure of the young population of the SMC.

• OSTI ID: 22089858
• Journal Information: Astronomical Journal (New York, N.Y. Online), Journal Name: Astronomical Journal (New York, N.Y. Online) Journal Issue: 4 Vol. 144; ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ACCURACY
ASTRONOMY
ASTROPHYSICS
CEPHEIDS
COLOR
DISTANCE
GRAVITATIONAL LENSES
INCLINATION
LUMINOSITY
MAGELLANIC CLOUDS
MILKY WAY
PHOTOMETRY
THREE-DIMENSIONAL CALCULATIONS