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Hα equivalent width variations across the face of a microlensed K giant in the galactic bulge

journal contribution
posted on 2023-05-16, 12:55 authored by Albrow, MD, An, J, Jean-Philippe BeaulieuJean-Philippe Beaulieu, Caldwell, JAR, Dominik, M, Greenhill, JG, Kym HillKym Hill, Kane, S, Martin, R, Menzies, J, Pollard, K, Sackett, PD, Sahu, KC, Vermaak, P, Watson, RD, Williams, A, Hauschildt, PH
We present Very Large Telescope FORS1 spectroscopy that temporally resolves the second caustic crossing of the Galactic bulge K giant source of microlensing event EROS 2000-BLG-5, the first time this has been accomplished for several phases of a caustic transit. The ∼1 ÅHα equivalent width of the source star increases slightly as the center of the star egresses the caustic and then plummets by 30% during the final limb crossing. These changes are not seen in contemporaneous spectra of control stars in the FORS1 slit but are qualitatively consistent with expectations from stellar atmosphere models as the caustic differentially magnifies different portions of the stellar face of the target. Observations such as these in a variety of stellar lines are equivalent to atmospheric tomography and are expected to provide a direct test of stellar models.

History

Publication title

The Astrophysical Journal

Volume

550

Pagination

L173-L177

ISSN

0004-637X

Department/School

School of Natural Sciences

Publisher

The University of Chicago Press

Place of publication

Chicago

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the physical sciences

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