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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, PHWe 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 JournalVolume
550Pagination
L173-L177ISSN
0004-637XDepartment/School
School of Natural SciencesPublisher
The University of Chicago PressPlace of publication
ChicagoRepository Status
- Restricted