Rapid Rotation of Low-mass Red Giants Using APOKASC: A Measure of Interaction Rates on the Post-main-sequence

Tayar, J. and Ceillier, T. and Garcia-Hernandez, D. A. and Troup, N. W. and Mathur, S. and Mészáros, Szabolcs (2015) Rapid Rotation of Low-mass Red Giants Using APOKASC: A Measure of Interaction Rates on the Post-main-sequence. ASTROPHYSICAL JOURNAL, 807 (1). ISSN 1538-4357

Preview

Text 1505.03536.pdf Available under License Creative Commons Attribution. Download (1MB) | Preview

Abstract

We investigate the occurrence rate of rapidly rotating (v sin i>10km s−1), low-mass giant stars in the APOGEE-Kepler (APOKASC) fieldswith asteroseismic mass and surface gravity measurements. Such stars arelikely merger products and their frequency places interesting constraintson stellar population models. We also identify anomalous rotators, i.e.stars with 5 km s−1<v sin i<10 km s−1 that are rotating significantlyfaster than both angular momentum evolution predictions and the mea-sured rates of similar stars. Our data set contains fewer rapid rotatorsthan one would expect given measurements of the Galactic field starpopulation, which likely indicates that asteroseismic detections are lesscommon in rapidly rotating red giants. The number of low-mass mod-erate (5-10 km s−1) rotators in our sample gives a lower limit of 7% forthe rate at which low-mass stars interact on the upper red giant branchbecause single stars in this mass range are expected to rotate slowly.Finally, we classify the likely origin of the rapid or anomalous rotationwhere possible. KIC 10293335 is identified as a merger product and KIC6501237 is a possible binary system of two oscillating red giants.

Actions (login required)

Edit Item