HD 63021: Chromospheric Activity and Mass Transfer in a Close Binary
- Department of Physics, Austin College, 900 N. Grand Avenue, Sherman, TX 75090 (United States)
- Department of Physics, Montana State University, P.O. Box 173840, Bozeman, MT 59717-3840 (United States)
- Instituto de Astronomia, Geofisica, e Ciencias Atmosfericas, Universidade de Sao Paulo (Brazil)
- Daglen Observatory, 33 Joy Rd., Mayhill, NM 88339 (United States)
- Grey Tree Observatory, P.O. Box 290, Mayhill, NM 88339 (United States)
- Center for Astrophysics and Space Astronomy, Department of Astrophysical and Planetary Sciences, University of Colorado at Boulder, 389 UCB, Boulder, CO 80309-0389 (United States)
- NASA Ames Research Center, Moffett Field, CA 94035 (United States)
- Department of Physics & Astronomy, Benedictine College, 1020 N. 2nd Street, Atchison, KS 66002 (United States)
- Department of Mathematics and Physical Sciences, The College of Idaho, 2112 Cleveland Boulevard, Caldwell, ID 83605 (United States)
Prompted by X-ray detections from multiple surveys, we investigated the A-type star HD 63021 and found that it is a double-lined spectroscopic binary with highly variable emission associated with the primary star. Analysis of our multiepoch spectroscopic observations, the majority of which were carried out on small-aperture telescopes, indicates a very short orbital period of just 2.9 days and a mass ratio M {sub 2}/M {sub 1} of 0.23. The A1 V star is a slow rotator, with a rotational speed of ∼34 km s{sup −1}. Assuming that its mass is 2.3 M {sub ⊙}, the present-day secondary is an evolved star of ∼0.5 M {sub ⊙} that nearly fills its Roche lobe. This secondary star rotates comparatively rapidly at ∼44 km s{sup −1}, and we see evidence that it is chromospherically active. Analysis of a photometric light curve from TESS reveals two strong periods, one at the orbital period for the system and another at half the orbital period. These findings suggest that HD 63021 is a close binary system undergoing mass transfer from the secondary star onto the primary star—in all ways like an Algol eclipsing binary system, except without the eclipse. We discuss the system’s mass transfer, which is not steady but seems to run in fits and bursts, and infer the system’s basic physical properties from an orbital parameter study, the Roche lobe geometry, and its extant X-ray emission.
- OSTI ID:
- 23159102
- Journal Information:
- The Astronomical Journal (Online), Journal Name: The Astronomical Journal (Online) Journal Issue: 2 Vol. 161; ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
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