ABSOLUTE PROPERTIES OF THE PRE-MAIN-SEQUENCE ECLIPSING BINARY STAR NP PERSEI
- Physics Department, University of Arkansas, Fayetteville, AR 72701 (United States)
- Center of Excellence in Information Systems, Tennessee State University, Nashville, TN 37209 (United States)
- Department of Physics, Faculty of Science, University of Zagreb, Bijenička cesta 32, 10000 Zagreb (Croatia)
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
NP Per is a well-detached, 2.2 day eclipsing binary whose components are both pre-main-sequence stars that are still contracting toward the main-sequence phase of evolution. We report extensive photometric and spectroscopic observations with which we have determined their properties accurately. Their surface temperatures are quite different: 6420 ± 90 K for the larger F5 primary star and 4540 ± 160 K for the smaller K5e star. Their masses and radii are 1.3207 ± 0.0087 solar masses and 1.372 ± 0.013 solar radii for the primary, and 1.0456 ± 0.0046 solar masses and 1.229 ± 0.013 solar radii for the secondary. The orbital period is variable over long periods of time. A comparison of the observations with current stellar evolution models from MESA indicates that the stars cannot be fit at a single age: the secondary appears significantly younger than the primary. If the stars are assumed to be coeval and to have the age of the primary (17 Myr), then the secondary is larger and cooler than predicted by current models. The H α spectral line of the secondary component is completely filled by, presumably, chromospheric emission due to a magnetic activity cycle.
- OSTI ID:
- 22663007
- Journal Information:
- Astronomical Journal (Online), Journal Name: Astronomical Journal (Online) Journal Issue: 1 Vol. 152; ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
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