Abstract
ABSTRACT Spectral features, radial velocities, elemental abundance estimates, other spectral data, and BVI C light curves are reported for the double-M dwarf eclipsing binary CU Cancri—a good target for a radius check versus the Zero Age Main Sequence (ZAMS) due to the low component masses and corresponding very slow evolutionary expansion. The estimate of [Fe/H] is about 0.4, although continuum placement and other difficulties due to line crowding introduce the usual uncertainties for red dwarfs. Detection of the Li i λ6707 line was attempted, with an estimated upper limit of 50 mÅ. Spectral and photometric indicators of stellar activity are described and illustrated. Other objectives were to measure the stellar radii via simultaneous velocity and light-curve solutions of earlier and new data while also improving the ephemeris by filling gaps in timewise coverage with the new velocities and eclipse data from the new light curves. The radii from our solutions agree within about 2% with those from Ribas, being slightly larger than expected for most estimates of the ZAMS. Some aspects of the red dwarf radius anomaly are briefly discussed. Evolution tracks show only very slight age-related expansion for masses near those in CU Cnc. Such expansion could be significant if CU Cnc were similar in age to the Galaxy, but then its Galactic velocity components should be representative of Population II, and they are not.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.