NOAO >   Observing Info >   Approved Programs >   2016B-0633

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Program Information for 2016B-0633


PI: Constantine Deliyannis, Indiana U., con@astro.indiana.edu
Address:

CoI: Robin Jeffries, Keele University
CoI: Richard Jackson, Keele University

Title: The radii of active low-mass stars, above and below the fully convective boundary

Abstract: The radius of a star is one of the most basic outputs of a stellar model. Yet observations of low-mass eclipsing binaries show that standard evolutionary calculations significantly underpredict their radii. This "radius inflation" is hypothesised to be due to magnetic activity, either inhibiting convection or blocking flux at the surface through starspots. We will test these ideas, using WIYN Hydra to estimate the average radii of {it single} magnetically active, low-mass stars in the young Pleiades cluster. Our technique models the projected radii determined from the product of spectroscopic measurements of rotational broadening and published rotation periods to yield average radii for groups of stars. Large, homogeneous statistical samples are required and owing to its proximity and richness, the Pleiades is the ideal target. In particular, it allows sensitive average radius estimates in several mass bins that straddle the fully convective boundary, where opposite trends with mass are predicted by the two competing flavors of magnetic radius inflation. Although our primary interest is stellar structure, there are significant implications for exoplanet science since improved stellar models and radii, particularly for low-mass and pre-main sequence stars, will lead to more accurate age estimates for stars and their planetary systems and better radii and densities for their transiting exoplanets.

Program Type: ITAC

Scheduled Nights:
Run 1 (2016B):  WIYN/HYDR -- 5n on Jan 04 2017, Jan 15 - Jan 18 2017


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



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