NOAO >   Observing Info >   Approved Programs >   2017A-0175

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Program Information for 2017A-0175


PI: Robin Jeffries, Keele University, r.d.jeffries@keele.ac.uk
Address: Astrophysics, Keele, Stoke-on-Trent, Staffordshire ST5 5BG UK

CoI: Richard Jackson, Keele University
CoI: Constantine Deliyannis, Indiana U.

Title: The radii of M-dwarfs in the Praesepe cluster

Abstract: The radius of a star is one of the most basic outputs of a stellar model. Yet observations of low-mass eclipsing binaries and pre-main- sequence (PMS) stars show that standard evolutionary calculations significantly underpredict their radii. This ``radius inflation'' is not yet fully explained -- it may be due to magnetic activity and rapid rotation, or it could be indicating some other deficiency in low-mass evolutionary models. There is a renewed urgency in accurately estimating the properties of low-mass M-dwarfs driven by the discovery of, and the need to characterise, their (habitable?) exoplanetary systems. We will use WIYN Hydra to estimate the average radii of M-dwarfs in the Praesepe cluster (age 600 Myr) and compare them with evolutionary models and the interferometric radii of nearby, but magnetically inactive field M- dwarfs. Our aim is to determine whether the radius inflation seen in PMS M-dwarfs at ages $leq 140$ Myr, persists in older stars of similar mass that are well-established on the main sequence, and whether any inflation correlates with magnetic activity or rotation. Our technique models projected radii determined from the product of WIYN measurements of rotational broadening and K2 rotation periods, to yield average radii for groups of stars. Large samples are required and owing to its proximity, richness and presence in the K2 campaign 5 field, the Praesepe cluster is an ideal and very important target for fiber spectroscopy.

Program Type: Standard/NASA WIYN

Scheduled Nights:
Run 1 (2017A):  WIYN/HYDR -- 4n on Feb 18 - Feb 21 2017


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NOAO >   Observing Info >   Approved Programs >   2017A-0175

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