NOAO >   Observing Info >   Approved Programs >   2017A-0422

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Program Information for 2017A-0422


PI: Constantine Deliyannis, Indiana U., con@astro.indiana.edu
Address: Astronomy Department, 727 E. 3rd St., 318 Swain Hall West, Bloomington, IN 47405-7105 USA

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

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. Last semester we requested time to observe 100's of stars in the young Pleiades cluster (age 100 Myr). We have already reduced Pleiades data taken in two second-half nights at the end of September (2016), using our custom- written pipeline, and have verified our expectations regarding SNR and ability to resolve down to 10km/sec. Here, we propose to estimate the average radii of M-dwarfs in the Praesepe cluster (age 700 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 less than 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: ITAC

Scheduled Nights:
Run 1 (2017A):  WIYN/HYDR -- 3n on Feb 01 - Feb 02 2017, Feb 17 2017


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