NOAO >   Observing Info >   Approved Programs >   2015A-0118

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Program Information for 2015A-0118


PI: Joerg Weingrill, Leibniz-Institut fuer Astrophysik, jweingrill@aip.de
Address: Branch I: Cosmic Magnetic Fields, An der Sternwarte 16, Potsdam 14482 Germany

CoI: Sydney A Barnes, Leibniz-Institut fuer Astrophysik
CoI: Klaus G Strassmeier, Leibniz-Institut fuer Astrophysik
CoI: Thomas Granzer, Leibniz-Institut fuer Astrophysik

Title: Radial velocity membership for the open cluster M 48

Abstract: Hyades-age open clusters display a single sequence of slowly rotating FGKM\,stars whose periods increase gradually with $B-V$ color. Younger clusters like M\,35 ($\sim$150\,Myr) have a corresponding slow sequence somewhat below the Hyades sequence, and also a fast one characterized by many stars with period $P \sim$1\,d. We need to study an intermediate-age cluster like the 400\,Myr-old M\,48 to understand {\em empirically} how the fast rotators spin down as a function of stellar mass. We have therefore performed a 2\,month-long time-series survey of a $40^{\prime} \times 40^{\prime}$ region centered on M\,48. This has provided a deep Color-Magnitude Diagram, and periods for $\sim$80 stars near the cluster's main sequence, providing a first cluster Color-Period Diagram. The results are promising, but lack of membership information is compromising the interpretation. We therefore seek appropriate WIYN+HYDRA Radial Velocity observations to (1) define the cluster's true Color-Period Diagram, including only members, (2) determine the basic cluster membership (beyond the rotators alone) down to $V \sim$17, and (3) support a deeper time-series survey of the cluster planned with the STELLA telescope in winter 2014/2015.

Program Type: Standard/Galactic

Scheduled Nights:
Run 1 (2015A):  WIYN/HYDR -- 3n on Feb 09 - Feb 11 2015


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NOAO >   Observing Info >   Approved Programs >   2015A-0118

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