The Lower End of the Hyades Initial Mass Function

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Session 58 -- Outflows and the Low Mass IMF
Oral presentation, Thursday, January 13, 10:15-11:45, Salon V Room (Crystal Gateway)

[58.06] The Lower End of the Hyades Initial Mass Function

C.Bryja (U.Minnesota)

We have used the Minnesota Automated Plate Scanner to complete a multi-epoch proper motion survey of the core of the Hyades region, for the purpose of extending the mass function of the Hyades cluster down to the lowest luminosities seen on the Palomar Observatory Sky Survey plates. Followup infrared photometry and optical spectroscopy of a few of our Hyades candidates have identified stars which are the faintest confirmed members of the cluster yet known, with estimated masses on the order of 0.1 $M_{\sun}$. We have also found many stars that have the Hyades motion, have the expected infrared colors of very low mass Hyads, but have optical colors incompatible with the expected cluster main sequence. Many of these stars would have the bolometric luminosities expected of brown dwarfs if they were at the mean Hyades distance. We discuss the difficult problem of estimating the field star contamination of our sample, and combine our data with other surveys to derive the form of the Hyades luminosity and mass functions below 0.25 $M_{\sun}$.

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