Abstract
We report the spectroscopic confirmation of four further white dwarf members of Praesepe. This brings the total number of confirmed white dwarf members to eleven making this the second largest collection of these objects in an open cluster identified to date. This number is consistent with the high mass end of the initial mass function of Praesepe being Salpeter in form. Furthermore, it suggests that the bulk of Praesepe white dwarfs did not gain a substantial recoil kick velocity from possible asymmetries in their loss of mass during the asymptotic giant branch phase of evolution. By comparing our estimates of the effective temperatures and the surface gravities of WD0833+194, WD0840+190, WD0840+205 and WD0843+184 to modern theoretical evolutionary tracks we have derived their masses to be in the range 0.72-0.76Msun and their cooling ages \~300Myrs. For an assumed cluster age of 625+/-50Myrs the infered progenitor masses are between 3.3-3.5Msun. Examining these new data in the context of the initial mass-final mass relation we find that it can be adequately represented by a linear function (a0=0.289+/-0.051, a1=0.133+/-0.015) over the initial mass range 2.7Msun to 6Msun. Assuming an extrapolation of this relation to larger initial masses is valid and adopting a maximum white dwarf mass of 1.3Msun, our results support a minimum mass for core-collapse supernovae progenitors in the range ~6.8-8.6Msun.
Highlights
The initial mass-final mass relation (IFMR) characterises the amount of material stars with primordial masses M
Until quite recently, the small numbers of WDs recovered in each open cluster (∼30 WDs in 14 clusters), their intrinsic faintness and the significant distances involved has meant that the uncertainties in clusters ages and in white dwarf mass determinations, have conspired to produce significant scatter in the semi-empirical IFMR (e.g. Claver et al 2001)
We have spectroscopically confirmed four more white dwarf members of Praesepe and argued that there are at least eleven white dwarfs in this cluster. We find that this number is consistent with that expected if the initial mass function of Praesepe was Salpeter in form
Summary
The initial mass-final mass relation (IFMR) characterises the amount of material stars with primordial masses M
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