The stellar mass function, binary content and radial structure of the open cluster Praesepe derived from PPMXL and SDSS data

Khalaj, P. and Baumgardt, H. (2013) The stellar mass function, binary content and radial structure of the open cluster Praesepe derived from PPMXL and SDSS data. Monthly Notices of the Royal Astronomical Society, 434 4: 3236-3245. doi:10.1093/mnras/stt1239


Author Khalaj, P.
Baumgardt, H.
Title The stellar mass function, binary content and radial structure of the open cluster Praesepe derived from PPMXL and SDSS data
Journal name Monthly Notices of the Royal Astronomical Society   Check publisher's open access policy
ISSN 0035-8711
1365-2966
Publication date 2013-10
Year available 2013
Sub-type Article (original research)
DOI 10.1093/mnras/stt1239
Open Access Status DOI
Volume 434
Issue 4
Start page 3236
End page 3245
Total pages 10
Place of publication Oxford, United Kingdom
Publisher Oxford University Press
Collection year 2014
Language eng
Formatted abstract
We have determined possible cluster members of the nearby open cluster Praesepe (M44) based on J and K photometry and proper motions from the PPMXL catalogue and z photometry from the Sloan Digital Sky Survey. In total, we identified 893 possible cluster members down to a magnitude of J = 15.5 mag, corresponding to a mass of about 0.15M for an assumed cluster distance modulus of (m - M)0 = 6.30 mag (d ≈ 182 pc), within a radius of 3 .∘5 around the cluster centre. We derive a new cluster centre for Praesepe (αcentre = 8h39m37s, δcentre = 19°35'02''). We also derive a total cluster mass of about 630M, and a 2D halfnumber and half-mass radius of 4.25 and 3.90 pc, respectively. The global mass function of the cluster members shows evidence for a turnover around m = 0.65M.While more massive stars can be fitted by a power law ξ (m) ~ m with slope α = 2.88 ± 0.22, stars less massive than m = 0.65M are best fitted with α = 0.85 ± 0.10. In agreement with its large dynamical age, we find that Praesepe is strongly mass segregated and that the mass function slope for high-mass stars steepens from a value of α = 2.32 ± 0.24 inside the half-mass radius to α = 4.90 ± 0.51 outside the half-mass radius. We finally identify a significant population of binaries and triples in the colour-magnitude diagram of Praesepe. Assuming non-random pairing of the binary components, a binary fraction of about 35 per cent for primaries in the mass range 0.6 < m/M < 2.20 is required to explain the observed number of binaries in the colour-magnitude diagram.
Keyword Stars: luminosity function
Mass function
Open clusters and associations: individual: Praesepe
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Mathematics and Physics
Official 2014 Collection
 
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Created: Thu, 24 Oct 2013, 10:59:22 EST by Dr Holger Baumgardt on behalf of Scholarly Communication and Digitisation Service