SIMBAD references

2003A&A...405..551F - Astronomy and Astrophysics, volume 405, 551-561 (2003/7-2)

Is Praesepe really different from the coeval Hyades cluster? The XMM-Newton view.


Abstract (from CDS):

The Praesepe open cluster represents a puzzle since it has about the same age as the Hyades, and only slightly different metallicity, yet previous ROSAT observations resulted in a detection rate of cluster sources significantly lower than for the Hyades. We present a new 50-ksec observation of Praesepe performed with the EPIC instrument on board XMM- Newton, which resulted in the detection of ∼200 sources, including 48 cluster members. We detected all solar-type (F-G) stars in the field of view, ∼90% of the K stars and ∼70% of the M stars. We find that the distribution of X-ray luminosities of solar-type Praesepe members is comparable to that of the Hyades, in contrast with the previous ROSAT results; however, the disagreement between the ROSAT and XMM-Newton results appears to be mostly due to X-ray faint Praesepe members falling outside the XMM-Newton field of view, while it is considerably reduced when considering only the subsample of stars in the ROSAT survey in common with the present observation. The finding supports an earlier suggestion that Praesepe may be formed by two merged clusters of different age.

Abstract Copyright:

Journal keyword(s): open clusters and associations: individual: Praesepe - stars: activity - stars: coronae - X-ray: stars

Nomenclature: Table 3: [FRP2003] N=24.

CDS comments: In table 3, GSC2 N231230081115 is a misprint for N23123008115. KW = Cl* NGC 2632 KW, JS = Cl* NGC 2632 JS, HSHJ = Cl* NGC 2632 HSHJ, WRS = Cl* NGC 2632 WRS in SIMBAD

Simbad objects: 90

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