Ages and masses of delta scuti stars in the praesepe cluster

Tsvetkov, Ts.

doi:10.1007/bf00658993

Cited by 6 publications

(4 citation statements)

References 19 publications

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“…Their value was obtained via the fitting of models describing the main sequence to the observed colour-magnitude diagrams (CMDs). The widest range of age estimates is reported by Tsvetkov (1993) who placed a similar lower limit of 540 Myr but an upper limit of over 1.5 Gyr. The method of Tsvetkov does not depend on the fitting of the zero-age main-sequence but instead relied on models used to calculate the ages of δ Scuti stars that are present within the cluster.…”

Section: Introductionmentioning

confidence: 90%

Low-mass stars and brown dwarfs in Praesepe

Baker¹,

Jameson²,

Casewell³

et al. 2010

Monthly Notices of the Royal Astronomical Society

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Presented are the results of a large and deep optical–near‐infrared multi‐epoch survey of the Praesepe open star cluster using data from the UKIRT Infrared Deep Sky Survey (UKIDSS) Galactic Clusters Survey. Multiple colour–magnitude diagrams were used to select potential members and proper motions were used to assign levels of membership probability. From our sample, 145 objects were designated as high probability members (p≥ 0.6) with most of these having been found by previous surveys although 14 new cluster members are also identified. Our membership assignment is restricted to the bright sample of objects (Z < 18). From the fainter sample, 39 candidates were found from an examination of multiple colour–magnitude plots. Of these, two have small but significant membership probabilities. Finally, using theoretical models, cluster luminosity and mass functions were plotted with the latter being fitted with a power law of α= 1.11 ± 0.37 for the mass range 0.6 to 0.125 M⊙ and an assumed cluster age of 500 Myr in the UKIDSS Z photometric band. Likewise taking an assumed cluster age of 1 Gyr we find α= 1.10 ± 0.37. Similar values were also found for the J and K bands. These results compare favourably with the result of Kraus & Hillenbrand (α= 1.4 ± 0.2) but are significantly lower than that of the more recent study conducted by Boudreault et al. (α= 1.8 ± 0.1).

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Section: Introductionmentioning

confidence: 90%

Low-mass stars and brown dwarfs in Praesepe

Baker¹,

Jameson²,

Casewell³

et al. 2010

Monthly Notices of the Royal Astronomical Society

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“…(g) Averages of measurements obtained from the Hipparcos parallaxes by van den Heuvel (1969);Maeder (1971); Mathieu & Mazeh (1988); Mazzei & Pigatto (1988); Boesgaard (1989);Tsvetkov (1993); Piatti et al (1995); Claria et al (1996); Hernandez et al (1998); Loktin & Beshenov (2001); Salaris et al (2004); Kraus & Hillenbrand (2007); and Gáspár et al (2009). assumed that log g = 4.437, T eff, = 5770 K and M bol, = 4.75, in conformity with the IAU recommendations (Andersen 1999). As above, we averaged all our estimates to obtain log g (phot) , listed in Col. 5 of Table 4.…”

Section: Referencesmentioning

confidence: 95%

Chemical abundance analysis of the open clusters Berkeley 32, NGC 752, Hyades, and Praesepe

Carrera

Pancino

2011

A&A

128

139

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Context. Open clusters are ideal test particles for studying the chemical evolution of the Galactic disc. However, the number and accuracy of existing high-resolution abundance determinations, not only of [Fe/H], but also of other key elements, remains largely insufficient. Aims. We attempt to increase the number of Galactic open clusters that have high quality abundance determinations, and to gather all the literature determinations published so far. Methods. Using high-resolution (R ∼ 30 000), high-quality (S /N ≥ 60 per pixel), we obtained spectra for twelve stars in four open clusters with the fibre spectrograph FOCES, at the 2.2 Calar Alto Telescope in Spain. We employ a classical equivalent-width analysis to obtain accurate abundances of sixteen elements: Al, Ba, Ca, Co, Cr, Fe, La, Mg, Na, Nd, Ni, Sc, Si, Ti, V, and Y. We derived oxygen abundances by means of spectral synthesis of the 6300 Å forbidden line. Results. We provide the first determination of abundance ratios other than Fe for NGC 752 giants, and ratios in agreement with the literature for the Hyades, Praesepe, and Be 32. We use a compilation of literature data to study Galactic trends of [Fe/H] and [α/Fe] with Galactocentric radius, age, and height above the Galactic plane. We find no significant trends, but some indication for a flattening of [Fe/H] at large R gc , and for younger ages in the inner disc. We also detect a possible decrease in [Fe/H] with |z| in the outer disc, and a weak increase in [α/Fe] with R gc .

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“…Aside from using pulsating variables (Tsvetkov 1993) or stellar rotation (Pace & Pasquini 2004) to estimate the age of the cluster, the only method is to fit theoretical stellar evolution turnoff points on the observed CMD. This procedure involves a precise simultaneous fitting of the cluster distance, reddening, metallicity and age.…”

Section: Age and Distance Estimatementioning

confidence: 99%

THE LOW LEVEL OF DEBRIS DISK ACTIVITY AT THE TIME OF THE LATE HEAVY BOMBARDMENT: ASPITZERSTUDY OF PRAESEPE

Gáspár¹,

Rieke²,

Su³

et al. 2009

ApJ

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We present 24 µm photometry of the intermediate-age open cluster Praesepe. We assemble a catalog of 193 probable cluster members that are detected in optical databases, the Two Micron All Sky Survey (2MASS), and at 24 µm, within an area of ∼ 2.47 square degrees. Mid-IR excesses indicating debris disks are found for one early-type and for three solar-type stars. Corrections for sampling statistics yield a 24 µm excess fraction (debris disk fraction) of 6.5 ± 4.1% for luminous and 1.9 ± 1.2% for solar-type stars. The incidence of excesses is in agreement with the decay trend of debris disks as a function of age observed for other cluster and field stars. The values also agree with those for older stars, indicating that debris generation in the zones that emit at 24 µm falls to the older 1-10 Gyr field star sample value by roughly 750 Myr.We discuss our results in the context of previous observations of excess fractions for early-and solar-type stars. We show that solar-type stars lose their debris disk 24 µm excesses on a shorter timescale than early-type stars. Simplistic Monte Carlo models suggest that, during the first Gyr of their evolution, up to 15-30% of solar-type stars might undergo an orbital realignment of giant planets such as the one thought to have led to the Late Heavy Bombardment, if the length of the bombardment episode is similar to the one thought to have happened in our Solar System.In the Appendix, we determine the cluster's parameters via boostrap Monte Carlo isochrone fitting, yielding an age of 757 Myr (± 36 Myr at 1σ confidence) and a distance of 179 pc (± 2 pc at 1σ confidence), not allowing for systematic errors.

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Ages and masses of delta scuti stars in the praesepe cluster

Cited by 6 publications

References 19 publications

Low-mass stars and brown dwarfs in Praesepe

Low-mass stars and brown dwarfs in Praesepe

Chemical abundance analysis of the open clusters Berkeley 32, NGC 752, Hyades, and Praesepe

THE LOW LEVEL OF DEBRIS DISK ACTIVITY AT THE TIME OF THE LATE HEAVY BOMBARDMENT: ASPITZERSTUDY OF PRAESEPE

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