Proper motions of open clusters within 1 kpc based on the TYCHO2 Catalogue

Dias, W. S.; Lépine, J. R. D.; Alessi, B. S.

doi:10.1051/0004-6361:20011021

Cited by 69 publications

(131 citation statements)

References 13 publications

(10 reference statements)

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“…The present version of the catalog contains 2174 objects, of which 1620 (74.5%) have published distances and ages, 1190 (54.7%) have published proper motions (most of them determined by our group (Dias et al (2001), Dias et al (2002b) and Dias et al (2006), hereafter DL06), and 543 (25.0%) have radial velocities.…”

Section: The Catalog Of Open Clustersmentioning

confidence: 99%

Proper motions of the optically visible open clusters based on the UCAC4 catalog

Dias

Monteiro

Caetano

et al. 2014

A&A

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173

207

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We present a catalog of mean proper motions and membership probabilities of individual stars for optically visible open clusters, which have been determined using data from the UCAC4 catalog in a homogeneous way. The mean proper motion of the cluster and the membership probabilities of the stars in the region of each cluster were determined by applying the statistical method in a modified fashion. In this study, we applied a global optimization procedure to fit the observed distribution of proper motions with two overlapping normal bivariate frequency functions, which also take the individual proper motion errors into account. For 724 clusters, this is the first determination of proper motion, and for the whole sample, we present results with a much larger number of identified astrometric member stars. Furthermore, it was possible to estimate the mean radial velocity of 364 clusters (102 unpublished so far) with the stellar membership using published radial velocity catalogs. These results provide an increase of 30% and 19% in the sample of open clusters with a determined mean absolute proper motion and mean radial velocity, respectively.

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Section: The Catalog Of Open Clustersmentioning

confidence: 99%

Proper motions of the optically visible open clusters based on the UCAC4 catalog

Dias

Monteiro

Caetano

et al. 2014

A&A

Self Cite

173

207

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“…Dias et al (2001Dias et al ( , 2002 have determined mean proper motions of more than 200 clusters, many of which were not included in the studies discussed above, using in most cases several tens of stars per cluster. They have derived membership probabilities based only on the proper motions, which are tightly clustered for an open cluster but (usually) have a considerably larger dispersion for field stars.…”

Section: Assessing Cluster Membershipmentioning

confidence: 99%

Searching for links between magnetic fields and stellar evolution

Landstreet¹,

Bagnulo²,

Andretta³

et al. 2007

A&A

177

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Context. The evolution of magnetic fields in Ap stars during the main sequence phase is presently mostly unconstrained by observation because of the difficulty of assigning accurate ages to known field Ap stars. Aims. We are carrying out a large survey of magnetic fields in cluster Ap stars with the goal of obtaining a sample of these stars with well-determined ages. In this paper we analyse the information available from the survey as it currently stands. Methods. We select from the available observational sample the stars that are probably (1) cluster or association members and (2) magnetic Ap stars. For the stars in this subsample we determine the fundamental parameters T eff , L/L , and M/M . With these data and the cluster ages we assign both absolute age and fractional age (the fraction of the main sequence lifetime completed). For this purpose we have derived new bolometric corrections for Ap stars. Results. Magnetic fields are present at the surfaces of Ap stars from the ZAMS to the TAMS. Statistically for the stars with M > 3 M the fields decline with advancing age approximately as expected from flux conservation together with increased stellar radius, or perhaps even faster than this rate, on a time scale of about 3 × 10 7 yr. In contrast, lower mass stars show no compelling evidence for field decrease even on a timescale of several times 10 8 yr. Conclusions. Study of magnetic cluster stars is now a powerful tool for obtaining constraints on evolution of Ap stars through the main sequence. Enlarging the sample of known cluster magnetic stars, and obtaining more precise rms fields, will help to clarify the results obtained so far. Further field observations are in progress.

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“…Additional four stars (LOX 2 = LOri 044, LOX 3 = LOri 052, LOX 14 = HD 245059, and LOX 30 = DM 20) show signatures of youth (strong Li i absorption and/or low-gravity lines) but have radial velocity inconsistent with membership (Alcalá et al 2000;Dolan & Mathieu 1999;Maxted et al 2008); HD 245059 also has a proper motion inconsistent with membership according to Dias et al (2001) and Kharchenko et al (2004) and is located significantly above the cluster sequence in colour-magnitude diagrams. The remaining two objects (LOX 64 = TYC 705-860-1 and LOX 113 = TYC 705-937-1) are located significantly above the cluster sequence, and we consider them as probable photometric nonmembers.…”

Section: Source Identificationmentioning

confidence: 99%

“…2.4, HD 245059 is located significantly above the cluster sequence and has a radial velocity of 19.8 ± 1.0 km s −1 (Alcalá et al 2000), inconsistent with that of the λ Ori cluster (27.0 ± 0.5 km s −1 , Sacco et al 2008;Maxted et al 2008). Its proper motion (μ α cos δ = 11.5 ± 1.5 mas yr −1 , μ δ = −35.3 ± 1.0 mas yr −1 ; Dias et al 2001) is also significantly higher than that of the cluster (0.5 ± 2.8 and −2.5 ± 2.8 mas yr −1 , Dias et al 2001). Recent Keck and Chandra observations have resolved it into a visual binary (Baldovin-Saavedra et al 2009), although there is no evidence of radial velocity variations (Fekel 1997;Alcalá et al 2000).…”

Section: Hd 245059mentioning

confidence: 99%

XMM-Newtonobservations of the young open cluster aroundλ Orionis

Franciosini

Sacco

2011

A&A

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Aims. We studied the X-ray properties of the young (∼1−8 Myr) open cluster around the hot (O8 III) star λ Ori and compared them with those of the similarly-aged σ Ori cluster to investigate possible effects of the different ambient environment. Methods. We analysed an XMM-Newton observation of the cluster using EPIC imaging and low-resolution spectral data. We studied the variability of detected sources, and performed a spectral analysis of the brightest sources in the field using multi-temperature models.Results. We detected 167 X-ray sources, of which 58 are identified with known cluster members and candidates, from massive stars down to low-mass stars with spectral types ∼M5.5. Another 23 sources were identified with new possible photometric candidates. Late-type stars have a median log L X /L bol ∼ −3.3, close to the saturation limit. Variability was observed in ∼35% of late-type members or candidates, including six flaring sources. The emission from the central hot star λ Ori is dominated by plasma at 0.2−0.3 keV, with a weaker component at 0.7 keV, consistently with a wind origin. The coronae of late-type stars can be described by two plasma components with temperatures T 1 ∼ 0.3−0.8 keV and T 2 ∼ 0.8−3 keV, and subsolar abundances Z ∼ 0.1−0.3 Z , similar to what is found in other star-forming regions and associations. No significant difference was observed between stars with and without circumstellar discs, although the smallness of the sample of stars with discs and accretion does not allow us to draw definitive conclusions. Conclusions. The X-ray properties of λ Ori late-type stars are comparable to those of the coeval σ Ori cluster, suggesting that stellar activity in λ Ori has not been significantly affected by the different ambient environment.

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Proper motions of open clusters within 1 kpc based on the TYCHO2 Catalogue

Cited by 69 publications

References 13 publications

Proper motions of the optically visible open clusters based on the UCAC4 catalog

Proper motions of the optically visible open clusters based on the UCAC4 catalog

Searching for links between magnetic fields and stellar evolution

XMM-Newtonobservations of the young open cluster aroundλ Orionis

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