- ID:
- ivo://CDS.VizieR/J/A+A/417/557
- Title:
- Rotation & variability of PMS Stars in NGC 2264
- Short Name:
- J/A+A/417/557
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Table 4 lists the 10554 stars in the area of NGC 2264 between I_C_=9.8mag and I_C_=21mag on which we did photometry. It contains information on the position, brightness, colours and the variability of these stars. It also lists the spectral type taken from the literature (if available) as well as the identification numbers of the stars in other studies. Table 6 lists the stars detected as periodic in this study and gives their brightness, periods determined by different periodogram techniques, and the period finally adopted as well as the estimated period error. Stars which passed the two adopted PMS tests are also indicated. Time series data were obtained in the I_C_ band in 44 nights between Dec. 2000 and March 2001 with the Wide Field Imager (WFI) on the MPG/ESO 2.2m telescope on La Silla (Chile).
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/402/1380
- Title:
- Rotation velocities in Pleiades and {alpha}Per
- Short Name:
- J/MNRAS/402/1380
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate to what extent the spin axes of stars in young open clusters are aligned. Assuming that the spin vectors lie uniformly within a conical section, with an opening half-angle between {lambda}=0{deg} (perfectly aligned) and {lambda}=90{deg} (completely random), we describe a Monte Carlo modelling technique that returns a probability density for this opening angle given a set of measured sini values, where i is the unknown inclination angle between a stellar spin vector and the line of sight.
- ID:
- ivo://CDS.VizieR/J/ApJ/746/15
- Title:
- Runaway massive stars from R136
- Short Name:
- J/ApJ/746/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We conduct a theoretical study on the ejection of runaway massive stars from R136 -the central massive, starburst cluster in the 30 Doradus complex of the Large Magellanic Cloud. Specifically, we investigate the possibility of the very massive star (VMS) VFTS 682 being a runaway member of R136. Recent observations of the above VMS, by virtue of its isolated location and its moderate peculiar motion, have raised the fundamental question of whether isolated massive star formation is indeed possible. We perform the first realistic N-body computations of fully mass-segregated R136-type star clusters in which all the massive stars are in primordial binary systems. These calculations confirm that the dynamical ejection of a VMS from an R136-like cluster, with kinematic properties similar to those of VFTS 682, is common. Hence, the conjecture of isolated massive star formation is unnecessary to account for this VMS. Our results are also quite consistent with the ejection of 30 Dor 016, another suspected runaway VMS from R136. We further note that during the clusters' evolution, mergers of massive binaries produce a few single stars per cluster with masses significantly exceeding the canonical upper limit of 150 M_{sun}_. The observations of such single super-canonical stars in R136, therefore, do not imply an initial mass function with an upper limit greatly exceeding the accepted canonical 150M_{sun}_limit, as has been suggested recently, and they are consistent with the canonical upper limit.
- ID:
- ivo://CDS.VizieR/J/ApJ/900/14
- Title:
- ~17000 runaways stars from the Orion Nebula Cluster
- Short Name:
- J/ApJ/900/14
- Date:
- 14 Mar 2022 08:53:06
- Publisher:
- CDS
- Description:
- We use Gaia DR2 to hunt for runaway stars from the Orion Nebula Cluster (ONC). We search a region extending 45{deg} around the ONC and out to 1 kpc to find sources that have overlapped in angular position with the cluster in the last ~10Myr. We find ~17000 runaway/walkaway candidates that satisfy this 2D traceback condition. Most of these are expected to be contaminants, e.g., caused by Galactic streaming motions of stars at different distances. We thus examine six further tests to help identify real runaways, namely: (1) possessing young stellar object (YSO) colors and magnitudes based on Gaia optical photometry; (2) having IR excess consistent with YSOs based on 2MASS and Wide-field Infrared Survey Explorer photometry; (3) having a high degree of optical variability; (4) having closest approach distances well-constrained to within the cluster half-mass radius; (5) having ejection directions that avoid the main Galactic streaming contamination zone; and (6) having a required radial velocity (RV) for 3D overlap of reasonable magnitude (or, for the 7% of candidates with measured RVs, satisfying 3D traceback). Thirteen sources, not previously noted as Orion members, pass all these tests, while another twelve are similarly promising, except they are in the main Galactic streaming contamination zone. Among these 25 ejection candidates, ten with measured RVs pass the most restrictive 3D traceback condition. We present full lists of runaway/walkaway candidates, estimate the high-velocity population ejected from the ONC, and discuss its implications for cluster formation theories via comparison with numerical simulations.
- ID:
- ivo://CDS.VizieR/J/A+A/625/A115
- Title:
- Ruprecht 147 DANCe. I.
- Short Name:
- J/A+A/625/A115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Ruprecht 147 is the oldest (2.5Gyr) open cluster in the solar vicinity (<300pc), making it an important target for stellar evolution studies and exoplanet searches. We aim to derive a census of members and the luminosity, mass, and spatial distributions of the cluster. We used an astro-photometric data set including all available information from the literature together with our own observations. We processed the data with an updated version of an existent membership selection methodology. We identify 259 high-probability candidate members, including 58 previously unreported. All these candidates cover the luminosity interval between G>6mag to i<21mag. The cluster luminosity and mass distributions are derived with an unprecedented level of details allowing us to recognize, among other features, the Wielen dip. The mass distribution in the low-mass regime drops sharply at 0.4M_{sun}_ even though our data are sensitive to stellar masses down to 0.1M_{sun}_, suggesting that most very-low-mass members left the cluster as the result of its dynamical evolution. In addition, the cluster is highly elongated (ellipticity~0.5) towards the galactic plane, and mass segregated. Our combined Gaia+DANCe data set allows us to obtain an extended list of cluster candidate members, and to derive luminosity, mass, and projected spatial distributions in the oldest open cluster of the solar vicinity.
- ID:
- ivo://CDS.VizieR/J/A+A/578/A27
- Title:
- RV and [Fe/H] in 5 open clusters
- Short Name:
- J/A+A/578/A27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Open clusters are key to studying the formation and evolution of the Galactic disc. However, there is a deficiency of radial velocity and chemical abundance determinations for open clusters in the literature. Aims. We intend to increase the number of determinations of radial velocities and metallicities from spectroscopy for open clusters. We acquired medium-resolution spectra (R~8000) in the infrared region CaII triplet lines (~8500{AA}) for several stars in five open clusters with the long-slit IDS spectrograph on the 2.5m Isaac Newton Telescope (Roque de los Muchachos Observatory, Spain). Radial velocities were obtained by cross-correlation fitting techniques. The relationships available in the literature between the strength of infrared Ca ii lines and metallicity were also used to derive the metallicity for each cluster.
- ID:
- ivo://CDS.VizieR/J/MNRAS/416/817
- Title:
- RV catalog of O-type stars in IC 2944 and Cen OB2
- Short Name:
- J/MNRAS/416/817
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using an extended set of multi-epoch high resolution high signal-to-noise ratio optical spectra, we re-address the multiplicity properties of the O-type stars in IC 2944 and in the Cen OB2 association. We present new evidence of binarity for five objects and we confirm the multiple nature of another two. We derive the first orbital solutions for HD 100099, HD 101436 and HD 101190 and we provide additional support for HD 101205 being a quadruple system. The minimal spectroscopic binary fraction in our sample is f_min_=0.57. Using numerical simulations, we show that the detection rate of our observational campaign is close to 90%, leaving thus little room for undetected spectroscopic binary systems. The statistical properties of the O-star population in IC 2944 are similar, within the uncertainties, to the results obtained in the earlier papers in this series despite the fact that sample size effects limit the significance of the comparison. Using newly derived spectroscopic parallaxes, we reassess the distance to IC 2944 and obtained 2.3+/-0.3kpc, in agreement with previous studies. We also confirm that, as far as the O stars are concerned, the IC 2944 cluster is most likely a single entity.
- ID:
- ivo://CDS.VizieR/J/MNRAS/400/1479
- Title:
- RV catalogue of O-type stars in NGC 6611
- Short Name:
- J/MNRAS/400/1479
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on a set of over 100 medium- to high-resolution optical spectra collected from 2003 to 2009, we investigate the properties of the O-type star population in NGC 6611 in the core of the Eagle Nebula (M16). Using a much more extended data set than previously available, we revise the spectral classification and multiplicity status of the nine O-type stars in our sample. We confirm two suspected binaries and derive the first SB2 orbital solutions for two systems. We further report that two other objects are displaying a composite spectrum, suggesting possible long- period binaries. Our analysis is supported by a set of Monte-Carlo simulations, allowing us to estimate the detection biases of our campaign and showing that the latter do not affect our conclusions. The absolute minimal binary fraction in our sample is f_min_=0.44 but could be as high as 0.67 if all the binary candidates are confirmed. As in NGC 6231 (see Paper I, Sana et al., Cat. J/MNRAS/386/447), up to 75% of the O star population in NGC 6611 are found in an O+OB system, thus implicitly excluding random pairing from a classical IMF as a process to describe the companion association in massive binaries. No statistical difference could be further identified in the binary fraction, mass-ratio and period distributions between NGC 6231 and NGC 6611, despite the difference in age and environment of the two clusters.
- ID:
- ivo://CDS.VizieR/J/other/Sci/337.444
- Title:
- RV curves of Galactic massive O stars
- Short Name:
- J/other/Sci/337.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The presence of a nearby companion alters the evolution of massive stars in binary systems, leading to phenomena such as stellar mergers, X-ray binaries and gamma-ray bursts. Unambiguous constraints on the fraction of massive stars affected by binary interaction were lacking. We simultaneously measured all relevant binary characteristics in a sample of Galactic massive O stars and quantified the frequency and nature of binary interactions. Over seventy per cent of all massive stars will exchange mass with a companion, leading to a binary merger in one third of the cases. These numbers greatly exceed previous estimates and imply that binary interaction dominates the evolution of massive stars, with implications for populations of massive stars and their supernovae.
- ID:
- ivo://CDS.VizieR/J/MNRAS/356/1583
- Title:
- RV of Sigma Ori low-mass candidate members
- Short Name:
- J/MNRAS/356/1583
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present radial velocities for 38 low-mass candidate members of the {sigma} Orionis young group. We have measured their radial velocities by cross-correlation of high-resolution (R>>6000) AF2/Wide Field Fibre Optical Spectrograph (WYFFOS) spectra of the gravity-sensitive NaI doublet at 8183,8195{AA}, on the nights of 2003 January 3 and 4. The total sample contained 117 objects, of which 54 have sufficient signal-to-noise ratio to detect NaI at an equivalent width of 3{AA}; however, we only detect NaI in 38 of these. This implies that very low-mass members of this young group display weaker NaI absorption than similarly aged objects in the Upper Scorpius OB association. We develop a technique to assess membership using radial velocities with a range of uncertainties that does not bias the selection when large uncertainties are present. The resulting membership probabilities are used to assess the issue of exclusion in photometric selections, and we find that very few members are likely to be excluded by such techniques. We also assess the level of contamination in the expected pre-main-sequence region of colour-magnitude space brighter than I=17. We find that contamination by non-members in the expected pre-main-sequence region of the colour-magnitude diagram is small. We conclude that although radial velocity alone is insufficient to confirm membership, high signal-to-noise ratio observations of the NaI doublet provide the opportunity to use the strength of NaI absorption in concert with radial velocities to asses membership down to the lowest masses, where lithium absorption no longer distinguishes youth.