- ID:
- ivo://CDS.VizieR/J/MNRAS/459/880
- Title:
- Open clusters in Auriga OB2
- Short Name:
- J/MNRAS/459/880
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the area around the HII region Sh 2-234, including the young open cluster Stock 8, to investigate the extent and definition of the association Aur OB2 and the possible role of triggering in massive cluster formation. We obtained Stromgren and J, H, Ks photometry for Stock 8 and Stromgren photometry for two other cluster candidates in the area, which we confirm as young open clusters and name Alicante 11 and Alicante 12. We took spectroscopy of ~33 early-type stars in the area, including the brightest cluster members. We calculate a common distance of 2.80+0.27-0.24kpc for the three open clusters and surrounding association. We derive an age 4-6Ma for Stock 8, and do not find a significantly different age for the other clusters or the association. The star LS V +34 23, with spectral type O8 II(f), is likely the main source of ionization of Sh 2-234. We observe an important population of pre-main-sequence stars, some of them with discs, associated with the B-type members lying on the main sequence. We interpret the region as an area of recent star formation with some residual and very localized ongoing star formation. We do not find evidence for sequential star formation on a large scale. The classical definition of Aur OB2 has to be reconsidered, because its two main open clusters, Stock 8 and NGC 1893, are not at the same distance. Stock 8 is probably located in the Perseus arm, but other nearby HII regions whose distances also place them in this arm show quite different distances and radial velocities and, therefore, are not connected.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/511/A38
- Title:
- Open clusters in third galactic quadrant
- Short Name:
- J/A+A/511/A38
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We aim to determine accurate distances and ages of eight open clusters in order to: (1) assess their possible binarity (2) provide probes to trace the structure of the Third Galactic Quadrant. Cluster reddenings, distances, ages and metallicities are derived from ZAMS and isochrone fits in UBVRI photometric diagrams. Field contamination is reduced by restricting analysis to stars within the cluster limits derived from star counts. Further membership control is done by requiring that stars have consistent positions in several diagrams and by using published spectral types.
- ID:
- ivo://CDS.VizieR/J/MNRAS/470/3937
- Title:
- 1876 open clusters multimembership catalog
- Short Name:
- J/MNRAS/470/3937
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The main objective of this work is to determine the cluster members of 1876 open clusters, using positions and proper motions of the astrometric fourth United States Naval Observatory (USNO) CCD Astrograph Catalog (UCAC4). For this purpose, we apply three different methods, all based on a Bayesian approach, but with different formulations: a purely parametric method, another completely non-parametric algorithm and a third, recently developed by Sampedro & Alfaro (2016MNRAS.457.3949S), using both formulations at different steps of the whole process. The first and second statistical moments of the members' phase-space subspace, obtained after applying the three methods, are compared for every cluster. Although, on average, the three methods yield similar results, there are also specific differences between them, as well as for some particular clusters. The comparison with other published catalogues shows good agreement. We have also estimated, for the first time, the mean proper motion for a sample of 18 clusters. The results are organized in a single catalogue formed by two main files, one with the most relevant information for each cluster, partially including that in UCAC4, and the other showing the individual membership probabilities for each star in the cluster area. The final catalogue, with an interface design that enables an easy interaction with the user, is available in electronic format at the Stellar Systems Group (SSG-IAA) web site (http://ssg.iaa.es/en/content/sampedro-cluster-catalog).
- ID:
- ivo://CDS.VizieR/J/A+A/652/A102
- Title:
- 3794 open clusters parameters
- Short Name:
- J/A+A/652/A102
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The structure and evolution of the spiral arms of the Milky Way are basic but long-standing questions in astronomy. Especially the lifetime of spiral arms, it is still a puzzle and has not been well constrained from observations. In this work, we aim to inspect these issues by using a large catalogue of open clusters. We have compiled a catalogue of 3794 OCs based on Gaia EDR3. A majority of them have accurately determined parallaxes, proper motions and radial velocities. The age parameters for these OCs are also collected or calculated. Then, we analysed their distributions on the Galactic plane, the kinematic properties, the vertical distributions and the regressed properties of subsamples of OCs in order to better understand the nearby spiral structure and its evolution. We find evidence that the nearby spiral arms are compatible with a long lived pattern and might have remained approximately stable for the past 80 million years. Especially, the Local Arm where our Sun is currently located in, is also suggested to be long-lived in nature, and probable a major arm segment in the Milky Way. The evolutionary characteristics of nearby spiral arms show that the dynamic spiral mechanism might be not suitable for our Galaxy. Instead, the density wave theory is more consistent with the observational properties.
- ID:
- ivo://CDS.VizieR/J/A+A/637/A95
- Title:
- 16 open clusters UBVI and Gaia DR2 photometry
- Short Name:
- J/A+A/637/A95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper has two main objectives: (1) To determine the intrinsic properties of sixteen faint and mostly unstudied open clusters in the poorly known sector of the Galaxy at 270{deg}-300{deg}, to probe the Milky Way structure in future investigations. (2) To address previously reported systematics in Gaia DR2 parallaxes by comparing the cluster distances derived from photometry with those derived from parallaxes. Deep UBVI photometry of 16 open clusters was carried out. Observations were reduced and analyzed in an automatic way using the ASteCA package to get individual distances, reddening, masses, ages and metallicities. Photometric distances were compared to those obtained from a Bayesian analysis of Gaia DR2 parallaxes. Ten out of the sixteen clusters are true or highly probable open clusters. Two of them are quite young and follow the trace of the Carina Arm and the already detected warp. The rest of the clusters are placed in the interarm zone between the Perseus and Carina Arms as expected for older objects. We found that the cluster van den Berg-Hagen 85 is 7.5x10^9^yrs old becoming then one of the oldest open cluster detected in our Galaxy so far. The relationship of these ten clusters with the Galaxy structure in the solar neighborhood is discussed. The comparison of distances from photometry and parallaxes data, in turn, reveals a variable level of disagreement. Various zero point corrections for Gaia DR2 parallax data recently reported were considered for a comparison between photometric and parallax based distances. The results tend to improve with some of these corrections. Photometric distance analysis suggest an average correction of ~+0.026mas (to be added to the parallaxes). The correction may have a more intricate distance dependency, but addressing that level of detail will require a larger cluster sample.
- ID:
- ivo://CDS.VizieR/J/A+A/640/A9
- Title:
- Open star cluster Coma Berenices multi-photometry
- Short Name:
- J/A+A/640/A9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We mainly aim to search for the lithium depletion boundary (LDB) among the sub-stellar population of the open star cluster Coma Berenices. Since the number of brown dwarf candidates in Coma Ber available in the literature is scarce, we carried out a search for additional candidates photometrically using colour-magnitude diagrams combining optical and infrared photometry from the latest public releases of the following large-scale surveys: the United Kingdom InfraRed Telescope Infrared Deep Sky Survey (UKIRT/UKIDSS), the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS), the Sloan Digital Sky Survey (SDSS), and AllWISE. We checked astrometric consistency with cluster membership using Gaia DR2. A search for Li in three new and five previously known brown dwarf candidate cluster members was performed via spectroscopic observations using the OSIRIS instrument at the 10.4m Gran Telescopio de Canarias (GTC). A couple dozen new photometric candidate brown dwarfs located inside the tidal radius of Coma Ber are reported, but none of these are significantly fainter and cooler than previously known members. No LiI resonance doublet at 6707.8{AA} was detected in any of eight Coma Ber targets in the magnitude range J=15-19 and G=20-23 observed with the GTC. Spectral types and radial velocities were derived from the GTC spectra. These values confirm the cluster membership of four L2-L2.5 dwarfs, two of which are new in the literature. The large Li depletion factors found among the four bona fide sub-stellar members in Coma Ber implies that the LDB must be located at spectral type later than L2.5 in this cluster. Using the latest evolutionary models for brown dwarfs, a lower limit of 550Myr on the cluster age is set. This constraint has been combined with other dating methods to obtain an updated age estimate of 780+/-230Myr for the Coma Ber open cluster. Identification of significantly cooler sub-stellar cluster members in Coma Ber awaits the advent of the Euclid wide survey, which should reach a depth of about J=23; this superb sensitivity will make it possible to determine the precise location of the sub-stellar LDB in this cluster and to carry out a complete census of its sub-stellar population.
- ID:
- ivo://CDS.VizieR/J/A+A/349/448
- Title:
- Open star clusters. I. NGC 581 (M 103)
- Short Name:
- J/A+A/349/448
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present CCD photometry and a proper motion study of the young open star cluster, NGC 581 (M 103). Fitting isochrones to the colour magnitude diagram, we found an age of 16+/-4Myr and a distance of roughly 3kpc for this cluster. The proper motion study identifies 77 stars of V=14.5mag or brighter to be cluster members. We combine membership determination by proper motions and statistical field star subtraction to derive the IMF of the cluster and find a quite steep slope of {Gamma}=-1.80.
- ID:
- ivo://CDS.VizieR/J/ApJ/809/59
- Title:
- Ophiuchus stellar stream with PS1 data
- Short Name:
- J/ApJ/809/59
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Ophiuchus stream is a recently discovered stellar tidal stream in the Milky Way. We present high-quality spectroscopic data for 14 stream member stars obtained using the Keck and MMT telescopes. We confirm the stream as a fast moving (v_los_~290km/s), kinematically cold group ({sigma}_{nu}_los__<~1km/s) of {alpha}-enhanced and metal-poor stars ([{alpha}/Fe]~0.4dex, [Fe/H]~-2.0dex). Using a probabilistic technique, we model the stream simultaneously in line-of-sight velocity, color-magnitude, coordinate, and proper motion space, and so determine its distribution in 6D phase-space. We find that the stream extends in distance from 7.5 to 9kpc from the Sun; it is 50 times longer than wide, merely appearing highly foreshortened in projection. The analysis of the stellar population contained in the stream suggests that it is ~12Gyr old, and that its initial stellar mass was ~2x10^4^M_{sun}_ (or at least >~7x10^3^M_{sun}_). Assuming a fiducial Milky Way potential, we fit an orbit to the stream that matches the observed phase-space distribution, except for some tension in the proper motions: the stream has an orbital period of ~350Myr, and is on a fairly eccentric orbit (e~0.66) with a pericenter of ~3.5kpc and an apocenter of ~17kpc. The phase-space structure and stellar population of the stream show that its progenitor must have been a globular cluster that was disrupted only ~240Myr ago. We do not detect any significant overdensity of stars along the stream that would indicate the presence of a progenitor, and conclude that the stream is all that is left of the progenitor.
- ID:
- ivo://CDS.VizieR/J/ApJ/884/L55
- Title:
- Opt. follow-up of galaxies within S190814bv region
- Short Name:
- J/ApJ/884/L55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- On 2019 August 14 the Laser Interferometer Gravitational Wave Observatory (LIGO) and the Virgo gravitational wave interferometer announced the detection of a binary merger, S190814bv, with a low false alarm rate of about 1 in 1.6x10^25^yr, a distance of 267+/-52Mpc, a 90% (50%) localization region of about 23 (5) deg^2^, and a probability of being a neutron star-black hole (NS-BH) merger of >99%. The LIGO/Virgo Collaboration (LVC) defines NS-BH such that the lighter binary member has a mass of <3M_{sun}_ and the more massive one has >5M_{sun}_, and this classification is in principle consistent with a BH-BH merger depending on the actual upper mass cutoff for neutron stars. Additionally, the LVC designated a probability that the merger led to matter outside the final BH remnant of <1%, suggesting that an electromagnetic (EM) counterpart is unlikely. Here we report our optical follow-up observations of S190814bv using the Magellan Baade 6.5m telescope to target all 96 galaxies in the Galaxy List for the Advanced Detector Era catalog within the 50% localization volume (representing about 70% of the integrated luminosity within this region). No counterpart was identified to a median 3{sigma} limiting magnitude of i=22.2 (M_i_~-14.9mag), comparable to the brightness of the optical counterpart of the binary neutron star merger GW170817 at the distance of S190814bv; similarly, we can rule out an on-axis jet typical of short GRBs. However, we cannot rule out other realistic models, such as a kilonova with only ~0.01M_{sun}_ of lanthanide-rich material, or an off-axis jet with a viewing angle of {theta}_obs_>~15{deg}.
- ID:
- ivo://CDS.VizieR/J/ApJ/848/L29
- Title:
- Opt. follow-up of GW170817 counterpart
- Short Name:
- J/ApJ/848/L29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of prompt optical follow-up of the electromagnetic counterpart of the gravitational-wave event GW170817 by the Transient Optical Robotic Observatory of the South Collaboration. We detected highly significant dimming in the light curves of the counterpart ({Delta}g=0.17+/-0.03mag, {Delta}r=0.14+/-0.02mag, {Delta}i=0.10+/-0.03mag) over the course of only 80 minutes of observations obtained ~35hr after the trigger with the T80-South telescope. A second epoch of observations, obtained ~59hr after the event with the EABA 1.5m telescope, confirms the fast fading nature of the transient. The observed colors of the counterpart suggest that this event was a "blue kilonova" relatively free of lanthanides.
