- ID:
- ivo://CDS.VizieR/J/A+A/635/A45
- Title:
- 570 new open clusters in the Galactic disc
- Short Name:
- J/A+A/635/A45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Open clusters are key targets for studies of Galaxy structure and evolution, and stellar physics. Since the Gaia data release 2 (DR2), the discovery of undetected clusters has shown that previous surveys were incomplete. Our aim is to exploit the Big Data capabilities of machine learning to detect new open clusters in Gaia DR2, and to complete the open cluster sample to enable further studies of the Galactic disc. We use a machine-learning based methodology to systematically search the Galactic disc for overdensities in the astrometric space and identify the open clusters using photometric information. First, we used an unsupervised clustering algorithm, DBSCAN, to blindly search for these overdensities in Gaia DR2 (l, b, varpi, mu_alpha_*, mu_delta_), then we used a deep learning artificial neural network trained on colour-magnitude diagrams to identify isochrone patterns in these overdensities, and to confirm them as open clusters. We find 570 new open clusters distributed along the Galactic disc in the region |b|<20{deg}. We detect substructure in complex regions, and identify the tidal tails of a disrupting cluster UBC 274 of ~3Gyr located at ~2kpc. Adapting the mentioned methodology to a Big Data environment allows us to target the search using the physical properties of open clusters instead of being driven by computational limitations. This blind search for open clusters in the Galactic disc increases the number of known open clusters by 45%.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/375/130
- Title:
- New PMS spectroscopic binaries in Orion
- Short Name:
- J/A+A/375/130
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Table 2 contains the heliocentric radial velocity data versus Heliocentric Julian Day for six X-ray selected double-lined spectroscopic binaries in Orion. Of these, the four systems RXJ 0529.4+0041, RXJ 0530.7-0434, RXJ 0532.1-0732, and RXJ 0541.4-0324 are pre-main sequence systems. Table 3 contains the radial velocity data for the third components of the spectroscopic systems RXJ 0441.0-0839, RXJ 0529.4+0041, and RXJ 0532.1-0732
- ID:
- ivo://CDS.VizieR/J/MNRAS/394/1249
- Title:
- New PNe in 6 early-type galaxies
- Short Name:
- J/MNRAS/394/1249
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new planetary nebulae (PNe) positions, radial velocities and magnitudes for six early-type galaxies obtained with the Planetary Nebulae Spectrograph (PNS), along with derived two-dimensional velocity and velocity dispersion fields, and the {alpha} parameters (i.e. the number of PNe per unit luminosity). We also present new deep absorption-line long-slit kinematics for three galaxies in the sample, obtained with the FOcal Reducer and low dispersion Spectrograph (FORS2) at the Very Large Telescope (VLT).
- ID:
- ivo://CDS.VizieR/J/ApJ/515/610
- Title:
- New PN in southern Galactic Bulge
- Short Name:
- J/ApJ/515/610
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a deep and uniform narrowband H{alpha} imaging survey for planetary nebulae (PNs) in the southern Galactic bulge. In our survey, we have found 56 new PNs and have rediscovered 45 known PNs. We have measured the radial velocities of this uniformly selected sample and have also remeasured radial velocities for a subset of 317 PNs from the Acker catalog. Using the COBE/DIRBE 1.25, 2.2, and 3.5{mu}m images, we show that there is a similar longitude distribution of the PNs and the COBE light in the zone of our deep survey. Also, we find that the extinction in our surveyed fields is not severe and that its distribution is fairly uniform. Finally, we present H{alpha} fluxes for 47 of our 56 newly discovered PNs and estimate the survey detection limit.
- ID:
- ivo://CDS.VizieR/J/ApJ/759/L41
- Title:
- New radial velocities of HD 97658
- Short Name:
- J/ApJ/759/L41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The radial velocity-discovered exoplanet HD 97658b was recently announced to transit, with a derived planetary radius of 2.93+/-0.28R_{oplus}_. As a transiting super-Earth orbiting a bright star, this planet would make an attractive candidate for additional observations, including studies of its atmospheric properties. We present and analyze follow-up photometric observations of the HD 97658 system acquired with the Microvariability and Oscillations of STars space telescope. Our results show no transit with the depth and ephemeris reported in the announcement paper. For the same ephemeris, we rule out transits for a planet with radius larger than 2.09R_{oplus}_, corresponding to the reported 3{sigma} lower limit. We also report new radial velocity measurements which continue to support the existence of an exoplanet with a period of 9.5 days, and obtain improved orbital parameters.
- ID:
- ivo://CDS.VizieR/J/A+A/540/A43
- Title:
- New redshifts for Abell 1758N galaxies
- Short Name:
- J/A+A/540/A43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The mechanisms producing the diffuse radio emission in galaxy clusters, and in particular their connection with cluster mergers, are still debated. We seek to explore the internal dynamics of the cluster Abell 1758N, which has been shown to host a radio halo and two relics, and is known to be a merging bimodal cluster. Our analysis is mainly based on new redshift data for 137 galaxies acquired at the Telescopio Nazionale Galileo, only four of which have redshifts previously listed in the literature. We also used photometric data from the Sloan Digital Sky Survey and from the Canada-France-Hawaii Telescope archive. We combined galaxy velocities and positions to select 92 cluster galaxies and analyzed the internal cluster dynamics.
- ID:
- ivo://CDS.VizieR/J/AJ/158/251
- Title:
- New reduction of UVES data for 35 M dwarfs
- Short Name:
- J/AJ/158/251
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The UVES (Ultraviolet and Visible Spectrometer) M Dwarf Planet Search program surveyed 40 M dwarfs and 1 M giant from 2000 through 2007 March. Two of the M dwarfs were double-lined spectroscopic binaries. The 38 single-lined M dwarfs in this survey are among the nearest and brightest M dwarfs. Starting with the reduced 1D spectra provided by the UVES team, we reanalyzed the UVES velocities of Proxima Cen as part of the "Pale Red Dot" program. The velocity rms decreased from 3.6 to 2.3 m/s. Motivated by this result, we have harvested all of the raw data from the UVES M Dwarf Planet Search from the European Southern Observatory (ESO) archives and have written custom packages to generate 1D spectra from the raw data, and velocities from the 1D spectra. The median improvement in the velocity rms from the new analysis is 1.8 m/s. Six of the 38 M dwarfs from the original study had a velocity rms<4 m/s. In the reanalysis presented here, 22 of these stars have a velocity rms<4 m/s. We improve the upper limits on possible planets orbiting these stars by a factor of typically two to three. For many of these M dwarfs, these observations represent the first epoch of high-precision velocity measurements.
- ID:
- ivo://CDS.VizieR/J/A+A/456/467
- Title:
- New sample of bright galaxy pairs in UZC
- Short Name:
- J/A+A/456/467
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new sample of bright galaxy pairs extracted applying an objective selection code to the UZC catalog. The sample is volume-limited to M_zw_=-18.9+5logh and contains 89 galaxy pairs. We analyze the kinematical, morphological, and photometrical properties of galaxies belonging to this sample.
- ID:
- ivo://CDS.VizieR/J/A+A/623/A129
- Title:
- New satellites of the LMC search
- Short Name:
- J/A+A/623/A129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A wealth of tiny galactic systems populates the surroundings of the Milky Way. However, some of these objects might have originated as former satellites of the Magellanic Clouds, in particular of the Large Magellanic Cloud (LMC). Examples of the importance of understanding how many systems are genuine satellites of the Milky Way or the LMC are the implications that the number and luminosity-mass function of satellites around hosts of different mass have for dark matter theories and the treatment of baryonic physics in simulations of structure formation. Here we aim at deriving the bulk motions and estimates of the internal velocity dispersion and metallicity properties in four recently discovered distant southern dwarf galaxy candidates, Columba I, Reticulum III, Phoenix II, and Horologium II. We combined Gaia DR2 astrometric measurements, photometry, and new FLAMES/GIRAFFE intermediate-resolution spectroscopic data in the region of the near-IR CaII triplet lines; this combination is essential for finding potential member stars in these low-luminosity systems. We find very likely member stars in all four satellites and are able to determine (or place limits on) the bulk motions and average internal properties of the systems. The systems are found to be very metal poor, in agreement with dwarf galaxies and dwarf galaxy candidates of similar luminosity. Of these four objects, we can only firmly place Phoenix II in the category of dwarf galaxies because of its resolved high velocity dispersion (9.5^+6.8^_-4.4_km/s) and intrinsic metallicity spread (0.33dex). For Columba I we also measure a clear metallicity spread. The orbital pole of Phoenix II is well constrained and close to that of the LMC, suggesting a prior association. The uncertainty on the orbital poles of the other systems is currently very large, so that an association cannot be excluded, except for Columba I. Using the numbers of potential former satellites of the LMC identified here and in the literature, we obtain for the LMC a dark matter mass of M_200_=1.9^+1.3^_-0.9_x10^11^M_{sun}_
- ID:
- ivo://CDS.VizieR/J/AJ/154/57
- Title:
- New SDSS and Washington photometry in Segue 3
- Short Name:
- J/AJ/154/57
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new SDSS and Washington photometry of the young outer-halo stellar system Segue 3. Combined with archival VI-observations, our most consistent results yield Z=0.006+/-0.001, log(Age)=9.42+/-0.08, (m-M)_0_=17.35+/-0.08, and E(B-V)=0.09+/-0.01, with a high binary fraction of 0.39+/-0.05 derived using the Padova models. We confirm that mass-segregation has occurred, supporting the hypothesis that this cluster is being tidally disrupted. A three-parameter King model yields a cluster radius of r_cl_=0.017{deg}+/-0.007{deg}, a core radius of r_c_=0.003{deg}+/-0.001{deg}, and a tidal radius of r_t_=0.04{deg}+/-0.02{deg}. A comparison of Padova and Dartmouth model-grids indicates that the cluster is not significantly {alpha}-enhanced, with a mean [Fe/H]=-0.55_-0.12_^+0.15^dex, and a population age of only 2.6+/-0.4Gyr. We rule out a statistically significant age spread at the main-sequence turnoff because of a narrow subgiant branch, and discuss the role of stellar rotation and cluster age, using Dartmouth and Geneva models: approximately 70% of the Seg 3 stars at or below the main-sequence turnoff have enhanced rotation. Our results for Segue 3 indicate that it is younger and more metal-rich than all previous studies have reported to date. From colors involving Washington C and SDSS-u filters, we identify several giants and a possible blue straggler for future follow-up spectroscopic studies, and we produce spectral energy distributions of previously known members and potential Segue 3 sources with Washington (CT_1_), Sloan (ugri), and VI-filters. Segue 3 shares the characteristics of unusual stellar systems that have likely been stripped from external dwarf galaxies as they are being accreted by the Milky Way, or that have been formed during such an event. Its youth, metallicity, and location are all inconsistent with Segue 3 being a cluster native to the Milky Way.
