- 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
1162. New Ori OB1 members
- ID:
- ivo://CDS.VizieR/J/AJ/129/907
- Title:
- New Ori OB1 members
- Short Name:
- J/AJ/129/907
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of a large-scale, multi-epoch optical survey of the Orion OB1 association, carried out with the QUEST camera at the Venezuela National Astronomical Observatory (CIDA). We identify for the first time the widely spread low-mass, young population in the Ori OB1a and OB1b subassociations. Candidate members were picked up by their variability in the V band and position in color-magnitude diagrams. We obtained spectra to confirm membership. In a region spanning ~68{deg}^2^, we found 197 new young stars; of these, 56 are located in the Ori OB1a subassociation and 141 in Ori OB1b.
- ID:
- ivo://CDS.VizieR/J/ApJ/753/27
- Title:
- New point sources in the WMAP 7yr data
- Short Name:
- J/ApJ/753/27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have developed a new needlet-based method to detect point sources in cosmic microwave background (CMB) maps and have applied it to the Wilkinson Microwave Anisotropy Probe (WMAP) 7 year data. We use both the individual frequency channels as well as internal templates, the latter being the difference between pairs of frequency channels and hence having the advantage that the CMB component is eliminated. Using the area of the sky outside the Kq85 galactic mask, we detect a total of 2102 point sources at the 5{sigma} level in either the frequency maps or the internal templates. Of these, 1116 are detected either at 5{sigma} directly in the frequency channels or at 5{sigma} in the internal templates and >=3{sigma} at the corresponding position in the frequency channels. Of the 1116 sources, 603 are detections that have not been reported so far in WMAP data. We have made a catalog of these sources available with position and flux estimated in the WMAP channels where they are seen. In total, we identified 1029 of the 1116 sources with counterparts at 5GHz and 69 at other frequencies.
- ID:
- ivo://CDS.VizieR/J/ApJS/170/108
- Title:
- NEWPS_5{sigma}_ source catalogue from WMAP
- Short Name:
- J/ApJS/170/108
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used the MHW2 filter to obtain estimates of the flux densities at the WMAP frequencies of a complete sample of 2491 sources, mostly brighter than 500mJy at 5GHz, distributed over the whole sky excluding a strip around the Galactic equator (|b|<=5{deg}). After having detected 933 sources at the >=3{sigma} level in the MHW2 filtered maps-our New Extragalactic WMAP Point Source Catalogue (NEWPS_3{sigma}_)-we are left with 381 sources at >=5{sigma} in at least one WMAP channel, 369 of which constitute our NEWPS_5{sigma}_ catalog. It is remarkable to note that 98 (i.e., 26%) sources detected at are "new," they are not present in the WMAP catalog.
- ID:
- ivo://CDS.VizieR/J/ApJS/253/48
- Title:
- New rotation measures from the CGPS
- Short Name:
- J/ApJS/253/48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Faraday rotation provides a valuable tracer of magnetic fields in the interstellar medium; catalogs of Faraday rotation measures provide key observations for studies of the Galactic magnetic field. We present a new catalog of rotation measures derived from the Canadian Galactic Plane Survey, covering a large region of the Galactic plane spanning 52{deg}<l<192{deg}, -3{deg}<b<5{deg}, along with northern and southern latitude extensions around l~105{deg}. We have derived rotation measures for 2234 sources (4 of which are known pulsars), 75% of which have no previous measurements, over an area of approximately 1300deg^2^. These new rotation measures increase the measurement density for this region of the Galactic plane by a factor of 2.
1166. NEWS catalog
- ID:
- ivo://CDS.VizieR/J/A+A/644/A69
- Title:
- NEWS catalog
- Short Name:
- J/A+A/644/A69
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalogue of candidates in extragalactic objects -- the Northern Extragalactic WISExPan-STARRS (NEWS), which covers almost 3/4 of the sky in a broad optical-infrared spectral range, with a depth of up to 23mag in optical filter g. To create the NEWS catalogue, we used the mid-IR data of the WISE survey (W1,W2) paired up with photometric information of the Pan-STARRS DR1 survey in the optical and near-IR (g,r,i,z,y) spectral ranges. Our catalogue is the result of a classification of the WISExPan-STARRS objects with the SVM machine-learning algorithm. The classification was based solely on photometric information and the automatic creation of features that was carried out using an autoencoder neural network. NEWS catalogue contains 40,350,492 extragalactic objects (galaxies and quasars), identified with a high classification quality (>98%).
1167. New SNe in SDSS DR9
- ID:
- ivo://CDS.VizieR/J/MNRAS/450/905
- Title:
- New SNe in SDSS DR9
- Short Name:
- J/MNRAS/450/905
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using a method to discover and classify supernovae (SNe) in galaxy spectra, we detect 91 Type Ia SNe (SNe Ia) and 16 Type II SNe (SNe II) among ~740000 galaxies of all types and ~215000 star-forming galaxies without active galactic nuclei, respectively, in Data Release 9 of the Sloan Digital Sky Survey. Of these SNe, 15 SNe Ia and eight SNe II are new discoveries reported here for the first time. We use our SN samples to measure SN rates per unit mass as a function of galaxy stellar mass, star-formation rate (SFR), and specific SFR (sSFR), as derived by the MPA-JHU Galspec pipeline. We show that correlations between SN Ia and SN II rates per unit mass and galaxy stellar mass, SFR, and sSFR can be explained by a combination of the respective SN delay-time distributions (the distributions of times that elapse between the formation of a stellar population and all ensuing SNe), the ages of the surveyed galaxies, the redshifts at which they are observed, and their star formation histories.
- ID:
- ivo://CDS.VizieR/J/A+A/567/A26
- Title:
- New standards in 18th century astrometry
- Short Name:
- J/A+A/567/A26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The present high accuracy of stellar positions and proper motions allows us to determine the positional accuracy of old stellar catalogues. This has already been done for the most important catalogues from before the 18th century. Our aim is to extend this study to several 18th century catalogues. To do this, I studied ten catalogues: those of Flamsteed and Romer, four catalogues of La Caille, and catalogues of Tobias Mayer, Bradley, Piazzi, and Lalande. A comparison with modern data, mostly from Hipparcos, compiled in the Simbad data base of the CDS allowed me to determine the position errors of these catalogues. I also compared the stellar visual magnitudes given in eight of these catalogues with photometric V magnitudes. Thanks to novel instruments, the r.m.s. positional accuracy improved from thousands to hundreds of arc seconds in older catalogues to less than one minute in that of Flamsteed, and to 2-6 arcseconds in the other catalogues I examined. These improvements allowed for the first time relatively accurate proper motions to be determined by 19th century astronomers.
- ID:
- ivo://CDS.VizieR/J/AJ/142/77
- Title:
- New T dwarfs identified in Pan-STARRS 1
- Short Name:
- J/AJ/142/77
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A complete well-defined sample of ultracool dwarfs is one of the key science programs of the Pan-STARRS 1 optical survey telescope (PS1). Here we combine PS1 commissioning data with the Two Micron All Sky Survey (2MASS) to conduct a proper motion search (0.1-2.0"/yr) for nearby T dwarfs, using optical+near-IR colors to select objects for spectroscopic follow-up. The addition of sensitive far-red optical imaging from PS1 enables discovery of nearby ultracool dwarfs that cannot be identified from 2MASS data alone. We have searched 3700deg^2^ of PS1 y-band (0.95-1.03um) data to y~19.5mag (AB) and J~16.5mag (Vega) and discovered four previously unknown bright T dwarfs. Three of the objects (with spectral types T1.5, T2, and T3.5) have photometric distances within 25pc and were missed by previous 2MASS searches due to more restrictive color selection criteria. The fourth object (spectral type T4.5) is more distant than 25pc and is only a single-band detection in 2MASS. We also examine the potential for completing the census of nearby ultracool objects with the PS1 3{PI} survey.
1170. New ultracool subdwarfs
- ID:
- ivo://CDS.VizieR/J/A+A/598/A92
- Title:
- New ultracool subdwarfs
- Short Name:
- J/A+A/598/A92
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We developed an efficient method to search for late-type subdwarfs. We carried out a search cross-matching SDSS, 2MASS, and UKIDSS with VO tools. We considered different photometric and proper motion criteria for our selection. We identified 100 late-type subdwarf candidates. We obtained our own low-resolution optical spectra for 71 of our candidates and retrieved Sloan spectra for 30 of them (9 in common to the 71). We classified 92 candidates based on optical spectra. Our new discoveries include 49 subdwarfs, 25 extreme subdwarfs, six ultrasubdwarfs, one subdwarf/extreme subdwarf, and two dwarfs/subdwarfs. In addition, we discovered three early-L subdwarfs. We double the numbers of cool subdwarfs and derived a surface density of late-type subdwarfs.
