- ID:
- ivo://CDS.VizieR/J/MNRAS/505/1135
- Title:
- Gaia/IPHAS catalogue of Ha-excess sources
- Short Name:
- J/MNRAS/505/1135
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We present a catalogue of point-like H{alpha}-excess sources in the Northern Galactic Plane. Our catalogue is created using a new technique that leverages astrometric and photometric information from Gaia to select H{alpha}-bright outliers in the INT Photometric H{alpha} Survey of the Northern Galactic Plane (IPHAS), across the colour-absolute magnitude diagram. To mitigate the selection biases due to stellar population mixing and to extinction, the investigated objects are first partitioned with respect to their positions in the Gaia colour-absolute magnitude space, and in the Galactic coordinates space, respectively. The selection is then performed on both partition types independently. Two significance parameters are assigned to each target, one for each partition type. These represent a quantitative degree of confidence that the given source is a reliable H{alpha}-excess candidate, with reference to the other objects in the corresponding partition. Our catalogue provides two flags for each source, both indicating the significance level of the H{alpha}-excess. By analysing their intensity in the H{alpha} narrow band, 28496 objects out of 7474835 are identified as H{alpha}-excess candidates with a significance higher than 3. The completeness fraction of the H{alpha} outliers selection is between 3% and 5%. The suggested 5sigma conservative cut yields a purity fraction of 81.9%.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/IV/36
- Title:
- Gaia-IPHAS/KIS Value-Added Catalogues
- Short Name:
- IV/36
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a sub-arcsecond cross-match of Gaia DR2 (Cat. I/345) against the INT Photometric H-alpha Survey of the Northern Galactic Plane Data Release 2 (IPHAS DR2, Cat. II/321) and the Kepler-INT Survey (KIS, Cat. J/AJ/144/24). The resulting value-added catalogues (VACs) provide additional precise photometry to the Gaia photometry (r, i and H-alpha for IPHAS, with additional U and g for KIS). In building the catalogue, proper motions given in Gaia DR2 are wound back to match the epochs of IPHAS DR2, thus ensuring high proper motion objects are appropriately cross-matched. The catalogues contain 7927224 and 791071 sources for IPHAS and KIS, respectively. The requirement of >5 sigma parallax detection for every included source means that distances out to 1-1.5kpc are well covered. We define two additional parameters for each catalogued object: (i) fc, a magnitude-dependent tracer of the quality of the Gaia astrometric fit; (ii) fFP, the false-positive rate for parallax measurements determined from astrometric fits of a given quality at a given magnitude. Selection cuts based on these parameters can be used to clean colour-magnitude and colour-colour diagrams in a controlled and justified manner. We provide both full and light versions of the VAC, with VAC-light containing only objects that represent our recommended trade-off between purity and completeness. Uses of the catalogues include the identification of new variable stars in the matched data sets, and more complete identification of H-alpha-excess emission objects thanks to separation of high-luminosity stars from the main sequence.
- ID:
- ivo://CDS.VizieR/J/AJ/160/108
- Title:
- Gaia-Kepler stellar properties catalog. II. Planets
- Short Name:
- J/AJ/160/108
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Studies of exoplanet demographics require large samples and precise constraints on exoplanet host stars. Using the homogeneous Kepler stellar properties derived using the Gaia Data Release 2 by Berger et al., we recompute Kepler planet radii and incident fluxes and investigate their distributions with stellar mass and age. We measure the stellar mass dependence of the planet radius valley to be dlogR_p/d_logM_{star}_=0.26_-0.16_^+0.21^, consistent with the slope predicted by a planet mass dependence on stellar mass (0.24-0.35) and core-powered mass loss (0.33). We also find the first evidence of a stellar age dependence of the planet populations straddling the radius valley. Specifically, we determine that the fraction of super-Earths (1-1.8{R_{Earth}_) to sub-Neptunes (1.8-3.5R_{Earth}_) increases from 0.61{+/-}0.09 at young ages (<1Gyr) to 1.00{+/-}0.10 at old ages (>1Gyr), consistent with the prediction by core-powered mass loss that the mechanism shaping the radius valley operates over Gyr timescales. Additionally, we find a tentative decrease in the radii of relatively cool (Fp<150{F}_{Earth}_) sub-Neptunes over Gyr timescales, which suggests that these planets may possess H/He envelopes instead of higher mean molecular weight atmospheres. We confirm the existence of planets within the hot sub-Neptunian "desert" (2.2R_{Earth}_<Rp<3.8R_{Earth}_, Fp>650F_{Earth}_) and show that these planets are preferentially orbiting more evolved stars compared to other planets at similar incident fluxes. In addition, we identify candidates for cool (Fp<20F_{Earth}_) inflated Jupiters, present a revised list of habitable zone candidates, and find that the ages of single and multiple transiting planet systems are statistically indistinguishable.
- ID:
- ivo://CDS.VizieR/J/AJ/159/280
- Title:
- Gaia-Kepler stellar properties catalog.I. KIC stars
- Short Name:
- J/AJ/159/280
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An accurate and precise Kepler Stellar Properties Catalog is essential for the interpretation of the Kepler exoplanet survey results. Previous Kepler Stellar Properties Catalogs have focused on reporting the best-available parameters for each star, but this has required combining data from a variety of heterogeneous sources. We present the Gaia-Kepler Stellar Properties Catalog, a set of stellar properties of 186301 Kepler stars, homogeneously derived from isochrones and broadband photometry, Gaia Data Release 2 parallaxes, and spectroscopic metallicities, where available. Our photometric effective temperatures, derived from g to Ks colors, are calibrated on stars with interferometric angular diameters. Median catalog uncertainties are 112K for Teff, 0.05dex for logg, 4% for R_*_, 7% for M_*_, 13% for {rho}_*_, 10% for L_*_, and 56% for stellar age. These precise constraints on stellar properties for this sample of stars will allow unprecedented investigations into trends in stellar and exoplanet properties as a function of stellar mass and age. In addition, our homogeneous parameter determinations will permit more accurate calculations of planet occurrence and trends with stellar properties.
- ID:
- ivo://CDS.VizieR/J/ApJ/867/L8
- Title:
- Gaia kinematic data of runaway & field OB stars in SMC
- Short Name:
- J/ApJ/867/L8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use Gaia Data Release 2 proper motions of field OB stars from the Runaways and Isolated O-Type Star Spectroscopic Survey of the Small Magellanic Cloud (SMC) to study the kinematics of runaway stars. The data reveal that the SMC Wing has a systemic peculiar motion relative to the SMC Bar of (v_{alpha}_,v_{delta}_)=(62+/-7,-18+/-5)km/s and relative radial velocity +4.5+/-5.0km/s. This unambiguously demonstrates that these two regions are kinematically distinct: the Wing is moving away from the Bar, and towards the Large Magellanic Cloud with a 3D velocity of 64+/-10km/s. This is consistent with models for a recent, direct collision between the Clouds. We present transverse velocity distributions for our field OB stars, confirming that unbound runaways comprise on the order of half our sample, possibly more. Using eclipsing binaries and double-lined spectroscopic binaries as tracers of dynamically ejected runaways, and high-mass X-ray binaries (HMXBs) as tracers of runaways accelerated by supernova kicks, we find significant contributions from both populations. The data suggest that HMXBs have lower velocity dispersion relative to dynamically ejected binaries, consistent with the former group corresponding to less energetic supernova kicks that failed to unbind the components. Evidence suggests that our fast runaways are dominated by dynamical, rather than supernova, ejections.
- ID:
- ivo://CDS.VizieR/J/A+A/606/A92
- Title:
- Gaia LMC eclipsing binary and multiple systems
- Short Name:
- J/A+A/606/A92
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The advent of large scale multi-epoch surveys raises the need for automated light curve (LC) processing. This is particularly true for eclipsing binaries (EBs), which form one of the most populated types of variable objects. The Gaia mission, launched at the end of 2013, is expected to detect of the order of few million EBs over a 5-year mission. We present an automated procedure to characterize EBs based on the geometric morphology of their LCs with two aims: first to study an ensemble of EBs on a statistical ground without the need to model the binary system, and second to enable the automated identification of EBs that display atypical LCs. We model the folded LC geometry of EBs using up to two Gaussian functions for the eclipses and a cosine function for any ellipsoidal-like variability that may be present between the eclipses. The procedure is applied to the OGLE-III data set of EBs in the Large Magellanic Cloud (LMC) as a proof of concept. The bayesian information criterion is used to select the best model among models containing various combinations of those components, as well as to estimate the significance of the components. Based on the two-Gaussian models, EBs with atypical LC geometries are successfully identified in two diagrams, using the Abbe values of the original and residual folded LCs, and the reduced chi^2^. Cleaning the data set from the atypical cases and further filtering out LCs that contain non-significant eclipse candidates, the ensemble of EBs can be studied on a statistical ground using the two-Gaussian model parameters. For illustration purposes, we present the distribution of projected eccentricities as a function of orbital period for the OGLE-III set of EBs in the LMC, as well as the distribution of their primary versus secondary eclipse widths.
- ID:
- ivo://CDS.VizieR/J/MNRAS/481/307
- Title:
- Gaia Nuclear Transient (GNT) cand.
- Short Name:
- J/MNRAS/481/307
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The high spatial resolution and precise astrometry and photometry of the Gaia mission should make it particularly apt at discovering and resolving transients occurring in, or near, the centres of galaxies. Indeed, some nuclear transients are reported by the Gaia Science Alerts (GSA) team, but not a single confirmed tidal disruption event (TDE) has been published. In order to explore the sensitivity of GSA, we performed an independent and systematic search for nuclear transients using Gaia observations. Our transient search is driven from an input galaxy catalogue (derived from the Sloan Digital Sky Survey Release 12). We present a candidate detection metric that is independent from the existing GSA methodology, to see if Gaia Alerts are biased against the discovery of nuclear transients, and in particular which steps may have an impact. Our technique does require significant manual vetting of candidates, making implementation in the GSA system impractical for daily operations, although it could be run weekly, which for month-to-year long transients would make a scientifically valuable addition. Our search yielded 480 nuclear transients, 5 of which were alerted and published by GSA. The list of (in some cases ongoing) transients includes candidates for events related to enhanced accretion on to a super-massive black hole and TDEs. An implementation of the detection methodology and criteria used in this paper as an extension of GSA could open up the possibility for Gaia to fulfil the role as a main tool to find transient nuclear activity as predicted in the literature.
- ID:
- ivo://CDS.VizieR/J/A+A/652/A76
- Title:
- Gaia Photometric Science Alerts
- Short Name:
- J/A+A/652/A76
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Since July 2014, the Gaia mission has been engaged in a high-spatial- resolution, time-resolved, precise, accurate astrometric, and photometric survey of the entire sky. We present the Gaia Science Alerts project, which has been in operation since 1 June 2016. We describe the system which has been developed to enable the discovery and publication of transient photometric events as seen by Gaia. We outline the data handling, timings, and performances, and we describe the transient detection algorithms and filtering procedures needed to manage the high false alarm rate. We identify two classes of events: (1) sources which are new to Gaia and (2) Gaia sources which have undergone a significant brightening or fading. Validation of the Gaia transit astrometry and photometry was performed, followed by testing of the source environment to minimise contamination from Solar System objects, bright stars, and fainter near-neighbours. We show that the Gaia Science Alerts project suffers from very low contamination, that is there are very few false- positives. We find that the external completeness for supernovae, C_E_=0.46, is dominated by the Gaia scanning law and the requirement of detections from both fields-of-view. Where we have two or more scans the internal completeness is C_I_=0.79 at 3 arcsec or larger from the centres of galaxies, but it drops closer in, especially within 1 arcsec. The per-transit photometry for Gaia transients is precise to 1 per cent at G=13, and 3 per cent at G=19. The per- transit astrometry is accurate to 55 milliarcseconds when compared to Gaia DR2. The Gaia Science Alerts project is one of the most homogeneous and productive transient surveys in operation, and it is the only survey which covers the whole sky at high spatial resolution (subarcsecond), including the Galactic plane and bulge.
- ID:
- ivo://CDS.VizieR/J/A+A/620/A155
- Title:
- Gaia proper motions of 7 UFD galaxies
- Short Name:
- J/A+A/620/A155
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present mean absolute proper motion measurements for seven ultra- faint dwarf galaxies orbiting the Milky Way, namely Bootes III, Carina II, Grus II, Reticulum II, Sagittarius II, Segue 2 and Tucana IV. For four of these dwarfs our proper motion estimate is the first ever provided. The adopted astrometric data come from the second data release of the Gaia mission. We determine the mean proper motion for each galaxy starting from an initial guess of likely members, based either on radial velocity measurements or using stars on the Horizontal Branch identified in the Gaia (G_BP_-G_RP_, G) colour-magnitude diagram in the field of view towards the UFD. We then refine their membership iteratively using both astrometry and photometry. We take into account the full covariance matrix among the astrometric parameters when deriving the mean proper motions for these systems. Our procedure provides mean proper motions with typical uncertainties of ~0.1mas/yr, even for galaxies without prior spectroscopic information. In the case of Segue 2 we find that using radial velocity members only leads to biased results, presumably because of the small number of stars with measured radial velocities. Conclusions: our procedure allows to maximize the number of member stars per galaxy regardless of the existence of prior spectroscopic information, and can therefore be applied on any faint or distant stellar system within reach of Gaia.
- ID:
- ivo://CDS.VizieR/I/343
- Title:
- Gaia-PS1-SDSS (GPS1) proper motion catalog
- Short Name:
- I/343
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We combine Gaia DR1, PS1, Sloan Digital Sky Survey (SDSS), and 2MASS astrometry to measure proper motions for 350 million sources across three-fourths of the sky down to a magnitude of m_r_~20. Using positions of galaxies from PS1, we build a common reference frame for the multi-epoch PS1, single-epoch SDSS and 2MASS data, and calibrate the data in small angular patches to this frame. As the Gaia DR1 excludes resolved galaxy images, we choose a different approach to calibrate its positions to this reference frame: we exploit the fact that the proper motions of stars in these patches are linear. By simultaneously fitting the positions of stars at different epochs of-Gaia DR1, PS1, SDSS, and 2MASS-we construct an extensive catalog of proper motions dubbed GPS1. GPS1 has a characteristic systematic error of less than 0.3mas/yr and a typical precision of 1.5-2.0mas/yr. The proper motions have been validated using galaxies, open clusters, distant giant stars, and QSOs. In comparison with other published faint proper motion catalogs, GPS1's systematic error (<0.3mas/yr) should be nearly an order of magnitude better than that of PPMXL and UCAC4 (>2.0mas/yr). Similarly, its precision (~1.5mas/yr) is a four-fold improvement relative to PPMXL and UCAC4 (~6.0mas/yr). For QSOs, the precision of GPS1 is found to be worse (~2.0-3.0mas/yr), possibly due to their particular differential chromatic refraction.