- ID:
- ivo://CDS.VizieR/J/A+A/608/A68
- Title:
- TeV/non-TeV BL Lacs multi-lambda fluxes
- Short Name:
- J/A+A/608/A68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have collected the most complete multi-wavelength (6.0-6.0E^-18^cm) dataset of very high energy (VHE) gamma-ray emitting (TeV) BL Lacs, which are the most numerous extragalactic VHE sources. Using significant correlations between different bands, we aim to identify the best TeV BL Lac candidates that can be discovered by the current and next generation of imaging air Cherenkovtelescopes. We formed five datasets from lower energy data, i.e. radio, mid-infrared, optical, X-rays, and GeV gamma-ray, and five VHE gamma-ray datasets to perform a correlation study between different bands and to construct the prediction method. The low energy datasets were averaged for individual sources, while the VHE gamma-ray data were divided into subsets according to the flux state of the source. We then looked for significant correlations and determined their best-fit parameters. Using the best-fit parameters we predicted the level of VHE gamma-ray flux for a sample of 182 BL Lacs, which have not been detected at TeV energies. We identified the most promising TeV BL Lac candidates based on the predicted VHE gamma-ray flux for each source. We found 14 significant correlations between radio, mid-infrared, optical, gamma-ray, and VHE gamma-ray bands. The correlation between optical and VHE gamma-ray luminosity is established for the first time. We attribute this to the more complete sample and more accurate handling of host galaxy flux in our work. We found nine BL Lac candidates whose predicted VHE gamma-ray flux is high enough for detection in less than 25 hours with current imaging air Cherenkov telescopes.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/357/1231
- Title:
- Texas-Oxford NVSS (TONS) radio galaxies
- Short Name:
- J/MNRAS/357/1231
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a clustering analysis of the Texas-Oxford NVSS Structure (TONS) radio galaxy redshift survey. This complete flux-limited survey consists of 268 radio galaxies with spectroscopic redshifts in three separate regions of the sky covering a total of 165{deg}^2^. By going to faint radio flux densities (S_1.4_>=3mJy) but imposing relatively bright optical limits (E~R~19.5), the TONS sample is optimized for looking at the clustering properties of low-luminosity radio galaxies in a region of moderate (0<=z<=0.5) redshifts. Description:
- ID:
- ivo://CDS.VizieR/VIII/42
- Title:
- Texas Survey of radio sources at 365MHz
- Short Name:
- VIII/42
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the Texas Survey of discrete radio sources between -35.5deg and 71.5deg declination (B1950), which was carried out at 365MHz with the Texas Interferometer during 1974-1983. The Survey lists accurate positions with internal errors of about an arcsecond, flux densities which for strong point sources have internal errors of about 1% and total errors of about 5%, simple structure models and indications of spectrum and variability for 66841 sources. Results of comparisons with other data are presented, and show that the Survey is 90% complete at 0.4Jy and 80% complete at 0.25Jy, is nearly free from spurious sources, and has a lobeshift incidence which is reasonably described by quality flags associated with each source.
- ID:
- ivo://CDS.VizieR/J/A+A/653/A66
- Title:
- TEXES spectra of Saturn from February 03 2013
- Short Name:
- J/A+A/653/A66
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The abundance of deuterium in giant planet atmospheres provides constraints on the reservoirs of ices incorporated into these worlds during their formation and evolution. Motivated by discrepancies in the measured deuterium-hydrogen ratio (D/H) on Jupiter and Saturn, we present a new measurement of the D/H ratio in methane for Saturn from ground-based measurements. We analysed a spectral cube (covering 1151-1160cm^-1^ from 6 February 2013) from the Texas Echelon Cross Echelle Spectrograph (TEXES) on NASA's Infrared Telescope Facility (IRTF) where emission lines from both methane and deuterated methane are well resolved. Our estimate of the D/H ratio in stratospheric methane, 1.65(-0.21/+0.27)*10^-5^ is in agreement with results derived from Cassini CIRS and ISO/SWS observations, confirming the unexpectedly low CH3D abundance. Assuming a fractionation factor of 1.34(+/-0.19) we derive a hydrogen D/H of 1.23(-0.23/+0.27)*10^-5^. This value remains lower than previous tropospheric hydrogen D/H measurements of (i) Saturn 2.10(+/-0.13)*10^-5^, (ii) Jupiter 2.6(+/-0.7)*10^-5^ and (iii) the proto-solar hydrogen D/H of 2.1(+/-0.5)*10^-5^, suggesting that the fractionation factor may not be appropriate for stratospheric methane, or that the D/H ratio in Saturn's stratosphere is not representative of the bulk of the planet.
- ID:
- ivo://CDS.VizieR/J/A+A/605/A79
- Title:
- TGAS Cepheids and RR Lyrae stars
- Short Name:
- J/A+A/605/A79
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Parallaxes for 331 classical Cepheids, 31 Type II Cepheids and 364 RR Lyrae stars in common between Gaia and the Hipparcos and Tycho-2 catalogues are published in Gaia Data Release 1 (DR1) as part of the Tycho-Gaia Astrometric Solution (TGAS). In order to test these first parallax measurements of the primary standard candles of the cosmological distance ladder, that involve astrometry collected by Gaia during the initial 14 months of science operation, we compared them with literature estimates and derived new period-luminosity (PL), period-Wesenheit (PW) relations for classical and Type II Cepheids and infrared PL, PL-metallicity (PLZ) and optical luminosity-metallicity (MV-[Fe/H]) relations for the RR Lyrae stars, with zero points based on TGAS. The new relations were computed using multi-band (V, I, J, Ks, W1) photometry and spectroscopic metal abundances available in the literature, and applying three alternative approaches: (i) by linear least squares fitting the absolute magnitudes inferred from direct transformation of the TGAS parallaxes, (ii) by adopting astrometric-based luminosities, and (iii) using a Bayesian fitting approach. TGAS parallaxes bring a significant added value to the previous Hipparcos estimates. The relations presented in this paper represent first Gaia-calibrated relations and form a "work-in-progress" milestone report in the wait for Gaia-only parallaxes of which a first solution will become available with Gaia's Data Release 2 (DR2) in 2018.
18646. TGAS distances
- ID:
- ivo://CDS.VizieR/J/MNRAS/478/3809
- Title:
- TGAS distances
- Short Name:
- J/MNRAS/478/3809
- Date:
- 10 Dec 2021 00:51:19
- Publisher:
- CDS
- Description:
- We derive unbiased distance estimates for the Gaia-TGAS data set by correcting for the bias due to the distance dependence of the selection function, which we measure directly from the data. From these distances and proper motions, we estimate the vertical and azimuthal velocities, W and V_{phi}_, and angular momentum L_z_ for stars in the Galactic centre and anticentre directions. The resulting mean vertical motion W^-^ hows a linear increase with both V_{phi}_ and L_z_ at 10{sigma} significance. Such a trend is expected from and consistent with the known Galactic warp. This signal extends to stars with guiding centre radii R_g_<R_0_, placing the onset of the warp at R<=7kpc. At equally high significance, we detect a previously unknown wave-like pattern of W^-^ over guiding centre R_g_ with an amplitude ~1km/s and a wavelength ~2.5kpc. This pattern is present in both the centre and anticentre directions, consistent with a winding (corrugated) warp or bending wave, likely related to known features in the outer disc (TriAnd and Monoceros overdensities), and may be caused by the interaction with the Sgr dwarf galaxy ~1Gyr ago. The only significant deviation from this simple fit is a stream-like feature near R_g_~9kpc (|L_z_|~2150kpc.km/s).
- ID:
- ivo://CDS.VizieR/J/A+A/615/A49
- Title:
- TGAS stars membership in 128 open clusters
- Short Name:
- J/A+A/615/A49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Tycho-Gaia Astrometric Solution (TGAS) subset of the first Gaia catalogue contains an unprecedented sample of proper motions and parallaxes for two million stars brighter than G~12 mag. We take advantage of the full astrometric solution available for those stars to identify the members of known open clusters and compute mean cluster parameters using either TGAS or UCAC4 proper motions, and TGAS parallaxes. We apply an unsupervised membership assignment procedure to select high probability cluster members, we use a Bayesian/MCMC technique to fit stellar isochrones to the observed 2MASS JHK magnitudes of the member stars and derive cluster parameters (age, metallicity, extinction, distance modulus), and we combine TGAS data with spectroscopic radial velocities to compute full Galactic orbits. We obtain mean astrometric parameters (proper motions and parallaxes) for 128 clusters closer than about 2kpc, and cluster parameters from isochrone fitting for 26 of them located inside 1kpc from us. We show the orbital parameters obtained from integrating 36 orbits in a Galactic potential.
- ID:
- ivo://CDS.VizieR/J/BaltA/20/317
- Title:
- TGU 619 stars spectral types and distances
- Short Name:
- J/BaltA/20/317
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Interstellar extinction is investigated in a 1.5 square degree area of the Cepheus Flare in the direction of the dark cloud TGU 619 at l=102.5{deg}, b=+15.5{deg} . The study is based on photometric classification of 658 stars in spectral and luminosity classes down to V=16mag using photometry in the Vilnius seven-color system published in Paper I (2009BaltA..18..161Z, Cat. J/BaltA/18/161). The extinction in the investigated area is very uneven: in the most transparent directions we find an extinction of 0.3-1.1mag while in the darkest directions the maximum extinction observed is 2.6mag. The real extinction should be considerably larger since in the direction of some cloud clumps no stars are seen. The distribution of stars in the AV vs. d plot gives evidence that the dust clouds are located at a distance of 286+/-20pc.
18649. TGU 619 Vilnius photometry
- ID:
- ivo://CDS.VizieR/J/BaltA/18/161
- Title:
- TGU 619 Vilnius photometry
- Short Name:
- J/BaltA/18/161
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog contains magnitudes and color indices of 1304 stars down to ~16.6mag in V measured in the seven-color Vilnius photometric system in the area of 1.5 square degrees with the center at Galactic coordinates 102.4{deg}, +15.5{deg}, containing the dark cloud TGU619 in the Cepheus Flare. For most of the stars spectral and luminosity classes determined from the photometric data are given.
- ID:
- ivo://CDS.VizieR/III/215
- Title:
- 7th Catalog of Galactic Wolf-Rayet stars
- Short Name:
- III/215
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The VIIth catalogue of galactic Population I Wolf Rayet stars provides improved coordinates, spectral types and bv photometry of known WR stars and adds 71 new WR stars to the previous WR catalogue. This census of galactic WR stars reaches 227 stars, comprising 127 WN stars, 87 WC stars, 10 WN/WC stars and 3 WO stars. This includes 15 WNL and 11 WCL stars within 30 pc of the Galactic Center. We compile and discuss WR spectral classification, variability, periodicity, binarity, terminal wind velocities, correlation with open clusters and OB associations, and correlation with H I bubbles, H II regions and ring nebulae. Intrinsic colours and absolute visual magnitudes per subtype are re-assessed for a re-determination of optical photometric distances and galactic distribution of WR stars. In the solar neighbourhood we find projected on the galactic plane a surface density of 3.3 WR stars per kpc^2^, with a WC/WN number ratio of 1.5, and a WR binary frequency (including probable binaries) of 39%. The galactocentric distance (R_WR_) distribution per subtype shows R_WR_ increasing with decreasing WR subtype, both for the WN and WC subtypes. This R_WR_ distribution allows for the possibility of WNE->WCE and WNL->WCL subtype evolution. The successive catalogues of galactic WR stars are: I 55 stars Campbell, 1884 Astronomy and Astrophysics 13, 448 (Northfield, Minn: Goodsell Observatory) II 108 stars Fleming, 1912 Harvard College Obs. Ann. 56, 165 III 92 stars Payne, 1930 The Stars of High Luminosity, Harvard Obs. Monographs No. 3, p. 19 IV 123 stars Roberts, 1962AJ.....67...79R V 127 stars Smith, 1968MNRAS.138..109S VI 157 stars van der Hucht et al., 1981SSRv...28..227V VII 227 stars van der Hucht, 2001NewAR..45..135V, this paper