- ID:
- ivo://CDS.VizieR/J/MNRAS/417/1210
- Title:
- DA-white dwarfs from SDSS and UKIDSS
- Short Name:
- J/MNRAS/417/1210
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a method which uses colour-colour cuts on the Sloan Digital Sky Survey (SDSS) photometry to select white dwarfs with hydrogen-rich (DA) atmospheres without the recourse to spectroscopy. This method results in a sample of DA white dwarfs that is 95 per cent complete at an efficiency of returning a true DA white dwarf of 62 per cent. The approach was applied to SDSS Data Release 7 for objects with and without SDSS spectroscopy.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/148/3
- Title:
- Debris disk candidates detected with AKARI/FIS
- Short Name:
- J/AJ/148/3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We cross-correlate the Hipparcos main-sequence star catalog with the AKARI/FIS catalog and identify 136 stars (at >90% reliability) with far-infrared detections in at least one band. After rejecting 57 stars classified as young stellar objects, Be stars and other type stars with known dust disks or with potential contaminations, and 4 stars without infrared excess emission, we obtain a sample of 75 candidate stars with debris disks. Stars in our sample cover spectral types from B to K with most being early types. This represents a unique sample of luminous debris disks that derived uniformly from an all-sky survey with a spatial resolution factor of four better than the previous such survey by IRAS. Moreover, by collecting the infrared photometric data from other public archives, almost three-quarters of them have infrared excesses in more than one band, allowing an estimate of the dust temperatures. We fit the blackbody model to the broadband spectral energy distribution of these stars to derive the statistical distribution of the disk parameters. Four B stars with excesses in four or more bands require a double blackbody model, with the high one around 100 or 200K and the low one around 40-50K.
- ID:
- ivo://CDS.VizieR/J/ApJ/636/1098
- Title:
- Debris disks around solar-type stars
- Short Name:
- J/ApJ/636/1098
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have searched for infrared excesses around a well-defined sample of 69 FGK main-sequence field stars. These stars were selected without regard to their age, metallicity, or any previous detection of IR excess; they have a median age of 4Gyr.
- ID:
- ivo://CDS.VizieR/J/MNRAS/478/3721
- Title:
- Deep ALMA photometry of distant X-ray AGN
- Short Name:
- J/MNRAS/478/3721
- Date:
- 10 Dec 2021 00:23:44
- Publisher:
- CDS
- Description:
- We present the star formation rates (SFRs) of a sample of 109 galaxies with X-ray-selected active galactic nuclei (AGNs) with moderate to high X-ray luminosities (L_2-8keV_=10^42^-10^45^erg/s), at redshifts 1<z<4.7, that were selected to be faint or undetected in the Herschel bands. We combine our deep Atacama large (sub-)millimetre array (ALMA) continuum observations with deblended 8-500um photometry from Spitzer and Herschel, and use infrared (IR) spectral energy distribution (SED) fitting and AGN - star formation decomposition methods. The addition of the ALMA photometry results in an order of magnitude more X-ray AGN in our sample with a measured SFR (now 37%). The remaining 63 % of the sources have SFR upper limits that are typically a factor of 2-10 times lower than the pre-ALMA constraints. With the improved constraints on the IR SEDs, we can now identify a mid-IR (MIR) AGN component in 50% of our sample, compared to only ~1% previously. We further explore the F_870um_/F_24um_ -redshift plane as a tool for the identification of MIR-emitting AGN, for three different samples representing AGN-dominated, star formation-dominated, and composite sources. We demonstrate that the F_870um_/F_24um_ -redshift plane can successfully split between AGN and star formation-dominated sources, and can be used as an AGN identification method.
- ID:
- ivo://CDS.VizieR/J/AJ/132/2409
- Title:
- Deep ATLAS radio observations of CDFS
- Short Name:
- J/AJ/132/2409
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results from the Australia Telescope Large Area Survey, which consists of deep radio observations of a 3.7deg^2^ field surrounding the Chandra Deep Field-South, largely coincident with the infrared Spitzer Wide-Area Infrared Extragalactic (SWIRE) Survey. We also list cross-identifications to infrared and optical photometry data from SWIRE, and ground-based optical spectroscopy. A total of 784 radio components are identified, corresponding to 726 distinct radio sources, nearly all of which are identified with SWIRE sources. Of the radio sources with measured redshifts, most lie in the redshift range 0.5-2 and include both star-forming galaxies and active galactic nuclei. We identify a rare population of infrared-faint radio sources that are bright at radio wavelengths but are not seen in the available optical, infrared, or X-ray data. Such rare classes of sources can only be discovered in wide, deep surveys such as this.
- ID:
- ivo://CDS.VizieR/J/ApJS/213/23
- Title:
- Deep Chandra obs. of the giant HII region N11 in LMC
- Short Name:
- J/ApJS/213/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A very sensitive X-ray investigation of the giant H II region N11 in the Large Megallanic Cloud was performed using the Chandra X-ray Observatory. The 300ks observation reveals X-ray sources with luminosities down to 10^32^erg/s, increasing the number of known point sources in the field by more than a factor of five. Among these detections are 13 massive stars (3 compact groups of massive stars, 9 O stars, and one early B star) with log (L_X_/L_BOL_)~-6.5 to -7, which may suggest that they are highly magnetic or colliding-wind systems. On the other hand, the stacked signal for regions corresponding to undetected O stars yields log (L_X_/L_BOL_)~-7.3, i.e., an emission level comparable to similar Galactic stars despite the lower metallicity. Other point sources coincide with 11 foreground stars, 6 late-B/A stars in N11, and many background objects. This observation also uncovers the extent and detailed spatial properties of the soft, diffuse emission regions, but the presence of some hotter plasma in their spectra suggests contamination by the unresolved stellar population.
- ID:
- ivo://CDS.VizieR/J/ApJ/725/2232
- Title:
- Deep NIR survey of the Pipe Nebula. II.
- Short Name:
- J/ApJ/725/2232
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new set of high-resolution dust extinction maps of the nearby and essentially starless Pipe Nebula molecular cloud. The maps were constructed from a concerted deep near-infrared imaging survey with the ESO-VLT, ESO-NTT, CAHA 3.5m telescopes, and 2MASS data. The new maps have a resolution three times higher than the previous extinction map of this cloud by Lombardi et al. (2006A&A...454..781L) and are able to resolve structures down to 2600AU. We detect 244 significant extinction peaks across the cloud. These peaks have masses between 0.1 and 18.4M_{sun}_, diameters between 1.2 and 5.7x10^4^AU (0.06 and 0.28pc), and mean densities of about 10^4^cm^-3^, all in good agreement with previous results. From the analysis of the mean surface density of companions we find a well-defined scale near 1.4x10^4^AU below which we detect a significant decrease in structure of the cloud. This scale is smaller than the Jeans length calculated from the mean density of the peaks. The surface density of peaks is not uniform but instead it displays clustering. Extinction peaks in the Pipe Nebula appear to have a spatial distribution similar to the stars in Taurus, suggesting that the spatial distribution of stars evolves directly from the primordial spatial distribution of high-density material.
- ID:
- ivo://CDS.VizieR/J/ApJS/219/21
- Title:
- Deep NIR survey toward Aquila. I. MHOs
- Short Name:
- J/ApJS/219/21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have performed an unbiased, deep near-infrared survey toward the Aquila molecular cloud with a sky coverage of ~1deg^2^. We identified 45 molecular hydrogen emission-line objects (MHOs), of which only 11 were previously known. Using the Spitzer archival data, we also identified 802 young stellar objects (YSOs) in this region. Based on the morphology and the location of MHOs and YSO candidates, we associate 43 MHOs with 40 YSO candidates. The distribution of jet length shows an exponential decrease in the number of outflows with increasing length, and the molecular hydrogen outflows seem to be oriented randomly. Moreover, there is no obvious correlation between jet lengths, jet opening angles, or jet H_2_ 1-0 S(1) luminosities and the spectral indices of the possible driving sources in this region. We also suggest that molecular hydrogen outflows in the Aquila molecular cloud are rather weak sources of turbulence, unlikely to generate the observed velocity dispersion in the region of survey.
- ID:
- ivo://CDS.VizieR/J/ApJ/668/1042
- Title:
- Dense cores in Perseus molecular cloud
- Short Name:
- J/ApJ/668/1042
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We survey the kinematics of over 150 candidate (and potentially star-forming) dense cores in the Perseus molecular cloud with pointed N_2_H^+^(1-0) and simultaneous C^18^O(2-1) observations. Our detection rate of N_2_H^+^ is 62%, rising to 84% for SCUBA-selected targets. In agreement with previous observations, we find that the dense N_2_H^+^ targets tend to display nearly thermal line widths, particularly those that appear to be starless (using Spitzer data), indicating that turbulent support on the small scales of molecular clouds is minimal. For those N_2_H^+^ targets that have an associated SCUBA dense core, we find that their internal motions are more than sufficient to provide support against the gravitational force on the cores.
- ID:
- ivo://CDS.VizieR/J/A+A/372/85
- Title:
- Detected sources at 12{mu}m in 47 Tuc
- Short Name:
- J/A+A/372/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The present paper investigates the properties of the dust mass loss in stars populating the giant branch of the globular cluster 47 Tuc, by combining ISOCAM and DENIS data. Raster maps of 5 fields covering areas ranging from 4x4 to 15x15arcmin^2^ at different distances from the center of the cluster have been obtained with ISOCAM at 11.5{mu}m (LW10 filter). The covered fields include most of the red variables known in this cluster. A detection threshold of about 0.2 mJy is achieved, allowing us to detect giant stars at 11.5{mu}m all the way down to the horizontal branch. No dust-enshrouded asymptotic giant branch stars have been found in the observed fields, contrary to the situation encountered in LMC/SMC globular clusters with larger turnoff masses. The color index [12]-[2] (based on the ISO 11.5{mu}m flux and on the DENIS K_S_ magnitude) is used as a diagnostic of dust emission (and hence dust mass loss). Its evolution with luminosity along the giant branch reveals that dust mass loss is only present in V3 (the only cluster Mira variable observed in the present study) and in V18, a star presenting intermittent variability. This conclusion confirms the importance of stellar pulsations in the dust formation and ensuing mass loss.
