- ID:
- ivo://CDS.VizieR/J/A+A/499/827
- Title:
- Disk of {upsilon} Sgr
- Short Name:
- J/A+A/499/827
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The aim of this paper is to determine the properties of the dusty environment of the hydrogen-deficient binary system upsilon Sgr, whose binary properties and other characteristics are poorly known. We obtained the first mid-IR interferometric observations of upsilon Sgr using the instrument MIDI of the VLTI used with different pairs of 1.8m and 8m telescopes. The calibrated visibilities, the N band spectrum, and the SED were compared with disk models computed with the MC3D code to determine the geometry and chemical composition of the envelope. ************************************************************************** * * * Sorry, but the author(s) never supplied the tabular material * * announced in the paper * * * **************************************************************************
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Search Results
- ID:
- ivo://CDS.VizieR/III/17B
- Title:
- Early-Type Emission-Line Stars
- Short Name:
- III/17B
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog contains 5326 early-type emission-line stars. Of these, 1424 have no spectral classification but are assumed to be of early type. Some 71 percent of the stars listed here can also be found in the Mount Wilson and the Mount Wilson-Michigan survey catalogs. The catalog contains numerous cross identifications to other designations (name, HD, DM, LS, MWC, TON, HIL, WRA, HEN, etc.), spectroscopic type, magnitudes (visual and blue), equatorial (B1900 and B1950), and galactic coordinates.
- ID:
- ivo://CDS.VizieR/J/ApJ/325/798
- Title:
- Einstein survey of stars in the Hyades
- Short Name:
- J/ApJ/325/798
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The paper reports the results of an extensive X-ray study of the Hyades region and improves on previous studies by using refined X-ray source detection algorithms and the complete set of Einstein Observatory IPC exposures covering the Hyades cluster region (a total of 63 1 x 1 deg images). Maximum likelihood integral X-ray luminosity functions were computed for the Hyades stars for given color index (B-V) ranges. The present results agree substantially with a previous survey about the ubiquity of the stellar activity in the Hyades cluster, especially among solar-type stars. The result of Stern et al. (1981ApJ...249..647S) that stellar X-ray emission is dependent on stellar age is confirmed.
- ID:
- ivo://CDS.VizieR/J/A+A/631/A118
- Title:
- Emission-line sources MUSE spectral catalogue
- Short Name:
- J/A+A/631/A118
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Globular clusters produce many exotic stars due to a much higher frequency of dynamical interactions in their dense stellar environments. Some of these objects were observed together with several hundred thousand other stars in our MUSE survey of 26 Galactic globular clusters. Assuming that at least a few exotic stars have exotic spectra (i.e. spectra that contain emission lines), we can use this large spectroscopic data set of over a million stellar spectra as a blind survey to detect stellar exotica in globular clusters. To detect emission lines in each spectrum, we modelled the expected shape of an emission line as a Gaussian curve. This template was used for matched filtering on the differences between each observed 1D spectrum and its fitted spectral model. The spectra with the most significant detections of H{alpha} emission are checked visually and cross-matched with published catalogues. We find 156 stars with H{alpha} emission, including several known cataclysmic variables (CV) and two new CVs, pulsating variable stars, eclipsing binary stars, the optical counterpart of a known black hole, several probable sub-subgiants and red stragglers, and 21 background emission-line galaxies. We find possible optical counterparts to 39 X-ray sources, as we detected H_alpha emission in several spectra of stars that are close to known positions of Chandra X-ray sources. This spectral catalogue can be used to supplement existing or future X-ray or radio observations with spectra of potential optical counterparts to classify the sources.
- ID:
- ivo://CDS.VizieR/J/A+AS/102/451
- Title:
- Emission-line stars and PNe in the SMC
- Short Name:
- J/A+AS/102/451
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An objective-prism survey of the Small Magellanic Cloud (SMC) has been performed through an H-{alpha} + [NII] interference filter, using the 90cm Curtis Schmidt telescope of Cerro Tololo. 1898 emission-line objects have been detected in the main body of this galaxy, almost quadrupling the number of those found in the same region by the previous objective-prism surveys. Among these objects are newly discovered planetary nebulae, compact HII regions and late-type stars. Continuum intensity, as well as the shape and relative strength of the H-{alpha} emission-line have been estimated; coordinates, cross-identifications for the listed objects are provided. The original paper contains in addition finding charts.
- ID:
- ivo://CDS.VizieR/J/A+A/385/986
- Title:
- FUSE UV spectrum of HR 5223
- Short Name:
- J/A+A/385/986
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New spectra have been obtained for the pole-on Be star HR 5223 (HD 120991) using the Far Ultraviolet Satellite Explorer (FUSE). We give a complete description of the far-UV spectral range (920 to 1180{AA}). The spectra are affected by strong blends with interstellar lines and molecular bands that also significantly lower the energy distribution of the star. We produce a synthetic spectrum of the interstellar medium (ISM) to determine the column densities of several elements (H_2_, H I, N I, O I ...) seen towards HR 5223 and to disentangle the components due to the ISM, the photosphere and/or to the circumstellar envelope.
- ID:
- ivo://CDS.VizieR/J/A+A/620/A128
- Title:
- Gaia DR2 study of Herbig Ae/Be stars
- Short Name:
- J/A+A/620/A128
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use Gaia Data Release 2 (DR2, Cat. I/345) to place 252 Herbig Ae/Be stars in the HR diagram and investigate their characteristics and properties. For all known Herbig Ae/Be stars with parallaxes in Gaia DR2, we collected their atmospheric parameters and photometric and extinction values from the literature. To these data we added near- and mid-infrared photometry, collected Halpha emission line properties such as equivalent widths and line profiles, and their binarity status. In addition, we developed a photometric variability indicator from Gaia's DR2 information. We provide masses, ages, luminosities, distances, photometric variabilities and infrared excesses homogeneously derived for the most complete sample of Herbig Ae/Be stars to date. We find that high mass stars have a much smaller infrared excess and have much lower optical variabilities compared to lower mass stars, with the break at around 7M_{sun}_. Halpha emission is generally correlated with infrared excess, with the correlation being stronger for infrared emission at wavelengths tracing the hot dust closest to the star. The variability indicator as developed by us shows that approximately 25% of all Herbig Ae/Be stars are strongly variable. We observe that the strongly variable objects display doubly peaked Halpha line profiles, indicating an edge-on disk. The fraction of strongly variable Herbig Ae stars is close to that found for A-type UX Ori stars. It had been suggested that this variability is in most cases due to asymmetric dusty disk structures seen edge-on. The observation here is in strong support of this hypothesis. Finally, the difference in dust properties occurs at 7M_{sun}_, while various properties traced at UV/optical wavelengths differ at a lower mass, 3M_{sun}_. The latter has been linked to different accretion mechanisms at work whereas the differing infrared properties and photometric variabilities are related to different or differently acting (dust-)disk dispersal mechanisms.
- ID:
- ivo://CDS.VizieR/J/A+A/581/A52
- Title:
- Gaia-ESO Survey: H{alpha} emission stars catalogue
- Short Name:
- J/A+A/581/A52
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We discuss the properties of H{alpha} emission stars across the sample of 22035 spectra from the Gaia-ESO Survey internal data release, observed with the GIRAFFE instrument and largely belonging to stars in young open clusters. Automated fits using two independent Gaussian profiles and a third component accounting for the nebular emission allow us to discern distinct morphological types of H{alpha} line profiles with the introduction of a simplified classification scheme. Altogether we find 3765 stars with intrinsic emission and sort their spectra into eight distinct morphological categories: single component emission, emission blend, sharp emission peaks, double emission, P-Cygni, inverted P-Cygni, self absorption, and emission in absorption. We have more than one observation for 1430 stars in our sample, thus allowing a quantitative discussion of the degree of variability of H{alpha} emission profiles, which is expected for young, active objects. We present a catalogue of stars with properties of their H{alpha} emission line profiles, morphological classification, analysis of variability with time and the supplementary information from SIMBAD, VizieR and ADS databases. The records in SIMBAD indicate the presence of H{alpha} emission for roughly 25% of all stars in our catalogue while at least 305 of them have already been more thoroughly investigated according to the references in ADS. The most frequently identified morphological categories in our sample of spectra are emission blend (23%), emission in absorption (22%), and self absorption (16%). Objects with repeated observations demonstrate that our classification into discrete categories is generally stable through time while seemingly less stable are categories P-Cygni and Self absorption, which is the consequence of discrete classification rules as well as of the fundamental change in profile shape. Such records of emission stars can be valuable for automatic pipelines in large surveys, where it may prove very useful to pinpoint outliers during calculation of general stellar properties and elemental abundances. They can find use in studies of star formation processes, interacting binaries and other fields of stellar physics.
- 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/MNRAS/500/4849
- Title:
- GALAH emission-line stars
- Short Name:
- J/MNRAS/500/4849
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a neural network autoencoder structure that is able to extract essential latent spectral features from observed spectra and then reconstruct a spectrum from those features. Because of the training with a set of unpeculiar spectra, the network is able to reproduce a spectrum of high signal-to-noise ratio that does not show any spectral peculiarities, even if they are present in an observed spectrum. Spectra generated in this manner were used to identify various emission features among spectra acquired by multiple surveys using the HERMES spectrograph at the Anglo-Australian telescope. Emission features were identified by a direct comparison of the observed and generated spectra. Using the described comparison procedure, we discovered 10364 candidate spectra with varying intensities (from partially filled-in to well above the continuum) of the H{alpha}/H{beta} emission component, produced by different physical mechanisms. A fraction of these spectra belong to the repeated observation that shows temporal variability in their emission profile. Among the emission spectra, we find objects that feature contributions from a nearby rarefied gas (identified through the emission of [NII] and [SII] lines) that was identified in 4004 spectra, which were not all identified as having H{alpha} emission. The positions of identified emission-line objects coincide with multiple known regions that harbour young stars. Similarly, detected nebular emission spectra coincide with visually prominent nebular clouds observable in the red all-sky photographic composites.
