- ID:
- ivo://CDS.VizieR/J/AJ/128/1233
- Title:
- LkH{alpha} 101 and the young cluster in NGC 1579
- Short Name:
- J/AJ/128/1233
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The central region of the dark cloud L1482 is illuminated by LkH{alpha} 101, a heavily reddened (A_V_~10mag) high-luminosity (>=8x10^3^L_Sun_) star having an unusual emission-line spectrum plus a featureless continuum. About 35 much fainter (mostly between R=16 and >21) H{alpha} emitters have been found in the cloud. Their color-magnitude distribution suggests a median age of about 0.5Myr, with considerable dispersion. There are also at least five bright B-type stars in the cloud, presumably of about the same age; none show the peculiarities expected of HAeBe stars. Dereddened, their apparent V magnitudes lead to a distance of about 700pc. Radio observations suggest that the optical object LkH{alpha} 101 is in fact a hot star surrounded by a small H II region, both inside an optically thick dust shell.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/555/A141
- Title:
- LMC emission-line stars. Armagh survey
- Short Name:
- J/A+A/555/A141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Accurate astrometry is required to reliably cross-match 20th-century photographic catalogues against 21st-century digital surveys. The present work provides modern-area identifications and astrometry for the 801 emission-line objects "of stellar appearance" in the Armagh survey (the largest of its nature to date). Targets have been individually identified in digital images using the Armargh Atlas and, in most cases, unambiguously matched to entries in the UCAC astrometric catalogues.
- ID:
- ivo://CDS.VizieR/J/other/NewA/10.325
- Title:
- 2MASS observations of Be stars
- Short Name:
- J/other/NewA/10.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A catalogue of almost all known Galactic Be stars in the 2MASS (<II/246>) database (1185 in total) and in the MSX (<V/114>) database (225 in total) is presented in this paper. From the color-color diagrams and spectral indexes, it is found that the IR excesses for many samples are due to free-free and free-bound emission from the ionized material around a Be star as suggested previously and that the mean spectral index derived for the samples is 1.50+/-0.34 between J to K bands and 1.14+/-0.42 between K to A bands, respectively. However, it is also found that there are eight Be stars that have large near infrared excess emission with spectral index values outside the range expected for freefree and freebound emission. This is likely attributed to circumstellar dust emission.
- ID:
- ivo://CDS.VizieR/J/MNRAS/473/4130
- Title:
- M31 center emission-line point-like sources
- Short Name:
- J/MNRAS/473/4130
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed description of the wavelength, astrometric and photometric calibration plan for SITELLE, the imaging Fourier transform spectrometer attached to the Canada-France-Hawaii telescope, based on observations of a red (647-685nm) data cube of the central region (11'x11') of the Andromeda galaxy. The first application, presented in this paper, is a radial-velocity catalogue (with uncertainties of ~2-6km/s) of nearly 800 emission-line point-like sources, including ~450 new discoveries. Most of the sources are likely planetary nebulae, although we also detect five novae (having erupted in the first 8 months of 2016) and one new supernova remnant candidate.
65. MHO Catalogue
- ID:
- ivo://CDS.VizieR/J/A+A/511/A24
- Title:
- MHO Catalogue
- Short Name:
- J/A+A/511/A24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalogue of Molecular Hydrogen emission-line Objects (MHOs) in outflows from young stars, most of which are deeply embedded. All objects are identified in the near-infrared lines of molecular hydrogen, all reside in the Milky Way, and all are associated with jets or molecular outflows. Objects in both low and high-mass star forming regions are included. This catalogue complements the existing database of Herbig-Haro objects; indeed, for completeness, HH objects that are detected in H_2_ emission are included in the MHO catalogue.
- ID:
- ivo://CDS.VizieR/J/A+A/531/A50
- Title:
- 1.3mm and 3mm emission maps or 4 Ae/Be stars
- Short Name:
- J/A+A/531/A50
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Herbig Ae stars (HAe) are the precursors of Vega-type systems and, therefore, crucial objects in planet formation studies. Thus far, only a few disks associated with HAe stars have been studied using millimetre interferometers. Our aim is to determine the dust evolution and the lifetime of the disks associated with Herbig Ae stars. We imaged the continuum emission at ~3mm and ~1.3mm of the Herbig Ae/Be stars BD+61154, RR Tau, VY Mon and LkH{alpha} 198 using the Plateau de Bure Interferometer (PdBI). These stars are in the upper end of the stellar mass range of the Herbig Ae stars (M_*_>3M_{sun}_). Our measurements were used to complete the Spectral Energy Distribution (SED). The modelling of the SED, in particular the FIR-mm part, allow us to determine the masses and dust properties of these disks. We detected the disks associated with BD+61154, RR Tau and VY Mon with disk masses of 0.35M_{sun}_, 0.05M_{sun}_ and 0.40M_{sun}_ respectively. The disk around LkH{alpha} 198 was not detected with an upper limit to the disk mass of 0.004M_{sun}_. We detected, however, the disks associated with the younger stellar objects LkH{alpha} 198--IR and LkH{alpha} 198--mm that are located in the vicinity of LkH{alpha} 198. The fitting of the mm part of the SED reveal that the grains in the mid-plane of the disks around BD+61154, RR Tau and VY Mon have sizes of ~1-1000um. Therefore, grains have not grown to centimetre sizes in these disks yet. These massive (M_*_>3M_{sun}_) and young (~1Myr) HAe stars are surrounded by massive (>~0.04M_{sun}_) disks with grains of micron-millimetre sizes. Although grain growth is proceeding in these disks, their evolutionary stage is prior to the formation of planetesimals. These disks are less evolved than those detected around T Tauri and Herbig Be stars.
- ID:
- ivo://CDS.VizieR/J/A+A/622/A75
- Title:
- MWC 480 ALMA image
- Short Name:
- J/A+A/622/A75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Gap-like structures in protoplanetary disks are likely related to planet formation processes. In this work, we present and analyze high-resolution 1.3mm ALMA continuum observations of the protoplanetary disk around the Herbig Ae star MWC 480. Our observations show for the first time a gap centered at ~74AU with a width of ~23AU, surrounded by a bright ring centered at ~98AU from the central star. Detailed radiative transfer modeling of the ALMA image and the broadband spectral energy distribution is used to constrain the surface density profile and structural parameters of the disk. If the width of the gap corresponds to 4-8 times the Hill radius of a single forming planet, then the putative planet would have a mass of 0.4~3M_J_. We test this prediction by performing global three-dimensional smoothed particle hydrodynamic gas/dust simulations of disks hosting a migrating and accreting planet. We find that the dust emission across the disk is consistent with the presence of an embedded planet with a mass of ~2.3M_J_ at an orbital radius of ~78AU. Given the surface density of the best-fit radiative transfer model, the amount of depleted mass in the gap is higher than the mass of the putative planet, which satisfies the basic condition for the formation of such a planet.
- ID:
- ivo://CDS.VizieR/J/other/Ap/57.500
- Title:
- New H{alpha} emission stars in Cep OB3
- Short Name:
- J/other/Ap/57.50
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A search of emission stars has been done on the basis of digitized photographic plates received with the 40" Schmidt telescope of Byurakan Observatory equipped with a 4{deg} objective prism. Forty-six new emission stars are found in a small area around the known FU Ori type variable V733 Cep. Emission stars on the J-H - H-K diagram are situated on or in the neighborhood of T Tau locus. V, R, I photometry for some of the emission stars is performed as well. Three new variable stars are found in the region. A rapid brightness variation is detected on V733 Cep.
- ID:
- ivo://CDS.VizieR/J/A+A/638/A21
- Title:
- New Herbig Ae/Be and classical Be stars catalog
- Short Name:
- J/A+A/638/A21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The intermediate-mass pre-main sequence (PMS) Herbig Ae/Be stars are key to understanding the differences in formation mechanisms between low- and high-mass stars. The study of the general properties of these objects is hampered by the lack of a well-defined, homogeneous sample, and because few and mostly serendipitously discovered sources are known. Our goal is to identify new Herbig Ae/Be candidates to create a homogeneous and well defined catalogue of these objects. We have applied machine learning techniques to 4150983 sources with data from Gaia DR2, 2MASS, WISE, and IPHAS or VPHAS+. Several observables were chosen to identify new Herbig Ae/Be candidates based on our current knowledge of this class, which is characterised by infrared excesses, photometric variabilities, and Halpha emission lines. Classical techniques are not efficient for identifying new Herbig Ae/Be stars mainly because of their similarity with classical Be stars (CBe), with which they share many characteristics. By focusing on disentangling these two types of objects, our algorithm has also identified new classical Be stars. We have obtained a large catalogue of 8470 new pre-main sequence candidates and another catalogue of 693 new classical Be candidates with a completeness of 78.8+/-1.4% and 85.5+/-1.2%, respectively. Of the catalogue of pre-main sequence candidates, at least 1361 sources are potentially new Herbig Ae/Be candidates according to their position in the Hertzsprung-Russell diagram. In this study we present the methodology used, evaluate the quality of the catalogues, and perform an analysis of their flaws and biases. For this assessment, we make use of observables that have not been accounted for by the algorithm and hence are selection-independent, such as coordinates and parallax based distances. The catalogue of new Herbig Ae/Be stars that we present here increases the number of known objects of the class by an order of magnitude.
- ID:
- ivo://CDS.VizieR/J/A+A/612/A48
- Title:
- 4 oxygen-rich evolved stars NH3 spectra
- Short Name:
- J/A+A/612/A48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The circumstellar ammonia (NH_3_) chemistry in evolved stars is poorly understood. Previous observations and modelling showed that NH_3_ abundance in oxygen-rich stars is several orders of magnitude above that predicted by equilibrium chemistry. We would like to characterise the spatial distribution and excitation of NH_3_ in the oxygen-rich circumstellar envelopes (CSEs) of four diverse targets: IK Tau, VY CMa, OH 231.8+4.2, and IRC +10420. We observed NH_3_ emission from the ground state in the inversion transitions near 1.3cm with the Very Large Array (VLA) and submillimetre rotational transitions with the Heterodyne Instrument for the Far-Infrared (HIFI) aboard Herschel Space Observatory from all four targets. For IK Tau and VY CMa, we observed NH_3_ rovibrational absorption lines in 2 band near 10.5um with the Texas Echelon Cross Echelle Spectrograph (TEXES) at the NASA Infrared Telescope Facility (IRTF).We also attempted to search for the rotational transition within the excited vibrational state (v_2_=1) near 2mm with the IRAM 30m Telescope. Non-LTE radiative transfer modelling, including radiative pumping to the vibrational state, was carried out to derive the radial distribution of NH_3_ in the CSEs of these targets. We detected NH_3_ inversion and rotational emission in all four targets. IK Tau and VY CMa show blueshifted absorption in the rovibrational spectra. We did not detect vibrationally excited rotational transition from IK Tau. Spatially resolved VLA images of IK Tau and IRC +10420 show clumpy emission structures; unresolved images of VY CMa and OH 231.8+4.2 indicate that the spatial-kinematic distribution of NH_3_ is similar to that of assorted molecules, such as SO and SO2, that exhibit localised and clumpy emission. Our modelling shows that the NH_3_ abundance relative to molecular hydrogen is generally of the order of 10^-7^, which is a few times lower than previous estimates that were made without considering radiative pumping and is at least ten times higher than that in the carbon-rich CSE of IRC +10216. NH_3_ in OH 231.8+4.2 and IRC +10420 is found to emit in gas denser than the ambient medium. Incidentally, we also derived a new period of IK Tau from its V-band light curve. NH_3_ is again detected in very high abundance in evolved stars, especially the oxygen-rich ones. Its emission mainly arises from localised spatial-kinematic structures that are probably denser than the ambient gas. Circumstellar shocks in the accelerated wind may contribute to the production of NH_3_. Future mid-infrared spectroscopy and radio imaging studies are necessary to constrain the radii and physical conditions of the formation regions of NH_3_.
