- ID:
- ivo://CDS.VizieR/J/ApJ/747/35
- Title:
- HST/WFC3 transit observation of GJ1214b
- Short Name:
- J/ApJ/747/35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Capitalizing on the observational advantage offered by its tiny M dwarf host, we present Hubble Space Telescope/Wide Field Camera 3 (WFC3) grism measurements of the transmission spectrum of the super-Earth exoplanet GJ1214b. These are the first published WFC3 observations of a transiting exoplanet atmosphere. After correcting for a ramp-like instrumental systematic, we achieve nearly photon-limited precision in these observations, finding the transmission spectrum of GJ1214b to be flat between 1.1 and 1.7{mu}m. Inconsistent with a cloud-free solar composition atmosphere at 8.2{sigma}, the measured achromatic transit depth most likely implies a large mean molecular weight for GJ1214b's outer envelope. A dense atmosphere rules out bulk compositions for GJ1214b that explain its large radius by the presence of a very low density gas layer surrounding the planet. High-altitude clouds can alternatively explain the flat transmission spectrum, but they would need to be optically thick up to 10 mbar or consist of particles with a range of sizes approaching 1 {mu}m in diameter.
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- ID:
- ivo://CDS.VizieR/J/A+A/649/A167
- Title:
- Hubble spectroscopy of LB-1 (LS V +22 25)
- Short Name:
- J/A+A/649/A167
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- LB-1 has variously been proposed as either an X-ray dim B-type star plus black hole (B+BH) binary, or a Be star plus an inflated stripped star (Be+Bstr) binary. The Space Telescope Imaging Spectrograph (STIS) on board HST was used to obtain a flux-calibrated spectrum that is compared with non-LTE spectral energy distributions (SED) and line profiles for the proposed models. The Hubble data, together with the Gaia EDR3 parallax, provide tight constraints on the properties and stellar luminosities of the system. In the case of the Be+Bstr model we adopt the published flux ratio for the Be and Bstr stars, re-determine the Teff of the Bstr using the silicon ionization balance, and infer Teff for the Be star from the fit to the SED. We derive stellar parameters consistent with previous results, but with greater precision enabled by the Hubble SED. While the Be+Bstr model is a better fit to the HeI lines and cores of the Balmer lines in the optical, the B+BH model provides a better fit to the SiIV resonance lines in the UV. The analysis also implies that the Bstr star has roughly twice solar silicon abundance, which is difficult to reconcile with a stripped star origin. The Be star on the other hand has a rather low luminosity, and a spectroscopic mass inconsistent with its possible dynamical mass. The fit to the UV can be significantly improved by reducing the Teff and radius of the Be star, though at the expense of leading to a different mass ratio. In the B+BH model, the single B-type spectrum is a good match to the UV spectrum. Adopting a mass ratio of 5.1+/-0.1 (Liu et al., 2020ApJ...900...42L) implies a BH mass of 21^+9^_-8_ solar masses.
- ID:
- ivo://CDS.VizieR/J/A+A/343/841
- Title:
- Imaging of symbiotic stars
- Short Name:
- J/A+A/343/841
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Narrowband images of 51 symbiotic stars were obtained at the ESO and ORM observatories to search for resolved optical nebulae. Ionized nebulae much larger than previously known are found around CH Cyg, HM Sge and V1016 Cyg, and they will be discussed in detail in forthcoming papers. A nebula with a deconvolved size between 0.9" and 1.5" is found around the symbiotic Mira H 1-36. The radio sources located few arcminutes aside of R Aqr (Hollis et al., 1987ApJ...321L..55H), which were suggested to be the remnant of a prehistoric eruption of the system, are found to be background galaxies. We also present a bibliographical compilation, updated to October 1998, of all the extended nebulae around symbiotic stars detected at optical and radio wavelengths, as well as a list of optical non-detections. The statistics of occurrence of these large ionized nebulae among symbiotic stars is discussed. Extended ionized nebulae appear to be a common component of the D-type symbiotics, and we infer that they are formed by the Mira wind and/or high velocity winds ejected by the hot component during outbursts. On the contrary, very few nebulae are detected around the systems containing normal red giants.
- ID:
- ivo://CDS.VizieR/J/MNRAS/335/233
- Title:
- Integrated Spectra of Open Clusters
- Short Name:
- J/MNRAS/335/233
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a library of 39 open cluster optical/near-IR integrated spectra. The data were obtained at CASLEO (San Juan, Argentina) and LNA (Itajuba, Brazil). Eight additional spectra obtained at ESO (La Silla, Chile), also employed in the present analysis, are already available at CDS (see cat. <III/219>). The data were combined in order to derive high S/N templates of young and intermediate-age populations sampling their evolutionary states with unprecedented time resolution at nearly solar metallicity. These template spectra, also included in the library, are useful, e.g., for population synthesis techniques applied to galaxies and for estimates of individual cluster parameters in the Milky Way as well as in external galaxies.
- ID:
- ivo://CDS.VizieR/VI/50
- Title:
- Intensity Distribution of Normal Stars
- Short Name:
- VI/50
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Mean energy distributions are given for 98 normal stars in the spectral range from O to M and luminosity classes V, IV, III, II, and I. The points cover the wavelength range from 1200A to 10500A and a include a point at 12500A.
- ID:
- ivo://CDS.VizieR/J/A+A/590/A67
- Title:
- Ionized gas maps of local U/LIRGs
- Short Name:
- J/A+A/590/A67
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a 2D study of star formation at kpc and sub-kpc scales of a sample of local (z<0.1) U/LIRGs, based on near-IR VLT-SINFONI observations. We obtained integrated measurements of the star formation rate (SFR) and star formation rate surface density, together with their 2D distributions, based on Br_gamma and Pa_alpha emission. We observe a tight linear correlation between the SFR derived from our extinction-corrected measurements and that derived from 24 micron data, and a reasonable agreement with SFR derived from total IR luminosity. Our near-IR measurements are on average a factor 3 larger than optical SFR, even when extinction corrections are applied. We found that LIRGs have a median-observed star formation rate surface density of 1.72M_{sun}_/yr/kpc^2^ for the extinction-corrected distribution, whilst ULIRGs have 0.23M_{sun}_/yr/kpc^2, respectively. These median values for ULIRGs increase up to 2.90M_{sun}_/yr/kpc^2^, when only their inner regions, covering the same size as the average FoV of LIRGs, are considered. We identified a total of 95 individual SF clumps in our sample, with sizes within 60-1500pc, and extinction-corrected Pa_alpha luminosities of 10^5^-10^8^L_{sun}_. Star-forming clumps in LIRGs are about ten times larger and thousands of times more luminous than typical clumps in spiral galaxies. Clumps in ULIRGs have sizes similar (x0.5-1) to those of high-z clumps, having Pa_alpha luminosities similar to some high-z clumps, and about 10 times less luminous than the most luminous high-z clumps identified so far. We also observed a change in the slope of the L-r relation. A likely explanation is that most luminous galaxies are interacting and merging, and therefore their size represents a combination of the distribution of the star-forming clumps within each galaxy in the system plus the effect of the projected distance.
- ID:
- ivo://CDS.VizieR/III/83
- Title:
- IUE Low-Dispersion Reference Atlas I, Normal Stars
- Short Name:
- III/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The atlas contains the fluxes (2 angstroms/step) of 229 low-dispersion stellar spectra collected by the International Ultraviolet Explorer (IUE) satellite, compiled for the purpose of establishing reference spectral sequences in the ultraviolet range. The sequences have been constructed and the standard stars selected directly from the ultraviolet material, staying as far as possible within the general MK frame. The catalog is essentially composed of stars exhibiting normal behaviour in the ultraviolet. A few peculiar objects have, however, been included as an illustration of typical abnormalities. This work clearly pointed out the dangers of extrapolating a spectral classification based on a given wavelength range to another one, and, in particular, of using the MK spectral type alone outside its definition range.
- ID:
- ivo://CDS.VizieR/J/A+A/610/L12
- Title:
- KIC 8462852 GTC spectra
- Short Name:
- J/A+A/610/L12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report ground-based spectrophotometry of KIC 8462852, during its first dimming events since the end of the Kepler mission. The dimmings show a clear colour-signature, and are deeper in visual blue wavelengths than in red ones. The flux loss' wavelength dependency can be described with an absorption Angstroem coefficient of 2.19+/-0.45, which is compatible with absorption by optically thin dust with particle sizes on the order of 0.0015 to 0.15um. These particles would be smaller than is required to be resistant against blow-out by radiation pressure when close to the star. During occultation events, these particles must be replenished on time-scales of days. If dust is indeed the source of KIC 8462852's dimming events, deeper dimming events should show more neutral colours, as is expected from optically thick absorbers.
- ID:
- ivo://CDS.VizieR/J/A+A/553/A104
- Title:
- LHA 120-N49 supernova remnant maps
- Short Name:
- J/A+A/553/A104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Supernova remnants commonly display strong internal inhomogeneities in physical properties; however, most of the observational studies found in the literature are limited to integrated data for extragalactic objects or data from very specific parts of the galactic objects. Thus, important information may be lost. We studied the spatial variation of the electron density and the kinematics of N49, the brightest supernova remnant in the Large Magellanic Cloud, based on spatial resolve observations sampling the whole object.
- ID:
- ivo://CDS.VizieR/J/A+AS/146/217
- Title:
- Library of Spectra (0.5 to 2.5um) of Cool Stars
- Short Name:
- J/A+AS/146/217
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The present catalogue contains 182 low resolution optical spectra, 145 medium resolution (R~1100) near-IR spectra, and 112 merged optical+near-IR spectra that range from about 510 to 2450 nm. The observed stars are luminous cool objects: the sample includes red giants, red supergiants, oxygen rich and carbon rich long period variables (asymptotic giant branch stars), as well as a few Galactic Bulge and LMC/SMC stars. The optical data were acquired on the so-called 74 inch Telescope at Mount Stromlo Observatory. The near-IR data were acquired with the Cryogenic Array Spectrometer and Imager CASPIR on the 2.3 meter Australian National University Telescope at Siding Spring Observatory. Optical and near-IR data for variable objects have been merged only when both were taken less than 15 days apart; but both spectral ranges are also provided separately. The spectra are corrected for telluric absorption. However, in regions where the transmission of the Earth atmosphere is close to zero the fluxes recovered remain highly uncertain. The flux calibration is based on a series of reference stars, for which a theoretical intrinsic energy distribution was assumed. An absolute flux calibration (to about 10% accuracy) was only achieved in exceptional cases; in the other cases, the absolute fluxes can be off their real values by an order of magnitude due to slit losses (for the programme star and/or the reference star) and to non-photometric wheather. Uncertainties in the relative values of fluxes along each spectrum are described in the paper.
