In order to investigate the influence of environment on supernova (SN) production, we have performed a statistical investigation of the SNe discovered in isolated galaxies, in pairs and in groups of galaxies. 22 SNe in 18 isolated galaxies, 48 SNe in 40 galaxy members of 37 pairs and 211 SNe in 170 galaxy members of 116 groups have been selected and studied.
We report on the detection of optically thick free-free radio sources in the galaxies M33, NGC 253, and NGC 6946 using data in the literature. We interpret these sources as being young embedded star birth regions that are likely to be clusters of ultracompact H II regions. All 35 of the sources presented in this article have positive radio spectral indices ({alpha}>0 for S_{nu}_){prop.to}{nu}^{alpha}^), suggesting an optically thick thermal bremsstrahlung origin from the H II region surrounding the hot stars.
Over 13500 continuum observations of extragalactic sources are presented. These observations of 157 sources at 22, 37 and 87GHz more than doubles the millimeter observations of these sources. The data are between 1990.5 and 1995.5, and combined with our earlier published data form a 15 year database.
The rotation measures of 555 extragalactic radio sources are calculated as a result of a large number of new linear polarization measurements carried out by us at several wavelengths between 1.59 and 10.5GHz. A summary of references for previous polarization measurements is included, and the procedure for optimizing the number of unambiguous rotation measures is described.
The study of the planet-debris disk connection can shed light on the formation and evolution of planetary systems and may help "predict" the presence of planets around stars with certain disk characteristics. In preliminary analyses of subsamples of the Herschel DEBRIS and DUNES surveys, Wyatt et al. (2012MNRAS.424.1206W) and Marshall et al. (2014A&A...565A..15M) identified a tentative correlation between debris and the presence of low-mass planets. Here we use the cleanest possible sample out of these Herschel surveys to assess the presence of such a correlation, discarding stars without known ages, with ages <1Gyr, and with binary companions <100AU to rule out possible correlations due to effects other than planet presence. In our resulting subsample of 204 FGK stars, we do not find evidence that debris disks are more common or more dusty around stars harboring high-mass or low-mass planets compared to a control sample without identified planets.
Spectroscopic observations of exoplanets are crucial to infer the composition and properties of their atmospheres. HD 189733b is one of the most extensively studied exoplanets and is a cornerstone for hot Jupiter models. In this paper, we report the dayside emission spectrum of HD 189733b in the wavelength range 1.1-1.7 {mu}m obtained with the Hubble Space Telescope Wide Field Camera 3 (WFC3) in spatial scan mode. The quality of the data is such that even a straightforward analysis yields a high-precision Poisson noise-limited spectrum: the median 1{sigma} uncertainty is 57 ppm per 0.02 {mu}m bin. We also build a white-light curve correcting for systematic effects and derive an absolute eclipse depth of 96+/-39 ppm. The resulting spectrum shows marginal evidence for water vapor absorption, but can also be well explained by a blackbody spectrum. However, the combination of these WFC3 data with previous Spitzer photometric observations is best explained by a dayside atmosphere of HD 189733b with no thermal inversion and a nearly solar or subsolar H_2_O abundance in a cloud-free atmosphere. Alternatively, this apparent subsolar abundance may be the result of clouds or hazes that future studies need to investigate.
The Extrasolar Planets Encyclopedia is a working tool, providing all the latest detections and data that have been announced by professional astronomers, Which is intended to be used to facilitate progress in exoplanetology. Ultimately, researchers willing to make a quantitative, scientific use of the catalog can make their own judgement on the likelihood of the data and the detections. The stellar data (positions, distances, V and other magnitudes, mass, metallicities etc) are taken from Simbad or from professional papers on exoplanets. Ongoing large extrasolar planets ('exoplanets') projects include: <pre> Anglo-Australian Planet Search <<a href="http://www.phys.unsw.edu.au/~cgt/planet/AAPS_Home.html">http://www.phys.unsw.edu.au/~cgt/planet/AAPS_Home.html</a>> California & Carnegie Planet Search <<a href="http://exoplanets.org/">http://exoplanets.org/</a>> Geneva Extrasolar Planet Search Programmes <<a href="http://obswww.unige.ch/~udry/planet/planet.html">http://obswww.unige.ch/~udry/planet/planet.html</a>> Transatlantic Exoplanet Survey <<a href="http://www.astro.caltech.edu/~ftod/tres/tres.html">http://www.astro.caltech.edu/~ftod/tres/tres.html</a>> University of Texas - Dept. of Astronomy <<a href="http://www.as.utexas.edu/astronomy/research/ss.html">http://www.as.utexas.edu/astronomy/research/ss.html</a>> </pre> This table is based on the VOTable format of the catalog obtained from the Extrasolar Planets Encyclopaedia website at <a href="http://exoplanet.eu/">http://exoplanet.eu/</a>. It is maintained by Jean Schneider and is updated on a frequent basis, as needed. This is a service provided by NASA HEASARC .
Extrasolar planets. Radial velocities of eight stars
Short Name:
J/A+A/538/A113
Date:
21 Oct 2021
Publisher:
CDS
Description:
The mass domain where massive extrasolar planets and brown dwarfs lie is still poorly understood. Indeed, not even a clear dividing line between massive planets and brown dwarfs has been established yet. This is partly because these objects are very scarce in close orbits around solar-type stars, the so-called brown dwarf desert. Owing to this, it has proven difficult to set up a strong observational base with which to compare models and theories of formation and evolution. We search to increase the current sample of massive sub-stellar objects with precise orbital parameters, and to constrain the true mass of detected sub-stellar candidates
We present radial-velocity measurements obtained in one of a number of programs underway to search for extrasolar planets with the spectrograph SOPHIE at the 1.93-m telescope of the Haute-Provence Observatory. Targets were selected from catalogs observed with ELODIE, which had been mounted previously at the telescope, in order to detect long-period planets with an extended database close to 15 years.
Long-period brown dwarf companions detected in radial velocity surveys are important targets for direct imaging and astrometry to calibrate the mass-luminosity relation of substellar objects. Through a 20-year radial velocity monitoring of solar-type stars that began with ELODIE and was extended with SOPHIE spectrographs, giant exoplanets and brown dwarfs with orbital periods longer than ten years are discovered. We report the detection of five new potential brown dwarfs with minimum masses between 32 and 83M_Jup_ orbiting solar-type stars with periods longer than ten years. An upper mass limit of these companions is provided using astrometric Hipparcos data, high-angular resolution imaging made with PUEO, and a deep analysis of the cross-correlation function of the main stellar spectra to search for blend effects or faint secondary components. These objects double the number of known brown dwarf companions with orbital periods longer than ten years and reinforce the conclusion that the occurrence of such objects increases with orbital separation. With a projected separation larger than 100mas, all these brown dwarf candidates are appropriate targets for high-contrast and high angular resolution imaging.