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- ID:
- ivo://CDS.VizieR/J/AJ/135/1249
- Title:
- The early spectra of eta Carinae
- Short Name:
- J/AJ/135/1249
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The observed behavior of {eta} Car from 1860 to 1940 has not been considered in most recent accounts, nor has it been explained in any quantitative model. We have used modern digital processing techniques to examine Harvard objective-prism spectra made from 1892 to 1941. Relatively high excitation HeI{lambda}4471 and [FeIII]4658 emission, conspicuous today, were weak and perhaps absent throughout those years. Feast et al. (2001MNRAS.322..741F) noted this qualitative fact for other pre-1920 spectra, but we quantify it and extend it to a time only three years before Gaviola (1953ApJ...118..234G)'s first observations of the high-excitation features. Evidently the supply of helium-ionizing photons ({lambda}<504{AA}) grew rapidly between 1941 and 1944. The apparent scarcity of such far-UV radiation before 1944 is difficult to explain in models that employ a hot massive secondary star, because no feasible dense wind or obscuration by dust would have hidden the photoionization caused by the proposed companion during most of its orbital period. We also discuss the qualitative near-constancy of the spectrum from 1900 to 1940, and {eta} Car's photometric and spectroscopic transition between 1940 and 1953.
- ID:
- ivo://CDS.VizieR/J/A+A/523/A57
- Title:
- The Earth as a transiting planet
- Short Name:
- J/A+A/523/A57
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An important goal within the quest for detecting an Earth-like extrasolar planet, will be to identify atmospheric gaseous bio-signatures. Aims. Observations of the light transmitted through the Earth's atmosphere, as for an extrasolar planet, will be the first important step for future comparisons. We have completed observations of the Earth during a lunar eclipse, a unique situation similar to that of a transiting planet. We aim at showing what species could be detected in its atmosphere at optical wavelengths, where a lot of photons are available in the masked stellar light. We present observations of the 2008 August 16 Moon eclipse performed with the SOPHIE spectrograph at the Observatoire de Haute- Provence (France). Locating the spectrograph's fibers in the penumbra of the eclipse, the Moon irradiance is then a mix of direct, unabsorbed Sun light and solar light that has passed through the Earth's atmosphere. This mixture essentially reproduces what is recorded during the transit of an extrasolar planet. We report here the clear detection of several Earth atmospheric compounds in the transmission spectra, such as ozone, molecular oxygen, and neutral sodium as well as molecular nitrogen and oxygen through the Rayleigh signature. Moreover, we present a method that allows us to derive the thickness of the atmosphere versus the wavelength for penumbra eclipse observations. We quantitatively evaluate the altitude at which the atmosphere becomes transparent for important species like molecular oxygen and ozone, two species thought to be tightly linked to the presence of life. The molecular detections presented here are an encouraging first attempt, necessary to better prepare for the future of extremely-large telescopes and transiting Earth-like planets. Instruments like SOPHIE will be mandatory when characterizing the atmospheres of transiting Earth-like planets from the ground and searching for bio-marker signatures.
21644. The 2E Catalogue
- ID:
- ivo://CDS.VizieR/IX/13
- Title:
- The 2E Catalogue
- Short Name:
- IX/13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog contains sources from EINSTEIN IPC (Imaging Proportional counter aboard the EINSTEIN (HEAO 2) satellite, in orbit between November 1978 and April 1981) detected during pointed observations. Note that a single source may have more than one entry in the catalog.
21645. The eclipsing binary EG Ser
- ID:
- ivo://CDS.VizieR/J/AJ/105/2291
- Title:
- The eclipsing binary EG Ser
- Short Name:
- J/AJ/105/2291
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stromgren b,y photometry of the detached A-type eclipsing binary EG Serpentis was obtained. Combined with the radial velocity curves in Popper [PASP, 98, 1312 (1986)], it was used to determine anew the system's parameters using the Wilson-Devinney code. The age of the system is derived from a comparison with the Bertelli et al. [A&AS, 85, 845 (1990)] isochrones. Within the accuracy limits, the results are in accordance with expectations.
- ID:
- ivo://CDS.VizieR/J/ApJ/718/683
- Title:
- The edge of the young Galactic disk
- Short Name:
- J/ApJ/718/683
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this work, we report and discuss the detection of two distant diffuse stellar groups in the third Galactic quadrant. They are composed of young stars, with spectral types ranging from late O to late B, and lie at galactocentric distances between 15 and 20kpc. These groups are located in the area of two cataloged open clusters (VdB-Hagen 04 and Ruprecht 30), projected toward the Vela-Puppis constellations, and within the core of the Canis Major overdensity. Their reddening and distances have been estimated by analyzing their color-color and color-magnitude diagrams, derived from deep UBV photometry. The existence of young star aggregates at such extreme distances from the Galactic center challenges the commonly accepted scenario in which the Galactic disk has a sharp cutoff at about 14kpc from the Galactic center and indicates that it extends to much greater distances (as also supported by the recent detection of CO molecular complexes well beyond this distance). While the groups we find in the area of Ruprecht 30 are compatible with the Orion and Norma-Cygnus spiral arms, respectively, the distant group we identify in the region of VdB-Hagen 04 lies in the external regions of the Norma-Cygnus arm, at a galactocentric distance (~20kpc) where no young stars have been detected so far in the optical.
- ID:
- ivo://CDS.VizieR/J/ApJ/854/99
- Title:
- The Einstein@Home gamma-ray pulsar survey. II.
- Short Name:
- J/ApJ/854/99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the analysis of 13 gamma-ray pulsars discovered in the Einstein@Home blind search survey using Fermi Large Area Telescope (LAT) Pass 8 data. The 13 new gamma-ray pulsars were discovered by searching 118 unassociated LAT sources from the third LAT source catalog (3FGL), selected using the Gaussian Mixture Model machine-learning algorithm on the basis of their gamma-ray emission properties being suggestive of pulsar magnetospheric emission. The new gamma-ray pulsars have pulse profiles and spectral properties similar to those of previously detected young gamma-ray pulsars. Follow-up radio observations have revealed faint radio pulsations from two of the newly discovered pulsars and enabled us to derive upper limits on the radio emission from the others, demonstrating that they are likely radio-quiet gamma-ray pulsars. We also present results from modeling the gamma-ray pulse profiles and radio profiles, if available, using different geometric emission models of pulsars. The high discovery rate of this survey, despite the increasing difficulty of blind pulsar searches in gamma rays, suggests that new systematic surveys such as presented in this article should be continued when new LAT source catalogs become available.
- ID:
- ivo://CDS.VizieR/IX/24
- Title:
- The Einstein Observatory HRI Source List
- Short Name:
- IX/24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Einstein Observatory is the second of NASA's three High Energy Astrophysical Observatories, HEAO-2, renamed Einstein after launch, and was the first fully imaging X-ray telescope put into space. It observed in the energy range 0.2-20keV. It was launched on 12 November 1978, and remained in operation until April 1981. The High Resolution Imager (HRI) is one fo the four instruments aboard the Einstein Observatory, operating in the 0.2-3.0keV energy range, with a spatial resolution of a few arcseconds, and a field of view of 25arcmin. Field and source parameters observed with this instrument are given here.
- ID:
- ivo://CDS.VizieR/J/ApJ/461/127
- Title:
- The Einstein Two-Sigma Catalog
- Short Name:
- J/ApJ/461/127
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The X-ray sources from the observations with the Einstein Observatory (HEAO-2) with intensities of 2-sigma above the background are compiled in this catalog. This catalog covers more sky at fainter flux levels than the Einstein Medium Sensitivity Survey. Fields with diffuse emission sources were excluded. Thus data within 10 degrees of the galactic plane as well as fields within the boundaries of the Magellanic Clouds were excluded. The catalog covers 1850 sq. degrees of the sky. The generation of the Einstein Two-Sigma Catalog was described in detail by Moran et al. (1996). Read this article carefully to ensure responsible use of the Catalog. Address any questions to Ed Moran (edhed@igpp.llnl.gov). In particular it should be noted that only 28%, or about 13,000 sources in the 2-sigma catalog are real sources. The authors show that cross-correlations with other catalogs is an effective way to select sources in this catalog that are probably real.
- ID:
- ivo://CDS.VizieR/J/ApJ/723/1072
- Title:
- The ELM survey. I. Low-mass white dwarfs
- Short Name:
- J/ApJ/723/1072
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze radial velocity observations of the 12 extremely low-mass (ELM), with <=0.25M_{sun}_, white dwarfs (WDs) in the MMT Hypervelocity Star Survey. Eleven of the twelve WDs are binaries with orbital periods shorter than 14hr; the one non-variable WD is possibly a pole-on system among our non-kinematically selected targets. Our sample is unique: it is complete in a well-defined range of apparent magnitude and color. The orbital mass functions imply that the unseen companions are most likely other WDs, although neutron star companions cannot be excluded. Six of the eleven systems with orbital solutions will merge within a Hubble time due to the loss of angular momentum through gravitational wave radiation. The quickest merger is J0923+3028, a g=15.7 ELM WD binary with a 1.08hr orbital period and a <=130Myr merger time. The chance of a supernova Ia event among our ELM WDs is only 1%-7%, however. Three binary systems (J0755+4906, J1233+1602, and J2119-0018) have extreme mass ratios and will most likely form stable mass-transfer AM CVn systems. Two of these objects, SDSS J1233+1602 and J2119-0018, are the lowest surface gravity WDs ever found; both show CaII absorption likely from accretion of circumbinary material. We predict that at least one of our WDs is an eclipsing detached double WD system, important for constraining helium core WD models.
