- ID:
- ivo://CDS.VizieR/J/AJ/106/1639
- Title:
- Speckle observations of binary stars
- Short Name:
- J/AJ/106/1639
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Speckle interferometric observations from the Canada-France-Hawaii 3.6m and Cerro Tololo 4 m telescopes are reported for 1123 stars selected from the Yale Bright Star Catalogue in a continuing effort to detect new binaries among the bright stars. Thirty-two previously unresolved binaries have been detected, including companions to Xi UMa and 15 S Mon. Measures of 107 previously resolved systems, many of which resulted from earlier speckle observations, are also presented. No evidence of duplicity within a specific (m,Delta(m),rho) window of detectability was found for 984 bright stars. These observations combined with two previously published surveys represent the inspection of 2088 stars, representing 23% of the members of the Bright Star Catalogue. Many of the systems discovered earlier have shown significant orbital motions, and we present preliminary orbital elements for six binaries. Eighteen other stars previously announced as bright binaries have not been confirmed following numerous attempts to do so, and we show that their apparently spurious nature is likely due to the domination of the speckle transfer function by moderate telescope aberrations under conditions of superb seeing encountered at the CFHT in 1985. After deletion of these spurious systems, this effort has resulted in the discovery of 75 new, bright binaries. We consider some aspects of the duplicity frequencies among the diverse spectral and luminosity classes represented in this sample. We anticipate that the completion of a speckle survey of the Bright Star Catalogue would lead to the discovery of at least 200 additional binary systems with angular separations mostly below 0.20". Many of these will have periods of the order of one decade and will be accessible to complementary radial velocity programs of enhanced precision.
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- ID:
- ivo://CDS.VizieR/J/AJ/106/352
- Title:
- Speckle observations of binary stars VIII
- Short Name:
- J/AJ/106/352
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- One-thousand eighty-eight observations of 947 binary star systems, observed by means of speckle interferometry with the 4 m telescope on Cerro Tololo, are presented. These measurements, made during the period 1989-1991, comprise the second installment of results stemming from the expansion of our speckle program to the southern hemisphere.
- ID:
- ivo://CDS.VizieR/J/AJ/111/393
- Title:
- Speckle observations of binary stars. XII
- Short Name:
- J/AJ/111/393
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Five hundred sixty-five measurements of 99 binary star systems are presented, obtained during 1984-1986 by means of speckle interferometry at the 1.8 m Perkins telescope on Anderson Mesa, Arizona. These observations were collected as part of a systematic program in which frequent speckle observations of nearby binary systems were to be used to attempt the detection of unseen companions through the analysis of residual motions in wide, visual binaries. This is the first of several papers in which these observations are presented and discussed.
- ID:
- ivo://CDS.VizieR/J/A+A/367/865
- Title:
- Speckle observations of binary systems
- Short Name:
- J/A+A/367/865
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From speckle observations made with the PISCO speckle camera at the Pic du Midi Observatory, we present high angular resolution astrometric data for 43 binary stars already observed by the Hipparcos satellite. This sample consists of mainly new Hipparcos eclipsing binaries with a visual companion closer than one arcsecond, chosen with the aim to study the dynamical implications of a third component on the observational parameters of the eclipsing system. In addition, we also included a selection of close visual binaries with few speckle data in order to analyse possible systematic departures between the speckle and the non-speckle orbits. The reduction method and the results are presented in detail. For the close visual binaries we confront our observations with the ephemerides based on the best known orbits. For the wide visual binaries the confrontation is made directly with the Hipparcos data. Our observations are consistent both with previous speckle data and with most of the Hipparcos measurements.
- ID:
- ivo://CDS.VizieR/J/AJ/158/167
- Title:
- Speckle observations & orbits of multiple stars
- Short Name:
- J/AJ/158/167
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report results of speckle-interferometric monitoring of visual hierarchical systems using the newly commissioned instrument NN-EXPLORE Exoplanet and Stellar Speckle Imager at the 3.5 m WIYN telescope. During one year, 390 measurements of 129 resolved subsystems were made, while some targets were unresolved. Using our astrometry and archival data, we computed 36 orbits (27 for the first time). Spectro-interferometric orbits of seven pairs are determined by combining positional measurements with radial velocities measured, mostly, with the Center for Astrophysics digital speedometers. For the hierarchical systems HIP 65026 (periods 49 and 1.23 yr) and HIP 85209 (periods 34 and 1.23 yr) we determined both the inner and the outer orbits using astrometry and radial velocities and measured the mutual orbit inclinations of 11.3{deg}+/-1.0{deg} and 12.0{deg}+/-3.0{deg}, respectively. Four bright stars are resolved for the first time; two of those are triple systems. Several visual subsystems announced in the literature are shown to be spurious. We note that subsystems in compact hierarchies with outer separations less than 100 au tend to have less eccentric orbits compared to wider hierarchies.
- ID:
- ivo://CDS.VizieR/J/AJ/162/75
- Title:
- Speckle observations TESS exoplanet host stars. II.
- Short Name:
- J/AJ/162/75
- Date:
- 18 Mar 2022 09:30:45
- Publisher:
- CDS
- Description:
- We present high-angular-resolution imaging observations of 517 host stars of TESS exoplanet candidates using the 'Alopeke and Zorro speckle cameras at Gemini North and South. The sample consists mainly of bright F, G, K stars at distances of less than 500pc. Our speckle observations span angular resolutions of ~20mas out to 1.2", yielding spatial resolutions of <10-500au for most stars, and our contrast limits can detect companion stars 5-9mag fainter than the primary at optical wavelengths. We detect 102 close stellar companions and determine the separation, magnitude difference, mass ratio, and estimated orbital period for each system. Our observations of exoplanet host star binaries reveal that they have wider separations than field binaries, with a mean orbital semimajor axis near 100 au. Other imaging studies have suggested this dearth of very closely separated binaries in systems which host exoplanets, but incompleteness at small separations makes it difficult to disentangle unobserved companions from a true lack of companions. With our improved angular resolution and sensitivity, we confirm that this lack of close exoplanet host binaries is indeed real. We also search for a correlation between planetary orbital radii versus binary star separation; but, given the very short orbital periods of the TESS planets, we do not find any clear trend. We do note that in exoplanet systems containing binary host stars, there is an observational bias against detecting Earth-size planet transits due to transit depth dilution caused by the companion star.
- ID:
- ivo://CDS.VizieR/J/ApJS/230/7
- Title:
- Spectral flux densities from 50MHz to 50GHz
- Short Name:
- J/ApJS/230/7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The flux-density scale of Perley & Butler (2013ApJS..204...19P) is extended downward to ~50MHz by utilizing recent observations with the Karl G. Jansky Very Large Array (VLA) of 20 sources between 220MHz and 48.1GHz, and legacy VLA observations at 73.8MHz. The derived spectral flux densities are placed on an absolute scale by utilizing the Baars+ (1977A&A....61...99B) values for Cygnus A (3C405) for frequencies below 2GHz, and the Mars-based polynomials for 3C286, 3C295, and 3C196 from Perley & Butler above 2GHz. Polynomial expressions are presented for all 20 sources, with accuracy limited by the primary standards to 3%-5% over the entire frequency range. Corrections to the scales proposed by Perley & Butler, and by Scaife & Heald (2012MNRAS.423L..30S) are given.
- ID:
- ivo://CDS.VizieR/J/A+A/621/A6
- Title:
- Spectro-interferometric observation of SW Vir
- Short Name:
- J/A+A/621/A6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a near-infrared spectro-interferometric observation of the non-Mira-type, semiregular asymptotic giant branch star SW Vir. Our aim is to probe the physical properties of the outer atmosphere with spatially resolved data in individual molecular and atomic lines. We observed SW Vir in the spectral window between 2.28 and 2.31 micron with the near-infrared interferometric instrument AMBER at ESO's Very Large Telescope Interferometer (VLTI). Thanks to AMBER's high spatial resolution and high spectral resolution of 12000, the atmosphere of SW Vir has been spatially resolved not only in strong CO first overtone lines but also in weak molecular and atomic lines of H_2_O, CN, HF, Ti, Fe, Mg, and Ca. While the uniform-disk diameter of the star is 16.23+/-0.20mas in the continuum, it increases up to 22-24mas in the CO lines. Comparison with the MARCS photospheric models reveals that the star appears larger than predicted by the hydrostatic models not only in the CO lines but also even in the weak molecular and atomic lines. We found that this is primarily due to the H2O lines (but also possibly due to the HF and Ti lines) originating in the extended outer atmosphere. Although the H_2_O lines manifest themselves very little in the spatially unresolved spectrum, the individual rovibrational H_2_O lines from the outer atmosphere can be identified in the spectro-interferometric data. Our modeling suggests an H_2_O column density of 10^19^-10^20^cm^-2^ in the outer atmosphere extending out to ~2R*. Our study has revealed that the effects of the nonphotospheric outer atmosphere are present in the spectro-interferometric data not only in the strong CO first overtone lines but also in the weak molecular and atomic lines. Therefore, analyses of spatially unresolved spectra, such as for example analyses of the chemical composition, should be carried out with care even if the lines appear to be weak.
- ID:
- ivo://CDS.VizieR/J/MNRAS/489/2595
- Title:
- Spectro-interferometry of 8 evolved stars
- Short Name:
- J/MNRAS/489/2595
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We determine the physical parameters of the outer atmosphere of a sample of eight evolved stars, including the red supergiant {alpha} Scorpii, the red giant branch stars {alpha} Bootis and {gamma} Crucis, the K giant {lambda} Velorum, the normal M giants BK Virginis and SW Virginis, and the Mira star W Hydrae (in two different luminosity phases) by spatially resolving the stars in the individual carbon monoxide (CO) first overtone lines. We used the Astronomical Multi-BEam combineR (AMBER) instrument at the Very Large Telescope Interferometer (VLTI), in high-resolution mode ({lambda}/{Delta}{lambda}~=12000) between 2.28 and 2.31um in the K band. The maximal angular resolution is 10mas, obtained using a triplet telescope configuration, with baselines from 7 to 48m. By using a numerical model of a molecular atmosphere in a spherical shells (MOLsphere), called PAMPERO (an acronym for the 'physical approach of molecular photospheric ejection at high angular resolution for evolved stars'), we add multiple extended CO layers above the photospheric MARCS model at an adequate spatial resolution. We use the differential visibilities and the spectrum to estimate the size (R) of the CO MOLsphere, its column density (NCO) and temperature (Tmol) distributions along the stellar radius. The combining of the {chi}^2^ minimization and a fine grid approach for uncertainty analysis leads to reasonable NCO and Tmol distributions along the stellar radius of the MOLsphere.
- ID:
- ivo://CDS.VizieR/J/ApJS/244/30
- Title:
- Spitzer catalog of Herschel star-forming galaxies
- Short Name:
- J/ApJS/244/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The largest Herschel extragalactic surveys, H-ATLAS and HerMES, have selected a sample of "ultrared" dusty star-forming galaxies (DSFGs) with rising SPIRE flux densities (S_500_>S_350_>S_250_; the so-called "500{mu}m risers") as an efficient way for identifying DSFGs at higher redshift (z>4). In this paper, we present a large Spitzer follow-up program of 300 Herschel ultrared DSFGs. We have obtained high-resolution Atacama Large Millimeter/submillimeter Array, Northern Extended Millimeter Array, and SMA data for 63 of them, which allow us to securely identify the Spitzer/IRAC counterparts and classify them as gravitationally lensed or unlensed. Within the 63 ultrared sources with high-resolution data, ~65% appear to be unlensed and ~27% are resolved into multiple components. We focus on analyzing the unlensed sample by directly performing multiwavelength spectral energy distribution modeling to derive their physical properties and compare with the more numerous z~2 DSFG population. The ultrared sample has a median redshift of 3.3, stellar mass of 3.7x10^11^M_{sun}_, star formation rate (SFR) of 730M_{sun}_/yr, total dust luminosity of 9.0x10^12^L_{sun}_, dust mass of 2.8x10^9^M_{sun}_, and V-band extinction of 4.0, which are all higher than those of the ALESS DSFGs. Based on the space density, SFR density, and stellar mass density estimates, we conclude that our ultrared sample cannot account for the majority of the star-forming progenitors of the massive, quiescent galaxies found in infrared surveys. Our sample contains the rarer, intrinsically most dusty, luminous, and massive galaxies in the early universe that will help us understand the physical drivers of extreme star formation.
