- ID:
- ivo://CDS.VizieR/J/ApJ/809/134
- Title:
- delta Orionis Aa. III. Radial velocities
- Short Name:
- J/ApJ/809/134
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on both high-precision photometry from the Microvariability and Oscillations of Stars (MOST) space telescope and ground-based spectroscopy of the triple system {delta} Ori A, consisting of a binary O9.5II+early-B (Aa1 and Aa2) with P=5.7days, and a more distant tertiary (O9IV P>400 years). This data was collected in concert with X-ray spectroscopy from the Chandra X-ray Observatory. Thanks to continuous coverage for three weeks, the MOST light curve reveals clear eclipses between Aa1 and Aa2 for the first time in non-phased data. From the spectroscopy, we have a well-constrained radial velocity (RV) curve of Aa1. While we are unable to recover RV variations of the secondary star, we are able to constrain several fundamental parameters of this system and determine an approximate mass of the primary using apsidal motion. We also detected second order modulations at 12 separate frequencies with spacings indicative of tidally influenced oscillations. These spacings have never been seen in a massive binary, making this system one of only a handful of such binaries that show evidence for tidally induced pulsations.
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- ID:
- ivo://CDS.VizieR/J/MNRAS/475/478
- Title:
- delta Scuti pulsating stars LAMOST views
- Short Name:
- J/MNRAS/475/478
- Date:
- 07 Dec 2021 13:11:57
- Publisher:
- CDS
- Description:
- About 766 {delta} Scuti stars were observed by LAMOST by 2017 June 16. Stellar atmospheric parameters of 525 variables were determined, while spectral types were obtained for all samples. In the paper, those spectroscopic data are catalogued. We detect a group of 131 unusual and cool variable stars (UCVs) that are distinguished from the normal {delta} Scuti stars (NDSTs). On the H-R diagram and the logg-T diagram, the UCVs are far beyond the red edge of pulsational instability trip. Their effective temperatures are lower than 6700K with periods in the range from 0.09 to 0.22d. NDSTs have metallicity close to that of the Sun as expected, while UCVs are slightly metal poor than NDSTs. The two peaks on the distributions of the period and stellar atmospheric parameters are all caused by the existence of UCVs. When those UCVs are excluded, it is discovered that the effective temperature, the gravitational acceleration, and the metallicity all are correlated with the pulsating period for NDSTs and their physical properties and evolutionary states are discussed. Detection of those UCVs indicates that about 25 per cent of the known {delta} Scuti stars may be misclassified. However, if some of them are confirmed to be pulsating stars, they will be a new-type pulsator and their investigations will shed light on theoretical instability domains and on the theories of interacting between the pulsation and the convection of solar-type stars. Meanwhile, 88 {delta} Scuti stars are detected to be the candidates of binary or multiple systems.
303. Delta Scuti stars
- ID:
- ivo://CDS.VizieR/J/A+AS/144/469
- Title:
- Delta Scuti stars
- Short Name:
- J/A+AS/144/469
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An extensive and up-dated list of {delta} Sct stars is presented here. More than 500 papers, published during the last few years, have been revised and 341 new variables have been added to our last list, six years ago. This catalogue is intended to be a comprehensive review on the observational characteristics of all the {delta} Sct stars known until now, including stars contained in earlier catalogues together with other new discovered variables, covering information published until January 2000. In summary, 636 variables, 1149 references and 182 individual notes are presented in this new list.
- ID:
- ivo://CDS.VizieR/J/A+AS/124/385
- Title:
- Dense molecular cores. V.
- Short Name:
- J/A+AS/124/385
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of the observations of 17 molecular clouds associated with bright FIR sources in the NH_3_ (1, 1) and (2, 2) lines with the 100-m radio telescope in Effelsberg. The lines were detected in 11 clouds and 10 of them have been mapped in these lines. The kinetic temperatures, sizes, masses and mean densities of the ammonia cores have been derived. For most of the detected clouds the masses derived under the assumption of a relative ammonia abundance of {chi}(NH_3_)=3x10^-8^ are close to virial masses. However, in S 88 B the ratio M/M_vir_ is only ~0.1 and in a few other cases this ratio is significantly lower than unity which may indicate ammonia underabundance. Almost all objects with the signs of underabundance are among the most luminous IR sources in our sample. Most of the mapped cores are elongated with noticeable velocity gradients along the major axis. The most prominent example is S 255. S 87 has a two-component structure with 2 distinct velocity components which overlap partly spatially. In about half of the mapped sources the NH_3_ line widths increase near the peaks of the ammonia emission. The kinetic temperatures are centrally peaked. They reach 20-28K in the centre and drop to 15-20K at the edges of the ammonia emitting regions. In S 76 E a weak extended emission in the (1, 1) line at the velocity blue-shifted by ~5km/s relative to the core emission was detected. Hyperfine intensity anomalies in the (1, 1) transition were found in S 199 in addition to the known case of these anomalies in S 87.
- ID:
- ivo://CDS.VizieR/J/ApJ/711/573
- Title:
- Detailed abundances in a halo stellar stream
- Short Name:
- J/ApJ/711/573
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a detailed abundance analysis of one of the confirmed building blocks of the Milky Way stellar halo, a kinematically coherent metal-poor stellar stream. We have obtained high-resolution and high signal-to-noise spectra of 12 probable stream members using the Magellan Inamori Kyocera Echelle spectrograph on the Magellan-Clay Telescope at Las Campanas Observatory and the 2dCoude spectrograph on the Smith Telescope at McDonald Observatory. We have derived abundances or upper limits for 51 species of 46 elements in each of these stars. The stream members show a range of metallicity (-3.4<[Fe/H]<-1.5) but are otherwise chemically homogeneous, with the same star-to-star dispersion in [X/Fe] as the rest of the halo. This implies that, in principle, a significant fraction of the Milky Way stellar halo could have formed from accreted systems like the stream. The stream stars show minimal evolution in the {alpha} or Fe-group elements over the range of metallicity. This stream is enriched with material produced by the main and weak components of the rapid neutron-capture process and shows no evidence for enrichment by the slow neutron-capture process.
- ID:
- ivo://CDS.VizieR/J/A+A/645/A7
- Title:
- Determining true mass of RV exoplanets with Gaia
- Short Name:
- J/A+A/645/A7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Mass is one of the most important parameters for determining the true nature of an astronomical object. Yet, many published exoplan- ets lack a measurement of their true mass, in particular those detected as a result of radial-velocity (RV) variations of their host star. For those examples, only the minimum mass, or msini, is known, owing to the insensitivity of RVs to the inclination of the detected orbit compared to the plane of the sky. The mass that is given in databases is generally that of an assumed edge-on system (~90{deg}), but many other inclinations are possible, even extreme values closer to 0{deg} (face-on). In such a case, the mass of the published object could be strongly underestimated by up to two orders of magnitude. In the present study, we use GASTON, a recently developed tool taking advantage of the voluminous Gaia astrometric database to constrain the inclination and true mass of several hundreds of published exoplanet candidates. We find 9 exoplanet candidates in the stellar or brown dwarf (BD) domain, among which 6 were never characterized. We show that 30 Ari B b, HD 141937 b, HD 148427 b, HD 6718 b, HIP 65891 b, and HD 16760 b have masses larger than 13.5 M_J_ at 3{sigma}. We also confirm the planetary nature of 27 exoplanets, including HD 10180 c, d and g. Studying the orbital periods, eccentricities, and host-star metallicities in the BD domain, we found distributions with respect to true masses consistent with other publications. The distribution of orbital periods shows of a void of BD detections below ~100d, while eccentricity and metallicity distributions agree with a transition between BDs similar to planets and BDs similar to stars in the range 40-50M_J_.
- ID:
- ivo://CDS.VizieR/J/A+A/585/A36
- Title:
- Deuterated water in prestellar cores
- Short Name:
- J/A+A/585/A36
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on new APEX observations of the ground state 1_0,1_-0_0,0_ HDO transition at 464.92452GHz toward the prestellar core L1544. The line is undetected and we present an extensive study on the conditions for its detectability in cold and dense cloud cores. The water and deuterated water abundances have been estimated using an advanced chemical model simplified for the limited number of reactions or processes that are active in cold regions (<15K). We use the LIME radiative transfer code to compute the expected intensity and profile of both H_2_O and HDO lines and compare them with the observations. We present several ad hoc profiles that best-fit the observations and compare the profiles with results from an astrochemical modeling, coupling gas phase and grain surface chemistry. Our comparison between observations, radiative transfer and chemical modeling shows the limits of detectability for singly deuterated water with single-dish telescopes as well as interferometric observations.
- ID:
- ivo://CDS.VizieR/J/AN/316/39
- Title:
- Diameter-limited Northern sky galaxies catalog
- Short Name:
- J/AN/316/39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In order to understand if the differences between the SSRS of Da Costa et al. (1988ApJ...327..544D) (which is diameter limited) and the CfA survey (Huchra et al., 1995, Cat. <VII/193>) (which is magnitude limited) are real or induced by the different selection criteria, the CfA survey has been directly compared with a diameter-limited sample covering the same region of the sky (UDLS, Bardelli et al., 1991A&A...248..354B, Zucca et al., 1991MNRAS.253..401Z). In this paper we present the data for the galaxies in the UDLS sample, in an updated version which collects velocity information from the literature until June 1993, leaving us with a velocity completeness better than ~95%.
- ID:
- ivo://CDS.VizieR/J/AJ/130/2866
- Title:
- Differential astrometry of {delta} Equulei
- Short Name:
- J/AJ/130/2866
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Delta Equulei is among the most well-studied nearby binary star systems. Results of its observation have been applied to a wide range of fundamental studies of binary systems and stellar astrophysics. It is widely used to calibrate and constrain theoretical models of the physics of stars. We report 27 high-precision differential astrometry measurements of {delta} Equ from the Palomar High-precision Astrometric Search for Exoplanet Systems (PHASES).
- ID:
- ivo://CDS.VizieR/J/AJ/146/146
- Title:
- Differential BV photometry of VV Crv
- Short Name:
- J/AJ/146/146
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained red-wavelength spectroscopy and Johnson B and V differential photoelectric photometry of the eclipsing binary VV Crv=HR 4821. The system is the secondary of the common proper motion double star ADS 8627, which has a separation of 5.2". VV Crv has an orbital period of 3.144536 days and a low but non-zero eccentricity of 0.085. With the Wilson-Devinney program we have determined a simultaneous solution of our spectroscopic and photometric observations. Those orbital elements produce masses of M_1_=1.978+/-0.010M_{sun}_ and M_2_=1.513+/-0.008M_{sun}_, and radii of R_1_=3.375+/-0.010R_{sun}_ and R_2_=1.650+/-0.008R_{sun}_for the primary and secondary, respectively. The effective temperatures of the two components are 6500K (fixed) and 6638K, so the star we call the primary is the more massive but cooler and larger component. A comparison with evolutionary tracks indicates that the components are metal rich with [Fe/H]=0.3, and the system has an age of 1.2Gyr. The primary is near the end of its main-sequence lifetime and is rotating significantly faster than its pseudosynchronous velocity. The secondary is still well ensconced on the main sequence and is rotating more slowly than its pseudosynchronous rate.