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511. HERMES spectra of LS V +22 25
ID:
ivo://CDS.VizieR/J/A+A/639/L6
Title:
HERMES spectra of LS V +22 25
Short Name:
J/A+A/639/L6
Date:
21 Oct 2021
Publisher:
CDS
Description:
The intriguing binary LS V +22 25 (LB-1) has drawn much attention following claims of it being a single-lined spectroscopic binary with a 79-day orbit comprising a B-type star and a ~70M_{sun}_ black hole - the most massive stellar black hole reported to date. Subsequent studies demonstrated a lack of evidence for a companion of such great mass. Recent analyses have implied that the primary star is a stripped He-rich star with peculiar sub-solar abundances of heavy elements, such as Mg and Fe. However, the nature of the secondary, which was proposed to be a black hole, a neutron star, or a main sequence star, remains unknown. Based on 26 newly acquired spectroscopic observations secured with the HERMES and FEROS spectrographs covering the orbit of the system, we perform an orbital analysis and spectral disentangling of LB-1 to elucidate the nature of the system. To derive the radial velocity semi-amplitude K2 of the secondary and extract the spectra of the two components, we used two independent disentangling methods: the shift-and-add technique and Fourier disentangling with FDBinary. We used atmosphere models to constrain the surface properties and abundances. Our disentangling and spectral analysis shows that LB-1 contains two components of comparable brightness in the optical. The narrow-lined primary, which we estimate to contribute 55% in the optical, has spectral properties that suggest that it is a stripped star: it has a small spectroscopic mass (~1M_{sun}_) for a B-type star and it is He- and N-rich. Unlike previous reports, the abundances of heavy elements are found to be solar. The 'hidden' secondary, which contributes about 45% of the optical flux, is a rapidly rotating (vsini~300km/s) B3 V star with a decretion disk - a Be star. As a result of its rapid rotation and dilution, the photospheric absorption lines of the secondary are not readily apparent in the individual observations.We measure a semi-amplitude for this star of K2=11.2+/-1.0km/s and adopting a mass of M2=72M_{sun}_ typical for B3 V stars, we derive an orbital mass for the stripped primary of M1=1.5+/-0.4 M_{sun}_. The orbital inclination of 394 implies a near-critical rotation for the Be secondary (v_eq_~470km/s). LB-1 does not contain a compact object. Instead, it is a rare Be binary system consisting of a stripped star (the former mass donor) and a Be star rotating at near its critical velocity (the former mass accretor). This system is a clear example that binary interactions play a decisive role in the production of rapid stellar rotators and Be stars.
512. High contrast images of NZ Lup
ID:
ivo://CDS.VizieR/J/A+A/625/A21
Title:
High contrast images of NZ Lup
Short Name:
J/A+A/625/A21
Date:
21 Oct 2021
Publisher:
CDS
Description:
Planetary systems hold the imprint of the formation and of the evolution of planets especially at young ages, and in particular at the stage when the gas has dissipated leaving mostly secondary dust grains. The dynamical perturbation of planets in the dust distribution can be revealed with high-contrast imaging in a variety of structures. SPHERE, the high-contrast imaging device installed at the VLT, was designed to search for young giant planets in long period, but is also able to resolve fine details of planetary systems at the scale of astronomical units in the scattered-light regime. As a young and nearby star, NZ Lup was observed in the course of the SPHERE survey. A debris disk had been formerly identified with HST/NICMOS. We observed this system in the near-infrared with the camera in narrow and broad band filters and with the integral field spectrograph. High contrasts are achieved by the mean of pupil tracking combined with angular differential imaging algorithms. The high angular resolution provided by SPHERE allows us to reveal a new feature in the disk which is interpreted as a superimposition of two belts of planetesimals located at stellocentric distances of ~85 and ~115au, and with a mutual inclination of about 5{deg}. Despite the very high inclination of the disk with respect to the line of sight, we conclude that the presence of a gap, that is, a void in the dust distribution between the belts, is likely. We discuss the implication of the existence of two belts and their relative inclination with respect to the presence of planets.
513. High-frequency A-type pulsators
ID:
ivo://CDS.VizieR/J/MNRAS/439/2078
Title:
High-frequency A-type pulsators
Short Name:
J/MNRAS/439/2078
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of a survey using the WASP archive to search for high-frequency pulsations in F-, A- and B-type stars. Over 1.5 million targets have been searched for pulsations with amplitudes greater than 0.5 millimagnitude. We identify over 350 stars which pulsate with periods less than 30min. Spectroscopic follow-up of selected targets has enabled us to confirm 10 new rapidly oscillating Ap stars, 13 pulsating Am stars and the fastest known {delta} Scuti star. We also observe stars which show pulsations in both the high-frequency domain and the low-frequency {delta} Scuti range. This work shows the power of the WASP photometric survey to find variable stars with amplitudes well below the nominal photometric precision per observation.
514. High spatial resolution observations of HM Sge
ID:
ivo://CDS.VizieR/J/A+A/493/1043
Title:
High spatial resolution observations of HM Sge
Short Name:
J/A+A/493/1043
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present high spatial resolution observations of the close circumstellar environment of the symbiotic system HM Sagittae obtained with the Very Large Telescope Interferometer (VLTI) of ESO's Paranal Observatory and MIDI, the MID-infrared Interferometric recombiner. MIDI combines the light of two telescopes and provides spectrally resolved visibilities in the N band atmospheric window. The observations of HM Sge were conducted with the VLT Auxiliary Telescopes (ATs) A0, D0, G1 and H0, providing projected baselines in the range of 64 to 89 meters oriented from PA=72 to 127{deg}. The ATs observations were made during the nights of April 04, May 08/10/16, and July 30. All the observations were made under good atmospheric conditions (average seeing ~0.62") with the worst seeing (~1.05") during the night of July 30 2007. The files includes all visibility and differential phase data recorded from these observations as well as all the characteristics concerning the observations. The log of the observations is shown in the third part of table1. The set of data are complementary to the ones corresponding to the first two parts of Table 1 of the paper previously published in Sacuto et al. (2007, Cat. <J/A+A/465/469>)
515. High spatial resolution observations of HM Sge
ID:
ivo://CDS.VizieR/J/A+A/465/469
Title:
High spatial resolution observations of HM Sge
Short Name:
J/A+A/465/469
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present high spatial resolution observations of the mid-infrared core of the dusty symbiotic system HM Sge obtained with the Very Large Telescope Interferometer (VLTI) of ESO's Paranal Observatory and MIDI, the MID-infrared Interferometric recombiner. MIDI combines the light of two telescopes and provides spectrally resolved visibilities in the N band atmospheric window. The observations of HM Sge were conducted with the VLT Unit Telescopes (UTs) UT2, UT3 and UT4, providing projected baselines in the range of 32-59 meters oriented from PA=42deg to 105deg and the Auxiliary Telescopes (ATs) E0 and G0, providing projected baselines in the range of 13.5-16 meters oriented around PA=75deg. The UTs observations were made during the nights of July 23-24th 2005, May 17th 2006 and June 11th 2006. The ATs observations were made during the nights of May 27th 2006 and June 16th 2006. All the observations were made under good atmospheric conditions (Mean[seeing]~1.01") with the worst seeing (~1.75") during the night of July 23th 2005. The files includes all visibility and differential phase data recorded from these observations as well as all the characteristics concerning the observations. The log of the observations is shown in Table 1 of the paper (table1.dat).
516. High spatial resolution observations of pi^1^ Gru
ID:
ivo://CDS.VizieR/J/A+A/482/561
Title:
High spatial resolution observations of pi^1^ Gru
Short Name:
J/A+A/482/561
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present high spatial resolution observations of the close circumstellar environment of the semi-regular S-type star pi^1^ Gruis obtained with the Very Large Telescope Interferometer (VLTI) of ESO's Paranal Observatory and MIDI, the MID-infrared Interferometric recombiner. MIDI combines the light of two telescopes and provides spectrally resolved visibilities in the N band atmospheric window. The observations of pi^1^ Gruis were conducted with the VLT Auxiliary Telescopes (ATs) A0, E0, D0 and G0, providing projected baselines in the range of 15 to 64 meters oriented from PA=41 to 102{deg}. The ATs observations were made during the nights of May 21-23-24-25-27 2006, June 19 2006, and August 08 2006. All the observations were made under good atmospheric conditions (average seeing ~0.94") with the worst seeing (~1.51") during the night of May 27 2006. The files includes all visibility and differential phase data recorded from these observations as well as all the characteristics concerning the observations. The log of the observations is shown in Table 1.
517. High Speed Photometer
ID:
ivo://archive.stsci.edu/hst/hsp
Title:
High Speed Photometer
Short Name:
HST.HSP
Date:
23 Jul 2020 19:49:53
Publisher:
Space Telescope Science Institute Archive
Description:
The High Speed Photometer (HSP) was one of the four original axial instruments on the Hubble Space Telescope (HST). The HSP was designed to make very rapid photometric observations of astrophysical sources in a variety of filters and passbands from the near ultraviolet to the visible. The HSP was removed from HST during the First Servicing Mission in December, 1993.
518. High-time-resolution photometry of AR Scorpii
ID:
ivo://CDS.VizieR/J/AJ/156/150
Title:
High-time-resolution photometry of AR Scorpii
Short Name:
J/AJ/156/150
Date:
21 Oct 2021
Publisher:
CDS
Description:
The unique binary AR Scorpii consists of an asynchronously rotating, magnetized white dwarf (WD) that interacts with its red-dwarf companion to produce a large-amplitude, highly coherent pulsation every 1.97 minutes. Over the course of two years, we obtained 39 hours of time-resolved, optical photometry of AR Sco at a typical cadence of 5 s to study this pulsation. We find that it undergoes significant changes across the binary orbital period and that its amplitude, phase, and waveform all vary as a function of orbital phase. We show that these variations can be explained by constructive and destructive interference between two periodic, double-peaked signals: the spin-orbit beat pulse, and a weaker WD spin pulse. Modeling of the light curve indicates that in the optical, the amplitude of the primary spin pulse is 50% of the primary beat amplitude, while the secondary maxima of the beat and spin pulses have similar amplitudes. Finally, we use our timings of the beat pulses to confirm the presence of the disputed spin-down of the WD. We measure a beat-frequency derivative of {nu}=(-5.14+/-0.32)x10^-17^ Hz/s and show that this is attributable to the spin-down of the WD. This value is approximately twice as large as the estimate from Marsh et al. but is nevertheless consistent with the constraints established in Potter & Buckley (2018MNRAS.478L..78P). Our precise measurement of the spin-down rate confirms that the decaying rotational energy of the magnetized WD is sufficient to power the excess electromagnetic radiation emitted by the binary.
519. H235 in NGC 752
ID:
ivo://CDS.VizieR/J/AJ/109/359
Title:
H235 in NGC 752
Short Name:
J/AJ/109/359
Date:
21 Oct 2021
Publisher:
CDS
Description:
The short-period variable star Heinemann 235 in the open cluster NGC 752 has been identified as a contact binary with a variable period of about 0.4118 d. BVRI light curves and radial velocity curves have been obtained and analyzed with enhanced versions of the Wilson-Devinney light curve program. We find that the system is best modeled as an A-type W UMa system, with a contact parameter of 0.21 +/- 0.11. The masses of the components are found to be 1.18 +/- 0.17 and 0.24 +/- 0.04 Msun, with bolometric magnitudes of 3.60 +/- 0.10 and 5.21 +/- 0.13, for the hotter (6500 K, assumed) and cooler (6421 K) components, respectively, with Delta T = 79 +/- 25 K. The distance to the binary is established at 381 +/- 17 pc. H235 becomes one of a relatively small number of open-cluster contact systems with detailed light curve analysis for which an age may be estimated. If it is coeval with the cluster, and with the detached eclipsing and double-lined spectroscopic binary H219 (DS And), H235 is ~1.8 Gyr old, and may provide a fiducial point for the evolution of contact systems. There is, however, evidence for dynamical evolution of the cluster and the likelihood of weak interactions over the age of the binary precludes the determination of its initial state with certainty.
520. Hipparcos Variability-Induced Movers
ID:
ivo://CDS.VizieR/J/A+A/399/1167
Title:
Hipparcos Variability-Induced Movers
Short Name:
J/A+A/399/1167
Date:
21 Oct 2021
Publisher:
CDS
Description:
Hipparcos observations of some variable stars, and especially of long-period (e.g. Mira) variables, reveal a motion of the photocenter correlated with the brightness variation (variability-induced mover, VIM), suggesting the presence of a binary companion. A re-analysis of the Hipparcos photometric and astrometric data (Cat. <I/239>) does not confirm the VIM solution for 62 among the 288 VIM objects (21%) in the Hipparcos catalogue. Most of these 288 VIMs are long-period (e.g. Mira) variables (LPV). The effect of a revised chromaticity correction, which accounts for the color variations along the light cycle, was then investigated. It is based on "instantaneous" V-I color indices derived from Hipparcos and Tycho-2 (Cat. <I/259>) epoch photometry. Among the 188 LPVs flagged as VIM in the Hipparcos catalogue, 89 (47%) are not confirmed as VIM after this improved chromaticity correction is applied. This dramatic decrease in the number of VIM solutions is not surprising, since the chromaticity correction applied by the Hipparcos reduction consortia was based on a fixed V-I color. Astrophysical considerations lead us to adopt a more stringent criterion for accepting a VIM solution (first-kind risk of 0.27% instead of 10% as in the Hipparcos catalogue). With this more severe criterion, only 27 LPV stars remain VIM, thus rejecting 161 of the 188 (86%) of the LPVs defined as VIMs in the Hipparcos catalogue.