Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/448/1137
- Title:
- Radial velocity curve of the HD170582 donor
- Short Name:
- J/MNRAS/448/1137
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a spectroscopic and photometric study of the double period variable HD 170582. Based on the study of the ASAS V-band light curve, we determine an improved orbital period of 16.87177+/-0.02084 d and a long period of 587 d. We disentangled the light curve into an orbital part, determining ephemerides and revealing orbital ellipsoidal variability with unequal maxima, and a long cycle, showing quasi-sinusoidal changes with amplitude {Delta}V=0.1mag. Assuming synchronous rotation for the cool stellar component and semidetached configuration we find a cool evolved star of M_2_=1.9+/-0.1 M_{sun}_, T_2_=8000+/-100 K and R_2_=15.6+/-0.2 R_{sun}_, and an early B-type dwarf of M_1_=9.0+/-0.2 M_{sun}_. The B-type star is surrounded by a geometrically and optically thick accretion disc of radial extension 20.8+/-0.3 R_{sun}_ contributing about 35 percent to the system luminosity at the V band. Two extended regions located at opposite sides of the disc rim, and hotter than the disc by 67 and 46 percent, fit the light-curve asymmetries. The system is seen under inclination 67.4{deg}+/-0.4{deg} and it is found at a distance of 238+/-10 pc. Specially interesting is the double line nature of HeI 5875; two absorption components move in antiphase during the orbital cycle; they can be associated with the shock regions revealed by the photometry. The radial velocity of one of the HeI 5875 components closely follows the donor radial velocity, suggesting that the line is formed in a wind emerging near the stream-disc interacting region.
- ID:
- ivo://CDS.VizieR/J/MNRAS/396/2194
- Title:
- Radial velocity curve of V440 Per
- Short Name:
- J/MNRAS/396/2194
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 440 Per is a Population I Cepheid with a period of 7.57d and low-amplitude, almost sinusoidal light and radial velocity curves. With no reliable data on the first harmonic, its pulsation mode identification remained controversial. We obtained a radial velocity curve of V440 Per with our new high-precision and high-throughput Poznan Spectroscopic Telescope.
- ID:
- ivo://CDS.VizieR/J/MNRAS/387/1563
- Title:
- Radial velocity curves of AE Aqr
- Short Name:
- J/MNRAS/387/1563
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-dispersion time-resolved spectroscopy of the unique magnetic cataclysmic variable AE Aqr is presented. A radial velocity analysis of the absorption lines yields K2=168.7+/-1km/s . Substantial deviations of the radial velocity curve from a sinusoid are interpreted in terms of intensity variations over the secondary star's surface. A complex rotational velocity curve as a function of orbital phase is detected which has a modulation frequency of twice the orbital frequency, leading to an estimate of the binary inclination angle that is close to 70{deg}. The minimum and maximum rotational velocities are used to indirectly derive a mass ratio of q=0.6 and a radial velocity semi-amplitude of the white dwarf of K1=101+/-3km/s. We present an atmospheric temperature indicator, based on the absorption-line ratio of FeI and CrI lines, whose variation indicates that the secondary star varies from K0 to K4 as a function of orbital phase. The ephemeris of the system has been revised, using more than 1000 radial velocity measurements, published over nearly five decades. From the derived radial velocity semi-amplitudes and the estimated inclination angle, we calculate that the masses of the stars are M1=0.63+/-0.05M_{sun}_; M2=0.37+/-0.04M_{sun}_ , and their separation is a=2.33+/-0.02R_{sun}. Our analysis indicates the presence of a late-type star whose radius is larger, by a factor of nearly 2, than the radius of a normal main-sequence star of the same mass. Finally, we discuss the possibility that the measured variations in the rotational velocity, temperature and spectral type of the secondary star as functions of orbital phase may, like the radial velocity variations, be attributable to regions of enhanced absorption on the star's surface.
- ID:
- ivo://CDS.VizieR/J/MNRAS/437/2303
- Title:
- Radial velocity curves of alpha Lib A
- Short Name:
- J/MNRAS/437/2303
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The spectroscopy of rapidly rotating binary stars occasionally encounters systems where - paradoxically - the primary is effectively hidden in the light of its secondary. Here, we report on a bright textbook example of this kind with the nearby A-type star {alpha} Lib A. Although discovered as a spectroscopic binary already in the year 1904, a radial velocity curve has never been published up to a point where the existence of the secondary became even suspicious. However, in this work, we demonstrate that {alpha} Lib A is indeed a double-lined spectroscopic binary with a rapidly rotating - and hence almost invisible - A-type primary, accompanied and predominated by a more slowly rotating late-A or early F-type secondary in an eccentric P=70.34d orbit. On account of the shallow absorption lines of the primary, uncertainties remain with its semi-amplitude and hence the exact mass ratio. Yet, with a maximal projected separation that should lie in the range 20 to 25mas, follow-up high-angular resolution observations might soon establish {alpha} Lib Aa-Ab as a visual binary, with a measure for the orbital inclination and precisely determined stellar masses.
- ID:
- ivo://CDS.VizieR/J/MNRAS/434/870
- Title:
- Radial velocity curves of 3 Cepheids
- Short Name:
- J/MNRAS/434/870
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of spectroscopic radial velocity and photometric data of three bright Galactic Cepheids: LR Trianguli Australis (LR TrA), RZ Velorum (RZ Vel) and BG Velorum (BG Vel). Based on new radial velocity data, these Cepheids have been found to be members of spectroscopic binary systems. The ratio of the peak-to-peak radial velocity amplitude to photometric amplitude indicates the presence of a companion for LR TrA and BG Vel. IUE spectra indicate that the companions of RZ Vel and BG Vel cannot be hot stars. The analysis of all available photometric data revealed that the pulsation period of RZ Vel and BG Vel varies monotonically, due to stellar evolution. Moreover, the longest period Cepheid in this sample, RZ Vel, shows period fluctuations superimposed on the monotonic period increase. The light-time effect interpretation of the observed pattern needs long-term photometric monitoring of this Cepheid. The pulsation period of LR TrA has remained constant since the discovery of its brightness variation. Using statistical data, it is also shown that a large number of spectroscopic binaries still remain to be discovered among bright classical Cepheids.
- ID:
- ivo://CDS.VizieR/J/A+A/622/A164
- Title:
- Radial velocity curves of 11 Cepheids
- Short Name:
- J/A+A/622/A164
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of the study of Galactic binary Cepheids combining interferometric and spectroscopic observations. For this purpose, we performed new spectroscopic observations to obtain high-precision radial velocity measurements of the Cepheids (primary component of the systems). We then fit the radial pulsation and orbital velocities to obtain the orbital elements.
- ID:
- ivo://CDS.VizieR/J/AJ/149/83
- Title:
- Radial velocity curves of HD 207651
- Short Name:
- J/AJ/149/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From numerous radial velocities obtained at KPNO and Fairborn Observatory, we have determined the orbital elements of the composite spectrum triple system HD 207651. This system consists of a broad-lined A8 V star and an unseen M dwarf companion in a 1.470739days orbit. Variations of the center-of-mass velocity of this short-period system and velocity variations of a narrow-lined F7: V star have an orbital period of 724.1days or 1.98yr and an eccentricity of 0.39. The revised Hipparcos parallax, corresponding to a distance of 255pc, appears to be too small to yield consistent properties. Instead, we adopt a distance of 150pc.
- ID:
- ivo://CDS.VizieR/J/A+A/533/A90
- Title:
- Radial velocity curves of HD 132563
- Short Name:
- J/A+A/533/A90
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As part of our radial velocity planet-search survey performed with SARG at TNG, we monitored the components of HD 132563 for ten years. It is a binary system formed by two rather similar solar type stars with a projected separation of 4.1arcsec, which corresponds to 400AU at the distance of 96 pc. The two components are moderately metal-poor and the age of the system is about 5Gyr. We detected RV variations of HD 132563B with period of 1544 days and semi-amplitude of 26m/s. From the star characteristics and line profile measurements, we infer their Keplerian origin. Therefore HD 132563B turns out to host a planet with a projected mass msini=1.49M_Jup_ at 2.6AU with a moderately eccentric orbit (e=0.22). The planet around HD 132563B is one of the few that are known in triple stellar systems, as we found that the primary HD 132563A is itself a spectroscopic binary with a period longer than 15 years and an eccentricity higher than 0.65. The spectroscopic component was not detected in adaptive-optics images taken with AdOpt@TNG, since it expected at a projected separation that was smaller than 0.2 arcsec at the time of our observations. A small excess in K band difference between the components with respect to the difference in V band is compatible with a companion of about 0.55M_{sun}_. A preliminary statistical analysis of the occurrence of planets in triple systems indicate a similar frequency of planets around the isolated component in a triple system, components of wide binaries and single stars. There is no significant iron abundance difference between the components. The lack of stars in binary systems and open clusters showing strong enhancements of iron abundance, comparable to the typical metallicity difference between stars with and without giant planets, agrees with the idea that accretion of planetary material producing iron abundance anomalies larger than 0.1dex is rare.
- ID:
- ivo://CDS.VizieR/J/A+A/496/527
- Title:
- Radial velocity curves of HD 47186 and HD 181433
- Short Name:
- J/A+A/496/527
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This Letter reports on the detection of two new multiple planet systems around solar-like stars HD 47186 and HD 181433. The first system includes a hot Neptune of 22.78M_{Earth}_ at 4.08-days period and a Saturn of 0.35M_{Jup}_ at 3.7-years period. The second system includes a Super-Earth of 7.5M_{Earth}_ at 9.4-days period, a 0.64M_{Jup}_ at 2.6-years period as well as a third companion of 0.54M_{Jup}_ with a period of about 6 years. These detections increase to 20 the number of close-in low-mass exoplanets (below 0.1M_Jup_) and strengthen the fact that 80% of these planets are in a multiple planetary systems.
