scholarly journals Fluorescence and Chromospheric Activity of V471 Tau

2002 ◽  
Vol 187 ◽  
pp. 167-172
Author(s):  
T.R. Vaccaro ◽  
R.E. Wilson
Keyword(s):  
Light Curve ◽  
Radial Velocity ◽  
Orbital Period ◽  
White Dwarf ◽  
Binary Star ◽  
Star Model ◽  
Orbital Inclination ◽  
Orbital Parameters ◽  
Maximum Emission ◽  
Chromospheric Activity

AbstractThe red dwarf + white dwarf eclipsing binary V471 Tau shows a variable Hα feature that varies from absorption during eclipse to maximum emission during white dwarf transit. In 1998 we obtained simultaneous BVRI photometry and Hα spectroscopy, with thorough phase coverage of the 12.5 hour orbital period. A binary star model was used with our light curve, radial velocity, and Hα data to refine stellar and orbital parameters. Combined absorption-emission profiles were generated by the model and fit to the observations, yielding a red star radius of 0.94R⊙. Orbital inclination 78° is required with this size and other known parameters. The model includes three spots 1,000 K cooler than the surrounding photosphere. The variable Hα profile was modeled as a chromospheric fluorescing region (essentially on the surface of the red star) centered at the substellar point. Additional emission seen outside our modeled profiles may be large co-rotating prominences that complicate the picture.

scholarly journals Barium and related stars, and their white-dwarf companions

2019 ◽  
Vol 626 ◽  
pp. A128 ◽  
Author(s):  
A. Escorza ◽  
D. Karinkuzhi ◽  
A. Jorissen ◽  
L. Siess ◽  
H. Van Winckel ◽  
...  
Keyword(s):  
Radial Velocity ◽  
White Dwarf ◽  
Main Sequence ◽  
Mass Function ◽  
Orbital Evolution ◽  
Asymptotic Giant Branch ◽  
Second Phase ◽  
Evolutionary Models ◽  
Orbital Inclination ◽  
Orbital Parameters

Barium (Ba) dwarfs and CH subgiants are the less evolved analogues of Ba and CH giants. They are F- to G-type main-sequence stars polluted with heavy elements by their binary companions when the companion was on the asymptotic giant branch (AGB). This companion is now a white dwarf that in most cases cannot be directly detected. We present a large systematic study of 60 objects classified as Ba dwarfs or CH subgiants. Combining radial-velocity measurements from HERMES and SALT high-resolution spectra with radial-velocity data from CORAVEL and CORALIE, we determine the orbital parameters of 27 systems. We also derive their masses by comparing their location in the Hertzsprung–Russell diagram with evolutionary models. We confirm that Ba dwarfs and CH subgiants are not at different evolutionary stages, and that they have similar metallicities, despite their different names. Additionally, Ba giants appear significantly more massive than their main-sequence analogues. This is likely due to observational biases against the detection of hotter main-sequence post-mass-transfer objects. Combining our spectroscopic orbits with the HIPPARCOS astrometric data, we derive the orbital inclination and the mass of the WD companion for four systems. Since this cannot be done for all systems in our sample yet (but should be possible with upcoming Gaia data releases), we also analyse the mass-function distribution of our binaries. We can model this distribution with very narrow mass distributions for the two components and random orbital orientations on the sky. Finally, based on BINSTAR evolutionary models, we suggest that the orbital evolution of low-mass Ba systems can be affected by a second phase of interactions along the red giant branch of the Ba star, which impact the eccentricities and periods of the giants.

scholarly journals Dynamical Study of the Exoplanet Host Binary System HD 106515

2017 ◽  
Vol 34 ◽  
Author(s):  
F. M. Rica ◽  
R. Barrena ◽  
J. A. Henríquez ◽  
F. M. Pérez ◽  
P. Vargas
Keyword(s):  
Radial Velocity ◽  
Proper Motion ◽  
Binary Star ◽  
Semimajor Axis ◽  
Numerical Code ◽  
Dynamical Study ◽  
Orbital Parameters ◽  
Instantaneous Position ◽  
Dynamical Parameters ◽  
Binary Star System

AbstractHD 106515 AB (STF1619 AB) is a high common proper motion and common radial velocity binary star system composed of two G-type bright stars located at 35 pc and separated by about 7 arcsec. This system was observed by theHipparcossatellite with a precision in distance and proper motion of 3 and 2%, respectively. The system includes a circumprimary planet of nearly 10 Jupiter masses and a semimajor axis of 4.59 AU, discovered using the radial velocity method. The observational arc of 21° shows a small curvature that evidences HD 106515 AB is a gravitationally bound system. This work determines the dynamical parameters for this system which reinforce the bound status of both stellar components. We determine orbital solutions from instantaneous position and velocity vectors. In addition, we provide a very preliminary orbital solution and a distribution of the orbital parameters, obtained from the line of sight (z). Our results show that HD 106515 AB presents an orbital period of about 4 800 years, a semimajor axis of 345 AU and an eccentricity of about 0.42. Finally, we use an N-body numerical code to perform simulations and reproduce the longer term octupole perturbations on the inner orbit.

scholarly journals Asteroseismic search for invisible binary companions

2015 ◽  
Vol 11 (A29B) ◽  
pp. 642-647
Author(s):  
Hiromoto Shibahashi ◽  
Simon J. Murphy ◽  
Donald W. Kurtz
Keyword(s):  
Radial Velocity ◽  
Frequency Modulation ◽  
Binary Systems ◽  
Binary Star ◽  
Orbital Parameters ◽  
Pulsating Stars ◽  
Kepler Mission ◽  
Orbital Frequency ◽  
Long Time ◽  
The Fourier Transform

AbstractContinuous and precise space-based photometry has made it possible to measure the orbital frequency modulation of pulsating stars in binary systems with extremely high precision over long time spans. We present the phase modulation (PM) method for finding binaries among pulsating stars. We demonstrate how the orbital elements of a pulsating binary star can be obtained analytically from photometry alone, without spectroscopic radial velocity measurement. Frequency modulation (FM) caused by binary orbital motion also manifests itself in the Fourier transform, as a multiplet with equal spacing of the orbital frequency. The orbital parameters can also be extracted by analysing the amplitudes and phases of the peaks in these multiplets. We derive analytically the theoretical relations between the multiplet properties and the orbital parameters, and present a method for determining these parameters, including the eccentricity and the argument of periapsis. This, too, is achievable with the photometry alone, without spectroscopic radial velocity measurements. We apply these two methods to Kepler mission data and demonstrate that the results are in good agreement with each other. These methods are used to search for invisible binary companions, including planets and invisible massive objects such as neutron stars and stellar-mass black holes.

scholarly journals Phase connected X-ray light curve and He II radial velocity measurements of NGC 300 X-1

2018 ◽  
Vol 14 (S346) ◽  
pp. 187-192
Author(s):  
S. Carpano ◽  
F. Haberl ◽  
P. Crowther ◽  
A. Pollock
Keyword(s):  
Black Hole ◽  
Light Curve ◽  
Radial Velocity ◽  
Orbital Period ◽  
High Mass ◽  
Velocity Measurements ◽  
X Ray ◽  
Black Hole Radiation ◽  
Ic 10 ◽  
Binary Evolution

Abstract. NGC 300 X-1 and IC 10 X-1 are currently the only two robust extragalactic candidates for being Wolf-Rayet/black hole X-ray binaries, the Galactic analogue being Cyg X-3. These systems are believed to be a late product of high-mass X-ray binary evolution and direct progenitors of black hole mergers. From the analysis of Swift data, the orbital period of NGC 300 X-1 was found to be 32.8 h. We here merge the full set of existing data of NGC 300 X-1, using XMM-Newton, Chandra and Swift observations to derive a more precise value of the orbital period of 32.7932 ± 0.0029 h above a confidence level of 99.99%. This allows us to phase connect the X-ray light curve of the source with radial velocity measurements of He II lines performed in 2010. We show that, as for IC 10 X-1 and Cyg X-3, the X-ray eclipse corresponds to maximum of the blueshift of the He II lines, instead of the expected zero velocity. This indicates that for NGC 300 X-1 as well, the wind of the WR star is completely ionised by the black hole radiation and that the emission lines come from the region of the WR star that is in the shadow. We also present for the first time the light curve of two recent very long XMM-Newton observations of the source, performed on the 16th to 20th of December 2016.

scholarly journals New Exosat Observations of TV Columbae: Preliminary Results

1987 ◽  
Vol 93 ◽  
pp. 261-267
Author(s):  
J. Schrijver ◽  
A.C. Brinkman ◽  
H. Van Der Woerd
Keyword(s):  
Light Curve ◽  
Orbital Period ◽  
White Dwarf ◽  
Lower Energy ◽  
Cataclysmic Variable ◽  
X Ray ◽  
Preliminary Results ◽  
First Results ◽  
Absorption Features ◽  
Energy Channels

AbstractThe first results of the analysis of new EXOSAT observations of the DQ Her type cataclysmic variable TV Col are presented. The period of the 1–10 kev X-ray pulsation associated with the white-dwarf rotation is now established as 1911 s. The pulsations are most pronounced in the lower energy channels (1–3.5 keV). The X-ray light curve shows absorption features associated with the orbital period of the system.

scholarly journals Two new double-lined spectroscopic binary white dwarfs

2020 ◽  
Vol 493 (2) ◽  
pp. 2805-2816 ◽  
Author(s):  
Mukremin Kilic ◽  
A Bédard ◽  
P Bergeron ◽  
Alekzander Kosakowski
Keyword(s):  
Radial Velocity ◽  
White Dwarf ◽  
White Dwarfs ◽  
Binary Systems ◽  
Mass Ratio ◽  
Orbital Parameters ◽  
Long Period ◽  
Spectroscopic Binary ◽  
Velocity Variations ◽  
Period System

ABSTRACT We present radial velocity observations of four binary white dwarf candidates identified through their overluminosity. We identify two new double-lined spectroscopic binary systems, WD 0311–649 and WD 1606+422, and constrain their orbital parameters. WD 0311–649 is a 17.7 h period system with a mass ratio of 1.44 ± 0.06 and WD 1606+422 is a 20.1 h period system with a mass ratio of 1.33 ± 0.03. An additional object, WD 1447–190, is a 43 h period single-lined white dwarf binary, whereas WD 1418–088 does not show any significant velocity variations over time-scales ranging from minutes to decades. We present an overview of the 14 overluminous white dwarfs that were identified by Bédard et al., and find the fraction of double- and single-lined systems to be both 31 per cent. However, an additional 31 per cent of these overluminous white dwarfs do not show any significant radial velocity variations. We demonstrate that these must be in long-period binaries that may be resolved by Gaia astrometry. We also discuss the overabundance of single low-mass white dwarfs identified in the SPY survey, and suggest that some of those systems are also likely long-period binary systems of more massive white dwarfs.

scholarly journals The formation of long-period eccentric binaries with a helium white dwarf companion

2019 ◽  
Vol 82 ◽  
pp. 107-118
Author(s):  
L. Siess
Keyword(s):  
Mass Transfer ◽  
Mass Loss ◽  
White Dwarf ◽  
Binary Star ◽  
Roche Lobe ◽  
High Eccentricity ◽  
Evolutionary Path ◽  
Orbital Parameters ◽  
Long Period ◽  
Red Giant

The recent discovery of long-period eccentric binaries hosting a He-white dwarf has been a challenge for binary-star modelling. Based on accurate determinations of the stellar and orbital parameters for IP Eri, a K0 + He-WD system, we propose an evolutionary path that is able to explain the observational properties of this system and, in particular, to account for its high eccentricity (0.25). Our scenario invokes an enhanced-wind mass loss on the first red giant branch in order to avoid mass transfer by Roche-lobe overflow, where tides systematically circularize the orbit.

scholarly journals Polarimetry of Binary Stars and Exoplanets

2011 ◽  
Vol 7 (S282) ◽  
pp. 173-180
Author(s):  
Karen S. Bjorkman
Keyword(s):  
Binary Stars ◽  
Binary Systems ◽  
Binary Star ◽  
Orbital Inclination ◽  
Orbital Parameters ◽  
Circumstellar Environments ◽  
Exoplanet Systems

AbstractPolarimetry is a useful diagnostic of asymmetries in both circumstellar environments and binary star systems. Its sensitivity to asymmetries in systems means that it can help to uncover details about system orbital parameters, including providing information about the orbital inclination. Polarimetry can probe the circumstellar and/or circumbinary material as well. A number of significant results on binary systems have been produced by polarimetric studies. One might therefore expect that polarimetry could similarly play a useful role in studies of exoplanets, and a number of possible diagnostics for exoplanets have been proposed. However, the application of polarimetry to exoplanet research is only in preliminary stages, and the difficulties with applying the technique to exoplanets are non-trivial. This review will discuss the successes of polarimetry in analyzing binary systems, and consider the possibilities and challenges for extending similar analysis to exoplanet systems.

scholarly journals The supergiant O + O binary system HD 166734: a new study

2016 ◽  
Vol 12 (S329) ◽  
pp. 402-402 ◽  
Author(s):  
E. Gosset ◽  
L. Mahy ◽  
Y. Damerdji ◽  
C. Nitschelm ◽  
H. Sana ◽  
...  
Keyword(s):  
Binary System ◽  
Light Curve ◽  
Radial Velocity ◽  
Velocity Curve ◽  
Physical Parameters ◽  
Radial Velocity Curve ◽  
X Ray ◽  
Orbital Parameters

AbstractWe present here a modern study of the radial velocity curve and of the photometric light curve of the very interesting supergiant O7.5If + O9I(f) binary system HD 166734. The physical parameters of the stars and the orbital parameters are carefully determined. We also perform the analysis of the observed X-ray light curve of this colliding-wind binary.

scholarly journals Photometric Evidence for the Presence of An Accretion Disk and for a Superhump - Like Phenomenon in the Classical Nova V1974 Cygni 1992

1997 ◽  
Vol 163 ◽  
pp. 788-789
Author(s):  
A. Retter ◽  
E.M. Leibowitz ◽  
E.O. Ofek
Keyword(s):  
Binary System ◽  
Light Curve ◽  
Accretion Disk ◽  
Orbital Period ◽  
White Dwarf ◽  
Disk Model ◽  
Classical Nova ◽  
Nova Outburst

AbstractThe light curve of V1974 Cyg shows two distinct periodicities. The shorter periodicity is clearly the orbital period of the binary system. We show that the longer variation has similar features to permanent superhumps. This result indicates the existence of an accretion disk in the system no later than 30 months after the nova outburst. We used the precessing disk model of the superhump phenomenon and previous results in order to estimate that the white dwarf mass is at the range 0.75 – 1.07 M⊙.

Sign in / Sign up

Export Citation Format

Share Document