scholarly journals LTD064402+245919: A Subgiant with a 1–3 M ⊙ Undetected Companion Identified from LAMOST-TD Data

2021 ◽  
Vol 923 (2) ◽  
pp. 226
Author(s):  
Fan Yang ◽  
Bo Zhang ◽  
Richard J. Long ◽  
You-Jun Lu ◽  
Su-Su Shan ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Orbital Period ◽  
Compact Object ◽  
Mass Function ◽  
General Purpose ◽  
Compact Objects ◽  
Spectroscopic Binaries ◽  
Single Line ◽  
X Rays ◽  
Primary Star

Abstract Single-line spectroscopic binaries have recently contributed to stellar-mass black hole discovery, independently of the X-ray transient method. We report the identification of a single-line binary system, LTD064402+245919, with an orbital period of 14.50 days. The observed component is a subgiant with a mass of 2.77 ± 0.68 M ⊙, radius 15.5 ± 2.5 R ⊙, effective temperature T eff 4500 ± 200 K, and surface gravity log g 2.5 ± 0.25 dex. The discovery makes use of the Large Sky Area Multi-Object fiber Spectroscopic Telescope time-domain and Zwicky Transient Facility survey. Our general-purpose software pipeline applies a Lomb–Scargle periodogram to determine the orbital period and uses machine learning to classify the variable type from the folded light curves. We apply a combined model to estimate the orbital parameters from both the light and radial velocity curves, taking constraints on the primary star mass, mass function, and detection limit of secondary luminosity into consideration. We obtain a radial velocity semiamplitude of 44.6 ± 1.5 km s−1, mass ratio of 0.73 ± 0.07, and an undetected component mass of 2.02 ± 0.49 M ⊙ when the type of the undetected component is not set. We conclude that the inclination is not well constrained, and that the secondary mass is larger than 1 M ⊙ when the undetected component is modeled as a compact object. According to our investigations using a Monte Carlo Markov Chain simulation, increasing the spectra signal-to-noise ratio by a factor of 3 would enable the secondary light to be distinguished (if present). The algorithm and software in this work are able to serve as general-purpose tools for the identification of compact objects quiescent in X-rays.

scholarly journals V479 And: CV, LMXB, or Symbiotic?

2011 ◽  
Vol 7 (S281) ◽  
pp. 113-116
Author(s):  
Diego González Buitrago ◽  
Gagik Tovmassian ◽  
Juan Echevarría ◽  
Sergey Zharikov ◽  
Takamitsu Miyaji ◽  
...  
Keyword(s):  
Orbital Period ◽  
Main Sequence ◽  
Compact Object ◽  
Close Binary System ◽  
Close Binary ◽  
Stellar Winds ◽  
Primary Star ◽  
Giant Star ◽  
X Ray ◽  
Low Mass

AbstractV479 And is a 14.26 hour, close binary system, comprised of a G8-K0 star departing from the main sequence and a compact primary star accreting matter from the donor. The object is an X-ray source, modulated with the orbital period. This, and the presence of an intense He II line, leads us to speculate that the compact object is a magnetic white dwarf. However, we do not find strong constraints on the upper mass limit of the compact object, and we may have a neutron star in a low mass X-ray binary instead of a cataclysmic variable. The orbital period is certainly too short for the donor star to be an evolved giant star, so classifying this object as a symbiotic binary may be a big stretch; however there is an evidence that the mass transfer occurs via stellar winds, rather than through the L1 point of Roche filling secondary, a phenomenon more common for symbiotic stars.

scholarly journals Effect of Compact Objects Near Be Stars

1987 ◽  
Vol 92 ◽  
pp. 516-518
Author(s):  
Krishna M.V. Apparao ◽  
S.P. Tarafdar
Keyword(s):  
Black Holes ◽  
Neutron Star ◽  
Rotation Period ◽  
Compact Object ◽  
Compact Objects ◽  
X Rays ◽  
Be Stars ◽  
Eccentric Orbit ◽  
X Ray ◽  
Be Star

Several Be stars are identified with bright X-ray sources. (Rappaport and Van den Heuvel, 1982). The bright X-ray emission and observed periodicities indicate the existence of compact objects (white dwarfs, neutron stars or black holes) near the Be stars. A prime example is the brightest X-ray source A0538-66 in LMC, which contains a neutron star with a rotation period of 59 ms. Apparao (1985) explained the X-ray emission, which occurs in periodic flares, by considering an inclined eccentric orbit for the neutron star around the assumed Be-star. The neutron star when it enters a gas ring (around the Be-star) accreting matter giving out X-rays.The X-ray emission from the compact objects, when the gas ring from the Be-star envelopes the objects, has interesting consequences. The X-ray emission produces an ionized region (compact object Stromgren sphere or COSS) in the gas surrounding the compact object (CO).

scholarly journals Wind Accretion vs Roche Lobe Overflow in HMXBs

1997 ◽  
Vol 163 ◽  
pp. 361-365 ◽  
Author(s):  
John M. Blondin ◽  
Michael P. Owen
Keyword(s):  
Mass Loss ◽  
Orbital Plane ◽  
Compact Object ◽  
Roche Lobe ◽  
High Mass ◽  
Critical Surface ◽  
X Rays ◽  
Primary Star ◽  
Tidal Stream ◽  
2D And 3D

AbstractWe present a series of time-dependent 2D and 3D numerical simulations illustrating the evolutionary sequence between high mass X-ray binaries fed by wind accretion (where the primary star sits well within its critical tidal lobe) and those fed by Roche lobe overflow (where the primary star extends out to its tidal lobe). When the primary lies well within its critical surface we find negligible tidal mass loss enhancement, and a system that is characterized by wind accretion with the development of a photoionization zone around the compact object. As the surface of the primary nears the critical surface, we observe tidally enhanced mass loss via a thin tidal stream, resulting in higher accretion wake densities. For full RLOF we observe the development of a steady accretion disk characterized by a total shadowing of the X-rays in the orbital plane.

scholarly journals The post-common-envelope X-ray binary nucleus of the planetary nebula NGC 2392

2019 ◽  
Vol 36 ◽  
Author(s):  
Brent Miszalski ◽  
Rajeev Manick ◽  
Hans Van Winckel ◽  
Ana Escorza
Keyword(s):  
Orbital Period ◽  
Indirect Evidence ◽  
Central Star ◽  
Mass Function ◽  
X Rays ◽  
Late Type ◽  
Echelle Spectrograph ◽  
Hard Component ◽  
X Ray ◽  
Common Envelope

Abstract The Chandra X-ray Observatory has detected relatively hard X-ray emission from the central stars of several planetary nebulae (PNe). A subset has no known late-type companions, making it very difficult to isolate which of several competing mechanisms may be producing the X-ray emission. The central star of NGC 2392 is one of the most vexing members, with substantial indirect evidence for a hot white dwarf (WD) companion. Here we report on the results of a radial velocity (RV) monitoring campaign of its central star with the HERMES échelle spectrograph of the Flemish 1.2 m Mercator telescope. We discover a single-lined spectroscopic binary with an orbital period of 1.902208 ± 0.000013 d and an RV semi-amplitude of 9.96 ± 0.13 km s−1. The high degree of nebula ionisation requires a WD companion (M ≳ 0.6M⊙), which the mass-function supports at orbital inclinations ≲ 7°, in agreement with the nebula orientation of 9°. The hard component of the X-ray spectrum may be explained by the companion accreting mass from the wind of the Roche lobe filling primary, while the softer component may be due to colliding winds. A companion with a stronger wind than the primary could produce the latter and would be consistent with models of the observed diffuse X-ray emission detected in the nebula. The diffuse X-rays may also be powered by the jets of up to 180 km s−1, and active accretion would imply that they may be the first active jets of a post-common-envelope PN, potentially making NGC 2392 an invaluable laboratory to study jet formation physics. The 1.9 d orbital period rules out a double-degenerate merger leading to a Type Ia supernova, and the weak wind of the primary likely also precludes a single-degenerate scenario. We suggest that a hard X-ray spectrum, in the absence of a late-type companion, could be a powerful tool to identify accreting WD companions.

scholarly journals Evidence for a Compact Object in the Aftermath of the Extra-Galactic Transient AT2018cow

2021 ◽  
Author(s):  
Dheeraj Pasham ◽  
Wynn Ho ◽  
William Alston ◽  
Ronald Remillard ◽  
Mason Ng ◽  
...  
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Compact Object ◽  
Compact Objects ◽  
Power Density Spectrum ◽  
High Time Resolution ◽  
X Rays ◽  
Density Spectrum ◽  
X Ray ◽  
Circumstellar Medium

Abstract Fast Blue Optical Transients (FBOTs) are mysterious extragalactic explosions that may represent a new class of astrophysical phenomena. Their fast time to maximum brightness of less than 10 days and decline over less than 2 months and unusual optical spectra and evolution are difficult to explain within the context of core-collapse of massive stars which are powered by radioactive decay of Nickel-56 and evolve slowly on months timescales. AT2018cow (at a redshift of 0.014) is an extreme FBOT both in terms of rapid evolution and high X-ray and bolometric luminosities. Several alternative hypotheses have been proposed to explain its unusual properties. These include shock interactions with dense circumstellar medium, tidal disruption of a star by a 10,000−million solar mass black hole, failed supernova with fallback accretion onto a newborn black hole, neutron star formed in a supernova or from merging compact objects, etc. Here, we present evidence for a high-amplitude (fractional root-mean-squared amplitude of>30%) quasi-periodic oscillation (QPO) of AT2018cow’s soft X-rays with a centroid frequency of roughly 225 Hz (statistically significant at the 3.7-sigma level, or a false alarm probability of 0.02%). This signal is found in the average power density spectrum of data taken over the entire outburst lasting roughly 60 days and thus suggests that the signal is highly persistent over several hundreds of millions of cycles (60 daysx225 Hz). This high frequency (rapid timescale) of 225 Hz (4.4 ms) argues for the presence of a compact object in AT2018cow which can either be a neutron star or a black hole, and disfavors circumstellar medium interactions for the origin of X-ray emission. Also, the QPO’s timescale sets an upper limit on the compact object's mass to be 850 solar masses, and thus disfavors models with a heavier black hole. If the QPO represents the spin period of a neutron star we can set upper limits on its magnetic field under different scenarios. This work highlights a new way of using high time-resolution X-ray observations to study FBOTs.

scholarly journals The Mass Distribution of Secondaries to Solar-Type Stars

2004 ◽  
Vol 191 ◽  
pp. 37-40 ◽  
Author(s):  
Helmut A. Abt ◽  
Daryl W. Willmarth
Keyword(s):  
Radial Velocity ◽  
Mass Distribution ◽  
Main Sequence ◽  
Mass Function ◽  
Spectroscopic Binaries ◽  
Orbital Elements ◽  
Main Sequence Stars ◽  
Solar Type ◽  
Low Mass ◽  
Good Agreement

AbstractTwo previous studies of the secondary mass function in spectroscopic binaries by Abt & Levy (1976) and by Duquennoy & Mayor (1991) are shown to be in good agreement if they are both plotted with the same abscissa scale. A new study of 271 main-sequence stars later than F6 V made with a radial-velocity accuracy of ±0.10 km s-1 yielded 10 new sets of orbital elements in addition to the 59 published ones. The resulting secondary mass function is nearly flat and shows that 2.2±1.5% of the primaries have low-mass (0.01–0.10 M⊙) companions. In contrast, the secondary mass function for visual binaries with separations >500 AU fits a van Rhijn function, as was shown previously by Abt and Levy.

scholarly journals Delimiting the black hole mass in the X-ray transient MAXI J1659-152 with Hα spectroscopy

2020 ◽  
Vol 501 (2) ◽  
pp. 2174-2181
Author(s):  
M A P Torres ◽  
P G Jonker ◽  
J Casares ◽  
J C A Miller-Jones ◽  
D Steeghs
Keyword(s):  
Black Hole ◽  
Orbital Period ◽  
Full Width Half Maximum ◽  
Compact Object ◽  
Mass Function ◽  
X Ray ◽  
Black Hole Candidate ◽  
Direct Irradiation ◽  
Hα Emission ◽  
X Ray Binaries

ABSTRACT MAXI J1659-152 is a 2.4 h orbital period X-ray dipping transient black hole candidate. We present spectroscopy of its I ≈ 23 quiescent counterpart, where we detect Hα emission with full width half maximum (FWHM) of 3200 ± 300 km s−1. Applying the correlation between the Hα FWHM and radial velocity semi-amplitude of the donor star for quiescent X-ray transients, we derive K2 = 750 ± 80 km s−1. The orbital period and K2 lead to a mass function of 4.4 ± 1.4 M⊙ (1σ). The donor to compact object mass ratio and binary inclination are likely in the range q = M2/M1 = 0.02–0.07 and i = 70○–80○. These constraints imply a 68 per cent confidence level interval for the compact object mass of 3.3 ≲ M1(M⊙) ≲ 7.5, confirming its black hole nature. These quasi-dynamical limits are compared to mass estimates from modelling of X-ray data and any discrepancies are discussed. We review the properties of optical spectroscopy and time-series photometry collected during the 2010–2011 outburst. We interpret the apparent modulations found soon after the onset of high-accretion activity and during the 2011 rebrightening event as originating in the accretion disc. These have signatures consistent with superhumps, with the 2011 modulation having a fractional period excess $\lt 0.6{\rm{per\, cent}}$ (3σ). We propose that direct irradiation of the donor by the central X-ray source was not possible due to its occultation by the disc outer regions. We argue that disc shielding significantly weakens the donor star contribution to the optical variability in systems with q ≲ 0.07, including neutron star ultra-compact X-ray binaries.

The Eclipsing Binary WX Eridani

1979 ◽  
Vol 46 ◽  
pp. 385
Author(s):  
M.B.K. Sarma ◽  
K.D. Abhankar
Keyword(s):  
Light Curve ◽  
Spectral Type ◽  
Orbital Period ◽  
Primary Component ◽  
Light Curves ◽  
Absorption Feature ◽  
Primary Star ◽  
Eclipsing Binary ◽  
The Times ◽  
Phase Angles

AbstractThe Algol-type eclipsing binary WX Eridani was observed on 21 nights on the 48-inch telescope of the Japal-Rangapur Observatory during 1973-75 in B and V colours. An improved period of P = 0.82327038 days was obtained from the analysis of the times of five primary minima. An absorption feature between phase angles 50-80, 100-130, 230-260 and 280-310 was present in the light curves. The analysis of the light curves indicated the eclipses to be grazing with primary to be transit and secondary, an occultation. Elements derived from the solution of the light curve using Russel-Merrill method are given. From comparison of the fractional radii with Roche lobes, it is concluded that none of the components have filled their respective lobes but the primary star seems to be evolving. The spectral type of the primary component was estimated to be F3 and is found to be pulsating with two periods equal to one-fifth and one-sixth of the orbital period.

scholarly journals Search for intermittent X-ray pulsations from neutron stars in low-mass X-ray binaries

2021 ◽  
Vol 38 ◽  
Author(s):  
Yunus Emre Bahar ◽  
Manoneeta Chakraborty ◽  
Ersin Göğüş
Keyword(s):  
Neutron Stars ◽  
Orbital Period ◽  
Oscillation Frequency ◽  
Orbital Motion ◽  
X Rays ◽  
X Ray ◽  
Second Stage ◽  
Corrected Data ◽  
Low Mass ◽  
X Ray Binaries

Abstract We present the results of our extensive binary orbital motion corrected pulsation search for 13 low-mass X-ray binaries. These selected sources exhibit burst oscillations in X-rays with frequencies ranging from 45 to 1 122 Hz and have a binary orbital period varying from 2.1 to 18.9 h. We first determined episodes that contain weak pulsations around the burst oscillation frequency by searching all archival Rossi X-ray Timing Explorer data of these sources. Then, we applied Doppler corrections to these pulsation episodes to discard the smearing effect of the binary orbital motion and searched for recovered pulsations at the second stage. Here we report 75 pulsation episodes that contain weak but coherent pulsations around the burst oscillation frequency. Furthermore, we report eight new episodes that show relatively strong pulsations in the binary orbital motion corrected data.

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