scholarly journals Eclipsing Binaries: Precise Clocks to Detect Extrasolar Planets

2012 ◽  
Vol 8 (S293) ◽  
pp. 165-167
Author(s):  
Emil Kundra ◽  
Theodor Pribulla ◽  
Martin Vaňko ◽  
Ľubomír Hambálek
Keyword(s):  
White Dwarf ◽  
Extrasolar Planets ◽  
Ccd Camera ◽  
Eclipsing Binaries ◽  
List Type ◽  
Object Selection ◽  
Low Mass ◽  
Selection For ◽  
Orbital Periods ◽  
M Dwarf

AbstractProject Dwarf is a new observing campaign focused on the detection of substellar companions to low-mass (composed of late-type, subdwarf (sd) or/and white dwarf (WD) components) detached eclipsing binaries using minima timing. The crucial condition for the object selection for this campaign is possibility to determine times of the minima with high precision. This is naturally fullfilled for eclipsing binaries with deep and narrow minima or systems hosting a WD component showing fast ingress or egress.The observing project includes three groups of close eclipsing binaries indicating presence of substellar circum-binary components: (i)systems with K or/and M dwarf components(ii)systems with hot subdwarf (sd) and M dwarf components(iii)systems with white dwarf (WD) component(s). The sample of the eclipsing systems have orbital periods in range of 0.1 to almost 3 days and their brightness fits possibilities of small telescopes equipped with a low-end CCD camera and at least VRI filter set. Such kind of telescopes allow us to develop observing network including also amateur astronomers.

scholarly journals The White Dwarf Binary Pathways Survey – IV. Three close white dwarf binaries with G-type secondary stars

2020 ◽  
Vol 501 (2) ◽  
pp. 1677-1689
Author(s):  
M S Hernandez ◽  
M R Schreiber ◽  
S G Parsons ◽  
B T Gänsicke ◽  
F Lagos ◽  
...  
Keyword(s):  
Spectral Type ◽  
White Dwarf ◽  
Binary Stars ◽  
Cataclysmic Variable ◽  
Common Envelope ◽  
History Of ◽  
Low Mass ◽  
Orbital Periods ◽  
M Dwarf

ABSTRACT Constraints from surveys of post-common envelope binaries (PCEBs) consisting of a white dwarf plus an M-dwarf companion have led to significant progress in our understanding of the formation of close white dwarf binary stars with low-mass companions. The white dwarf binary pathways project aims at extending these previous surveys to larger secondary masses, i.e. secondary stars of spectral-type AFGK. Here, we present the discovery and observational characterization of three PCEBs with G-type secondary stars and orbital periods between 1.2 and 2.5 d. Using our own tools as well as MESA, we estimate the evolutionary history of the binary stars and predict their future. We find a large range of possible evolutionary histories for all three systems and identify no indications for differences in common envelope evolution compared to PCEBs with lower mass secondary stars. Despite their similarities in orbital period and secondary spectral type, we estimate that the future of the three systems is very different: TYC 4962-1205-1 is a progenitor of a cataclysmic variable system with an evolved donor star, TYC 4700-815-1 will run into dynamically unstable mass transfer that will cause the two stars to merge, and TYC 1380-957-1 may appear as supersoft source before becoming a rather typical cataclysmic variable star.

scholarly journals Low-mass eclipsing binaries in the WFCAM Transit Survey: the persistence of the M-dwarf radius inflation problem

2018 ◽  
Vol 476 (4) ◽  
pp. 5253-5267 ◽  
Author(s):  
Patricia Cruz ◽  
Marcos Diaz ◽  
Jayne Birkby ◽  
David Barrado ◽  
Brigitta Sipöcz ◽  
...  
Keyword(s):  
Eclipsing Binaries ◽  
Low Mass ◽  
M Dwarf

scholarly journals Close-In Substellar Companions and the Formation of sdB-Type Close Binary Stars

2015 ◽  
Vol 2 (1) ◽  
pp. 183-187 ◽  
Author(s):  
L. Y. Zhu ◽  
S. B. Qian ◽  
E.-G. Zhao ◽  
E. Fernández Lajús ◽  
Z.-T. Han
Keyword(s):  
Binary Stars ◽  
Eclipsing Binaries ◽  
Close Binary ◽  
Close Binaries ◽  
Close Binary Stars ◽  
Cataclysmic Binaries ◽  
Low Mass ◽  
Substellar Companions ◽  
Orbital Periods

The sdB-type close binaries are believed to have experienced a common-envelope phase and may evolve into cataclysmic binaries (CVs). About 10% of all known sdB binaries are eclipsing binaries consisting of very hot subdwarf primaries and low-mass companions with short orbital periods. The eclipse profiles of these systems are very narrow and deep, which benefits the determination of high precise eclipsing times and makes the detection of small and close-in tertiary bodies possible. Since 2006 we have monitored some sdB-type eclipsing binaries to search for the close-in substellar companions by analyzing the light travel time effect. Here some progresses of the program are reviewed and the formation of sdB-type binary is discussed.

scholarly journals Classical Novae – Before and After Outburst

1988 ◽  
Vol 108 ◽  
pp. 226-231
Author(s):  
Mario Livio
Keyword(s):  
White Dwarf ◽  
Main Sequence ◽  
Orbital Parameters ◽  
Classical Novae ◽  
Classical Nova ◽  
Before And After ◽  
Low Mass ◽  
Orbital Periods ◽  
Thermonuclear Runaway ◽  
Nova Outburst

Classical nova (CN) and dwarf nova (DN) systems have the same binary components (a low-mass main sequence star and a white dwarf) and the same orbital periods. An important question that therefore arises is: are these systems really different ? (and if so, what is the fundamental difference ?) or, are these the same systems, metamorphosing from one class to the other ?The first thing to note in this respect is that the white dwarfs in DN systems are believed to accrete continuously (both at quiescence and during eruptions). At the same time, both analytic (e.g. Fujimoto 1982) and numerical calculations show, that when sufficient mass accumulates on the white dwarf, a thermonuclear runaway (TNR) is obtained and a nova outburst ensues (see e.g. reviews by Gallagher and Starrfield 1978, Truran 1982). It is thus only natural, to ask the question, is the fact that we have not seen a DN undergo a CN outburst (in about 50 years of almost complete coverage) consistent with observations of DN systems ? In an attempt to answer this question, we have calculated the probability for a nova outburst not to occur (in 50 years) in 86 DN systems (for which at least some of the orbital parameters are known).

scholarly journals Hidden in Plain Sight: A double-lined White Dwarf Binary 26 pc away and a Distant Cousin

2021 ◽  
Author(s):  
Mukremin Kilic ◽  
A Bédard ◽  
P Bergeron
Keyword(s):  
High Resolution ◽  
Orbital Period ◽  
White Dwarf ◽  
White Dwarfs ◽  
Model Atmosphere ◽  
High Resolution Spectroscopy ◽  
Low Mass ◽  
Orbital Periods ◽  
Velocity Changes ◽  
Cool White Dwarfs

Abstract We present high-resolution spectroscopy of two nearby white dwarfs with inconsistent spectroscopic and parallax distances. The first one, PG 1632+177, is a 13th magnitude white dwarf only 25.6 pc away. Previous spectroscopic observations failed to detect any radial velocity changes in this star. Here, we show that PG 1632+177 is a 2.05 d period double-lined spectroscopic binary (SB2) containing a low-mass He-core white dwarf with a more-massive, likely CO-core white dwarf companion. After L 870-2, PG 1632+177 becomes the second closest SB2 white dwarf currently known. Our second target, WD 1534+503, is also an SB2 system with an orbital period of 0.71 d. For each system, we constrain the atmospheric parameters of both components through a composite model-atmosphere analysis. We also present a new set of NLTE synthetic spectra appropriate for modeling high-resolution observations of cool white dwarfs, and show that NLTE effects in the core of the Hα line increase with decreasing effective temperature. We discuss the orbital period and mass distribution of SB2 and eclipsing double white dwarfs with orbital constraints, and demonstrate that the observed population is consistent with the predicted period distribution from the binary population synthesis models. The latter predict more massive CO + CO white dwarf binaries at short (<1 d) periods, as well as binaries with several day orbital periods; such systems are still waiting to be discovered in large numbers.

scholarly journals Influence of the initial orbital period and accretion efficiency on the low-mass binary evolution

2021 ◽  
pp. 25-30
Author(s):  
J. Petrovic
Keyword(s):  
Mass Transfer ◽  
Orbital Period ◽  
White Dwarf ◽  
Binary Systems ◽  
Evolutionary Models ◽  
Stable Case ◽  
Long Period ◽  
Low Mass ◽  
Orbital Periods ◽  
Binary Evolution

This paper presents detailed evolutionary models of low-mass binary systems (1.25 + 1 M?) with initial orbital periods of 10, 50 and 100 days and accretion efficiency of 10%, 20%, 50%, and a conservative assumption. All models are calculated with the MESA (Modules for Experiments in Stellar Astrophysics) evolutionary code. We show that such binary systems can evolve via a stable Case B mass transfer into long period helium white dwarf systems.

scholarly journals Possible substellar companions in low-mass eclipsing binaries: GU Bootis and YY Geminorum

2018 ◽  
Vol 620 ◽  
pp. A72
Author(s):  
M. Wolf ◽  
H. Kučáková ◽  
P. Zasche ◽  
J. Vraštil ◽  
K. Hoňková ◽  
...  
Keyword(s):  
Precise Determination ◽  
Time Effect ◽  
Eclipsing Binaries ◽  
Physical Parameters ◽  
The Third ◽  
Low Mass ◽  
Orbital Periods ◽  
First Time

We present the next results of our long-term observational project to analyze the variations in the orbital periods of low-mass eclipsing binaries. About 70 new precise mid-eclipse times recorded with a CCD were obtained for two eclipsing binaries with short orbital periods: GU Boo (P = 0.​d49) and YY Gem (0.​d81). Observed-minus-calculated diagrams of the stars were analyzed using all reliable timings, and new parameters of the light-time effect were obtained. We derived for the first time or improved the short orbital periods of possible third bodies of 11 and 54 years for these low-mass binaries, respectively. We calculated that the minimum masses of the third components are close to 50 MJup, which corresponds to the mass of brown dwarfs. The multiplicity of these systems also plays an important role in the precise determination of their physical parameters.

scholarly journals Towards the characterization of the hot Neptune/super-Earth population around nearby bright stars

2008 ◽  
Vol 4 (S253) ◽  
pp. 502-505 ◽  
Author(s):  
C. Lovis ◽  
M. Mayor ◽  
F. Bouchy ◽  
F. Pepe ◽  
D. Queloz ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Extrasolar Planets ◽  
Large Population ◽  
Long Term Stability ◽  
Data Points ◽  
Solar Type ◽  
Low Mass ◽  
Orbital Periods

AbstractThe HARPS search for low-mass extrasolar planets has been ongoing for more than 4 years, targeting originally about 400 bright FGK dwarfs in the solar neighbourhood. The published low-mass planetary systems coming from this survey are fully confirmed by subsequent observations, which demonstrate the sub-m/s long-term stability reached by HARPS. The complex RV curves of these systems have led us to focus on a smaller sample of stars, accumulating more data points per star. We perform a global search in our data to assess the existence of the large population of ice giants and super-Earths predicted by numerical simulations of planet formation. We indeed detect about 45 candidates having minimum masses below 30 M⊕ and orbital periods below 50 days. These numbers are preliminary since the existence of these objects has to be confirmed by subsequent observations. However, they indicate that about 30% of solar-type stars may have such close-in, low-mass planets. Some emerging properties of this low-mass population are presented. We finally discuss the prospects for finding transiting objects among these candidates, which may possibly yield the first nearby, transiting super-Earth.

scholarly journals Doppler Detection of Extrasolar Planets

1999 ◽  
Vol 170 ◽  
pp. 121-130
Author(s):  
G. W. Marcy ◽  
R. Paul Butler ◽  
D. A. Fischer
Keyword(s):  
Main Sequence ◽  
Extrasolar Planets ◽  
Mass Function ◽  
Solar Neighborhood ◽  
Main Sequence Stars ◽  
Low Mass Stars ◽  
Pile Up ◽  
Solar Type ◽  
Low Mass ◽  
M Dwarf

AbstractWe have measured the radial velocities of 540 G and K main sequence stars with a precision of 3−10 ms−1 using the Lick and Keck échelle spectrometers. We had detected 6 companions that have m sin i < 7 MJup. We announce here the discovery of a new planet around Gliese 876, found in our Doppler measurements from both Lick and Keck. This is the first planet found around an M dwarf, which indicates that planets occur around low-mass stars, in addition to solar-type stars. We combine our entire stellar sample with that of Mayor et al. to derive general properties of giant planets within a few AU of these stars. Less than 1% of G and K main sequence stars harbor brown dwarf companions with masses between 5 and 70 MJup. Including Gliese 876b, 8 companions exhibit m sin i < 5 MJup which constitute the best planet candidates to date. Apparently, 4% of stars have planetary companions within the range m sin i = 0.5 to 5 MJup. Planets are distinguished from brown dwarfs by the discontinuous jump in the mass function at 5 MJup. About 2/3 of the planets orbit within just 0.3 AU due in part to their favorable detectability, but also possibly due to a real “pile up” of planets near the star. Inward orbital migration after formation may explain this, but the mechanism to stop the migration remains unclear. Five of eight planets have orbital eccentricities greater than that of our Jupiter, eJup = 0.048, and tidal circularization may explain most of the circular orbits. Thus, eccentric orbits are common and may arise from gravitational interactions with other planets, stars, or the protoplanetary disk. The planet-bearing stars are systematically metal-rich, as is the Sun, compared to the solar neighborhood.

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