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- ID:
- ivo://CDS.VizieR/J/ApJ/854/145
- Title:
- Opt. photometry & NIR spectroscopy of Wolf 1130
- Short Name:
- J/ApJ/854/145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Following the discovery of the T8 subdwarf WISE J200520.38+542433.9 (Wolf 1130C), which has a proper motion in common with a binary (Wolf 1130AB) consisting of an M subdwarf and a white dwarf, we set out to learn more about the old binary in the system. We find that the A and B components of Wolf 1130 are tidally locked, which is revealed by the coherence of more than a year of V-band photometry phase-folded to the derived orbital period of 0.4967 days. Forty new high-resolution, near-infrared spectra obtained with the Immersion Grating Infrared Spectrometer (IGRINS) provide radial velocities and a projected rotational velocity (vsini) of 14.7+/-0.7km/s for the M subdwarf. In tandem with a Gaia parallax-derived radius and verified tidal locking, we calculate an inclination of i=29{deg}+/-2{deg}. From the single-lined orbital solution and the inclination we derive an absolute mass for the unseen primary (1.24_-0.15_^+0.19^M_{sun}_). Its non-detection between 0.2 and 2.5{mu}m implies that it is an old (>3.7Gyr) and cool (T_eff_<7000K) ONe white dwarf. This is the first ultramassive white dwarf within 25pc. The evolution of Wolf 1130AB into a cataclysmic variable is inevitable, making it a potential SN Ia progenitor. The formation of a triple system with a primary mass >100 times the tertiary mass and the survival of the system through the common-envelope phase, where ~80% of the system mass was lost, is remarkable. Our analysis of Wolf 1130 allows us to infer its formation and evolutionary history, which has unique implications for understanding low-mass star and brown dwarf formation around intermediate-mass stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/844/103
- Title:
- Orbit alignment in triple stars
- Short Name:
- J/ApJ/844/103
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The statistics of the angle {Phi} between orbital angular momenta in hierarchical triple systems with known inner visual or astrometric orbits are studied. A correlation between apparent revolution directions proves the partial orbit alignment known from earlier works. The alignment is strong in triples with outer projected separation less than ~50au, where the average {Phi} is about 20{deg}. In contrast, outer orbits wider than 1000 au are not aligned with the inner orbits. It is established that the orbit alignment decreases with the increasing mass of the primary component. The average eccentricity of inner orbits in well-aligned triples is smaller than in randomly aligned ones. These findings highlight the role of dissipative interactions with gas in defining the orbital architecture of low-mass triple systems. On the other hand, chaotic dynamics apparently played a role in shaping more massive hierarchies. The analysis of projected configurations and triples with known inner and outer orbits indicates that the distribution of {Phi} is likely bimodal, where 80% of triples have {Phi}<70{deg} and the remaining ones are randomly aligned.
- ID:
- ivo://CDS.VizieR/J/ApJS/214/17
- Title:
- Orbital monitoring of AstraLux binaries
- Short Name:
- J/ApJS/214/17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Orbital monitoring of M-type binaries is essential for constraining their fundamental properties. This is particularly useful in young systems, where the extended pre-main-sequence evolution can allow for precise isochronal dating. Here, we present the continued astrometric monitoring of the more than 200 binaries of the AstraLux Large Multiplicity Survey, building both on our previous work, archival data, and new astrometric data spanning the range of 2010-2012. The sample is very young overall --all included stars have known X-ray emission, and a significant fraction (18%) of them have recently also been identified as members of young moving groups in the solar neighborhood. We identify ~30 targets that both have indications of being young and for which an orbit either has been closed or appears possible to close in a reasonable time frame (a few years to a few decades). One of these cases, GJ 4326, is, however, identified as probably being substantially older than has been implied from its apparent moving group membership, based on astrometric and isochronal arguments. With further astrometric monitoring, these targets will provide a set of empirical isochrones, against which theoretical isochrones can be calibrated, and which can be used to evaluate the precise ages of nearby young moving groups.
- ID:
- ivo://CDS.VizieR/J/ApJ/835/209
- Title:
- Orbital nature of 81 ellipsoidal red giant binaries
- Short Name:
- J/ApJ/835/209
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we collect a sample of 81 ellipsoidal red giant binaries in the Large Magellanic Cloud (LMC), and we study their orbital natures individually and statistically. The sample contains 59 systems with circular orbits and 22 systems with eccentric orbits. We derive orbital solutions using the 2010 version of the Wilson-Devinney code (Wilson & Devinney 1971ApJ...166..605W ; Wilson 1979ApJ...234.1054W, 1990ApJ...356..613W ; Wilson+ 2009, J/ApJ/702/403). The sample is selection-bias corrected, and the orbital parameter distributions are compared to model predictions for the LMC and to observations in the solar vicinity. The masses of the red giant primaries are found to range from about 0.6 to 9M_{sun}_ with a peak at around 1.5M_{sun}_, in agreement with studies of the star formation history of the LMC, which find a burst of star formation beginning around 4 Gyr ago. The observed distribution of mass ratios q=m_2_/m_1_ is more consistent with the flat q distribution derived for the solar vicinity by Raghavan+ (2010, J/ApJS/190/1) than it is with the solar vicinity q distribution derived by Duquennoy & Mayor (1991A&A...248..485D). There is no evidence for an excess number of systems with equal mass components. We find that about 20% of the ellipsoidal binaries have eccentric orbits, twice the fraction estimated by Soszynski+ (2004, J/AcA/54/347). Our eccentricity evolution test shows that the existence of eccentric ellipsoidal red giant binaries on the upper parts of the red giant branch (RGB) can only be explained if tidal circularization rates are ~1/100 the rates given by the usual theory of tidal dissipation in convective stars.
- ID:
- ivo://CDS.VizieR/J/MNRAS/474/4322
- Title:
- Orbital parameters of 341 new binaries
- Short Name:
- J/MNRAS/474/4322
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The orbital parameters of binaries at intermediate periods (10^2^-10^3^d) are difficult to measure with conventional methods and are very incomplete. We have undertaken a new survey, applying our pulsation timing method to Kepler light curves of 2224 main-sequence A/F stars and found 341 non-eclipsing binaries. We calculate the orbital parameters for 317 PB1 systems (single-pulsator binaries) and 24 PB2s (double-pulsators), tripling the number of intermediate-mass binaries with full orbital solutions. The method reaches down to small mass ratios q~0.02 and yields a highly homogeneous sample. We parametrize the mass-ratio distribution using both inversion and MCMC forward-modelling techniques, and find it to be skewed towards low-mass companions, peaking at q~0.2. While solar-type primaries exhibit a brown dwarf desert across short and intermediate periods, we find a small but statistically significant (2.6{sigma}) population of extreme-mass-ratio companions (q<0.1}) to our intermediate-mass primaries. Across periods of 100-1500d and at q>0.1, we measure the binary fraction of current A/F primaries to be 15.4%+/-1.4%, though we find that a large fraction of the companions (21%+/-6%) are white dwarfs in post-mass-transfer systems with primaries that are now blue stragglers, some of which are the progenitors of Type Ia supernovae, barium stars, symbiotics, and related phenomena. Excluding these white dwarfs, we determine the binary fraction of original A/F primaries to be 13.9%+/-2.1% over the same parameter space. Combining our measurements with those in the literature, we find the binary fraction across these periods is a constant 5% for primaries M_1_<0.8M_{sun}_, but then increases linearly with logM_1_, demonstrating that natal discs around more massive protostars M_1_>~1M_{sun}_} become increasingly more prone to fragmentation. Finally, we find the eccentricity distribution of the main-sequence pairs to be much less eccentric than the thermal distribution.
- ID:
- ivo://CDS.VizieR/J/AJ/133/1209
- Title:
- Orbits and system masses of 14 visual double stars
- Short Name:
- J/AJ/133/1209
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents revised orbits and system masses of 14 visual double stars, in all of which at least one component is of early spectral type: WDS 00546+1911 (STT 20 AB), WDS 01040+3528 (HO 213), WDS 02039+4220 (STT 38 BC), WDS 03503+2535 (STT 65), WDS 06393+4200 (STT 150), WDS 08285-0231 (A551 AB), WDS 15088-4517 (SEE 219 AB), WDS 15416+1940 (HU 580 AB), WDS 16514+0113 (STT 315), WDS 17104-1544 (BU 1118 AB), WDS 19172-6640 (GLE 3), WDS 19411+1349 (KUI 93), WDS 22241-0450 (BU 172 AB), and WDS 23382+5514 (A1493). Star masses were calculated from Hipparcos parallax data whenever the precision was good enough (10 cases); otherwise, dynamical parallaxes were used, except in one case involving component multiplicity. Other physical and orbital properties of these stars are also discussed.
- ID:
- ivo://CDS.VizieR/J/AJ/154/110
- Title:
- Orbits based on SOAR speckle interferometry. II.
- Short Name:
- J/AJ/154/110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Orbits of 44 close and fast visual binaries are computed using the latest speckle observations; 23 orbits are determined for the first time, and the rest are revisions, some of those substantial. Six combined orbits use radial velocities. The median period is 15.6 years, and the shortest period is one year. Most stars are nearby late-type dwarfs. Dynamical parallaxes and estimates of the masses are derived from the orbital elements and the photometry of the components.
- ID:
- ivo://CDS.VizieR/J/AJ/152/138
- Title:
- Orbits based on speckle interferometry at SOAR
- Short Name:
- J/AJ/152/138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The orbits of 55 visual binary stars are computed using recent speckle interferometry data from the SOAR telescope: 33 first-time orbits and 22 revisions of previous orbit calculations. The orbital periods range from 1.4-370 years, and the quality of the orbits ranges from definitive to preliminary and tentative. Most binaries consist of low-mass dwarfs and have short periods (median period 31 years). The dynamical parallaxes and masses are evaluated and compared to the Hipparcos parallaxes. Using differential speckle photometry, binary components are placed on the color-magnitude diagram.
- ID:
- ivo://CDS.VizieR/J/AJ/131/2681
- Title:
- Orbits for three visual binaries
- Short Name:
- J/AJ/131/2681
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The first orbit for visual binary A 1529 and improved orbital elements for HU 610 and COU 2031 based on new speckle measurements with the 6m telescope of the Special Astrophysical Observatory (Russia) are presented. On the basis of simultaneously obtained differential photometry data, individual masses and spectral types are roughly estimated.
