- ID:
- ivo://CDS.VizieR/J/ApJ/716/615
- Title:
- Binary compact object coalescence rates
- Short Name:
- J/ApJ/716/615
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we estimate binary compact object merger detection rates for LIGO, including the potentially significant contribution from binaries that are produced in elliptical galaxies near the epoch of peak star formation. Specifically, we convolve hundreds of model realizations of elliptical- and spiral-galaxy population syntheses with a model for elliptical- and spiral-galaxy star formation history as a function of redshift. Our results favor local merger rate densities of 4x10^-3^Mpc^-3^/Myr for binary black holes (BHs), 3x10^-2^Mpc^-3^/Myr for binary neutron stars (NSs), and 10^-2^Mpc^-3^/Myr for BH-NS binaries. Assuming a detection signal-to-noise ratio threshold of 8 for a single detector (in practice as part of a network, to reduce its noise), corresponding to radii Dbns of the effective volume inside of which a single LIGO detector could observe the inspiral of two 1.4M_{sun}_ NSs of 14Mpc and 197Mpc, for initial and advanced LIGO, we find event rates of any merger type of 2.9x10^-2^-0.46 and 25-400yr^-1^ (at 90% confidence level), respectively.
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1852. Binary evolution
- ID:
- ivo://CDS.VizieR/J/MNRAS/319/215
- Title:
- Binary evolution
- Short Name:
- J/MNRAS/319/215
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using Eggleton's stellar evolution code, we carry out 150 runs of Population I binary evolution calculations with the initial primary mass between 1 and 8 solar masses, the initial mass ratio q=M_1/M_2 between 1.1 and 4, and the onset of Roche lobe overflow (RLOF) at an early, middle or late Hertzsprung-gap stage. We assume that the RLOF is conservative in the calculations. We list characteristics for binaries with different initial parameters at the beginning of RLOF, minimum luminosity during RLOF, the end of the last episode of RLOF and the end of the evolutionary calculations. The characteristics includes the age of the primary, its mass, mass transfer rate, its effective temperature, its luminosity, its radius, its helium core mass, its carbon-oxygen core mass, the hydrogen abundance at its surface, the mass ratio of the binary, and the orbital period.
- ID:
- ivo://CDS.VizieR/J/A+A/496/813
- Title:
- Binary PNe towards the Galactic bulge
- Short Name:
- J/A+A/496/813
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Binarity has been hypothesised to play an important, if not ubiquitous, role in the formation of planetary nebulae (PNe). Yet there remains a severe paucity of known binary central stars required to test the binary hypothesis and to place strong constraints on the physics of the common-envelope (CE) phase of binary stellar evolution. Large photometric surveys offer an unrivalled opportunity to efficiently discover many binary central stars. We have combined photometry from the OGLE microlensing survey with the largest sample of PNe towards the Galactic bulge to systematically search for new binaries. A total of 21 periodic binaries were found thereby more than doubling the known sample. The orbital period distribution was found to be best described by CE population synthesis models when no correlation between primary and secondary masses is assumed for the initial mass ratio distribution. A comparison with post-CE white dwarf binaries indicates both distributions are representative of the true post-CE period distribution with most binaries exhibiting periods less than one day. An estimated close binary fraction of 12-21% is derived and is the first robust and independent validation of the prevailing 10-15% fraction estimated by Bond (2000, in Asymmetrical Planetary Nebulae II: From Origins to Microstructures, 199, 115). This suggests that binarity is not a precondition for the formation of PNe and that close binaries do not play a dominant role in the shaping of nebular morphologies. Systematic effects and biases of the survey are discussed with implications for future photometric surveys.
- ID:
- ivo://CDS.VizieR/J/A+A/620/A85
- Title:
- Binary post-AGB stars radial velocities
- Short Name:
- J/A+A/620/A85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Binary post-asymptotic giant branch (post-AGB) stars are thought to be the products of a strong but poorly-understood interaction during the AGB phase. The aim of this contribution is to update the orbital elements of a sample of galactic post-AGB binaries observed in a long-term radial-velocity monitoring campaign, by analysing these systems in a homogeneous way. Radial velocities are computed from high signal-to-noise spectra by use of a cross-correlation method. The radial-velocity curves are fitted by using both a least-squares algorithm and a Nelder-Mead simplex algorithm. We use a Monte Carlo method to compute uncertainties on the orbital elements. The resulting mass functions are used to derive a companion mass distribution by optimising the predicted to the observed cumulative mass-function distributions, after correcting for observational bias. As a result, we derive and update orbital elements for 33 galactic post-AGB binaries, among which 3 are new orbits. The orbital periods of the systems range from 100 to about 3000 days. Over 70 percent (23 out of 33) of our binaries have significant non-zero eccentricities ranging over all periods. Their orbits are non-circular despite the fact that the Roche-lobe radii are smaller than the maximum size of a typical AGB star and tidal circularisation should have been strong when the objects were on the AGB. We derive a distribution of companion masses that is peaked around 1.09M_{sun}_ with a standard deviation of 0.62M_{sun}_. The large spread in companion masses highlights the diversity of post-AGB binary systems. Post-AGB binaries are often chemically peculiar, showing in their photospheres the result of an accretion process of circumstellar gas devoid of refractory elements. We find that only post-AGB stars with high effective temperatures (>5500K) in wide orbits are depleted in refractory elements, suggesting that re-accretion of material from a circumbinary disc is an ongoing process. It appears, however, that depletion is inefficient for the closest orbits irrespective of the actual surface temperature.
- ID:
- ivo://CDS.VizieR/J/A+A/586/A158
- Title:
- Binary properties of CH and CEMP stars
- Short Name:
- J/A+A/586/A158
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The HERMES spectrograph installed on the 1.2-m Mercator telescope has been used to monitor the radial velocity of 13 low-metallicity carbon stars, among which seven carbon-enhanced metal-poor (CEMP) stars and six CH stars. All stars but one show clear evidence for binarity. New orbits are obtained for eight systems. The sample covers an extended range in orbital periods, extending from 3.4d (for the dwarf carbon star HE 0024-2523) to about 54yr (for the CH star HD 26, the longest known among barium, CH, and extrinsic S stars). The period - eccentricity diagram for the 40 low-metallicity carbon stars with orbits now available shows no difference between CH and CEMP-s stars (the latter corresponding to those CEMP stars enriched in s-process elements, as are CH stars). We suggest that they must be considered as one and the same family and that their different names only stem from historical reasons. Indeed, these two families have as well very similar mass-function distributions, corresponding to companions with masses in the range 0.5-0.7M_{sun}_, indicative of white-dwarf companions, adopting 0.8-0.9M_{sun}_ for the primary component. This result confirms that CH and CEMP-s stars obey the same mass-transfer scenario as their higher-metallicity analogues, barium stars. The P-e diagrams of barium, CH, and CEMP-s stars are indeed very similar. They reveal two different groups of systems: one with short orbital periods (P<1000d) and mostly circular or almost circular orbits, and another with longer period and eccentric (e>0.1) orbits. These two groups either trace different evolutionary channels during the mass-transfer episode responsible for the chemical peculiarities of the Ba/CH/CEMP-s stars, or result from the operation of tidal circularisation in a more recent past, when the current giant star was ascending the first giant branch.
- ID:
- ivo://CDS.VizieR/J/A+A/564/A117
- Title:
- Binary quasars from LQAC-2
- Short Name:
- J/A+A/564/A117
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Thanks to huge surveys, such as the Sloan Digital Sky Survey (SDSS), the last decade has shown a dramatic increase in the number of known quasars. In the second release of the general compiled catalogue Large Quasar Astrometric Catalogue (LQAC), 187504 objects are recorded. From this catalogue, we carry out statistical studies dealing with several topics: the astrometric accuracy of the quasars, their spatial location, the distribution of the distance to the closest neighbour, the identification of binary quasars, the completness of catalogues at a given magnitude and the estimation of the number of quasars expected to be detected by the astrometric space mission Gaia. We analyse the astrometric improvements brought by the LQAC-2 in terms of equatorial coordinates off-sets. We plot the bi-dimensional spatial distribution of the LQAC-2 quasars according to their equatorial, galactic, and ecliptic coordinates, thus exploring the anisotropy of the distribution. We compare the observed distribution of closest neighbours with the theoretical values based on a Poisson distribution. Moreover, we perform a comparison between two catalogues, the SDSS and the 2dF inside a huge common field. By extrapolating to the whole sky we deduce the number of quasars that will be detected by Gaia.
- ID:
- ivo://CDS.VizieR/J/AJ/131/1
- Title:
- Binary quasars in the SDSS
- Short Name:
- J/AJ/131/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a sample of 221 new quasar pairs with proper transverse separations R_prop_<1h^1^Mpc over the redshift range 0.5<z<3.0, discovered from an extensive follow-up campaign to find companions around the Sloan Digital Sky Survey (Cat. <VII/243>) and 2dF QSO Redshift Survey (Cat. <VII/241>) quasars. This sample includes 26 new binary quasars with separations R_prop_<50h^-1^kpc ({thetas}<10"), more than doubling the number of such systems known. We define a statistical sample of binaries selected with homogeneous criteria and compute its selection function, taking into account sources of incompleteness. The first measurement of the quasar correlation function on scales 10h^-1^kpc<R_prop_<400h^-1^kpc is presented.
- ID:
- ivo://CDS.VizieR/J/ApJ/875/124
- Title:
- Binary red supergiants. II. B-type companions
- Short Name:
- J/ApJ/875/124
- Date:
- 20 Jan 2022 11:13:46
- Publisher:
- CDS
- Description:
- The percentage of massive main-sequence OB stars in binary systems is thought to be as high as 100%. However, very few Galactic binary red supergiants (RSGs) have been identified, despite the fact that these stars are the evolved descendants of OB stars. As shown in our recent paper, binary RSGs will likely have B-type companions, as dictated by stellar evolution considerations. Such a system will have a very unique photometric signature due to the shape of the spectral energy distribution. Using photometric cutoffs, it should therefore be possible to detect candidate RSG+B star binary systems. Here we present our spectroscopic follow-up observations of such candidates. Out of our initial list of 280 candidates in M31 and M33, we observed 149 and confirmed 63 as newly discovered RSG+B star binary systems. Additional spectra of four candidate systems in the Small Magellanic Cloud confirmed all of them as new RSG+B star binaries including the first known RSG+Be star system. By fitting BSTAR06 and MARCS model atmospheres to the newly obtained spectra, we place estimates on the temperatures and subtypes of both the B stars and RSGs. Overall, we have found 87 new RSG+B star binary systems in M31, M33 and the Small and Large Magellanic Clouds. Our future studies are aimed at determining the binary fraction of RSGs.
- ID:
- ivo://CDS.VizieR/J/AJ/127/1181
- Title:
- Binary speckle measurements at Calar Alto
- Short Name:
- J/AJ/127/1181
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Results of our second observational run of binary star interferometric measurements with an ICCD speckle camera attached to the 1.52m telescope of the Observatorio Astronomico Nacional at Calar Alto (Almeria, Spain) in 2000 June-July are presented. The measured angular separations range from 0.096" to 6.558". With the use of the new speckle data, the orbits of the visual binaries WDS 14369+4813 and WDS 21597+4908 are improved.
- ID:
- ivo://CDS.VizieR/J/A+A/366/868
- Title:
- Binary speckle measurements at Calar Alto. I.
- Short Name:
- J/A+A/366/868
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results of our speckle interferometric measurements of binary stars made with the ICCD speckle camera using the 1.52-m telescope of the Observatorio Astronomico Nacional at Calar Alto (Spain) in September, 1999. The data contain 123 observations of 83 systems. The measured angular separations range from 0.153" to 6.727". We have used there new speckle measurements to improve the orbital elements for the binaries COU 247 and BU 524 AB.
