- ID:
- ivo://CDS.VizieR/J/A+A/643/A98
- Title:
- VIsual Binary Exoplanet survey with SPHERE
- Short Name:
- J/A+A/643/A98
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent surveys indicate that planets in binary systems are more abunda- nt than previously thought, which is in agreement with theoretical work on disc dynamics and planet formation in binaries. So far, most observational surveys, however, have focused on short-period planets in binaries, thus little is known about the occurrence rates of planets on longer periods (>10au). In order to measure the abundance and physical characteristics of wide-orbit giant exoplanets in binary systems, we have designed the 'VIsual Binary Exoplanet survey with Sphere' (VIBES) to search for planets in visual binaries. It uses the SPHERE instrument at VLT to search for planets in 23 visual binary and four visual triple systems with ages of <145Myr and distances of <150pc. We used the IRDIS dual-band imager on SPHERE to acquire high-contrast images of the sample targets. For each binary, the two components were observed at the same time with a coronagraph masking only the primary star. For the triple star, the tight components were treated as a single star for data reduction. This enabled us to effectively search for companions around 50 individual stars in binaries and four binaries in triples. We derived upper limits of <13.7% for the frequency of sub-stellar companions around primaries in visual binaries, <26.5% for the fraction of sub-stellar companions around secondaries in visual binaries, and an occurrence rate of <9.0% for giant planets and brown dwarfs around either component of visual binaries. We have combined our observations with literature measurements to astrometrically confirm, for the first time, that 20 binaries and two triple systems, which were previously known, are indeed physically bound. Finally, we discovered a third component of the binary HD 121336. The upper limits we derived are compatible with planet formation through the core accretion and the gravitational instability processes in binaries. These limits are also in line with limits found for single star and circumbinary planet search surveys.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/861/113
- Title:
- VLBA astrometry combined with Gaia DR1 epoch
- Short Name:
- J/ApJ/861/113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The canonical methods for gravitational wave detection are ground- and space- based laser interferometry, pulsar timing, and polarization of the cosmic microwave background. But as has been suggested by numerous investigators, astrometry offers an additional path to gravitational wave detection. Gravitational waves deflect light rays of extragalactic objects, creating apparent proper motions in a quadrupolar (and higher-order modes) pattern. Astrometry of extragalactic radio sources is sensitive to gravitational waves with frequencies between roughly 10^-18^ and 10^-8^Hz (H_0_ and 1/3yr^-1^), overlapping and bridging the pulsar timing and CMB polarization regimes. We present a methodology for astrometric gravitational wave detection in the presence of large intrinsic uncorrelated proper motions (i.e., radio jets). We obtain 95% confidence limits on the stochastic gravitational wave background using 711 radio sources, {Omega}_GW_<0.0064, and using 508 radio sources combined with the first Gaia data release: {Omega}_GW_<0.011. These limits probe gravitational wave frequencies 6x10^-18^Hz<~f<~1x10^-9^Hz. Using a WISE-Gaia catalog of 567721 AGN, we predict a limit expected from Gaia alone of {Omega}_GW_<0.0006, which is significantly higher than was originally forecast. Incidentally, we detect and report on 22 new examples of optical superluminal motion with redshifts 0.13-3.89.
- ID:
- ivo://CDS.VizieR/J/ApJS/141/13
- Title:
- VLBA calibrator survey: VCS1 catalog
- Short Name:
- J/ApJS/141/13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A catalog containing milli-arcsecond-accurate positions of 1332 extragalactic radio sources distributed over the northern sky is presented - the Very Long Baseline Array Calibrator Survey (VCS1). The positions have been derived from astrometric analysis of dual-frequency 2.3 and 8.4 GHz VLBA snapshot observations; in a majority of cases, images of the sources are also available. These radio sources are suitable for use in geodetic and astrometric experiments, and as phase-reference calibrators in high-sensitivity astronomical imaging. The VCS1 is the largest high-resolution radio survey ever undertaken and triples the number of sources available to the radio astronomy community for VLBI applications. In addition to the astrometric role, this survey can be used in active galactic nuclei, Galactic, gravitational lens, and cosmological studies.
- ID:
- ivo://CDS.VizieR/J/ApJ/899/141
- Title:
- VLBA observations of the AGN TXS 0128+554
- Short Name:
- J/ApJ/899/141
- Date:
- 14 Mar 2022 07:07:50
- Publisher:
- CDS
- Description:
- We have carried out a Chandra X-ray and multifrequency radio Very Long Baseline Array study of the active galactic nucleus (AGN) TXS0128+554, which is associated with the Fermi {gamma}-ray source 4FGLJ0131.2+5547. The AGN is unresolved in a target 19.3ks Chandra image, and its spectrum is well fit by a simple absorbed power-law model, with no distinguishable spectral features. Its relatively soft X-ray spectrum compared to other compact symmetric objects (CSOs) may be indicative of a thermal emission component, for which we were able to obtain an upper temperature limit of kT=0.08keV. The compact radio morphology and measured advance speed of 0.32c{+/-}0.07c indicate a kinematic age of only 82yr{+/-}17yr, placing TXS0128+554 among the youngest members of the CSO class. The lack of compact, inverted spectrum hotspots and an emission gap between the bright inner jet and outer radio lobe structure indicate that the jets have undergone episodic activity, and were relaunched a decade ago. The predicted {gamma}-ray emission from the lobes, based on an inverse Compton-emitting cocoon model, is three orders of magnitude below the observed Fermi-LAT flux. A comparison to other Fermi-detected and non-Fermi-detected CSOs with redshift z<0.1 indicates that the {gamma}-ray emission likely originates in the inner jet/core region, and that nearby, recently launched AGN jets are primary candidates for detection by the Fermi-LAT instrument.
- ID:
- ivo://CDS.VizieR/J/ApJS/230/13
- Title:
- VLBI Ecliptic Plane Survey: VEPS-1
- Short Name:
- J/ApJS/230/13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present here the results of the first part of the VLBI Ecliptic Plane Survey (VEPS) program. The goal of the program is to find all compact sources within 7.5{deg} of the ecliptic plane that are suitable as calibrators for anticipated phase referencing observations of spacecraft, and determine their positions with accuracy at the 1.5 nrad level. We run the program in two modes: search and refine. In the search mode, a complete sample of all sources brighter than 50mJy at 5GHz listed in the Parkes-MIT-NRAO and Green Bank 6cm (GB6) catalogs, except those previously detected with VLBI, is observed. In the refining mode, the positions of all ecliptic plane sources, including those found in the search mode, are improved. By 2016 October, thirteen 24hr sessions that targeted all sources brighter than 100mJy have been observed and analyzed. Among 3320 observed target sources, 555 objects have been detected. We also conducted a number of follow-up VLBI experiments in the refining mode and improved the positions of 249 ecliptic plane sources.
646. VLBI ICRF2
- ID:
- ivo://CDS.VizieR/J/AJ/150/58
- Title:
- VLBI ICRF2
- Short Name:
- J/AJ/150/58
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the second realization of the International Celestial Reference Frame (ICRF2) at radio wavelengths using nearly 30 years of Very Long Baseline Interferometry observations. ICRF2 contains precise positions of 3414 compact radio astronomical objects and has a positional noise floor of ~40{mu}as and a directional stability of the frame axes of ~10{mu}as. A set of 295 new "defining" sources was selected on the basis of positional stability and the lack of extensive intrinsic source structure. The positional stability of these 295 defining sources and their more uniform sky distribution eliminates the two greatest weaknesses of the first realization of the International Celestial Reference Frame (ICRF1). Alignment of ICRF2 with the International Celestial Reference System was made using 138 positionally stable sources common to both ICRF2 and ICRF1. The resulting ICRF2 was adopted by the International Astronomical Union as the new fundamental celestial reference frame, replacing ICRF1 as of 2010 January 1.
647. VLBI ICRF. II
- ID:
- ivo://CDS.VizieR/J/AJ/127/3587
- Title:
- VLBI ICRF. II
- Short Name:
- J/AJ/127/3587
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use very long baseline interferometry data obtained between mid-1995 and the end of 2002 May together with older data to extend and revise the International Celestial Reference Frame (ICRF). Revised positions of ICRF candidate and "other" sources, based on inclusion of the additional data, are presented. Positions, in the frame of the ICRF, for an additional 109 new sources are also presented. All but four of the new sources are located north of {delta}=-30{deg}. Positions of the ICRF defining sources remain unchanged. We present a summary of current astrometric and geodetic observing programs and discuss the evolution and future of the ICRF.
- ID:
- ivo://CDS.VizieR/I/251
- Title:
- VLBI International Celestial Reference Frame (ICRF)
- Short Name:
- I/251
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- of the 1998AJ....116..516M paper: A quasi-inertial reference frame is defined based on the radio positions of 212 extragalactic sources distributed over the entire sky. The positional accuracy of these sources is better than about 1mas in both coordinates. The radio positions are based upon a general solution for all applicable dual-frequency 2.3 and 8.4GHz Mark III very long baseline interferometry data available through the middle of 1995, consisting of 1.6 million pairs of group delay and phase delay rate observations. Positions and details are also given for an additional 396 objects that either need further observation or are currently unsuitable for the definition of a high-accuracy reference frame. The final orientation of the frame axes has been obtained by a rotation of the positions into the system of the International Celestial Reference System and is consistent with the FK5 J2000.0 optical system, within the limits of the link accuracy. The resulting International Celestial Reference Frame has been adopted by the International Astronomical Union as the fundamental celestial reference frame, replacing the FK5 optical frame as of 1998 January 1.
- ID:
- ivo://CDS.VizieR/J/AZh/81/1032
- Title:
- VLBI Position Measurements
- Short Name:
- J/AZh/81/1032
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A large number (~2 million) of VLBI observations have been reduced in order to re ne the measured coordinates of the observed radio sources. The data reduction was carried out in the OCCAM package using the least squares colocation method. Corrections to the coordinates of 642 objects were derived. The accuracy of the catalog is no worse than 0.2 milliseconds of arc for stable sources.
- ID:
- ivo://CDS.VizieR/I/40
- Title:
- WASHINGTON 20 Catalog
- Short Name:
- I/40
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalogue contains the two parts: the 9989 first stars are the standard and intermediary stars, +90 to -36 degrees of declination, observed in the years 1913 to 1926, and reduced without proper motion to the equinox 1920.0 ; the second part (stars numbered 9990 to 10571) are 582 miscellaneous stars.
