- ID:
- ivo://CDS.VizieR/J/A+A/480/495
- Title:
- Patterns of color variations in close binaries
- Short Name:
- J/A+A/480/495
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the first of a series of papers in which we present the results of a long-term photometric monitoring project carried out at Catania Astrophysical Observatory aimed at studying magnetic activity in late-type components of close binary systems, its dependence on global stellar parameters, and its evolution on different time scales from days to years. In this first paper, we present the complete observation dataset and new results of an investigation into the origin of brightness and color variations observed in the well-known magnetically active close binary stars: AR Psc, VY Ari, UX Ari, V711 Tau, EI Eri, V1149 Ori, DH Leo, HU Vir, RS CVn, V775 Her, AR Lac, SZ Psc, II Peg and BY Dra . About 38000 high-precision photoelectric nightly observations in the U, B and V filters are analysed. Correlation and regression analyses of the V magnitude vs. U-B and B-V color variations are carried out and a comparison with model variations for a grid of active region temperature and filling factor values is also performed. We find the existence of two different patterns of color variation. Eight stars in our sample: BY Dr, VY Ari, V775 Her, II Peg, V1149 Ori, HU Vir, EI Eri and DH Leo become redder when they become fainter, as is expected from the presence of active regions consisting of cool spots. The other six stars show the opposite behaviour, i.e. they become bluer when they become fainter. For V711 Tau this behaviour could be explained by the increased relative U- and B- flux contribution by the earlier-type component of the binary system when the cooler component becomes fainter. On the other hand, for AR Psc, UX Ari, RS CVn, SZ Psc and AR Lac the existence of hot photospheric faculae must be invoked. We also found that in single-lined and double-lined binary stars in which the fainter component is inactive or much less active the V magnitude is correlated to B-V and U-B color variations in more than 60% of observation seasons. The correlation is found in less than 40% of observation seasons when the fainter component has a non-negligible level of activity and/or hot faculae are present but they are either spatially or temporally uncorrelated to spots.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/640/1051
- Title:
- 25pc sample of Sun-like stars
- Short Name:
- J/ApJ/640/1051
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Sun-like stars have stellar, brown dwarf, and planetary companions. To help constrain their formation and migration scenarios, we analyze the close companions (orbital period<5yr) of nearby Sun-like stars. By using the same sample to extract the relative numbers of stellar, brown dwarf, and planetary companions, we verify the existence of a very dry brown dwarf desert and describe it quantitatively.
- ID:
- ivo://CDS.VizieR/J/A+A/632/A25
- Title:
- PDS70 VLT/SPHERE images
- Short Name:
- J/A+A/632/A25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- PDS 70 is a young (5.4Myr), nearby (~113pc) star hosting a known transition disk with a large gap. Recent observations with SPHERE and NACO in the near-infrared (NIR) allowed us to detect a planetary mass companion, PDS70b, within the disk cavity. Moreover, observations in H{alpha} with MagAO and MUSE revealed emission associated to PDS 70 b and to another new companion candidate, PDS70c, at a larger separation from the star. PDS 70 is the only multiple planetary system at its formation stage detected so far through direct imaging. Our aim is to confirm the discovery of the second planet PDS 70 c using SPHERE at VLT, to further characterize its physical properties, and search for additional point sources in this young planetary system. Methods. We re-analyzed archival SPHERE NIR observations and obtained new data in Y, J, H and K spectral bands for a total of four different epochs. The data were reduced using the data reduction and handling pipeline and the SPHERE data center. We then applied custom routines (e.g. ANDROMEDA and PACO) to subtract the starlight. We re-detect both PDS 70 b and c and confirm that PDS70c is gravitationally bound to the star. We estimate this second planet to be less massive than 5M_Jup_ and with a Teff around 900K. Also, it has a low gravity with log g between 3.0 and 3.5dex. In addition, a third object has been identified at short separation (~0.12") from the star and gravitationally bound to the star. Its spectrum is however very blue, so that we are probably seeing stellar light reflected by dust and our analysis seems to demonstrate that it is a feature of the inner disk. We, however, cannot completely exclude the possibility that it is a planetary mass object enshrouded by a dust envelope. In this latter case, its mass should be of the order of few tens of M_{Earth}_. Moreover, we propose a possible structure for the planetary system based on our data that, however, cannot be stable on a long timescale.
- ID:
- ivo://CDS.VizieR/J/A+A/602/A117
- Title:
- Periods of 2290 CoRoT binaries
- Short Name:
- J/A+A/602/A117
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The CoRoT mission during its flight-phase 2007-2012 delivered the light-curves for over 2000 eclipsing binaries. Data from the Kepler mission have proven the existence of several transiting circumbinary planets. Albeit light-curves from CoRoT have typically lower precision and shorter coverage, CoRoT's number of targets is similar to Kepler, and some of the known circumbinary planets could potentially be detected in CoRoT data as well. The aim of this work has been a revision of the entire CoRoT data-set for the presence of circumbinary planets, and the derivation of limits to the abundances of such planets. We developed a code which removes the light curve of the eclipsing binaries and searches for quasi-periodic transit-like features in a light curve after removal of binary eclipses and instrumental features. The code needs little information on the sample systems and can be used for other space missions as well, like Kepler, K2, TESS and PLATO. The code is broad in the requirements leading to detections, but was tuned to deliver an amount of detections that is manageable in a subsequent, mainly visual, revision about their nature. In the CoRoT sample we identified three planet candidates whose transits would have arisen from a single pass across the central binary. No candidates remained however with transit events from multiple planetary orbits. We calculated the upper limits for the number of Jupiter, Saturn and Neptune sized planets in co-planar orbits for different orbital period ranges. We found that there are much less giant planets in short-periodic orbits around close binary systems than around single stars.
- ID:
- ivo://CDS.VizieR/J/AJ/140/1623
- Title:
- PHASES diff. astrometry data archive. II.
- Short Name:
- J/AJ/140/1623
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Differential astrometry measurements from the Palomar High-precision Astrometric Search for Exoplanet Systems have been combined with lower precision single-aperture measurements covering a much longer timespan (from eyepiece measurements, speckle interferometry, and adaptive optics) to determine improved visual orbits for 20 binary stars. In some cases, radial velocity observations exist to constrain the full three-dimensional orbit and determine component masses. The visual orbit of one of these binaries - {alpha} Com (HD 114378) - shows that the system is likely to have eclipses, despite its very long period of 26 years. The next eclipse is predicted to be within a week of 2015 January 24.
- ID:
- ivo://CDS.VizieR/J/AJ/140/1657
- Title:
- PHASES diff. astrometry data archive. V.
- Short Name:
- J/AJ/140/1657
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Palomar High-precision Astrometric Search for Exoplanet Systems monitored 51 subarcsecond binary systems to evaluate whether tertiary companions as small as Jovian planets orbited either the primary or secondary stars, perturbing their otherwise smooth Keplerian motions. Six binaries are presented that show evidence of substellar companions orbiting either the primary or secondary star. Of these six systems, the likelihoods of two of the detected perturbations to represent real objects are considered to be "high confidence," while the remaining four systems are less certain and will require continued observations for confirmation.
- ID:
- ivo://CDS.VizieR/J/AJ/140/1579
- Title:
- PHASES differential astrometry data archive
- Short Name:
- J/AJ/140/1579
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Palomar High-precision Astrometric Search for Exoplanet Systems (PHASES) monitored 51 subarcsecond binary systems to determine precision binary orbits, study the geometries of triple and quadruple star systems, and discover previously unknown faint astrometric companions as small as giant planets. PHASES measurements made with the Palomar Testbed Interferometer (PTI) from 2002 until PTI ceased normal operations in late 2008 are presented. Infrared differential photometry of several PHASES targets were measured with Keck Adaptive Optics and are presented.
- ID:
- ivo://CDS.VizieR/J/AJ/108/2338
- Title:
- Photographic astrometry. VIII.
- Short Name:
- J/AJ/108/2338
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 300 trigonometric parallaxes, 15 revised binary-star orbits, and 24 mass ratios are listed and annotated.
- ID:
- ivo://CDS.VizieR/J/AZh/91/130
- Title:
- Photographic catalog of wide visual double stars
- Short Name:
- J/AZh/91/130
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of the long-term uniform observations of visual double and multiple stars by 26-inch refractor. Set of observations (all plates) is measured with one measuring device for each star. For 259 pairs of visual double stars which were included in 194 systems, relative positions are calculated. For 127 pairs relative motions are also calculated. For 48 stars with well certain parallaxes from the Gipparkos catalog also the bottom limits for the total masses of systems are received under condition of the elliptic orbit is possible (dynamic mass). Comparison of accuracy of three measuring devices, which were applied to measurement of photographic plates, is executed. It is shown that differences in distances between the components, measured on the different measuring devices can reach 0.2" that proves advantage of uniform observations.
- ID:
- ivo://CDS.VizieR/J/A+AS/107/235
- Title:
- Photographic observations of visual binaries
- Short Name:
- J/A+AS/107/235
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the analysis result of photographic observations of 221 visual double stars, observed in the years 1987-1989 with the 60-cm double-refractor at the Bosscha Observatory at Lembang, Java.
