- ID:
- ivo://CDS.VizieR/J/AJ/160/131
- Title:
- Compilation of 289 eclipsing binaries parameters
- Short Name:
- J/AJ/160/131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate directly imaging exoplanets around eclipsing binaries using the eclipse as a natural tool for dimming the binary and thus increasing the planet to star brightness contrast. At eclipse, the binary becomes pointlike, making coronagraphy possible. We select binaries where the planet-star contrast would be boosted by >10x during eclipse, making it possible to detect a planet that is >~10x fainter or in a star system that is ~2-3x more massive than otherwise. Our approach will yield insights into planet occurrence rates around binaries versus individual stars. We consider both self-luminous (SL) and reflected light (RL) planets. In the SL case, we select binaries whose age is young enough so that an orbiting SL planet would remain luminous; in U Cep and AC Sct, respectively, our method is sensitive to SL planets of ~4.5 and ~9 M_J_ with current ground- or near-future space-based instruments and ~1.5 and ~6 M_J_ with future ground-based observatories. In the RL case, there are three nearby (<~50 pc) systems-V1412 Aql, RR Cae, and RT Pic-around which a Jupiter-like planet at a planet-star separation of >~20mas might be imaged with future ground- and space-based coronagraphs. A Venus-like planet at the same distance might be detectable around RR Cae and RT Pic. A habitable Earth-like planet represents a challenge; while the planet-star contrast at eclipse and planet flux are accessible with a 6-8m space telescope, the planet-star separation is 1/3-1/4 of the angular separation limit of modern coronagraphy.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/384/145
- Title:
- Compiled catalog of Per OB2 star forming complex
- Short Name:
- J/A+A/384/145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Compiled Catalogue (CC) is a photometric and astrometric survey with the center at (RA, DE)_J2000 = (3.86h, 34.6{deg}) and radius of 10 degrees of a nearby region of star formation including the Per OB2 association. The CC is based on recently published astronomical catalogues, e.g. Hipparcos and Tycho-2, and supplemented by relevant astrophysical data from numerous data sources. The CC is complete down to V=11.6mag, in general, and to V=18.5mag in the one square degree field with the IC 348 cluster. The coordinates and proper motions are reduced to the Hipparcos system and the photometry in the Johnson system. Typical accuracies of 1-20mas for coordinates, 1-3mas/yr for proper motions, 0.01-0.05mag for BV magnitudes were achieved for majority of 29452 CC stars (V<12mag). For a large number of stars we also collected parallaxes and spectral classes (about 7000 stars), the R (about 2000 stars), I, J, H, K (about 500 stars) magnitudes, radial velocities (330 stars). Stars in the Compiled Catalogue are sorted in right ascension order.
- ID:
- ivo://CDS.VizieR/J/ApJ/878/63
- Title:
- Cool WD atmosphere models. IV. Spectral evolution
- Short Name:
- J/ApJ/878/63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As a result of competing physical mechanisms, the atmospheric composition of white dwarfs changes throughout their evolution, a process known as spectral evolution. Because of the ambiguity of their atmospheric compositions and the difficulties inherent to the modeling of their dense atmospheres, no consensus exists regarding the spectral evolution of cool white dwarfs (Teff<6000K). In the previous papers of this series, we presented and observationally validated a new generation of cool white dwarf atmosphere models that include all the necessary constitutive physics to accurately model those objects. Using these new models and a homogeneous sample of 501 cool white dwarfs, we revisit the spectral evolution of cool white dwarfs. Our sample includes all spectroscopically identified white dwarfs cooler than 8300K for which a parallax is available in Gaia DR2 and photometric observations are available in Pan-STARRS1 and 2MASS. Except for a few cool carbon-polluted objects, our models allow an excellent fit to the spectroscopic and photometric observations of all objects included in our sample. We identify a decrease of the ratio of hydrogen- to helium-rich objects between 7500 and 6250K, which we interpret as the signature of convective mixing. After this decrease, hydrogen-rich objects become more abundant up to 5000K. This puzzling increase, reminiscent of the non-DA gap, has yet to be explained. At lower temperatures, below 5000K, hydrogen-rich white dwarfs become rarer, which rules out the scenario in which the accretion of hydrogen from the interstellar medium dominates the spectral evolution of cool white dwarfs.
- ID:
- ivo://CDS.VizieR/J/A+A/634/A98
- Title:
- Corona-Australis DANCe. I.
- Short Name:
- J/A+A/634/A98
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Corona-Australis is one of the nearest regions to the Sun with recent and ongoing star formation, but the current picture of its stellar (and substellar) content is not complete yet. We take advantage of the second data release of the Gaia space mission to revisit the stellar census and search for additional members of the young stellar association in Corona-Australis. We applied a probabilistic method to infer membership probabilities based on a multidimensional astrometric and photometric data set over a field of 128deg^2^ around the dark clouds of the region. We identify 313 high-probability candidate members to the Corona-Australis association, 262 of which had never been reported as members before. Our sample of members covers the magnitude range between G>~5mag and G<~20mag, and it reveals the existence of two kinematically and spatially distinct subgroups. There is a distributed 'off-cloud' population of stars located in the north of the dark clouds that is twice as numerous as the historically known 'on-cloud' population that is concentrated around the densest cores. By comparing the location of the stars in the HR-diagram with evolutionary models, we show that these two populations are younger than 10Myr. Based on their infrared excess emission, we identify 28 Class II and 215 Class III stars among the sources with available infrared photometry, and we conclude that the frequency of Class~II stars (i.e. `disc-bearing' stars) in the on-cloud region is twice as large as compared to the off-cloud population. The distance derived for the Corona-Australis region based on this updated census is d=149.4^+0.4^_-0.4_pc, which exceeds previous estimates by about 20 pc. In this paper we provide the most complete census of stars in Corona-Australis available to date that can be confirmed with Gaia data. Furthermore, we report on the discovery of an extended and more evolved population of young stars beyond the region of the dark clouds, which was extensively surveyed in the past.
- ID:
- ivo://CDS.VizieR/J/A+A/584/A26
- Title:
- Cosmography of OB stars in the solar neighbourhood
- Short Name:
- J/A+A/584/A26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We construct a 3D map of the spatial density of OB stars within 500pc from the Sun using the Hipparcos catalogue and find three large-scale stream-like structures that allow a new view on the solar neighbourhood. The spatial coherence of these blue streams and the monotonic age sequence over hundreds of parsecs suggest that they are made of young stars, similar to the young streams that are conspicuous in nearby spiral galaxies. The three streams are 1) the Scorpius to Canis Majoris stream, covering 350pc and 65Myr of star formation history; 2) the Vela stream, encompassing at least 150pc and 25Myr of star formation history; and 3) the Orion stream, including not only the well-known Orion OB1abcd associations, but also a large previously unreported foreground stellar group lying only 200pc from the Sun. The map also reveals a remarkable and previously unknown nearby OB association, between the Orion stream and the Taurus molecular clouds, which might be responsible for the observed structure and star formation activity in this cloud complex. This new association also appears to be the birthplace of Betelgeuse, as indicated by the proximity and velocity of the red giant. If this is confirmed, it would solve the long-standing puzzle of the origin of Betelgeuse. The well-known nearby star-forming low-mass clouds, including the nearby T and R associations Lupus, Cha, Oph, CrA, Taurus, Vela R1, and various low-mass cometary clouds in Vela and Orion, appear in this new view of the local neighbourhood to be secondary star formation episodes that most likely were triggered by the feedback from the massive stars in the streams. We also recover well-known star clusters of various ages that are currently cruising through the solar neighbourhood. Finally, we find no evidence of an elliptical structure such as the Gould belt, a structure we suggest is a 2D projection effect, and not a physical ring.
- ID:
- ivo://CDS.VizieR/J/ApJ/872/85
- Title:
- Detached eclipsing binaries with Gaia parallaxes
- Short Name:
- J/ApJ/872/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using a sample of 81 Galactic, detached eclipsing binary stars we investigated the global zero-point shift of their parallaxes with the Gaia Data Release 2 (DR2) parallaxes. The stars in the sample lay in a distance range of 0.04-2kpc from the Sun. The photometric parallaxes {omega}_Phot_ of the eclipsing binaries were determined by applying a number of empirical surface brightness-color (SBC) relations calibrated on optical-infrared colors. For each SBC relation we calculated the individual differences d{varpi}_i_=({varpi}_Gaia_-{varpi}_Phot_)_i_ and then we calculated unweighted and weighted means. As the sample covers the whole sky we interpret the weighted means as the global shifts of the Gaia DR2 parallaxes with respect to our eclipsing binary sample. Depending on the choice of the SBC relation the shifts vary from -0.094 to -0.025mas. The weighted mean of the zero-point shift from all colors and calibrations used is d{omega}=-0.054+/-0.024mas. However, the SBC relations based on (B-K) and (V-K) colors, which are the least reddening dependent and have the lowest intrinsic dispersions, give a zero-point shift of d{omega}=-0.031+/-0.011mas in full agreement with results obtained by Lindegren+ (2018A&A...616A...2L) and Arenou+ (2018A&A...616A..17A). Our result confirms the global shift of Gaia DR2 parallaxes of d{omega}=-0.029mas reported by the Gaia team, but we do not confirm the larger zero-point shift reported by a number of follow-up papers.
- ID:
- ivo://CDS.VizieR/J/MNRAS/492/L40
- Title:
- Disentangling cataclysmic variables in Gaia DR2
- Short Name:
- J/MNRAS/492/L40
- Date:
- 07 Dec 2021 09:36:41
- Publisher:
- CDS
- Description:
- Cataclysmic Variables (CVs) are interacting binaries consisting of at least three components that control their colour and magnitude. Using Gaia we here investigate the influence of the physical properties of these binaries on their position in the Hertzsprung-Russell diagram (HR-diagram). The CVs are on average located between the main sequence and the white dwarf regime, the maximum density being at G_BP_-G_RP_~=0.56 and G_abs_~10.15. We nd a trend of the orbital period with colour and absolute brightness: with decreasing period, the CVs become bluer and fainter. We also identify the location of the various CV sub-types in the HR-diagram and discuss the possible location of detached CVs, going through the orbital period gap.
- ID:
- ivo://CDS.VizieR/J/AJ/136/2107
- Title:
- Distances of cataclysmic variables
- Short Name:
- J/AJ/136/2107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report parallax and distance estimates for 12 more cataclysmic binaries and related objects observed with the 2.4m Hiltner telescope at MDM Observatory. The final parallax accuracy is typically ~1mas.
- ID:
- ivo://CDS.VizieR/J/AJ/126/3017
- Title:
- Distances of Cataclysmic variables
- Short Name:
- J/AJ/126/3017
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The 2.4m Hiltner Telescope at MDM Observatory was used in an attempt to measure trigonometric parallaxes for 14 cataclysmic variable stars. Techniques are described in detail. In the best cases the parallax uncertainties are below 1mas, and significant parallaxes are found for most of the program stars. A Bayesian method that combines the parallaxes together with proper motions and absolute magnitude constraints is developed and used to derive distance estimates and confidence intervals. The most precise distance derived here is for WZ Sge, for which is found to be 43.3^+1.6^_-1.5_pc. Six Luyten Half-Second stars with previous precise parallax measurements were remeasured to test the techniques, and good agreement was found.
- ID:
- ivo://CDS.VizieR/J/ApJ/833/119
- Title:
- Distances of Gaia DR1 TGAS sources
- Short Name:
- J/ApJ/833/119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We infer distances and their asymmetric uncertainties for two million stars using the parallaxes published in the Gaia DR1 (GDR1) catalogue. We do this with two distance priors: A minimalist, isotropic prior assuming an exponentially decreasing space density with increasing distance, and an anisotropic prior derived from the observability of stars in a Milky Way model. We validate our results by comparing our distance estimates for 105 Cepheids which have more precise, independently estimated distances. For this sample we find that the Milky Way prior performs better (the RMS of the scaled residuals is 0.40) than the exponentially decreasing space density prior (RMS is 0.57), although for distances beyond 2kpc the Milky Way prior performs worse, with a bias in the scaled residuals of -0.36 (vs. -0.07 for the exponentially decreasing space density prior). We do not attempt to include the photometric data in GDR1 due to the lack of reliable colour information. Our distance catalogue is available at http://www.mpia.de/homes/calj/tgas_distances/main.html. These should only be used to give individual distances. Combining data or testing models should be done with the original parallaxes, and attention paid to correlated and systematic uncertainties.
