- ID:
- ivo://CDS.VizieR/J/ApJ/734/109
- Title:
- Follow-up photometry of HAT-P-27
- Short Name:
- J/ApJ/734/109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of HAT-P-27b, an exoplanet transiting the moderately bright G8 dwarf star GSC 0333-00351 (V=12.214). The orbital period is 3.039586+/-0.000012 days, the reference epoch of transit is 2455186.01879+/-0.00054 (BJD), and the transit duration is 0.0705+/-0.0019 days. The host star with its effective temperature 5300+/-90K is somewhat cooler than the Sun and is more metal-rich with a metallicity of +0.29+/-0.10. Its mass is 0.94+/-0.04M_{sun}_ and radius is 0.90^+0.05^_-0.04_R_{sun}_. For the planetary companion we determine a mass of 0.660+/-0.033M_J_ and radius of 1.038^+0.077^_-0.058_R_J_. For the 30 known transiting exoplanets between 0.3M_J_ and 0.8M_J_, a negative correlation between host star metallicity and planetary radius and an additional dependence of planetary radius on equilibrium temperature are confirmed at a high level of statistical significance.
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- ID:
- ivo://CDS.VizieR/J/AJ/145/5
- Title:
- Follow-up photometry of HATS-1
- Short Name:
- J/AJ/145/5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of HATS-1b, a transiting extrasolar planet orbiting the moderately bright V=12.05 G dwarf star GSC 6652-00186, and the first planet discovered by HATSouth, a global network of autonomous wide-field telescopes. HATS-1b has a period of P{approx}3.4465days, mass of M_p_{approx}1.86M_J_, and radius of R_p_{approx}1.30R_J_. The host star has a mass of 0.99M_{sun}_ and radius of 1.04R_{sun}_. The discovery light curve of HATS-1b has near-continuous coverage over several multi-day timespans, demonstrating the power of using a global network of telescopes to discover transiting planets.
- ID:
- ivo://CDS.VizieR/J/MNRAS/487/2474
- Title:
- GALAH unresolved triple Sun-like star
- Short Name:
- J/MNRAS/487/2474
- Date:
- 02 Mar 2022 00:37:36
- Publisher:
- CDS
- Description:
- The latest Gaia data release enables us to accurately identify stars that are more luminous than would be expected on the basis of their spectral type and distance. During an investigation of the 329 best solar twin candidates uncovered among the spectra acquired by the GALAH survey, we identified 64 such overluminous stars. In order to investigate their exact composition, we developed a data-driven methodology that can generate a synthetic photometric signature and spectrum of a single star. By combining multiple such synthetic stars into an unresolved binary or triple system and comparing the results to the actual photometric and spectroscopic observations, we uncovered 6 definitive triple stellar system candidate and an additional 14 potential candidates whose combined spectrum mimics the solar spectrum. Considering the volume correction factor for a magnitude-limited survey, the fraction of probable unresolved triple stars with long orbital periods is 2 per cent. Possible orbital configurations of the candidates were investigated using the selection and observational limits. To validate the discovered multiplicity fraction, the same procedure was used to evaluate the multiplicity fraction of other stellar types.
- ID:
- ivo://CDS.VizieR/J/MNRAS/336/879
- Title:
- G and K dwarfs UBV(RI)c and ubvy photometry
- Short Name:
- J/MNRAS/336/879
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- K dwarfs have lifetimes older than the present age of the Galactic disc, and are thus ideal stars for investigating the chemical evolution of the disc. We have developed several photometric metallicity indicators for K dwarfs, based on a sample of accurate spectroscopic metallicities for 34 disc and halo G and K dwarfs. The photometric metallicities lead us to develop a metallicity index for K dwarfs based only on their position in the colour-absolute-magnitude diagram. Metallicities have been determined for 431 single K dwarfs drawn from the Hipparcos catalogue, selecting the stars by absolute magnitude and removing multiple systems. The sample is essentially a complete reckoning of the metal content in nearby K dwarfs. We use stellar isochrones to mark the stars by mass, and select a subset of 220 of the stars, which is complete within a narrow mass interval. We fit the data with a model of the chemical evolution of the solar cylinder. We find that only a modest cosmic scatter is required to fit our age-metallicity relation. The model assumes two main infall episodes for the formation of the halo-thick disc and thin disc, respectively. The new data confirm that the solar neighbourhood formed on a long time-scale of the order of 7Gyr.
- ID:
- ivo://CDS.VizieR/J/A+A/574/A116
- Title:
- G and K giant stars stellar parameters
- Short Name:
- J/A+A/574/A116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained precise radial velocities for a sample of 373 G and K type giants at Lick Observatory regularly over more than 12 years. Planets have been identified around 15 of these giant stars, and an additional 20 giant stars host planet candidates. We are interested in the occurrence rate of substellar companions around giant stars as a function of stellar mass and metallicity. We probe the stellar mass range from approximately 1 to beyond 3M_{sun}_, which is not being explored by main-sequence samples. We fit the giant planet occurrence rate as a function of stellar mass and metallicity with a Gaussian and an exponential distribution, respectively.
- ID:
- ivo://CDS.VizieR/J/MNRAS/444/2251
- Title:
- G0-G3 main-sequence stars with V<15
- Short Name:
- J/MNRAS/444/2251
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The basic stellar atmospheric parameters (effective temperature, surface gravity and global metallicity) were determined simultaneously for a sample of 233 stars, limited in magnitude (V<15), with spectral types between G0 and G3 and luminosity class V (main sequence). The analysis was based on spectroscopic observations collected at the Observatorio Astrofisico Guillermo Haro and using a set of Lick-like indices defined in the spectral range 3800-4800{AA}. An extensive set of indices computed in a grid of theoretical spectra was used as a comparison tool in order to determine the photospheric parameters. The method was validated by matching the results from spectra of the asteroids Vesta and Ceres with the Sun parameters. The main results were as follows: (i) the photospheric parameters were determined for the first time for 213 objects in our sample and (ii) a sample of 20 new super-metal-rich star candidates was found.
- ID:
- ivo://CDS.VizieR/J/A+A/599/A121
- Title:
- Glycolaldehyde in Perseus young solar analogs
- Short Name:
- J/A+A/599/A121
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The earliest evolutionary stages of low-mass protostars are characterised by the so-called hot-corino stage, when the newly born star heats the surrounding material and enrich the gas chemically. Studying this evolutionary phase of solar protostars may help understand the evolution of prebiotic complex molecules in the development of planetary systems. In this paper we focus on the occurrence of glycolaldehyde (HCOCH_2_OH) in young solar analogs by performing the first homogeneous and unbiased study of this molecule in the Class 0 protostars of the nearby Perseus star forming region. We obtained sub-arcsec angular resolution maps at 1.3mm and 1.4mm of glycolaldehyde emission lines using the IRAM Plateau de Bure (PdB) interferometer in the framework of the CALYPSO IRAM large program.
- ID:
- ivo://CDS.VizieR/J/AJ/160/129
- Title:
- HARPS, HIRES and AAT Radial Velocities of HD 136352
- Short Name:
- J/AJ/160/129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Some of the most scientifically valuable transiting planets are those that were already known from radial velocity (RV) surveys. This is primarily because their orbits are well characterized and they preferentially orbit bright stars that are the targets of RV surveys. The Transiting Exoplanet Survey Satellite (TESS) provides an opportunity to survey most of the known exoplanet systems in a systematic fashion to detect possible transits of their planets. HD136352 (Nu Lupi) is a naked-eye (V=5.78) G-type main-sequence star that was discovered to host three planets with orbital periods of 11.6, 27.6, and 108.1days via RV monitoring with the High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph. We present the detection and characterization of transits for the two inner planets of the HD136352 system, revealing radii of 1.482_-0.056_^+0.058^ R{Earth} and 2.608_-0.077_^+0.078^ R{Earth} for planets b and c, respectively. We combine new HARPS observations with RV data from the Keck/High Resolution Echelle Spectrometer and the Anglo-Australian Telescope, along with TESS photometry from Sector 12, to perform a complete analysis of the system parameters. The combined data analysis results in extracted bulk density values of {rho}_b_=7.8_-1.1_^+1.2^g/cm3 and {rho}_c_=3.50_-0.36_^+0.41^g/cm3 for planets b and c, respectively, thus placing them on either side of the radius valley. The combination of the multitransiting planet system, the bright host star, and the diversity of planetary interiors and atmospheres means this will likely become a cornerstone system for atmospheric and orbital characterization of small worlds.
- ID:
- ivo://CDS.VizieR/J/ApJ/794/110
- Title:
- HARPS timeseries data for HD41248
- Short Name:
- J/ApJ/794/110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Gaining a better understanding of the effects of stellar-induced radial velocity noise is critical for the future of exoplanet studies since the discovery of the lowest-mass planets using this method will require us to go below the intrinsic stellar noise limit. An interesting test case in this respect is that of the southern solar analog HD 41248. The radial velocity time series of this star has been proposed to contain either a pair of signals with periods of around 18 and 25 days, which could be due to a pair of resonant super-Earths, or a single and varying 25 day signal that could arise due to a complex interplay between differential rotation and modulated activity. In this work, we build up more evidence for the former scenario, showing that the signals are still clearly significant, even after more than 10 yr of observations, and they likely do not change in period, amplitude, or phase as a function of time, the hallmarks of static Doppler signals. We show that over the last two observing seasons, this star was more intrinsically active and the noise reddened, highlighting why better noise models are needed to find the lowest amplitude signals, in particular, models that consider noise correlations. This analysis shows that there is still sufficient evidence for the existence of two super-Earths on the edge of, or locked into, a 7:5 mean motion resonance orbiting HD 41248.
- ID:
- ivo://CDS.VizieR/J/A+A/523/A15
- Title:
- HARPS XXIII: RV data for the 8 targets
- Short Name:
- J/A+A/523/A15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we present our HARPS radial-velocity data for eight low-activity solar-type stars belonging to the HARPS volume-limited sample: HD6718, HD8535, HD28254, HD290327, HD43197, HD44219, HD148156, and HD156411. Keplerian fits to these data reveal the presence of low-mass companions around these targets. With minimum masses ranging from 0.58 to 2.54M_{Jup}_, these companions are in the planetary mass domain. The orbital periods of these planets range from slightly less than one to almost seven years. The eight orbits presented in this paper exhibit a wide variety of eccentricities: from 0.08 to above 0.8.
