- ID:
- ivo://CDS.VizieR/J/A+A/620/A142
- Title:
- HAT-P-12b 2016-2017 light curve
- Short Name:
- J/A+A/620/A142
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Two independent investigations of the atmosphere of the hot Jupiter HAT-P-12b by two different groups resulted in discrepant solutions. Using broad-band photometry from the ground, one study found a flat and featureless transmission spectrum which was interpreted as a gray absorption by dense cloud coverage. The second study made use of the Hubble Space Telescope (HST) observations and found Rayleigh scattering at optical wavelengths caused by haze. The main purpose of this work is to find the source of this inconsistency and provide feedback to prevent similar discrepancies in future analyses of other exoplanetary atmospheres. We studied the observed discrepancy via two methods. With further broad-band observations in the optical wavelength regions, we strengthened the previous measurements in precision and with a homogeneous reanalysis of the published data, we managed to assess the systematic errors and the independent analyses of the two different groups. Repeating the analysis steps of both works, we found that deviating values for the orbital parameters are the reason for the aforementioned discrepancy. Our work showed a degeneracy of the planetary spectral slope with these parameters. In a homogeneous reanalysis of all data, the two literature data sets and the new observations converge to a consistent transmission spectrum, showing a low-amplitude spectral slope and a tentative detection of potassium absorption.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/558/A55
- Title:
- HATS-2b griz light curves
- Short Name:
- J/A+A/558/A55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of HATS-2b, the second transiting extrasolar planet detected by the HATSouth survey. HATS- 2b is moving on a circular orbit around a V=13.6mag, K-type dwarf star (GSC 6665-00236), at a separation of 0.0230+/-0.0003AU and with a period of 1.3541-days. The planetary parameters have been robustly determined using a simultaneous t of the HATSouth, MPG/ESO 2.2m/GROND, Faulkes Telescope South/Spectral transit photometry, and MPG/ESO 2.2m/FEROS, Euler 1.2m/CORALIE, AAT 3.9m/CYCLOPS radial-velocity measurements.
- ID:
- ivo://CDS.VizieR/J/ApJ/872/17
- Title:
- HAZMAT. V. UV and X-ray evolution of K stars
- Short Name:
- J/ApJ/872/17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Knowing the high-energy radiation environment of a star over a planet's formation and evolutionary period is critical in determining if that planet is potentially habitable and if any biosignatures could be detected, as UV radiation can severely change or destroy a planet's atmosphere. Current efforts for finding a potentially habitable planet are focused on M stars, yet K stars may offer more habitable conditions due to decreased stellar activity and more distant and wider habitable zones (HZs). While M star activity evolution has been observed photometrically and spectroscopically, there has been no dedicated investigation of K star UV evolution. We present the first comprehensive study of the near-UV, far-UV, and X-ray evolution of K stars. We used members of young moving groups and clusters ranging in age from 10 to 625Myr combined with field stars and their archived GALEX UV and ROSAT X-ray data to determine how the UV and X-ray radiation evolve. We find that the UV and X-ray flux incident on an HZ planet is 5-50 times lower than that of HZ planets around early-M stars and 50-1000 times lower than those around late-M stars, due to both an intrinsic decrease in K dwarf stellar activity occurring earlier than for M dwarfs and the more distant location of the K dwarf HZ.
- ID:
- ivo://CDS.VizieR/J/ApJ/795/41
- Title:
- HD 128311 radial velocity and astrometric data
- Short Name:
- J/ApJ/795/41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used high-cadence radial velocity measurements from the Hobby-Eberly Telescope with published velocities from the Lick 3 m Shane Telescope, combined with astrometric data from the Hubble Space Telescope (HST) Fine Guidance Sensors to refine the orbital parameters of the HD 128311 system, and determine an inclination of 55.95{deg}+/-14.55{deg} and true mass of 3.789_-0.432_^+0.924^ M_JUP_ for HD 128311 c. The combined radial velocity data also reveal a short period signal which could indicate a third planet in the system with an Msin i of 0.133+/-0.005 M_JUP_or stellar phenomena. Photometry from the T12 0.8 m automatic photometric telescope at the Fairborn Observatory and HST are used to determine a photometric period close to, but not within the errors of the radial velocity signal. We performed a cross-correlation bisector analysis of the radial velocity data to look for correlations with the photometric period and found none. Dynamical integrations of the proposed system show long-term stability with the new orbital parameters of over 10 million years. Our new orbital elements do not support the claims of HD 128311 b and c being in mean motion resonance.
- ID:
- ivo://CDS.VizieR/J/MNRAS/460/1356
- Title:
- Hercules stream K giants analysis
- Short Name:
- J/MNRAS/460/1356
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An abundance analysis is reported of 58-K giants identified by Famaey et al. (2005, J/A+A/430/165) as highly probable members of the Hercules stream selected from stars north of the celestial equator in the Hipparcos catalogue. The giants have compositions spanning the interval [Fe/H] from -0.17 to +0.42 with a mean value of +0.15 and relative elemental abundances [El/Fe] representative of the Galactic thin disc. Selection effects may have biased the selection from the Hipparcos catalogue against the selection of metal-poor stars. Our reconsideration of the recent extensive survey by Bensby et al. of FG dwarfs, including metal-poor stars, provides a [Fe/H] distribution for the Hercules stream, which is similar to that from the 58 giants. It appears that the stream is dominated by metal-rich stars from the thin disc. We discuss suggestions in the literature that the stream includes metal-poor stars from the thick disc.
- ID:
- ivo://CDS.VizieR/J/AJ/105/1962
- Title:
- K and M stars photometry
- Short Name:
- J/AJ/105/1962
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Broadband UBVRI photometry is presented for 687 stars from among the dwarf K and M stars found spectroscopically by Vyssotsky [1958AJ.....63..211V]. Of these, 211 are without previous photometry.
- ID:
- ivo://CDS.VizieR/J/A+A/612/A95
- Title:
- K2-141 b radial velocity and light curve
- Short Name:
- J/A+A/612/A95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the discovery of K2-141 b (EPIC 246393474 b), an ultra-short-period super-Earth on a 6.7-hour orbit transiting an active K7 V star based on data from K2 campaign 12. We confirmed the planet's existence and measured its mass with a series of follow-up observations: seeing-limited MuSCAT imaging, NESSI high-resolution speckle observations, and FIES and HARPS high-precision radial-velocity monitoring. K2-141 b has a mass of 5.31+/-0.46M_{Earth}_ and radius of 1.54+0.10-0.09R_{Earth}_, yielding a mean density of 8.00^+1.83^_-1.45_g/cm^3^ and suggesting a rocky-iron composition. Models indicate that iron cannot exceed ~70% of the total mass. With an orbital period of only 6.7 hours, K2-141 b is the shortest-period planet known to date with a precisely determined mass.
- ID:
- ivo://CDS.VizieR/J/A+AS/97/835
- Title:
- K giants at the South Galactic Pole
- Short Name:
- J/A+AS/97/835
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/other/RAA/17.76
- Title:
- K giant stars along Sagittarius streams
- Short Name:
- J/other/RAA/17.7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Large Sky-Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) Data Release 3 provided 341 691 K giant stars with stellar parameters. Based on the models of Law & Majewski (2010ApJ...714..229L), we identified 252 K giant stars in the leading stream associated with the Sagittarius (Sgr) dwarf galaxy. We obtained 132 K giant stars belonging to the trailing arm of Sgr using the model of Belokurov et al. We studied the metallicity distribution of member stars along the streams and found a flat gradient in the first wrap of the leading stream, -(0.88+/-0.3)x10^-3^dex/deg in the second wrap of the leading stream and -(1.2+/-0.3)x10^-3^dex/deg in the first wrap of the trailing stream. Moreover, we obtained a combined metallicity gradient with our sample and data from the literature. We also analyzed the properties of an overdensity, which is located in the leading stream of the Sgr.
- ID:
- ivo://CDS.VizieR/J/ApJ/880/65
- Title:
- LAMOST K giants in Galactic halo substructures
- Short Name:
- J/ApJ/880/65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We construct a large halo K-giant sample by combining the positions, distances, radial velocities, and metallicities of over 13000 LAMOST DR5 halo K giants with the Gaia DR2 proper motions, which covers a Galactocentric distance range of 5-120kpc. Using a position-velocity clustering estimator (the 6Distance), we statistically quantify the presence of position-velocity substructure at high significance: K giants have more close pairs in position-velocity space than a smooth stellar halo. We find that the amount of substructure in the halo increases with increasing distance and metallicity. With a percolation algorithm named friends-of-friends to identify groups, we identify members belonging to Sagittarius (Sgr) Streams, Monoceros Ring, Virgo Overdensity, Hercules-Aquila Cloud, Orphan Streams, and other unknown substructures and find that the Sgr streams account for a large part of grouped stars beyond 20kpc and enhance the increase of substructure with distance and metallicity. For the first time, we identify spectroscopic members of Monoceros Ring in the southern and northern Galactic hemispheres, which presents a rotation of about 185km/s and a mean metallicity of -0.66dex.
