- ID:
- ivo://CDS.VizieR/J/A+A/627/A49
- Title:
- Teegarden's Star RV and H{alpha} curves
- Short Name:
- J/A+A/627/A49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Teegarden's Star is the brightest and one of the nearest ultra-cool dwarfs in the solar neighbourhood. For its late spectral type (M7.0 V), the star shows relatively little activity and is a prime target for near-infrared radial velocity surveys such as CARMENES. As part of the CARMENES search for exoplanets around M dwarfs, we obtained more than 200 radial-velocity measurements of Teegarden's Star and analysed them for planetary signals. We find periodic variability in the radial velocities of Teegarden's Star. We studied photometric measurements to rule out stellar brightness variations mimicking planetary signals. We find evidence for two planet candidates, each with 1.1M_{Earth}_ minimum mass, orbiting at periods of 4.91d and 11.4d, respectively. No evidence for planetary transits could be found in archival and follow-up photometry. Small photometric variability is suggestive of slow rotation and old age. The two planets are among the lowest-mass planets discovered so far, and they are the first Earth-mass planets around an ultra-cool dwarf for which the masses have been determined using radial velocities.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/892/31
- Title:
- Teff and metallicities of M dwarfs in APOGEE DR14
- Short Name:
- J/ApJ/892/31
- Date:
- 07 Mar 2022 13:23:27
- Publisher:
- CDS
- Description:
- M dwarfs have enormous potential for our understanding of structure and formation on both Galactic and exoplanetary scales through their properties and compositions. However, current atmosphere models have limited ability to reproduce spectral features in stars at the coolest temperatures (Teff<4200K) and to fully exploit the information content of current and upcoming large-scale spectroscopic surveys. Here we present a catalog of spectroscopic temperatures, metallicities, and spectral types for 5875 M dwarfs in the Apache Point Observatory Galactic Evolution Experiment (APOGEE) and Gaia-DR2 surveys using The Cannon (Ness+ 2015, J/ApJ/808/16 ; Casey+ 2016, arXiv:1603.03040; Ho+ 2017, J/ApJ/836/5; Behmard+ 2019ApJ...876...68B): a flexible, data-driven spectral-modeling and parameter-inference framework demonstrated to estimate stellar-parameter labels (Teff, logg, [Fe/H], and detailed abundances) to high precision. Using a training sample of 87 M dwarfs with optically derived labels spanning 2860K<Teff<4130K calibrated with bolometric temperatures, and -0.5<[Fe/H]<0.5dex calibrated with FGK binary metallicities, we train a two-parameter model with predictive accuracy (in cross-validation) to 77K and 0.09dex respectively. We also train a one-dimensional spectral classification model using 51 M dwarfs with Sloan Digital Sky Survey optical spectral types ranging from M0 to M6, to predictive accuracy of 0.7 types. We find Cannon temperatures to be in agreement to within 60 K compared to a subsample of 1702 sources with color-derived temperatures, and Cannon metallicities to be in agreement to within 0.08 dex metallicity compared to a subsample of 15 FGK+M or M+M binaries. Finally, our comparison between Cannon and APOGEE pipeline (ASPCAP DR14) labels finds that ASPCAP is systematically biased toward reporting higher temperatures and lower metallicities for M dwarfs.
- ID:
- ivo://CDS.VizieR/J/A+A/603/A33
- Title:
- Temperature evolution in massive clumps
- Short Name:
- J/A+A/603/A33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observational identification of a solid evolutionary sequence for high-mass star-forming regions is still missing. Spectroscopic observations give the opportunity to test possible schemes and connect the phases identified to physical processes. We aim to use the progressive heating of the gas caused by the feedback of high-mass young stellar objects to prove the statistical validity of the most common schemes used to observationally define an evolutionary sequence for high-mass clumps, and characterise the sensitivity of different tracers to this process. From the spectroscopic follow-ups carried out towards submillimeter continuum (dust) emission-selected massive clumps (the ATLASGAL TOP100 sample) with the IRAM 30m, Mopra, and APEX telescopes between 84GHz and 365GHz, we selected several multiplets of CH_3_N, CH_3_CH, and CH_3_H emission lines to derive and compare the physical properties of the gas in the clumps along the evolutionary sequence, fitting simultaneously the large number of lines that these molecules have in the observed band. Our findings are compared with results obtained from optically thin CO isotopologues, dust, and ammonia from previous studies on the same sample. The chemical properties of each species have a major role on the measured physical properties. Low temperatures are traced by ammonia, methanol, and CO (in the early phases), the warm and dense envelope can be probed with CH_3_N, CH_3_CH, and, in evolved sources where CO is abundant in the gas phase, via its optically thin isotopologues. CH_3_H and CH_3_N are also abundant in the hot cores, and we suggest that their high-excitation transitions are good tools to study the kinematics in the hot gas associated with the inner envelope surrounding the young stellar objects that these clumps are hosting. All tracers show, to different degrees according to their properties, progressive warming with evolution. The relation between gas temperature and the luminosity-to-mass (L/M) ratio is reproduced by a simple toy model of a spherical, internally heated clump.
- ID:
- ivo://CDS.VizieR/J/ApJ/693/1084
- Title:
- Ten new and updated multiplanet systems
- Short Name:
- J/ApJ/693/1084
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the latest velocities for ten multiplanet systems, including a re-analysis of archival Keck and Lick data, resulting in improved velocities that supersede our previously published measurements. We derive updated orbital fits for 10 Lick and Keck systems, including two systems (HD 11964, HD 183263) for which we provide confirmation of second planets only tentatively identified elsewhere, and two others (HD 187123 and HD 217107) for which we provide a major revision of the outer planet's orbit. We compile orbital elements from the literature to generate a catalog of the 28 published multiple-planet systems around stars within 200pc.
- ID:
- ivo://CDS.VizieR/J/MNRAS/473/2004
- Title:
- TESS-HERMES Survey Data Release 1 catalog
- Short Name:
- J/MNRAS/473/2004
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Transiting Exoplanet Survey Satellite (TESS) will provide high-precision time series photometry for millions of stars with at least a half-hour cadence. Of particular interest are the circular regions of 12{deg} radius centred around the ecliptic poles that will be observed continuously for a full year. Spectroscopic stellar parameters are desirable to characterize and select suitable targets for TESS, whether they are focused on exploring exoplanets, stellar astrophysics or Galactic archaeology. Here, we present spectroscopic stellar parameters (Teff, logg, [Fe/H], vsini, vmicro) for about 16000 dwarf and subgiant stars in TESS' southern continuous viewing zone. For almost all the stars, we also present Bayesian estimates of stellar properties including distance, extinction, mass, radius and age using theoretical isochrones. Stellar surface gravity and radius are made available for an additional set of roughly 8500 red giants. All our target stars are in the range 10<V<13.1. Among them, we identify and list 227 stars belonging to the Large Magellanic Cloud. The data were taken using the High Efficiency and Resolution Multi-Element Spectrograph (HERMES; R~28000) at the Anglo-Australian Telescope as part of the TESS-HERMES survey. Comparing our results with the TESS Input Catalogue (TIC) shows that the TIC is generally efficient in separating dwarfs and giants, but it has flagged more than 100 cool dwarfs (Teff<4800K) as giants, which ought to be high-priority targets for the exoplanet search. The catalogue can be accessed via http://www.physics.usyd.edu.au/tess-hermes/, or at Mikulski Archive for Space Telescopes (MAST).
- ID:
- ivo://CDS.VizieR/J/AJ/162/265
- Title:
- TESS-Keck survey. VI. HIP-97166 radial velocity
- Short Name:
- J/AJ/162/265
- Date:
- 16 Mar 2022 06:42:57
- Publisher:
- CDS
- Description:
- We report the discovery of HIP-97166b (TOI-1255b), a transiting sub-Neptune on a 10.3day orbit around a K0 dwarf 68pc from Earth. This planet was identified in a systematic search of TESS Objects of Interest for planets with eccentric orbits, based on a mismatch between the observed transit duration and the expected duration for a circular orbit. We confirmed the planetary nature of HIP-97166b with ground-based radial-velocity measurements and measured a mass of M_b_=20{+/-}2M{Earth} along with a radius of R_b_=2.7{+/-}0.1R{Earth} from photometry. We detected an additional nontransiting planetary companion with M_c_sini=10{+/-}2M{Earth} on a 16.8day orbit. While the short transit duration of the inner planet initially suggested a high eccentricity, a joint RV-photometry analysis revealed a high impact parameter b=0.84{+/-}0.03 and a moderate eccentricity. Modeling the dynamics with the condition that the system remain stable over >10^5^ orbits yielded eccentricity constraints e_b_=0.16{+/-}0.03 and e_c_<0.25. The eccentricity we find for planet b is above average for the small population of sub-Neptunes with well-measured eccentricities. We explored the plausible formation pathways of this system, proposing an early instability and merger event to explain the high density of the inner planet at 5.3{+/-}0.9g/cc as well as its moderate eccentricity and proximity to a 5:3 mean-motion resonance.
- ID:
- ivo://CDS.VizieR/J/AJ/162/215
- Title:
- TESS-Keck survey.V. Radial velocities of HD63935
- Short Name:
- J/AJ/162/215
- Date:
- 14 Mar 2022 08:19:39
- Publisher:
- CDS
- Description:
- We present the discovery of two nearly identically sized sub-Neptune transiting planets orbiting HD63935, a bright (V=8.6mag), Sun-like (Teff=5560K) star at 49pc. TESS identified the first planet, HD63935b (TOI-509.01), in Sectors 7 and 34. We identified the second signal (HD63935c) in Keck High Resolution Echelle Spectrometer and Lick Automated Planet Finder radial velocity data as part of our follow-up campaign. It was subsequently confirmed with TESS photometry in Sector 34 as TOI-509.02. Our analysis of the photometric and radial velocity data yielded a robust detection of both planets with periods of 9.0600{+/-}0.007 and 21.40{+/-}0.0019days, radii of 2.99{+/-}0.14 and 2.90{+/-}0.13R{Earth}, and masses of 10.8{+/-}1.8 and 11.1{+/-}2.4M{Earth}. We calculated densities for planets b and c consistent with a few percent of the planet mass in hydrogen/helium envelopes. We also describe our survey's efforts to choose the best targets for James Webb Space Telescope atmospheric follow-up. These efforts suggest that HD 63935 b has the most clearly visible atmosphere of its class. It is the best target for transmission spectroscopy (ranked by the transmission spectroscopy metric, a proxy for atmospheric observability) in the so far uncharacterized parameter space comprising sub-Neptune-sized (2.6R{Earth}<Rp<4R{Earth}), moderately irradiated (100F{Earth}<Fp<1000F{Earth}) planets around G stars. Planet c is also a viable target for transmission spectroscopy, and given the indistinguishable masses and radii of the two planets, the system serves as a natural laboratory for examining the processes that shape the evolution of sub-Neptune planets.
- ID:
- ivo://CDS.VizieR/J/AJ/158/45
- Title:
- TESS light curve & radial velocities for HD 1397
- Short Name:
- J/AJ/158/45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of a transiting planet first identified as a candidate in Sector 1 of the Transiting Exoplanet Survey Satellite (TESS), and then confirmed with precision radial velocities. HD 1397b has a mass of M_P_=0.367_-0.023_^+0.022^ M_J_, a radius of R_P_=1.023_-0.013_^+0.013^ R_J_, and orbits its bright host star (V=7.8 mag) with an orbital period of 11.5366+/-0.0003 d on a moderately eccentric orbit (e=0.216_-0.026_^+0.027^). With a mass of M_*_=1.257_-0.029_^+0.029^ M_{sun}_, a radius of R_*_=2.341_-0.019_^+0.022^ R_{sun}_, and an age of 4.46+/-0.25 Gyr, the solar-metallicity host star has already departed from the main sequence. We find evidence in the radial velocity measurements of a secondary signal with a longer period. We attribute it to the rotational modulation of stellar activity, but a long-term radial velocity monitoring would be necessary to discard if this signal is produced by a second planet in the system. The HD 1397 system is among the brightest ones currently known to host a transiting planet, which will make it possible to perform detailed follow-up observations in order to characterize the properties of giant planets orbiting evolved stars.
- ID:
- ivo://CDS.VizieR/J/A+A/461/613
- Title:
- The anomalous Cepheid XZ Ceti
- Short Name:
- J/A+A/461/613
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- XZ Ceti is the only known anomalous Cepheid in the Galactic field. Being the nearest and brightest such variable star, a detailed study of XZ Ceti may shed light on the behaviour of anomalous Cepheids whose representatives have been mostly detected in external galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/780/59
- Title:
- The Araucaria project: eclipsing binaries in SMC
- Short Name:
- J/ApJ/780/59
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a distance determination to the Small Magellanic Cloud (SMC) based on an analysis of four detached, long-period, late-type eclipsing binaries discovered by the Optical Gravitational Lensing Experiment (OGLE) survey. The components of the binaries show negligible intrinsic variability. A consistent set of stellar parameters was derived with low statistical and systematic uncertainty. The absolute dimensions of the stars are calculated with a precision of better than 3%. The surface brightness-infrared color relation was used to derive the distance to each binary. The four systems clump around a distance modulus of (m - M) = 18.99 with a dispersion of only 0.05 mag. Combining these results with the distance published by Graczyk et al. for the eclipsing binary OGLE SMC113.3 4007, we obtain a mean distance modulus to the SMC of 18.965+/-0.025 (stat.)+/-0.048 (syst.) mag. This corresponds to a distance of 62.1+/-1.9 kpc, where the error includes both uncertainties. Taking into account other recent published determinations of the SMC distance we calculated the distance modulus difference between the SMC and the Large Magellanic Cloud equal to 0.458+/-0.068 mag. Finally, we advocate {mu}_SMC_= 18.95+/-0.07 as a new "canonical" value of the distance modulus to this galaxy.
