- ID:
- ivo://CDS.VizieR/J/ApJ/704/1107
- Title:
- Transiting planet candidates in HATNet field 205
- Short Name:
- J/ApJ/704/1107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of HAT-P-8b, a transiting planet with mass M_p_=1.52^+0.18^_-0.16_M_J_, radius R_p_=1.50^+0.08^_-0.06_R_J_, and photometric period P=3.076days. HAT-P-8b has a somewhat inflated radius for its mass, and a somewhat large mass for its period. The host star is a solar-metallicity F dwarf, with mass M_*_=1.28+/-0.04M_{sun}_ and R_*_=1.58^+0.08^_-0.06R_{sun}_. HAT-P-8b was initially identified as one of the 32 transiting-planet candidates in HATNet field G205. We describe the procedures that we have used to follow up these candidates with spectroscopic and photometric observations, and we present a status report on our interpretation for 28 of the candidates. Eight are eclipsing binaries with orbital solutions whose periods are consistent with their photometric ephemerides; two of these spectroscopic orbits are single-lined and six are double-lined.
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- ID:
- ivo://CDS.VizieR/J/A+A/602/A107
- Title:
- 231 transiting planets eccentricity and mass
- Short Name:
- J/A+A/602/A107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We carried out a Bayesian homogeneous determination of the orbital parameters of 231 transiting giant planets (TGPs) that are alone or have distant companions; we employed differential evolution Markov chain Monte Carlo methods to analyse radial-velocity (RV) data from the literature and 782 new high-accuracy RVs obtained with the HARPS-N spectrograph for 45 systems over ~3 years. Our work yields the largest sample of systems with a transiting giant exoplanet and coherently determined orbital, planetary, and stellar parameters. We found that the orbital parameters of TGPs in non-compact planetary systems are clearly shaped by tides raised by their host stars. Indeed, the most eccentric planets have relatively large orbital separations and/or high mass ratios, as expected from the equilibrium tide theory. This feature would be the outcome of planetary migration from highly eccentric orbits excited by planet-planet scattering, Kozai-Lidov perturbations, or secular chaos. The distribution of {alpha}=a/a_R_, where a and a_R_ are the semi-major axis and the Roche limit, for well-determined circular orbits peaks at 2.5; this agrees with expectations from the high-eccentricity migration (HEM), although it might not be limited to this migration scenario. The few planets of our sample with circular orbits and {alpha}>5 values may have migrated through disc-planet interactions instead of HEM. By comparing circularisation times with stellar ages, we found that hot Jupiters with a<0.05au have modified tidal quality factors 10^5^<~Qp<~10^9^, and that stellar Qs>~10^6^-10^7^ are required to explain the presence of eccentric planets at the same orbital distance.
- ID:
- ivo://CDS.VizieR/J/AJ/157/174
- Title:
- Transiting planets in Kepler-47 circumbinary system
- Short Name:
- J/AJ/157/174
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Of the nine confirmed transiting circumbinary planet systems, only Kepler-47 is known to contain more than one planet. Kepler-47 b (the "inner planet") has an orbital period of 49.5 days and a radius of about 3 R_{Earth}_. Kepler-47 c (the "outer planet") has an orbital period of 303.2 days and a radius of about 4.7 R_{Earth}_. Here we report the discovery of a third planet, Kepler-47 d (the "middle planet"), which has an orbital period of 187.4 days and a radius of about 7 R_{Earth}_. The presence of the middle planet allows us to place much better constraints on the masses of all three planets, where the 1{sigma} ranges are less than 26 M_{Earth}_, between 7-43 M_{Earth}_, and between 2-5 M_{Earth}_ for the inner, middle, and outer planets, respectively. The middle and outer planets have low bulk densities, with {rho}_middle_<0.68 g/cm^3^ and {rho}_outer_<0.26 g/cm^3^ at the 1{sigma} level. The two outer planets are "tightly packed", assuming the nominal masses, meaning no other planet could stably orbit between them. All of the orbits have low eccentricities and are nearly coplanar, disfavoring violent scattering scenarios and suggesting gentle migration in the protoplanetary disk.
- ID:
- ivo://CDS.VizieR/J/AJ/157/149
- Title:
- Transit parameters for planets around subgiants
- Short Name:
- J/AJ/157/149
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discovery of seven new planets and eight planet candidates around subgiant stars, as additions to the known sample of planets around "retired A stars". Among these are the possible first three-planet systems around subgiant stars, HD 163607 and HD 4917. Additionally, we present calculations of possible transit times, durations, depths, and probabilities for all known planets around subgiant (3<logg<4) stars, focused on possible transits during the TESS mission. While most have transit probabilities of 1%-2%, we find that there are three planets with transit probabilities >9%.
- ID:
- ivo://CDS.VizieR/J/AJ/159/239
- Title:
- Transmission Spectroscopy Metric of exoplanets
- Short Name:
- J/AJ/159/239
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent years have seen increasing interest in the characterization of sub-Neptune-sized planets because of their prevalence in the Galaxy, contrasted with their absence in our solar system. HD97658 is one of the brightest stars hosting a planet of this kind, and we present the transmission spectrum of this planet by combining four Hubble Space Telescope transits, 12 Spitzer/IRAC transits, and eight Microvariability and Oscillations of Stars Telescope (MOST) transits of this system. Our transmission spectrum has a higher signal-to-noise ratio than those from previous works, and the result suggests that the slight increase in transit depth from wavelength 1.1-1.7{mu}m reported in previous works on the transmission spectrum of this planet is likely systematic. Nonetheless, our atmospheric modeling results are inconclusive, as no model provides an excellent match to our data. Nonetheless, we find that atmospheres with high C/O ratios (C/O~>0.8) and metallicities of ~>100 solar metallicity are favored. We combine the mid-transit times from all of the new Spitzer and MOST observations and obtain an updated orbital period of P=9.489295{+/-}0.000005, with a best-fit transit time center at T0=2456361.80690{+/-}0.00038(BJD). No transit timing variations are found in this system. We also present new measurements of the stellar rotation period (34{+/-}2days) and stellar activity cycle (9.6yr) of the host star HD97658. Finally, we calculate and rank the Transmission Spectroscopy Metric of all confirmed planets cooler than 1000K and with sizes between 1R_{Earth}_ and 4R_{Earth}_. We find that at least a third of small planets cooler than 1000K can be well characterized using James Webb Space Telescope, and of those, HD97658b is ranked fifth, meaning that it remains a high-priority target for atmospheric characterization.
- ID:
- ivo://CDS.VizieR/J/ApJ/793/62
- Title:
- Triangulum-Andromeda stellar properties
- Short Name:
- J/ApJ/793/62
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As large-scale stellar surveys have become available over the past decade, the ability to detect and characterize substructures in the Galaxy has increased dramatically. These surveys have revealed the Triangulum-Andromeda (TriAnd) region to be rich with substructures in the distance range 20-30 kpc, and the relation of these features to each other, if any, remains unclear. An exploration using Two Micron All Sky Survey (2MASS) photometry reveals not only the faint sequence in M giants detected by Rocha-Pinto et al. (2004ApJ...615..732R) spanning the range 100{deg}<l<160{deg} and -50{deg}<b<-15{deg}, but, in addition, a second, brighter and more densely populated sequence. These sequences are likely associated with the distinct main sequences (MSs) discovered (and labeled TriAnd1 and TriAnd2) by Martin et al. (2007ApJ...668L.123M) in an optical survey in the direction of M31, where TriAnd2 is the optical counterpart of the fainter red giant branch (RGB)/asymptotic giant branch sequence of Rocha-Pinto et al. Here, the age, distance, and metallicity ranges for TriAnd1 and TriAnd2 are estimated by simultaneously fitting isochrones to the 2MASS RGB tracks and the optical MS/MS turn-off features. The two populations are clearly distinct in age and distance: the brighter sequence (TriAnd1) is younger (6-10 Gyr) and closer (distance of ~15-21 kpc), whereas the fainter sequence (TriAnd2) is older (10-12 Gyr) and at an estimated distance of ~24-32 kpc. A comparison with simulations demonstrates that the differences and similarities between TriAnd1 and TriAnd2 can simultaneously be explained if they represent debris originating from the disruption of the same dwarf galaxy, but torn off during two distinct pericentric passages.
- ID:
- ivo://CDS.VizieR/J/A+A/603/A81
- Title:
- Trumpler 14 and 16 in the Carina nebula
- Short Name:
- J/A+A/603/A81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first extensive spectroscopic study of the global population in star clusters Trumpler 16, Trumpler 14, and Collinder 232 in the Carina nebula, using data from the Gaia-ESO Survey, down to solar-mass stars. In addition to the standard homogeneous survey data reduction, a special processing was applied here because of the bright nebulosity surrounding Carina stars. We find about 400 good candidate members ranging from OB types down to slightly subsolar masses. About 100 heavily reddened early-type Carina members found here were previously unrecognized or poorly classified, including two candidate O stars and several candidate Herbig Ae/Be stars. Their large brightness makes them useful tracers of the obscured Carina population. The spectroscopically derived temperatures for nearly 300 low-mass members enables the inference of individual extinction values and the study of the relative placement of stars along the line of sight. We find a complex spatial structure with definite clustering of low-mass members around the most massive stars and spatially variable extinction. By combining the new data with existing X-ray data, we obtain a more complete picture of the three-dimensional spatial structure of the Carina clusters and of their connection to bright and dark nebulosity and UV sources. The identification of tens of background giants also enables us to determine the total optical depth of the Carina nebula along many sightlines. We are also able to put constraints on the star formation history of the region with Trumpler 14 stars found to be systematically younger than stars in other subclusters. We find a large percentage of fast-rotating stars among Carina solar-mass members, which provide new constraints on the rotational evolution of pre-main-sequence stars in this mass range.
- ID:
- ivo://CDS.VizieR/J/A+A/635/A152
- Title:
- Tucana dSph galaxy spectroscopic dataset
- Short Name:
- J/A+A/635/A152
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Isolated local group (LG) dwarf galaxies have evolved most or all of their life unaffected by interactions with the large LG spirals and therefore offer the opportunity to learn about the intrinsic characteristics of this class of objects. Our aim is to explore the internal kinematic and metallicity properties of one of the three isolated LG early-type dwarf galaxies, the Tucana dwarf spheroidal. This is an intriguing system, as it has been found in the literature to have an internal rotation of up to 16km/s, a much higher velocity dispersion than dwarf spheroidals of similar luminosity, and a possible exception to the too-big-too-fail problem. We present the results of a new spectroscopic dataset that we procured from the Very Large Telescope (VLT) taken with the FORS2 instrument in the region of the Ca II triplet for 50 candidate red giant branch stars in the direction of the Tucana dwarf spheroidal. These yielded line-of-sight (l.o.s.) velocity and metallicity ([Fe/H]) measurements of 39 effective members that double the number of Tucana's stars with such measurements. In addition, we re-reduce and include in our analysis the other two spectroscopic datasets presented in the literature, the VLT/FORS2 sample by Fraternali et al. (2009A&A...499..121F), and the VLT/FLAMES one from Gregory et al. (2019MNRAS.485.2010G). Across the various datasets analyzed, we consistently measure a l.o.s. systemic velocity of 180+/-1.3km/s and find that a dispersion-only model is moderately favored over models that also account for internal rotation. Our best estimate of the internal l.o.s. velocity dispersion is 6.2_-1.3_^+1.6^km/s, much smaller than the values reported in the literature and in line with similarly luminous dwarf spheroidals; this is consistent with NFW halos of circular velocities <30km/s. Therefore, Tucana does not appear to be an exception to the too-big-to-fail problem, nor does it appear to reside in a dark matter halo much more massive than those of its siblings. As for the metallicity properties, we do not find anything unusual; there are hints of the presence of a metallicity gradient, but more data are needed to pinpoint its presence.
- ID:
- ivo://CDS.VizieR/J/A+A/572/A108
- Title:
- 47 Tuc red giants chemical composition
- Short Name:
- J/A+A/572/A108
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The study of chemical abundance patterns in globular clusters is of key importance to constrain the different candidates for intra-cluster pollution of light elements. We aim at deriving accurate abundances for a large range of elements in the globular cluster 47 Tucanae (NGC 104) to add new constraints to the pollution scenarios for this particular cluster, expanding the range of previously derived element abundances. Using tailored 1D LTE atmospheric models together with a combination of equivalent width measurements, LTE, and NLTE synthesis we derive stellar parameters and element abundances from high-resolution, high signal-to-noise spectra of 13 red giant stars near the tip of the RGB. We derive abundances of a total 27 elements (O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Mo, Ru, Ba, La, Ce, Pr, Nd, Eu, Dy). Departures from LTE were taken into account for Na, Al and Ba. We find a mean [Fe/H]=-0.78+/-0.07 and [alpha/Fe]=0.34+/-0.03 in good agreement with previous studies. The remaining elements show good agreement with the literature, but the inclusion of NLTE for Al has a significant impact on the behaviour of this key element. We confirm the presence of an Na-O anti-correlation in 47 Tucanae found by several other works. Our NLTE analysis of Al shifts the [Al/Fe] to lower values, indicating that this may be overestimated in earlier works. No evidence for an intrinsic variation is found in any of the remaining elements.
- ID:
- ivo://CDS.VizieR/J/AJ/113/22
- Title:
- Tully-Fisher Relation. I.
- Short Name:
- J/AJ/113/22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observational parameters which can be used for redshift-independent distance determination using the Tully-Fisher (TF) technique are given for 782 spiral galaxies in the fields of 24 clusters or groups. I band photometry for the full sample was either obtained by us or compiled from published literature. Rotational velocities are derived either from 21 cm spectra or optical emission line long-slit spectra, and converted to a homogeneous scale. In addition to presenting the data, a discussion of the various sources of error on TF parameters is introduced, and the criteria for the assignment of membership to each cluster are given.