- ID:
- ivo://CDS.VizieR/J/AJ/161/82
- Title:
- Photometric & spectroscopic obs. of TOI-954 and K2-329
- Short Name:
- J/AJ/161/82
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of two short-period Saturn-mass planets, one transiting the G subgiant TOI-954 (TIC44792534, V=10.343, T=9.78) observed in TESS sectors 4 and 5 and one transiting the G dwarf K2-329 (EPIC246193072, V=12.70, K=10.67) observed in K2 campaigns 12 and 19. We confirm and characterize these two planets with a variety of ground-based archival and follow-up observations, including photometry, reconnaissance spectroscopy, precise radial velocity, and high-resolution imaging. Combining all available data, we find that TOI-954b has a radius of 0.852_-0.062_^+0.053^R_Jup_ and a mass of 0.174_-0.017_^+0.018^M_Jup_ and is in a 3.68day orbit, while K2-329b has a radius of 0.774_-0.024_^+0.026^R_Jup_ and a mass of 0.260_-0.022_^+0.020^M_Jup_ and is in a 12.46day orbit. As TOI-954b is 30 times more irradiated than K2-329b but more or less the same size, these two planets provide an opportunity to test whether irradiation leads to inflation of Saturn-mass planets and contribute to future comparative studies that explore Saturn-mass planets at contrasting points in their lifetimes.
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- ID:
- ivo://CDS.VizieR/J/AJ/154/226
- Title:
- Photometry and radial velocities of K2-131
- Short Name:
- J/AJ/154/226
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of a new ultra-short-period planet and summarize the properties of all such planets for which the mass and radius have been measured. The new planet, K2-131b, was discovered in K2 Campaign 10. It has a radius of 1.81_-0.12_^+0.16^ R_{Earth}_ and orbits a G dwarf with a period of 8.9 hr. Radial velocities obtained with Magellan/PFS and TNG/HARPS-N show evidence for stellar activity along with orbital motion. We determined the planetary mass using two different methods: (1) the "floating chunk offset" method, based only on changes in velocity observed on the same night; and (2) a Gaussian process regression based on both the radial velocity and photometric time series. The results are consistent and lead to a mass measurement of 6.5+/-1.6 M_{Earth}_ and a mean density of 6.0_-2.7_^+3.0^ g/cm^3^.
- ID:
- ivo://CDS.VizieR/J/AJ/160/192
- Title:
- Photometry and RVs of K2-25b with HPF
- Short Name:
- J/AJ/160/192
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using radial velocity data from the Habitable Zone Planet Finder, we have measured the mass of the Neptune-sized planet K2-25b, as well as the obliquity of its M4.5 dwarf host star in the 600-800Myr Hyades cluster. This is one of the youngest planetary systems for which both of these quantities have been measured and one of the very few M dwarfs with a measured obliquity. Based on a joint analysis of the radial velocity data, time-series photometry from the K2 mission, and new transit light curves obtained with diffuser-assisted photometry, the planet's radius and mass are 3.44{+/-}0.12R_{Earth}_ and 24.5_-5.2_^+5.7^M_{Earth}_. These properties are compatible with a rocky core enshrouded by a thin hydrogen-helium atmosphere (5% by mass). We measure an orbital eccentricity of e=0.43{+/-}0.05. The sky-projected stellar obliquity is {lambda}=3{deg}{+/-}16{deg}, compatible with spin- orbit alignment, in contrast to other "hot Neptunes" that have been studied around older stars.
- ID:
- ivo://CDS.VizieR/J/A+A/628/A108
- Title:
- Photometry of Kepler-82b and c transits
- Short Name:
- J/A+A/628/A108
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From the Kepler mission four planets were detected and confirmed in the Kepler-82 system. The two inner ones (d and e) show no transit timing variations (TTVs) and are dynamically independent from the two outer ones (b and c), which are showing TTVs. A dynamical analysis of the Kepler-82b/c system delivered a very high, hardly to explain, density ratio of about ten between the planets. A chopping component in the TTVs of the outer planet (Kepler-82b) is not explained by the two-planet model. This chopping component hints on another outer planet near the 3:2 or 3:1 resonance to planet c. The time span of Kepler observations are too short for distinguishing between the two models, the dynamical cycle is not fully covered. The completion of the dynamical cycle of this and other Kepler Objects of Interest (KOIs) showing TTVs is the aim of the KOINet. Within the network follow-up observations with ground-based telescopes are organized. These follow-up observations of Kepler-82b/c transits helped to distinguish between the two models, resulting is the detection of a new planet near the 3:2 resonance to Kepler-82d in the system. A detailed photodynamical modelling of the system was carried out to fully characterise the system parameters. The inclusion of the new planet also lead to a more reasonable density ratio of planet b to c of about two.
- ID:
- ivo://CDS.VizieR/J/A+A/618/A41
- Title:
- Photometry of Kepler-9b and c transits
- Short Name:
- J/A+A/618/A41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Kepler-9b/c system is a prime example of anti-correlated transit timing variations (TTVs). These TTVs results from the dynamical interaction amplified by the near 2:1 period resonance of the planets. The dynamical cycle was only almost finished when the Kepler telescope stopped the observations on that field. To complement the dynamical cycle of this and other Kepler Objects of Interest (KOIs) showing TTVs, the KOINet was build to organize follow-up observations with ground-based telescopes. These follow-up observations of Kepler-9b/c transits were used in a detailed photodynamical modelling of the system and increased the accuracy of the derivable system parameters.
- ID:
- ivo://CDS.VizieR/J/AJ/162/203
- Title:
- Photometry of OGLE-2019-BLG-0304 with OGLE & KMTNet
- Short Name:
- J/AJ/162/203
- Date:
- 01 Feb 2022 07:08:03
- Publisher:
- CDS
- Description:
- We analyze the microlensing event OGLE-2019-BLG-0304, whose light curve exhibits two distinctive features: a deviation in the peak region and a second bump appearing ~61days after the main peak. Although a binary-lens model can explain the overall features, it leaves subtle but noticeable residuals in the peak region. We find that the residuals can be explained by the presence of either a planetary companion located close to the primary of the binary lens (3L1S model) or an additional close companion to the source (2L2S model). Although the 3L1S model is favored over the 2L2S model, with {Delta}{chi}2~8, securely resolving the degeneracy between the two models is difficult with the currently available photometric data. According to the 3L1S interpretation, the lens is a planetary system, in which a planet with a mass 0.51_-0.23_^+0.51^M_J_ is in an S-type orbit around a binary composed of stars with masses 0.27_-0.12_^+0.27^M{odot} and 0.10_-0.04_^+0.10^M{odot}. According to the 2L2S interpretation, however, the source is composed of G- and K-type giant stars and the lens is composed of a low-mass M dwarf and a brown dwarf with masses 0.12_-0.05_^+0.12^M{odot} and 0.045_-.019_^+0.045^M{odot}, respectively. The event illustrates the need for thorough model testing in the interpretation of lensing events with complex features in light curves.
- ID:
- ivo://CDS.VizieR/J/AJ/155/12
- Title:
- Photometry of Proxima Centauri observed by BSST
- Short Name:
- J/AJ/155/12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Proxima Centauri is known as the closest star to the Sun. Recently, radial velocity (RV) observations revealed the existence of an Earth-mass planet around it. With an orbital period of ~11 days, Proxima Centauri b is probably in the habitable zone of its host star. We undertook a photometric monitoring campaign to search for its transit, using the Bright Star Survey Telescope at the Zhongshan Station in Antarctica. A transit-like signal appearing on 2016 September 8 has been tentatively identified. Its midtime, T_C_=2457640.1990+/-0.0017 HJD, is consistent with the predicted ephemeris based on the RV orbit in a 1{sigma} confidence interval. Time-correlated noise is pronounced in the light curve of Proxima Centauri, affecting the detection of transits. We develop a technique, in a Gaussian process framework, to gauge the statistical significance of a potential transit detection. The tentative transit signal reported here has a confidence level of 2.5{sigma}. Further detection of its periodic signals is necessary to confirm the planetary transit of Proxima Centauri b. We plan to monitor Proxima Centauri in the next polar night at Dome A in Antarctica, taking advantage of continuous darkness. Kipping et al. (2017, J/AJ/153/93) reported two tentative transit-like signals of Proxima Centauri b observed by the Microvariability and Oscillation of Stars space telescope in 2014 and 2015. The midtransit time of our detection is 138 minutes later than that predicted by their transit ephemeris. If all of the signals are real transits, the misalignment of the epochs plausibly suggests transit timing variations of Proxima Centauri b induced by an outer planet in this system.
- ID:
- ivo://CDS.VizieR/J/AJ/155/257
- Title:
- Photometry & RV follow-up observations of K2-18
- Short Name:
- J/AJ/155/257
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- K2-18 is a nearby M2.5 dwarf, located at 34 pc and hosting a transiting planet that was first discovered by the K2 mission and later confirmed with Spitzer Space Telescope observations. With a radius of ~2 R_{Earth}_ and an orbital period of ~33 days, the planet lies in the temperate zone of its host star and receives stellar irradiation similar to that of Earth. Here we perform radial velocity follow-up observations with the visual channel of CARMENES with the goal of determining the mass and density of the planet. We measure a planetary semi-amplitude of K_b_~3.5 m/s and a mass of M_b_~9 M_{Earth}_, yielding a bulk density around {rho}_b_~4 g/cm^3^. This indicates a low-mass planet with a composition consistent with a solid core and a volatile-rich envelope. A signal at 9 days was recently reported using radial velocity measurements taken with the HARPS spectrograph. This was interpreted as being due to a second planet. We see a weaker, time- and wavelength-dependent signal in the CARMENES data set and thus favor stellar activity for its origin. K2-18 b joins the growing group of low-mass planets detected in the temperate zone of M dwarfs. The brightness of the host star in the near-infrared makes the system a good target for detailed atmospheric studies with the James Webb Space Telescope.
- ID:
- ivo://CDS.VizieR/J/AJ/159/173
- Title:
- Photometry & RVs of 4 dwarfs hosting giant planets
- Short Name:
- J/AJ/159/173
- Date:
- 09 Dec 2021
- Publisher:
- CDS
- Description:
- We report the discovery of four transiting giant planets around K-dwarfs. The planets HATS-47b, HATS-48Ab, HATS-49b, and HATS-72b have masses of 0.369_-0.021_^+0.031^M_J_, 0.243_-0.030_^+0.022^M_J_, 0.353_-0.027_^+0.038^M_J_, and 0.1254{+/-}0.0039M_J_, respectively, and radii of 1.117{+/-}0.014R_J_, 0.800{+/-}0.015R_J_, 0.765{+/-}0.013R_J_, and 0.7224{+/-}0.0032R_J_, respectively. The planets orbit close to their host stars with orbital periods of 3.9228days, 3.1317days, 4.1480days, and 7.3279days, respectively. The hosts are main-sequence K-dwarfs with masses of 0.674_-0.012_^+0.016^M_{odot}_, 0.7279{+/-}0.0066M_{odot}_, 0.7133{+/-}0.0075M_{odot}_, and 0.7311{+/-}0.0028, and with V-band magnitudes of V=14.829{+/-}0.010, 14.35{+/-}0.11, 14.998{+/-}0.040 and 12.469{+/-}0.010. The super-Neptune HATS-72b (a.k.a. WASP-191b and TOI294.01) was independently identified as a transiting planet candidate by the HATSouth, WASP, and TESS surveys, and we present a combined analysis of all of the data gathered by each of these projects (and their follow-up programs). An exceptionally precise mass is measured for HATS-72b thanks to high-precision radial velocity (RV) measurements obtained with VLT/ESPRESSO, FEROS, HARPS, and Magellan/PFS. We also incorporate TESS observations of the warm Saturn-hosting systems HATS-47 (a.k.a. TOI1073.01), HATS-48A, and HATS-49. HATS-47 was independently identified as a candidate by the TESS team, while the other two systems were not previously identified from the TESS data. The RV orbital variations are measured for these systems using Magellan/PFS. HATS-48A has a resolved 5.4" neighbor in Gaia DR2, which is a common-proper-motion binary star companion to HATS-48A with a mass of 0.22M_{odot}_ and a current projected physical separation of ~1400au.
- ID:
- ivo://CDS.VizieR/J/A+A/640/A73
- Title:
- pi Men radial velocity curves
- Short Name:
- J/A+A/640/A73
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Measuring the geometry of multi-planet extrasolar systems can provide insight into their dynamical history and the processes of planetary formation. These types of measurements are challenging for systems that are detected through indirect techniques such as radial velocity and transit, having only been measured for a handful of systems to date. We aim to place constraints on the orbital geometry of the outer planet in the {pi} Mensae system, a G0V star at a distance of 18.3pc that is host to a wide-orbit super-Jovian (Msini=10.02+/-0.15M_Jup_) with a 5.7-year period and an inner transiting super-Earth (M=4.82+/-0.85M_{Earth}_) with a 6.3-d period. The reflex motion induced by the outer planet on the Mensae star causes a significant motion of the photocenter of the system on the sky plane over the course of the 5.7-year orbital period of the planet. We combined astrometric measurements from the Hipparcos and Gaia satellites with a precisely determined spectroscopic orbit in an attempt to measure this reflex motion, and in turn we constrained the inclination of the orbital plane of the outer planet. We measure an inclination of i_b_=49.9^+5.3^_-4.5_deg for the orbital plane of {pi} Mensae b, leading to a direct measurement of its mass of 13:01^+1.03^_-0.95_M_{Jup}_. We find a significant mutual inclination between the orbital planes of the two planets, with a 95% credible interval for i_mut_ of between 34.5{deg} and 140.6{deg} after accounting for the unknown position angle of the orbit of {pi} Mensae c, strongly excluding a co-planar scenario for the two planets within this system. All orbits are stable in the present-day configuration, and secular oscillations of planet c's eccentricity are quenched by general relativistic precession. Planet c may have undergone high eccentricity tidal migration triggered by Kozai-Lidov cycles, but dynamical histories involving disk migration or in situ formation are not ruled out. Nonetheless, this system provides the first piece of direct evidence that giant planets with large mutual inclinations have a role to play in the origins and evolution of some super-Earth systems.
