- ID:
- ivo://CDS.VizieR/J/A+A/650/A145
- Title:
- TOI-269 b light curves
- Short Name:
- J/A+A/650/A145
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We present the confirmation of a new sub-Neptune close to the transition between Super-Earths and sub-Neptunes transiting the M2 dwarf TOI-269. The exoplanet candidate is identified in multiple TESS sectors and is validated with high-precision spectroscopy from HARPS and ground-based photometric follow-up from ExTrA and LCO-CTIO. We determine mass, radius and bulk density of the exoplanet by jointly modeling both photometry and radial velocities with juliet. The transiting exoplanet has an orbital period of P=3.7 days, a radius of 2.77+/-0.12R_{Earth}_, and a mass of 8.8+/-1.4M_{Earth}_. Since TOI-269 b lies among the best targets of its category for atmospheric characterization, it would be interesting to probe the atmosphere of this exoplanet with transmission spectroscopy in order to compare it to other sub-Neptunes. With an eccentricity e=0.425^+0.082^_-0.086_, TOI-269 b has one of the highest eccentricity among exoplanets with periods less than 10 days. The star being likely a few Gyr old, this system does not appear to be dynamically young. We surmise TOI-269 b may have acquired a high eccentricity as it migrated inward through planet-planet interactions.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/160/22
- Title:
- TOI-1235 Radial velocities & optical spectroscopy
- Short Name:
- J/AJ/160/22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Small planets on close-in orbits tend to exhibit envelope mass fractions of either effectively zero or up to a few percent depending on their size and orbital period. Models of thermally driven atmospheric mass loss and of terrestrial planet formation in a gas-poor environment make distinct predictions regarding the location of this rocky/nonrocky transition in period-radius space. Here we present the confirmation of TOI-1235b (P=3.44days, r_p_=1.738_-0.076_^+0.087^R_{Earth}_), a planet whose size and period are intermediate between the competing model predictions, thus making the system an important test case for emergence models of the rocky/nonrocky transition around early M dwarfs (R_s_=0.630{+/-}0.015R_{sun}_, M_s_=0.640{+/-}0.016M_{sun}_). We confirm the TESS planet discovery using reconnaissance spectroscopy, ground-based photometry, high- resolution imaging, and a set of 38 precise radial velocities (RVs) from HARPS-N and HIRES. We measure a planet mass of 6.91_-0.85_^+0.75^M_{Earth}_, which implies an iron core mass fraction of 20_-12_^+15^% in the absence of a gaseous envelope. The bulk composition of TOI-1235b is therefore consistent with being Earth-like, and we constrain an H/He envelope mass fraction to be <0.5% at 90% confidence. Our results are consistent with model predictions from thermally driven atmospheric mass loss but not with gas-poor formation, suggesting that the former class of processes remains efficient at sculpting close-in planets around early M dwarfs. Our RV analysis also reveals a strong periodicity close to the first harmonic of the photometrically determined stellar rotation period that we treat as stellar activity, despite other lines of evidence favoring a planetary origin (P=21.8_-0.8_^+0.9^days, m_p_sini=13.0_-5.3_^+3.8^M_{Earth}_) that cannot be firmly ruled out by our data.
- ID:
- ivo://CDS.VizieR/J/A+A/656/A124
- Title:
- TOI-1201 RV and activity index
- Short Name:
- J/A+A/656/A124
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We present the discovery of a transiting mini-Neptune around TOI-1201, a relatively bright and moderately young early M dwarf (J~9.5mag, ~600-800Myr) in an equal-mass ~8arcsecond-wide binary system, using data from the Transiting Exoplanet Survey Satellite (TESS), along with follow-up transit observations. With an orbital period of 2.49d, TOI-1201~b is a warm mini-Neptune with a radius of R_b_=2.415+/-0.090R_{Earth}_. This signal is also present in the precise radial velocity measurements from CARMENES, confirming the existence of the planet and providing a planetary mass of M_b_=6.28+/-0.88M_{Earth}_ and, thus, an estimated bulk density of 2.45^+0.48^_-0.42_g/cm^3^. The spectroscopic observations additionally show evidence of a signal with a period of 19d and a long periodic variation of undetermined origin. In combination with ground-based photometric monitoring from WASP-South and ASAS-SN, we attribute the 19d signal to the stellar rotation period (P_rot_=19-23d), although we cannot rule out that the variation seen in photometry belongs to the visually close binary companion. We calculate precise stellar parameters for both TOI-1201 and its companion. The transiting planet is an excellent target for atmosphere characterization (the transmission spectroscopy metric is 97^+21^_-16_) with the upcoming James Webb Space Telescope. It is also feasible to measure its spin-orbit alignment via the Rossiter-McLaughlin effect using current state-of-the-art spectrographs with submeter per second radial velocity precision.
- ID:
- ivo://CDS.VizieR/J/AJ/159/83
- Title:
- Transit analysis for the K2-25 system
- Short Name:
- J/AJ/159/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The abundance of planets with orbital periods of a few to tens of days suggests that exoplanets experience complex dynamical histories. Planets in young stellar clusters or associations have well-constrained ages and therefore provide an opportunity to explore the dynamical evolution of exoplanets. K2-25b is a Neptune-sized planet in an eccentric, 3.48day orbit around an M4.5 dwarf star in the Hyades cluster (650Myr). In order to investigate its non-zero eccentricity and tight orbit, we analyze transit timing variations (TTVs) which could reveal clues to the migration processes that may have acted on the planet. We obtain 12 nonconsecutive transits using the MEarth observatories and long-term photometric monitoring, which we combine with 10 transits from the Spitzer Space Telescope and 20 transits from K2. Tables of MEarth photometry accompany this work. We fit each transit lightcurve independently. We first investigate whether inhomogeneities on the stellar surface (such as spots or plages) are differentially affecting our transit observations. The measured transit depth does not vary significantly between transits, though we see some deviations from the fiducial transit model. We then looked for TTVs as evidence of a nontransiting perturber in the system. We find no evidence for >1M_{Earth}_ mass companions within a 2:1 period ratio, or for >5M_{Earth}_ mass planets within a 7:2 period ratio.
- ID:
- ivo://CDS.VizieR/J/AJ/161/72
- Title:
- 180 Transit and occultation times for WASP-12b
- Short Name:
- J/AJ/161/72
- Date:
- 10 Dec 2021
- Publisher:
- CDS
- Description:
- Theory suggests that the orbits of some close-in giant planets should decay due to tidal interactions with their host stars. To date, WASP-12b is the only hot Jupiter reported to have a decaying orbit, at a rate of 29{+/-}2ms/yr. We analyzed data from NASA's Transiting Exoplanet Survey Satellite (TESS) to verify that WASP-12b's orbit is indeed changing. We find that the TESS transit and occultation data are consistent with a decaying orbit with an updated period of 1.091420090{+/-}0.000000041days and a decay rate of 32.53{+/-}1.62ms/yr. We find an orbital decay timescale of {tau}=P/|P|=2.90{+/-}0.14Myr. If the observed decay results from tidal dissipation, the modified tidal quality factor is Q_*_'=1.39{+/-}0.15x10^5^, which falls at the lower end of values derived for binary star systems and hot Jupiters. Our result highlights the power of space-based photometry for investigating the orbital evolution of short-period exoplanets.
- ID:
- ivo://CDS.VizieR/J/AJ/161/174
- Title:
- Transit depth biases & error bars for 31 planets
- Short Name:
- J/AJ/161/174
- Date:
- 20 Jan 2022
- Publisher:
- CDS
- Description:
- The occurrence of a planet transiting in front of its host star offers the opportunity to observe the planet's atmosphere filtering starlight. The fraction of occulted stellar flux is roughly proportional to the optically thick area of the planet, the extent of which depends on the opacity of the planet's gaseous envelope at the observed wavelengths. Chemical species, haze, and clouds are now routinely detected in exoplanet atmospheres through rather small features in transmission spectra, i.e., collections of planet-to-star area ratios across multiple spectral bins and/or photometric bands. Technological advances have led to a shrinking of the error bars down to a few tens of parts per million (ppm) per spectral point for the brightest targets. The upcoming James Webb Space Telescope (JWST) is anticipated to deliver transmission spectra with precision down to 10ppm. The increasing precision of measurements requires a reassessment of the approximations hitherto adopted in astrophysical models, including transit light-curve models. Recently, it has been shown that neglecting the planet's thermal emission can introduce significant biases in the transit depth measured with the JWST/Mid-InfraRed Instrument, integrated between 5 and 12{mu}m. In this paper, we take a step forward by analyzing the effects of the approximation on transmission spectra over the 0.6-12{mu}m wavelength range covered by various JWST instruments. We present open-source software to predict the spectral bias, showing that, if not corrected, it may affect the inferred molecular abundances and thermal structure of some exoplanet atmospheres.
- ID:
- ivo://CDS.VizieR/J/A+A/657/A102
- Title:
- Transit events of 4 extrasolar planets
- Short Name:
- J/A+A/657/A102
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Meter-sized ground-based telescopes are frequently used today for the follow-up of extrasolar planet candidates. While the transit signal of a Jupiter-sized object can typically be detected to a high level of confidence with small telescope apertures as well, the shallow transit dips of planets with the size of Neptune and smaller are more challenging to reveal. We employ new observational data to illustrate the photometric follow-up capabilities of meter-sized telescopes for shallow exoplanet transits. We describe in detail the capability of distinguishing the photometric signal of an exoplanet transit from an underlying trend in the light curve. The transit depths of the six targets we observed, Kepler-94b, Kepler-63b, K2-100b, K2-138b, K2-138c, and K2-138e, range from 3.9ppt down to 0.3ppt. For five targets of this sample, we provide the first ground-based photometric follow-up. The timing of three targets is precisely known from previous observations, and the timing of the other three targets is uncertain and we aim to constrain it. We detect or rule out the transit features significantly in single observations for the targets that show transits of 1.3ppt or deeper. The shallower transit depths of two targets of 0.6 and 0.8ppt were detected tentatively in single light curves, and were detected significantly by repeated observations. Only for the target of the shallowest transit depth of 0.3ppt were we unable to draw a significant conclusion despite combining five individual light curves. An injection-recovery test on our real data shows that we detect transits of 1.3ppt depth significantly in single light curves if the transit is fully covered, including out-of-transit data toward both sides, in some cases down to 0.7ppt depth. For Kepler-94b, Kepler-63b, and K2-100b, we were able to verify the ephemeris. In the case of K2-138c with a 0.6ppt deep transit, we were able to refine it, and in the case of K2-138e, we ruled out the transit in the time interval of more than +/-1.5{sigma} of its current literature ephemeris.
- ID:
- ivo://CDS.VizieR/J/MNRAS/506/3810
- Title:
- 7 transiting exoplanets CHEOPS light curves
- Short Name:
- J/MNRAS/506/3810
- Date:
- 03 Dec 2021 00:34:45
- Publisher:
- CDS
- Description:
- We present 17 transit light curves of seven known warm-Jupiters observed with the CHaracterising ExOPlanet Satellite (CHEOPS). The light curves have been collected as part of the CHEOPS Guaranteed Time Observation (GTO) program that searches for transit-timing variation (TTV) of warm-Jupiters induced by a possible external perturber to shed light on the evolution path of such planetary systems. We describe the CHEOPS observation process, from the planning to the data analysis. In this work we focused on the timing performance of CHEOPS, the impact of the sampling of the transit phases, and the improvement we can obtain combining multiple transits together. We reached the highest precision on the transit time of about 13-16s for the brightest target (WASP-38, G=9.2) in our sample. From the combined analysis of multiple transits of fainter targets with G>=11 we obtained a timing precision of ~2min. Additional observations with CHEOPS, covering a longer temporal baseline, will further improve the precision on the transit times and will allow us to detect possible TTV signals induced by an external perturber.
- ID:
- ivo://CDS.VizieR/J/AJ/153/191
- Title:
- Transiting planet GJ 1132
- Short Name:
- J/AJ/153/191
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Detecting the atmospheres of low-mass, low-temperature exoplanets is a high-priority goal on the path to ultimately detecting biosignatures in the atmospheres of habitable exoplanets. High-precision HST observations of several super-Earths with equilibrium temperatures below 1000K have to date all resulted in featureless transmission spectra, which have been suggested to be due to high-altitude clouds. We report the detection of an atmospheric feature in the atmosphere of a 1.6M_{Earth}_ exoplanet, GJ 1132 b, with an equilibrium temperature of ~600K and orbiting a nearby M dwarf. We present observations of nine transits of the planet obtained simultaneously in the griz and JHK passbands. We find an average radius of 1.43+/-0.16R_{Earth}_ for the planet, averaged over all the passbands, and a radius of 0.255+/-0.023R_{sun}_ for the star, both of which are significantly greater than previously found. The planet radius can be decomposed into a "surface radius" at ~1.375R_{Earth}_ overlaid by atmospheric features that increase the observed radius in the z and K bands. The z-band radius is 4{sigma} higher than the continuum, suggesting a strong detection of an atmosphere. We deploy a suite of tests to verify the reliability of the transmission spectrum, which are greatly helped by the existence of repeat observations. The large z-band transit depth indicates strong opacity from H_2_O and/or CH_4_ or a hitherto-unconsidered opacity. A surface radius of 1.375+/-0.16R_{Earth}_ allows for a wide range of interior compositions ranging from a nearly Earth-like rocky interior, with ~70% silicate and ~30% Fe, to a substantially H_2_O-rich water world.
- 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.
