scholarly journals The TOI-763 system: sub-Neptunes orbiting a Sun-like star

2020 ◽  
Vol 498 (3) ◽  
pp. 4503-4517
Author(s):  
M Fridlund ◽  
J Livingston ◽  
D Gandolfi ◽  
C M Persson ◽  
K W F Lam ◽  
...  
Keyword(s):  
Light Curve ◽  
Orbital Period ◽  
Planetary System ◽  
Space Mission ◽  
The Sun ◽  
Minimum Mass ◽  
Dwarf Star ◽  
Stellar Spectrum ◽  
Transit Signals

ABSTRACT We report the discovery of a planetary system orbiting TOI-763(aka CD-39 7945), a V = 10.2, high proper motion G-type dwarf star that was photometrically monitored by the TESS space mission in Sector 10. We obtain and model the stellar spectrum and find an object slightly smaller than the Sun, and somewhat older, but with a similar metallicity. Two planet candidates were found in the light curve to be transiting the star. Combining TESS transit photometry with HARPS high-precision radial velocity (RV) follow-up measurements confirm the planetary nature of these transit signals. We determine masses, radii, and bulk densities of these two planets. A third planet candidate was discovered serendipitously in the RV data. The inner transiting planet, TOI-763 b, has an orbital period of Pb  =  5.6 d, a mass of Mb  =  9.8 ± 0.8 M⊕, and a radius of Rb  =  2.37 ± 0.10 R⊕. The second transiting planet, TOI-763 c, has an orbital period of Pc  =  12.3 d, a mass of Mc  =  9.3 ± 1.0 M⊕, and a radius of Rc  =  2.87 ± 0.11 R⊕. We find the outermost planet candidate to orbit the star with a period of ∼48 d. If confirmed as a planet, it would have a minimum mass of Md  =  9.5 ± 1.6 M⊕. We investigated the TESS light curve in order to search for a mono transit by planet d without success. We discuss the importance and implications of this planetary system in terms of the geometrical arrangements of planets orbiting G-type stars.

scholarly journals Discovery of a hot, transiting, Earth-sized planet and a second temperate, non-transiting planet around the M4 dwarf GJ 3473 (TOI-488)

2020 ◽  
Vol 642 ◽  
pp. A236
Author(s):  
J. Kemmer ◽  
S. Stock ◽  
D. Kossakowski ◽  
A. Kaminski ◽  
K. Molaverdikhani ◽  
...  
Keyword(s):  
Orbital Period ◽  
Emission Spectroscopy ◽  
Thermal Emission ◽  
Mass Measurement ◽  
Minimum Mass ◽  
Dwarf Star ◽  
Dynamical Mass ◽  
Planetary Mass ◽  
Thermal Emission Spectroscopy

We present the confirmation and characterisation of GJ 3473 b (G 50–16, TOI-488.01), a hot Earth-sized planet orbiting an M4 dwarf star, whose transiting signal (P = 1.1980035 ± 0.0000018 d) was first detected by the Transiting Exoplanet Survey Satellite (TESS). Through a joint modelling of follow-up radial velocity observations with CARMENES, IRD, and HARPS together with extensive ground-based photometric follow-up observations with LCOGT, MuSCAT, and MuSCAT2, we determined a precise planetary mass, Mb = 1.86 ± 0.30 M⊕, and radius, Rb = 1.264 ± 0.050 R⊕. Additionally, we report the discovery of a second, temperate, non-transiting planet in the system, GJ 3473 c, which has a minimum mass, Mc sin i = 7.41 ± 0.91 M⊕, and orbital period, Pc = 15.509 ± 0.033 d. The inner planet of the system, GJ 3473 b, is one of the hottest transiting Earth-sized planets known thus far, accompanied by a dynamical mass measurement, which makes it a particularly attractive target for thermal emission spectroscopy.

scholarly journals SOPHIE velocimetry of Kepler transit candidates

2019 ◽  
Vol 623 ◽  
pp. A104 ◽  
Author(s):  
G. Hébrard ◽  
A. S. Bonomo ◽  
R. F. Díaz ◽  
A. Santerne ◽  
N. C. Santos ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Orbital Period ◽  
Planetary System ◽  
Giant Planet ◽  
Eccentric Orbit ◽  
Promising Candidate ◽  
Single Star ◽  
Orbital Periods ◽  
Host Stars

Whereas thousands of transiting giant exoplanets are known today, only a few are well characterized with long orbital periods. Here we present KOI-3680b, a new planet in this category. First identified by the Kepler team as a promising candidate from the photometry of the Kepler spacecraft, we establish here its planetary nature from the radial velocity follow-up secured over 2 yr with the SOPHIE spectrograph at Observatoire de Haute-Provence, France. The combined analysis of the whole dataset allows us to fully characterize this new planetary system. KOI-3680b has an orbital period of 141.2417 ± 0.0001 days, a mass of 1.93 ± 0.20 MJup, and a radius of 0.99 ± 0.07 RJup. It exhibits a highly eccentric orbit (e = 0.50 ± 0.03) around an early G dwarf. KOI-3680b is the transiting giant planet with the longest period characterized so far around a single star; it offers opportunities to extend studies which were mainly devoted to exoplanets close to their host stars, and to compare both exoplanet populations.

scholarly journals A super-Earth and a sub-Neptune orbiting the bright, quiet M3 dwarf TOI-1266

2020 ◽  
Vol 642 ◽  
pp. A49 ◽  
Author(s):  
B.-O. Demory ◽  
F. J. Pozuelos ◽  
Y. Gómez Maqueo Chew ◽  
L. Sabin ◽  
R. Petrucci ◽  
...  
Keyword(s):  
High Resolution ◽  
Orbital Period ◽  
System Architecture ◽  
Planetary System ◽  
High Resolution Spectroscopy ◽  
San Pedro ◽  
Night Side ◽  
Model Independent ◽  
The Masses

We report the discovery and characterisation of a super-Earth and a sub-Neptune transiting the bright (K = 8.8), quiet, and nearby (37 pc) M3V dwarf TOI-1266. We validate the planetary nature of TOI-1266 b and c using four sectors of TESS photometry and data from the newly-commissioned 1-m SAINT-EX telescope located in San Pedro Mártir (México). We also include additional ground-based follow-up photometry as well as high-resolution spectroscopy and high-angular imaging observations. The inner, larger planet has a radius of R = 2.37−0.12+0.16 R⊕ and an orbital period of 10.9 days. The outer, smaller planet has a radius of R = 1.56−0.13+0.15 R⊕ on an 18.8-day orbit. The data are found to be consistent with circular, co-planar and stable orbits that are weakly influenced by the 2:1 mean motion resonance. Our TTV analysis of the combined dataset enables model-independent constraints on the masses and eccentricities of the planets. We find planetary masses of Mp = 13.5−9.0+11.0 M⊕ (<36.8 M⊕ at 2-σ) for TOI-1266 b and 2.2−1.5+2.0 M⊕ (<5.7 M⊕ at 2-σ) for TOI-1266 c. We find small but non-zero orbital eccentricities of 0.09−0.05+0.06 (<0.21 at 2-σ) for TOI-1266 b and 0.04 ± 0.03 (< 0.10 at 2-σ) for TOI-1266 c. The equilibrium temperatures of both planets are of 413 ± 20 and 344 ± 16 K, respectively, assuming a null Bond albedo and uniform heat redistribution from the day-side to the night-side hemisphere. The host brightness and negligible activity combined with the planetary system architecture and favourable planet-to-star radii ratios makes TOI-1266 an exquisite system for a detailed characterisation.

scholarly journals Revisiting the HD 21749 Planetary System with Stellar Activity Modeling*

2020 ◽  
Author(s):  
Tianjun Gan ◽  
Sharon Xuesong Wang ◽  
Johanna K Teske ◽  
Shude Mao ◽  
Ward S Howard ◽  
...  
Keyword(s):  
Orbital Period ◽  
Planetary System ◽  
Mass Measurement ◽  
Terrestrial Planet ◽  
Stellar Rotation ◽  
Stellar Activity ◽  
Activity Modeling ◽  
Error Bar ◽  
High Cadence

Abstract HD 21749 is a bright (V = 8.1 mag) K dwarf at 16 pc known to host an inner terrestrial planet HD 21749c as well as an outer sub-Neptune HD 21749b, both delivered by TESS. Follow-up spectroscopic observations measured the mass of HD 21749b to be 22.7 ± 2.2 M⊕ with a density of $7.0^{+1.6}_{-1.3}$ g cm−3, making it one of the densest sub-Neptunes. However, the mass measurement was suspected to be influenced by stellar rotation. Here we present new high-cadence PFS RV data to disentangle the stellar activity signal from the planetary signal. We find that HD 21749 has a similar rotational timescale as the planet’s orbital period, and the amplitude of the planetary orbital RV signal is estimated to be similar to that of the stellar activity signal. We perform Gaussian Process (GP) regression on the photometry and RVs from HARPS and PFS to model the stellar activity signal. Our new models reveal that HD 21749b has a radius of 2.86 ± 0.20 R⊕, an orbital period of 35.6133 ± 0.0005 d with a mass of Mb = 20.0 ± 2.7 M⊕ and a density of $4.8^{+2.0}_{-1.4}$ g cm−3 on an eccentric orbit with e = 0.16 ± 0.06, which is consistent with the most recent values published for this system. HD 21749c has an orbital period of 7.7902 ± 0.0006 d, a radius of 1.13 ± 0.10 R⊕, and a 3σ mass upper limit of 3.5 M⊕. Our Monte Carlo simulations confirm that without properly taking stellar activity signals into account, the mass measurement of HD 21749b is likely to arrive at a significantly underestimated error bar.

scholarly journals Planet Hunters TESS I: TOI 813, a subgiant hosting a transiting Saturn-sized planet on an 84-day orbit

2020 ◽  
Vol 494 (1) ◽  
pp. 750-763 ◽  
Author(s):  
N L Eisner ◽  
O Barragán ◽  
S Aigrain ◽  
C Lintott ◽  
G Miller ◽  
...  
Keyword(s):  
Light Curve ◽  
Parameter Space ◽  
Orbital Period ◽  
Semimajor Axis ◽  
First Year ◽  
Speckle Imaging ◽  
Long Period ◽  
Upper Limit ◽  
Detailed Modelling

ABSTRACT We report on the discovery and validation of TOI 813 b (TIC 55525572 b), a transiting exoplanet identified by citizen scientists in data from NASA’s Transiting Exoplanet Survey Satellite (TESS) and the first planet discovered by the Planet Hunters TESS project. The host star is a bright (V = 10.3 mag) subgiant ($R_\star =1.94\, R_\odot$, $M_\star =1.32\, M_\odot$). It was observed almost continuously by TESS during its first year of operations, during which time four individual transit events were detected. The candidate passed all the standard light curve-based vetting checks, and ground-based follow-up spectroscopy and speckle imaging enabled us to place an upper limit of $2\, M_{\rm Jup}$ (99 per cent confidence) on the mass of the companion, and to statistically validate its planetary nature. Detailed modelling of the transits yields a period of $83.8911 _{ - 0.0031 } ^ { + 0.0027 }$ d, a planet radius of 6.71 ± 0.38 R⊕ and a semimajor axis of $0.423 _{ - 0.037 } ^ { + 0.031 }$ AU. The planet’s orbital period combined with the evolved nature of the host star places this object in a relatively underexplored region of parameter space. We estimate that TOI 813 b induces a reflex motion in its host star with a semi-amplitude of ∼6 m s−1, making this a promising system to measure the mass of a relatively long-period transiting planet.

scholarly journals Orbital Period Refinement of CoRoT Planets with TESS Observations

2021 ◽  
Vol 8 ◽  
Author(s):  
Peter Klagyivik ◽  
Hans J. Deeg ◽  
Szilárd Csizmadia ◽  
Juan Cabrera ◽  
Grzegorz Nowak
Keyword(s):  
Orbital Period ◽  
Space Mission ◽  
Future Generations ◽  
Large Uncertainty ◽  
Main Motivation ◽  
Transiting Planets

CoRoT was the first space mission dedicated to exoplanet detection. Operational between 2007 and 2012, this mission discovered 37 transiting planets, including CoRoT-7b, the first terrestrial exoplanet with a measured size. The precision of the published transit ephemeris of most of these planets has been limited by the relative short durations of the CoRoT pointings, which implied a danger that the transits will become unobservable within a few years due to the uncertainty of their future transit epochs. Ground-based follow-up observations of the majority of the CoRoT planets have been published in recent years. Between Dec. 2018 and Jan. 2021, the TESS mission in its sectors 6 and 33 re-observed those CoRoT fields that pointed towards the Galactic anti-center. These data permitted the identification of transits from nine of the CoRoT planets, and the derivation of precise new transit epochs. The main motivation of this study has been to derive precise new ephemerides of the CoRoT planets, in order to keep these planets’ transits observable for future generations of telescopes. The TESS data were analyzed for the presence of transits and the epochs of these re-observed transits were measured. The original CoRoT epochs, epochs from ground-based follow-up observations and those from TESS were collected. From these data, updated ephemerides are presented for nine transiting planets discovered by the CoRoT mission in its fields pointing towards the Galactic anti-center. In three cases (CoRoT-4b, 19b and 20b), transits that would have been lost for ground observations, due to the large uncertainty in the previous ephemeris, have been recovered. The updated ephemerides permit transit predictions with uncertainties of less than 30 min for observations at least until the year 2030. No significant transit timing variations were found in these systems.

scholarly journals A Pair of Warm Giant Planets near the 2:1 Mean Motion Resonance around the K-dwarf Star TOI-2202*

2021 ◽  
Vol 162 (6) ◽  
pp. 283
Author(s):  
Trifon Trifonov ◽  
Rafael Brahm ◽  
Nestor Espinoza ◽  
Thomas Henning ◽  
Andrés Jordán ◽  
...  
Keyword(s):  
Orbital Period ◽  
Dynamical Evolution ◽  
Giant Planets ◽  
Light Curves ◽  
Dynamical Analysis ◽  
Dwarf Star ◽  
Mean Motion ◽  
Robotic Telescope ◽  
Mean Motion Resonance

Abstract TOI-2202 b is a transiting warm Jovian-mass planet with an orbital period of P = 11.91 days identified from the Full Frame Images data of five different sectors of the TESS mission. Ten TESS transits of TOI-2202 b combined with three follow-up light curves obtained with the CHAT robotic telescope show strong transit timing variations (TTVs) with an amplitude of about 1.2 hr. Radial velocity follow-up with FEROS, HARPS, and PFS confirms the planetary nature of the transiting candidate (a b = 0.096 ± 0.001 au, m b = 0.98 ± 0.06 M Jup), and a dynamical analysis of RVs, transit data, and TTVs points to an outer Saturn-mass companion (a c = 0.155 ± 0.002 au, m c = 0.37 ± 0.10 M Jup) near the 2:1 mean motion resonance. Our stellar modeling indicates that TOI-2202 is an early K-type star with a mass of 0.82 M ⊙, a radius of 0.79 R ⊙, and solar-like metallicity. The TOI-2202 system is very interesting because of the two warm Jovian-mass planets near the 2:1 mean motion resonance, which is a rare configuration, and their formation and dynamical evolution are still not well understood.

scholarly journals KMT-2018-BLG-0748Lb: sub-Saturn microlensing planet orbiting an ultracool host

2020 ◽  
Vol 641 ◽  
pp. A105 ◽  
Author(s):  
Cheongho Han ◽  
In-Gu Shin ◽  
Youn Kil Jung ◽  
Doeon Kim ◽  
Jennifer C. Yee ◽  
...  
Keyword(s):  
High Resolution ◽  
Bayesian Analysis ◽  
Light Curve ◽  
Planetary System ◽  
Lens Model ◽  
Mass Ratio ◽  
Brown Dwarf ◽  
Short Event ◽  
Einstein Radius

Aims. We announce the discovery of a microlensing planetary system, in which a sub-Saturn planet is orbiting an ultracool dwarf host. Methods. We detected the planetary system by analyzing the short-timescale (tE ~ 4.4 days) lensing event KMT-2018-BLG-0748. The central part of the light curve exhibits asymmetry due to negative deviations in the rising side and positive deviations in the falling side. Results. We find that the deviations are explained by a binary-lens model with a mass ratio between the lens components of q ~ 2 × 10−3. The short event timescale, together with the small angular Einstein radius, θE ~ 0.11 mas, indicate that the mass of the planet host is very small. The Bayesian analysis conducted under the assumption that the planet frequency is independent of the host mass indicates that the mass of the planet is Mp = 0.18−0.10+0.29 MJ, and the mass of the host, Mh = 0.087−0.047+0.138 M⊙, is near the star–brown dwarf boundary, but the estimated host mass is sensitive to this assumption about the planet hosting probability. High-resolution follow-up observations would lead to revealing the nature of the planet host.

The Eclipsing Binary WX Eridani

1979 ◽  
Vol 46 ◽  
pp. 385
Author(s):  
M.B.K. Sarma ◽  
K.D. Abhankar
Keyword(s):  
Light Curve ◽  
Spectral Type ◽  
Orbital Period ◽  
Primary Component ◽  
Light Curves ◽  
Absorption Feature ◽  
Primary Star ◽  
Eclipsing Binary ◽  
The Times ◽  
Phase Angles

AbstractThe Algol-type eclipsing binary WX Eridani was observed on 21 nights on the 48-inch telescope of the Japal-Rangapur Observatory during 1973-75 in B and V colours. An improved period of P = 0.82327038 days was obtained from the analysis of the times of five primary minima. An absorption feature between phase angles 50-80, 100-130, 230-260 and 280-310 was present in the light curves. The analysis of the light curves indicated the eclipses to be grazing with primary to be transit and secondary, an occultation. Elements derived from the solution of the light curve using Russel-Merrill method are given. From comparison of the fractional radii with Roche lobes, it is concluded that none of the components have filled their respective lobes but the primary star seems to be evolving. The spectral type of the primary component was estimated to be F3 and is found to be pulsating with two periods equal to one-fifth and one-sixth of the orbital period.

RSCVn Stars in the Southern Hemisphere

1979 ◽  
Vol 46 ◽  
pp. 371-384 ◽  
Author(s):  
J.B. Hearnshaw
Keyword(s):  
Light Curve ◽  
Southern Hemisphere ◽  
Orbital Period ◽  
Binary Stars ◽  
Small Amplitude ◽  
Light Variation ◽  
Orbital Phase

RSCVn stars are fully detached binary stars which show intrinsic small amplitude (up to 0.3 amplitude peak-to-peak) light variations, as well as, in most of the known cases, eclipses. The spectra are F to G, IV to V for the hotter component and usually KOIV for the cooler. They are also characterised by abnormally strong H and K emission from the cooler star, or, occasionally, from both components. The orbital and light curve periods are in the range 1 day to 2 weeks. An interesting feature is the migration of the light variations to earlier orbital phase, as the light variation period is shorter than the orbital period by a few parts in 10+4to a few parts in 10+3.

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