Abstract
The K-type star TOI-2525 has an estimated mass of
M
=
0.849
−
0.033
+
0.024
M
⊙
and radius of
R
=
0.785
−
0.007
+
0.007
R
⊙
observed by the TESS mission in 22 sectors (within sectors 1 and ...39). The TESS light curves yield significant transit events of two companions, which show strong transit timing variations (TTVs) with a semiamplitude of ∼6 hr. We performed TTV dynamical and photodynamical light-curve analysis of the TESS data combined with radial velocity measurements from FEROS and PFS, and we confirmed the planetary nature of these companions. The TOI-2525 system consists of a transiting pair of planets comparable to Neptune and Jupiter with estimated dynamical masses of
m
b
=
0.088
−
0.004
+
0.005
and
m
c
=
0.709
−
0.033
+
0.034
M
Jup
, radii of
r
b
=
0.88
−
0.02
+
0.02
and
r
c
=
0.98
−
0.02
+
0.02
R
Jup
, and orbital periods of
P
b
=
23.288
−
0.002
+
0.001
and
P
c
=
49.260
−
0.001
+
0.001
days for the inner and outer planet, respectively. The period ratio is close to the 2:1 period commensurability, but the dynamical simulations of the system suggest that it is outside the mean-motion resonance (MMR) dynamical configuration. Object TOI-2525 b is among the lowest-density Neptune-mass planets known to date, with an estimated median density of
ρ
b
=
0.174
−
0.015
+
0.016
g cm
−3
. The TOI-2525 system is very similar to the other K dwarf systems discovered by TESS, TOI-2202 and TOI-216, which are composed of almost identical K dwarf primaries and two warm giant planets near the 2:1 MMR.
Abstract
High-eccentricity tidal migration is a possible way for giant planets to be placed in short-period orbits. If this happens often, one would expect to catch proto hot Jupiters on highly ...elliptical orbits undergoing high-eccentricity tidal migration. As of yet, few such systems have been discovered. Here, we introduce TOI-3362b (TIC-464300749b), an 18.1 day, 5
M
Jup
planet orbiting a main-sequence F-type star that is likely undergoing high-eccentricity tidal migration. The orbital eccentricity is 0.815
−
0.032
+
0.023
. With a semimajor axis of 0.153
−
0.003
+
0.002
au, the planet’s orbit is expected to shrink to a final orbital radius of 0.051
−
0.006
+
0.008
au after complete tidal circularization. Several mechanisms could explain the extreme value of the planet’s eccentricity, such as planet–planet scattering and secular interactions. Such hypotheses can be tested with follow-up observations of the system, e.g., measuring the stellar obliquity and searching for companions in the system with precise, long-term radial-velocity observations. The variation in the planet’s equilibrium temperature as it orbits the host star and the tidal heating at periapse make this planet an intriguing target for atmospheric modeling and observation. Because the planet’s orbital period of 18.1 days is near the limit of TESS’s period sensitivity, even a few such discoveries suggest that proto hot Jupiters may be quite common.
ABSTRACT
We present the confirmation of a hot super-Neptune with an exterior Neptune companion orbiting a bright (V = 10.1 mag) F-dwarf identified by the Transiting Exoplanet Survey Satellite ...(TESS). The two planets, observed in sectors 45, 46, and 48 of the TESS extended mission, are $4.74_{-0.14}^{+0.16}$ and $3.86_{-0.16}^{+0.17}$ R⊕ with $5.4588385_{-0.0000072}^{+0.0000070}$ and $17.8999_{-0.0013}^{+0.0018}$ d orbital periods, respectively. We also obtained precise space-based photometric follow-up of the system with ESA’s CHaracterising ExOplanets Satellite to constrain the radius and ephemeris of TOI-5126 b. TOI-5126 b is located in the ‘hot Neptune Desert’ and is an ideal candidate for follow-up transmission spectroscopy due to its high-predicted equilibrium temperature (Teq = ${1442}_{-40}^{+46}$ K) implying a cloud-free atmosphere. TOI-5126 c is a warm Neptune (Teq = $971_{-27}^{+31}$ K) also suitable for follow-up. Tentative transit timing variations have also been identified in analysis, suggesting the presence of at least one additional planet, however this signal may be caused by spot-crossing events, necessitating further precise photometric follow-up to confirm these signals.
Abstract
We present the Transiting Exoplanet Survey Satellite (TESS) discovery of the LHS 1678 (TOI-696) exoplanet system, comprised of two approximately Earth-sized transiting planets and a likely ...astrometric brown dwarf orbiting a bright (
V
J
= 12.5,
K
s
= 8.3) M2 dwarf at 19.9 pc. The two TESS-detected planets are of radius 0.70 ± 0.04
R
⊕
and 0.98 ± 0.06
R
⊕
in 0.86 day and 3.69 day orbits, respectively. Both planets are validated and characterized via ground-based follow-up observations. High Accuracy Radial Velocity Planet Searcher RV monitoring yields 97.7 percentile mass upper limits of 0.35
M
⊕
and 1.4
M
⊕
for planets b and c, respectively. The astrometric companion detected by the Cerro Tololo Inter-American Observatory/Small and Moderate Aperture Telescope System 0.9 m has an orbital period on the order of decades and is undetected by other means. Additional ground-based observations constrain the companion to being a high-mass brown dwarf or smaller. Each planet is of unique interest; the inner planet has an ultra-short period, and the outer planet is in the Venus zone. Both are promising targets for atmospheric characterization with the James Webb Space Telescope and mass measurements via extreme-precision radial velocity. A third planet candidate of radius 0.9 ± 0.1
R
⊕
in a 4.97 day orbit is also identified in multicycle TESS data for validation in future work. The host star is associated with an observed gap in the lower main sequence of the Hertzsprung–Russell diagram. This gap is tied to the transition from partially to fully convective interiors in M dwarfs, and the effect of the associated stellar astrophysics on exoplanet evolution is currently unknown. The culmination of these system properties makes LHS 1678 a unique, compelling playground for comparative exoplanet science and understanding the formation and evolution of small, short-period exoplanets orbiting low-mass stars.
Abstract
The radius valley carries implications for how the atmospheres of small planets form and evolve, but this feature is visible only with highly precise characterizations of many small planets. ...We present the characterization of nine planets and one planet candidate with both NASA TESS and ESA CHEOPS observations, which adds to the overall population of planets bordering the radius valley. While five of our planets—TOI 118 b, TOI 262 b, TOI 455 b, TOI 560 b, and TOI 562 b—have already been published, we vet and validate transit signals as planetary using follow-up observations for four new TESS planets, including TOI 198 b, TOI 244 b, TOI 444 b, and TOI 470 b. While a three times increase in primary mirror size should mean that one CHEOPS transit yields an equivalent model uncertainty in transit depth as about nine TESS transits in the case that the star is equally as bright in both bands, we find that our CHEOPS transits typically yield uncertainties equivalent to between two and 12 TESS transits, averaging 5.9 equivalent transits. Therefore, we find that while our fits to CHEOPS transits provide overall lower uncertainties on transit depth and better precision relative to fits to TESS transits, our uncertainties for these fits do not always match expected predictions given photon-limited noise. We find no correlations between number of equivalent transits and any physical parameters, indicating that this behavior is not strictly systematic, but rather might be due to other factors such as in-transit gaps during CHEOPS visits or nonhomogeneous detrending of CHEOPS light curves.
Abstract
The imminent launch of space telescopes designed to probe the atmospheres of exoplanets has prompted new efforts to prioritize the thousands of transiting planet candidates for follow-up ...characterization. We report the detection and confirmation of TOI-1842b, a warm Saturn identified by TESS and confirmed with ground-based observations from M
inerva
-Australis, NRES, and the Las Cumbres Observatory Global Telescope. This planet has a radius of
1.04
−
0.05
+
0.06
R
J
, a mass of
0.214
−
0.038
+
0.040
M
J
, an orbital period of
9.5739
−
0.0001
+
0.0002
days, and an extremely low density (
ρ
= 0.252 ± 0.091 g cm
−3
). TOI-1842b has among the best known combinations of large atmospheric scale height (893 km) and host-star brightness (
J
= 8.747 mag), making it an attractive target for atmospheric characterization. As the host star is beginning to evolve off the main sequence, TOI-1842b presents an excellent opportunity to test models of gas giant reinflation. The primary transit duration of only 4.3 hr also makes TOI-1842b an easily-schedulable target for further ground-based atmospheric characterization.
We report the discovery of GJ 1252 b, a planet with a radius of 1.193 0.074 and an orbital period of 0.52 days around an M3-type star (0.381 0.019 , 0.391 0.020 ) located 20.385 0.019 pc away. We use ...Transiting Exoplanet Survey Satellite (TESS) data, ground-based photometry and spectroscopy, Gaia astrometry, and high angular resolution imaging to show that the transit signal seen in the TESS data must originate from a transiting planet. We do so by ruling out all false-positive scenarios that attempt to explain the transit signal as originating from an eclipsing stellar binary. Precise Doppler monitoring also leads to a tentative mass measurement of 2.09 0.56 M⊕. The host star proximity, brightness (V = 12.19 mag, K = 7.92 mag), low stellar activity, and the system's short orbital period make this planet an attractive target for detailed characterization, including precise mass measurement, looking for other objects in the system, and planet atmosphere characterization.
Abstract
We report the discovery and validation of TOI 122b and TOI 237b, two warm planets transiting inactive M dwarfs observed by the Transiting Exoplanet Survey Satellite (TESS). Our analysis ...shows that TOI 122b has a radius of 2.72 ± 0.18
R
⊕
and receives 8.8 ± 1.0 times Earth’s bolometric insolation, and TOI 237b has a radius of 1.44±0.12
R
⊕
and receives 3.7 ± 0.5 times Earth’s insolation, straddling the 6.7 × Earth insolation that Mercury receives from the Sun. This makes these two of the cooler planets yet discovered by TESS, even on their 5.08 and 5.43 day orbits. Together, they span the small-planet radius valley, providing useful laboratories for exploring volatile evolution around M dwarfs. Their relatively nearby distances (62.23 ± 0.21 pc and 38.11 ± 0.23 pc, respectively) make them potentially feasible targets for future radial velocity follow-up and atmospheric characterization, although such observations may require substantial investments of time on large telescopes.
Abstract
NASA’s Transiting Exoplanet Survey Satellite (TESS) is an all-sky survey mission designed to find transiting exoplanets orbiting nearby bright stars. It has identified more than 329 ...transiting exoplanets, and almost 6000 candidates remain unvalidated. In this manuscript, we discuss the findings from the ongoing Validation of Transiting Exoplanets using Statistical Tools (VaTEST) project, which aims to validate new exoplanets for further characterization. We validated 11 new exoplanets by examining the light curves of 24 candidates using the
LATTE
and
TESS-Plot
tools and computing the false-positive probabilities using the statistical validation tool
TRICERATOPS
. These include planets suitable for atmospheric characterization using transmission spectroscopy (TOI-2194b), emission spectroscopy (TOI-3082b and TOI-5704b) and for both transmission and emission spectroscopy (TOI-672b, TOI-1694b, and TOI-2443b). Our validated planets have one super-Earth (TOI-2194b) orbiting a bright (
V
= 8.42 mag), metal-poor (Fe/H = −0.3720 ± 0.1) star, and one short-period Neptune-like planet (TOI-5704) in the hot-Neptune desert. In total, we validated one super-Earth, seven sub-Neptunes, one Neptune-like, and two sub-Saturn or super-Neptune-like exoplanets. Additionally, we identify five likely planet candidates (TOI-323, TOI-1180, TOI-2200, TOI-2408, and TOI-3913), which can be further studied to establish their planetary nature.
Abstract
We present the discovery and characterization of HIP 33609 b, a transiting warm brown dwarf orbiting a late B star, discovered by NASA's Transiting Exoplanet Survey Satellite as TOI-588 b. ...HIP 33609 b is a large (
R
b
=
1.580
−
0.070
+
0.074
R
J
) brown dwarf on a highly eccentric (
e
=
0.560
−
0.031
+
0.029
) orbit with a 39 days period. The host star is a bright (
V
= 7.3 mag),
T
eff
= 10,400
−
660
+
800
K star with a mass of
M
*
=
2.383
−
0.095
+
0.10
M
⊙
and radius of
R
*
=
1.863
−
0.082
+
0.087
R
⊙
, making it the hottest transiting brown dwarf host star discovered to date. We obtained radial velocity measurements from the CHIRON spectrograph confirming the companion's mass of
M
b
=
68.0
−
7.1
+
7.4
M
J
as well as the host star's rotation rate (
v
sin
i
*
=
55.6
±
1.8
km s
−1
). We also present the discovery of a new comoving group of stars, designated as MELANGE-6, and determine that HIP 33609 is a member. We use a combination of rotation periods and isochrone models fit to the cluster members to estimate an age of 150 ± 25 Myr. With a measured mass, radius, and age, HIP 33609 b becomes a benchmark for substellar evolutionary models.
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