Context. The detection and characterization of exoplanets and brown dwarfs around massive AF-type stars is essential to investigate and constrain the impact of stellar mass on planet properties. ...However, such targets are still poorly explored in radial velocity (RV) surveys because they only feature a small number of stellar lines and those are usually broadened and blended by stellar rotation as well as stellar jitter. As a result, the available information about the formation and evolution of planets and brown dwarfs around hot stars is limited.
Aims. We aim to increase the sample and precisely measure the masses and eccentricities of giant planets and brown dwarfs transiting early-type stars detected by the Transiting Exoplanet Survey Satellite (TESS).
Methods. We followed bright (V < 12 mag) stars with Teff > 6200 K that host giant companions (R > 7 R⊕) using ground-based photometric observations as well as high precision radial velocity measurements from the CORALIE, CHIRON, TRES, FEROS, and MINERVA-Australis spectrographs.
Results. In the context of the search for exoplanets and brown dwarfs around early-type stars, we present the discovery of three brown dwarf companions, TOI-629b, TOI-1982b, and TOI-2543b, and one massive planet, TOI-1107b. From the joint analysis of TESS and ground-based photometry in combination with high precision radial velocity measurements, we find the brown dwarfs have masses between 66 and 68 MJup, periods between 7.54 and 17.17 days, and radii between 0.95 and 1.11 RJup. The hot Jupiter TOI-1107b has an orbital period of 4.08 days, a radius of 1.30 RJup, and a mass of 3.35 MJup. As a by-product of this program, we identified four low-mass eclipsing components (TOI-288b, TOI-446b, TOI-478b, and TOI-764b).
Conclusions. Both TOI-1107b and TOI-1982b present an anomalously inflated radius with respect to the age of these systems. TOI-629 is among the hottest stars with a known transiting brown dwarf. TOI-629b and TOI-1982b are among the most eccentric brown dwarfs. The massive planet and the three brown dwarfs add to the growing population of well-characterized giant planets and brown dwarfs transiting AF-type stars and they reduce the apparent paucity.
Abstract
The James Webb Space Telescope will be able to probe the atmospheres and surface properties of hot, terrestrial planets via emission spectroscopy. We identify 18 potentially terrestrial ...planet candidates detected by the Transiting Exoplanet Survey Satellite (TESS) that would make ideal targets for these observations. These planet candidates cover a broad range of planet radii (
R
p
∼ 0.6–2.0
R
⊕
) and orbit stars of various magnitudes (
K
s
= 5.78–10.78,
V
= 8.4–15.69) and effective temperatures (
T
eff
∼ 3000–6000 K). We use ground-based observations collected through the TESS Follow-up Observing Program (TFOP) and two vetting tools—
DAVE
and
TRICERATOPS
—to assess the reliabilities of these candidates as planets. We validate 13 planets: TOI-206 b, TOI-500 b, TOI-544 b, TOI-833 b, TOI-1075 b, TOI-1411 b, TOI-1442 b, TOI-1693 b, TOI-1860 b, TOI-2260 b, TOI-2411 b, TOI-2427 b, and TOI-2445 b. Seven of these planets (TOI-206 b, TOI-500 b, TOI-1075 b, TOI-1442 b, TOI-2260 b, TOI-2411 b, and TOI-2445 b) are ultra-short-period planets. TOI-1860 is the youngest (133 ± 26 Myr) solar twin with a known planet to date. TOI-2260 is a young (321 ± 96 Myr) G dwarf that is among the most metal-rich (Fe/H = 0.22 ± 0.06 dex) stars to host an ultra-short-period planet. With an estimated equilibrium temperature of ∼2600 K, TOI-2260 b is also the fourth hottest known planet with
R
p
< 2
R
⊕
.
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
We report the discovery of TOI-4641b, a warm Jupiter transiting a rapidly rotating F-type star with a stellar effective temperature of 6560 K. The planet has a radius of 0.73 RJup, a mass ...smaller than 3.87 MJup(3σ), and a period of 22.09 d. It is orbiting a bright star (V=7.5 mag) on a circular orbit with a radius and mass of 1.73 R⊙ and 1.41 M⊙. Follow-up ground-based photometry was obtained using the Tierras Observatory. Two transits were also observed with the Tillinghast Reflector Echelle Spectrograph, revealing the star to have a low projected spin-orbit angle (λ=$1.41^{+0.76}_{-0.76}$°). Such obliquity measurements for stars with warm Jupiters are relatively few, and may shed light on the formation of warm Jupiters. Among the known planets orbiting hot and rapidly rotating stars, TOI-4641b is one of the longest period planets to be thoroughly characterized. Unlike hot Jupiters around hot stars which are more often misaligned, the warm Jupiter TOI-4641b is found in a well-aligned orbit. Future exploration of this parameter space can add one more dimension to the star–planet orbital obliquity distribution that has been well sampled for hot Jupiters.
Abstract
We present the spectroscopic confirmation and precise mass measurement of the warm giant planet TOI-199 b. This planet was first identified in TESS photometry and confirmed using ...ground-based photometry from ASTEP in Antarctica including a full 6.5 hr long transit, PEST, Hazelwood, and LCO; space photometry from NEOSSat; and radial velocities (RVs) from FEROS, HARPS, CORALIE, and CHIRON. Orbiting a late G-type star, TOI-199 b has a
104.854
−
0.002
+
0.001
day
period, a mass of 0.17 ± 0.02
M
J
, and a radius of 0.810 ± 0.005
R
J
. It is the first warm exo-Saturn with a precisely determined mass and radius. The TESS and ASTEP transits show strong transit timing variations (TTVs), pointing to the existence of a second planet in the system. The joint analysis of the RVs and TTVs provides a unique solution for the nontransiting companion TOI-199 c, which has a period of
273.69
−
0.22
+
0.26
days
and an estimated mass of
0.28
−
0.01
+
0.02
M
J
. This period places it within the conservative habitable zone.
Abstract
We report the discovery and orbital characterization of three new transiting warm giant planets. These systems were initially identified as presenting single-transit events in the light ...curves generated from the full-frame images of the Transiting Exoplanet Survey Satellite. Follow-up radial velocity measurements and additional light curves were used to determine the orbital periods and confirm the planetary nature of the candidates. The planets orbit slightly metal-rich late F- and early G-type stars. We find that TOI 4406b has a mass of
M
P
= 0.30 ± 0.04
M
J
, a radius of
R
P
= 1.00 ± 0.02
R
J
, and a low-eccentricity orbit (
e
= 0.15 ± 0.05) with a period of
P
= 30.08364 ±0.00005 days. TOI 2338b has a mass of
M
P
= 5.98 ± 0.20
M
J
, a radius of
R
P
= 1.00 ± 0.01
R
J
, and a highly eccentric orbit (
e
= 0.676 ± 0.002) with a period of
P
= 22.65398 ± 0.00002 days. Finally, TOI 2589b has a mass of
M
P
= 3.50 ± 0.10
M
J
, a radius of
R
P
= 1.08 ± 0.03
R
J
, and an eccentric orbit (
e
= 0.522 ± 0.006) with a period of
P
= 61.6277 ± 0.0002 days. TOI 4406b and TOI 2338b are enriched in metals compared to their host stars, while the structure of TOI 2589b is consistent with having similar metal enrichment to its host star.
We report the discovery of TOI-4127 b, which is a transiting, Jupiter-sized exoplanet on a long period (P=56.39879 +0.00010-0.00010days) and a high-eccentricity orbit around a late F-type dwarf star. ...This warm Jupiter was first detected and identified as a promising candidate from a search for single-transit signals in TESS Sector 20 data and was later characterized as a planet following two subsequent transits (TESS Sectors 26 and 53) and follow-up ground-based RV observations with the NEID and SOPHIE spectrographs. We jointly fit the transit and RV data to constrain the physical (Rp=1.096+0.039-0.032RJ, Mp=2.30+0.11-0.11MJ) and orbital parameters of the exoplanet. Given its high orbital eccentricity (𝓮=0.7471+0.0078-0.0086), TOI-4127 b is a compelling candidate for studies of warm Jupiter populations and of hot Jupiter formation pathways. We show that the present periastron separation of TOI-4127 b is too large for high-eccentricity tidal migration to circularize its orbit, and that TOI-4127 b is unlikely to be a hot Jupiter progenitor unless it is undergoing angular momentum exchange with an undetected outer companion. Although we find no evidence for an external companion, the available observational data are insufficient to rule out the presence of a perturber that can excite eccentricity oscillations and facilitate tidal migration.
We report the discovery of TOI 694 b and TIC 220568520 b, two low-mass stellar companions in eccentric orbits around metal-rich Sun-like stars, first detected by the Transiting Exoplanet Survey ...Satellite (TESS). TOI 694 b has an orbital period of 48.05131 0.00019 days and eccentricity of 0.51946 0.00081, and we derive a mass of 89.0 5.3 (0.0849 0.0051 ) and radius of 1.111 0.017 (0.1142 0.0017 ). TIC 220568520 b has an orbital period of 18.55769 0.00039 days and eccentricity of 0.0964 0.0032, and we derive a mass of 107.2 5.2 (0.1023 0.0050 ) and radius of 1.248 0.018 (0.1282 0.0019 ). Both binary companions lie close to and above the hydrogen-burning mass threshold that separates brown dwarfs and the lowest-mass stars, with TOI 694 b being 2 above the canonical mass threshold of 0.075 . The relatively long periods of the systems mean that the magnetic fields of the low-mass companions are not expected to inhibit convection and inflate the radius, which according to one leading theory is common in similar objects residing in short-period tidally synchronized binary systems. Indeed we do not find radius inflation for these two objects when compared to theoretical isochrones. These two new objects add to the short but growing list of low-mass stars with well-measured masses and radii, and highlight the potential of the TESS mission for detecting such rare objects orbiting bright stars.
Abstract
We present the Distant Giants Survey, a three-year radial velocity campaign to measure P(DG∣CS), the conditional occurrence of distant giant planets (DG;
M
p
∼ 0.3–13
M
J
,
P
> 1 yr) in ...systems hosting a close-in small planet (CS;
R
p
< 10
R
⊕
). For the past two years, we have monitored 47 Sun-like stars hosting small transiting planets detected by TESS. We present the selection criteria used to assemble our sample and report the discovery of two distant giant planets, TOI-1669 b and TOI-1694 c. For TOI-1669 b we find that
M
sin
i
=
0.573
±
0.074
M
J
,
P
= 502 ± 16 days, and
e
< 0.27, while for TOI-1694 c,
M
sin
i
=
1.05
±
0.05
M
J
,
P
= 389.2 ± 3.9 days, and
e
= 0.18 ± 0.05. We also confirmed the 3.8 days transiting planet TOI-1694 b by measuring a true mass of
M
= 26.1 ± 2.2
M
⊕
. At the end of the Distant Giants Survey, we will incorporate TOI-1669 b and TOI-1694 c into our calculation of P(DG∣CS), a crucial statistic for understanding the relationship between outer giants and small inner companions.
Abstract
Observations and statistical studies have shown that giant planets are rare around M dwarfs compared with Sun-like stars. The formation mechanism of these extreme systems has remained under ...debate for decades. With the help of the TESS mission and ground-based follow-up observations, we report the discovery of TOI-4201b, the most massive and densest hot Jupiter around an M dwarf known so far with a radius of 1.22 ± 0.04
R
J
and a mass of 2.48 ± 0.09
M
J
, about 5 times heavier than most other giant planets around M dwarfs. It also has the highest planet-to-star mass ratio (
q
∼ 4 × 10
−3
) among such systems. The host star is an early M dwarf with a mass of 0.61 ± 0.02
M
⊙
and a radius of 0.63 ± 0.02
R
⊙
. It has significant supersolar iron abundance (Fe/H = 0.52 ± 0.08 dex). However, interior structure modeling suggests that its planet TOI-4201b is metal-poor, which challenges the classical core-accretion correlation of stellar−planet metallicity, unless the planet is inflated by additional energy sources. Building on the detection of this planet, we compare the stellar metallicity distribution of four planetary groups: hot/warm Jupiters around G/M dwarfs. We find that hot/warm Jupiters show a similar metallicity dependence around G-type stars. For M-dwarf host stars, the occurrence of hot Jupiters shows a much stronger correlation with iron abundance, while warm Jupiters display a weaker preference, indicating possible different formation histories.
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