Abstract
The Transiting Exoplanet Survey Satellite mission was designed to find transiting planets around bright, nearby stars. Here, we present the detection and mass measurement of a small, ...short-period (≈4 days) transiting planet around the bright (
V
= 7.9), solar-type star HD 86226 (TOI-652, TIC 22221375), previously known to host a long-period (∼1600 days) giant planet. HD 86226c (TOI-652.01) has a radius of 2.16 ± 0.08
R
⊕
and a mass of
M
⊕
, based on archival and new radial velocity data. We also update the parameters of the longer-period, not-known-to-transit planet, and find it to be less eccentric and less massive than previously reported. The density of the transiting planet is 3.97 g cm
−3
, which is low enough to suggest that the planet has at least a small volatile envelope, but the mass fractions of rock, iron, and water are not well-constrained. Given the host star brightness, planet period, and location of the planet near both the “radius gap” and the “hot Neptune desert,” HD 86226c is an interesting candidate for transmission spectroscopy to further refine its composition.
Abstract
Mature super-Earths and sub-Neptunes are predicted to be ≃ Jovian radius when younger than 10 Myr. Thus, we expect to find 5–15
R
⊕
planets around young stars even if their older ...counterparts harbor none. We report the discovery and validation of TOI 1227b, a 0.85 ± 0.05
R
J
(9.5
R
⊕
) planet transiting a very-low-mass star (0.170 ± 0.015
M
⊙
) every 27.4 days. TOI 1227's kinematics and strong lithium absorption confirm that it is a member of a previously discovered subgroup in the Lower Centaurus Crux OB association, which we designate the Musca group. We derive an age of 11 ± 2 Myr for Musca, based on lithium, rotation, and the color–magnitude diagram of Musca members. The TESS data and ground-based follow-up show a deep (2.5%) transit. We use multiwavelength transit observations and radial velocities from the IGRINS spectrograph to validate the signal as planetary in nature, and we obtain an upper limit on the planet mass of ≃0.5
M
J
. Because such large planets are exceptionally rare around mature low-mass stars, we suggest that TOI 1227b is still contracting and will eventually turn into one of the more common <5
R
⊕
planets.
As an all-sky survey, NASA’s Transiting Exoplanet Survey Satellite (TESS) mission is able to detect the brightest and rarest types of transiting planetary systems, including young planets that enable ...study of the evolutionary processes that occur within the first billion years. Here we report the discovery of a young, multiplanet system orbiting the bright K4.5V star, TOI-712 (V = 10.838, M* = 0.733+0.026-0.025 M⨀, R* = 0.674 ± 0.016 R⨀, Teff = 4622+61-60 K). From the TESS light curve, we measure a rotation period of 12.48 days and derive an age between about 500 Myr and 1.1 Gyr. The photometric observations reveal three transiting mini-Neptunes (Rb = 2.049+0.120-0.080 R⊕, Rc = 2.701+0.092-0.082 R⊕, Rd = 2.474+0.090-0.082 R⊕), with orbital periods of Pb = 9.531 days, Pc = 51.699 days, and Pd = 84.839 days. After modeling the three-planet system, an additional Earth-sized candidate is identified, TOI-712.05 (P = 4.32 days, RP = 0.81 ± 0.11 R⊕). We calculate that the habitable zone falls between 0.339 and 0.844 au (82.7 and 325.3 days), placing TOI-712 d near its inner edge. Among planetary systems harboring temperate planets, TOI-712 (T = 9.9) stands out as a relatively young star bright enough to motivate further characterization.
We explore the transit timing variations (TTVs) of the young (22 Myr) nearby AU Mic planetary system. For AU
Mic b, we introduce three Spitzer (4.5 μm) transits, five TESS transits, 11 LCO transits, ...one PEST transit, one
Brierfield transit, and two transit timing measurements from Rossiter–McLaughlin observations; for AU Mic c, we
introduce three TESS transits. We present two independent TTV analyses. First, we use EXOFASTv2 to jointly
model the Spitzer and ground-based transits and obtain the midpoint transit times. We then construct an O − C
diagram and model the TTVs with Exo-Striker. Second, we reproduce our results with an independent
photodynamical analysis. We recover a TTV mass for AU Mic c of -10.8+2.22.3 M⊕. We compare the TTV-derived
constraints to a recent radial velocity (RV) mass determination. We also observe excess TTVs that do not appear to
be consistent with the dynamical interactions of b and c alone or due to spots or flares. Thus, we present a
hypothetical nontransiting “middle-d” candidate exoplanet that is consistent with the observed TTVs and candidate
RV signal and would establish the AU Mic system as a compact resonant multiplanet chain in a 4:6:9 period
commensurability. These results demonstrate that the AU Mic planetary system is dynamically interacting,
producing detectable TTVs, and the implied orbital dynamics may inform the formation mechanisms for this
young system. We recommend future RV and TTV observations of AU Mic b and c to further constrain the masses
and confirm the existence of possible additional planet(s).
Abstract
We report the discovery of two short-period massive giant planets from NASA’s Transiting Exoplanet Survey Satellite (TESS). Both systems, TOI-558 (TIC 207110080) and TOI-559 (TIC 209459275), ...were identified from the 30 minute cadence full-frame images and confirmed using ground-based photometric and spectroscopic follow-up observations from TESS’s follow-up observing program working group. We find that TOI-558 b, which transits an F-dwarf (
M
*
=
1.349
−
0.065
+
0.064
M
⊙
,
R
*
=
1.496
−
0.040
+
0.042
R
⊙
,
T
eff
=
6466
−
93
+
95
K, age
1.79
−
0.73
+
0.91
Gyr) with an orbital period of 14.574 days, has a mass of 3.61 ± 0.15
M
J
, a radius of
1.086
−
0.038
+
0.041
R
J
, and an eccentric (
e
=
0.300
−
0.020
+
0.022
) orbit. TOI-559 b transits a G dwarf (
M
*
= 1.026 ± 0.057
M
⊙
,
R
*
=
1.233
−
0.026
+
0.028
R
⊙
,
T
eff
=
5925
−
76
+
85
K, age
6.8
−
2.0
+
2.5
Gyr) in an eccentric (
e
= 0.151 ± 0.011) 6.984 days orbit with a mass of
6.01
−
0.23
+
0.24
M
J
and a radius of
1.091
−
0.025
+
0.028
R
J
. Our spectroscopic follow up also reveals a long-term radial velocity trend for TOI-559, indicating a long-period companion. The statistically significant orbital eccentricity measured for each system suggests that these planets migrated to their current location through dynamical interactions. Interestingly, both planets are also massive (>3
M
J
), adding to the population of massive giant planets identified by TESS. Prompted by these new detections of high-mass planets, we analyzed the known mass distribution of hot and warm Jupiters but find no significant evidence for multiple populations. TESS should provide a near magnitude-limited sample of transiting hot Jupiters, allowing for future detailed population studies.
ABSTRACT
We present the bright (Vmag = 9.12), multiplanet system TOI-431, characterized with photometry and radial velocities (RVs). We estimate the stellar rotation period to be 30.5 ± 0.7 d using ...archival photometry and RVs. Transiting Exoplanet Survey Satellite (TESS) objects of Interest (TOI)-431 b is a super-Earth with a period of 0.49 d, a radius of 1.28 ± 0.04 R⊕, a mass of 3.07 ± 0.35 M⊕, and a density of 8.0 ± 1.0 g cm−3; TOI-431 d is a sub-Neptune with a period of 12.46 d, a radius of 3.29 ± 0.09 R⊕, a mass of $9.90^{+1.53}_{-1.49}$ M⊕, and a density of 1.36 ± 0.25 g cm−3. We find a third planet, TOI-431 c, in the High Accuracy Radial velocity Planet Searcher RV data, but it is not seen to transit in the TESS light curves. It has an Msin i of $2.83^{+0.41}_{-0.34}$ M⊕, and a period of 4.85 d. TOI-431 d likely has an extended atmosphere and is one of the most well-suited TESS discoveries for atmospheric characterization, while the super-Earth TOI-431 b may be a stripped core. These planets straddle the radius gap, presenting an interesting case-study for atmospheric evolution, and TOI-431 b is a prime TESS discovery for the study of rocky planet phase curves.
Hot Jupiters are rarely accompanied by other planets within a factor of a few in orbital distance. Previously, only two such systems have been found. Here, we report the discovery of a third system ...using data from the Transiting Exoplanet Survey Satellite (TESS). The host star, TOI-1130, is an eleventh magnitude K-dwarf in Gaia G-band. It has two transiting planets: a Neptune-sized planet (3.65 0.10 ) with a 4.1 days period, and a hot Jupiter ( ) with an 8.4 days period. Precise radial-velocity observations show that the mass of the hot Jupiter is . For the inner Neptune, the data provide only an upper limit on the mass of 0.17 (3 ). Nevertheless, we are confident that the inner planet is real, based on follow-up ground-based photometry and adaptive-optics imaging that rule out other plausible sources of the TESS transit signal. The unusual planetary architecture of and the brightness of the host star make TOI-1130 a good test case for planet formation theories, and an attractive target for future spectroscopic observations.
Temperate Earth-sized exoplanets around late-M dwarfs offer a rare opportunity to explore under which conditions planets can develop hospitable climate conditions. The small stellar radius amplifies ...the atmospheric transit signature, making even compact secondary atmospheres dominated by N
or CO
amenable to characterization with existing instrumentation
. Yet, despite large planet search efforts
, detection of low-temperature Earth-sized planets around late-M dwarfs has remained rare and the TRAPPIST-1 system, a resonance chain of rocky planets with seemingly identical compositions, has not yet shown any evidence of volatiles in the system
. Here we report the discovery of a temperate Earth-sized planet orbiting the cool M6 dwarf LP 791-18. The newly discovered planet, LP 791-18d, has a radius of 1.03 ± 0.04 R
and an equilibrium temperature of 300-400 K, with the permanent night side plausibly allowing for water condensation. LP 791-18d is part of a coplanar system
and provides a so-far unique opportunity to investigate a temperate exo-Earth in a system with a sub-Neptune that retained its gas or volatile envelope. On the basis of observations of transit timing variations, we find a mass of 7.1 ± 0.7 M
for the sub-Neptune LP 791-18c and a mass of Formula: see text for the exo-Earth LP 791-18d. The gravitational interaction with the sub-Neptune prevents the complete circularization of LP 791-18d's orbit, resulting in continued tidal heating of LP 791-18d's interior and probably strong volcanic activity at the surface
.
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
Hot Jupiters—short-period giant planets—were the first extrasolar planets to be discovered, but many questions about their origin remain. NASA’s Transiting Exoplanet Survey Satellite (TESS), ...an all-sky search for transiting planets, presents an opportunity to address these questions by constructing a uniform sample of hot Jupiters for demographic study through new detections and unifying the work of previous ground-based transit surveys. As the first results of an effort to build this large sample of planets, we report here the discovery of 10 new hot Jupiters (TOI-2193A b, TOI-2207b, TOI-2236b, TOI-2421b, TOI-2567b, TOI-2570b, TOI-3331b, TOI-3540A b, TOI-3693b, TOI-4137b). All of the planets were identified as planet candidates based on periodic flux dips observed by TESS, and were subsequently confirmed using ground-based time-series photometry, high-angular-resolution imaging, and high-resolution spectroscopy coordinated with the TESS Follow-up Observing Program. The 10 newly discovered planets orbit relatively bright F and G stars (
G
< 12.5,
T
eff
between 4800 and 6200 K). The planets’ orbital periods range from 2 to 10 days, and their masses range from 0.2 to 2.2 Jupiter masses. TOI-2421b is notable for being a Saturn-mass planet and TOI-2567b for being a “sub-Saturn,” with masses of 0.322 ± 0.073 and 0.195 ± 0.030 Jupiter masses, respectively. We also measured a detectably eccentric orbit (
e
= 0.17 ± 0.05) for TOI-2207b, a planet on an 8 day orbit, while placing an upper limit of
e
< 0.052 for TOI-3693b, which has a 9 day orbital period. The 10 planets described here represent an important step toward using TESS to create a large and statistically useful sample of hot Jupiters.
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