NASA's Transiting Exoplanet Survey Satellite (TESS) presents us with an unprecedented volume of space-based photometric observations that must be analyzed in an efficient and unbiased manner. With at ...least ∼1,000,000 new light curves generated every month from full-frame images alone, automated planet candidate identification has become an attractive alternative to human vetting. Here we present a deep learning model capable of performing triage and vetting on TESS candidates. Our model is modified from an existing neural network designed to automatically classify Kepler candidates, and is the first neural network to be trained and tested on real TESS data. In triage mode, our model can distinguish transit-like signals (planet candidates and eclipsing binaries) from stellar variability and instrumental noise with an average precision (the weighted mean of precisions over all classification thresholds) of 97.0% and an accuracy of 97.4%. In vetting mode, the model is trained to identify only planet candidates with the help of newly added scientific domain knowledge, and achieves an average precision of 69.3% and an accuracy of 97.8%. We apply our model on new data from Sector 6, and present 288 new signals that received the highest scores in triage and vetting and were also identified as planet candidates by human vetters. We also provide a homogeneously classified set of TESS candidates suitable for future training.
Abstract
We present updated radial-velocity (RV) analyses of the AU Mic system. AU Mic is a young (22 Myr) early-M dwarf known to host two transiting planets—
P
b
∼ 8.46 days,
R
b
=
4.38
−
0.18
+
...0.18
R
⊕
,
P
c
∼ 18.86 days,
R
c
=
3.51
−
0.16
+
0.16
R
⊕
. With visible RVs from Calar Alto high-Resolution search for M dwarfs with Exo-earths with Near-infrared and optical echelle Spectrographs (CARMENES)-VIS, CHIRON, HARPS, HIRES, M
inerva
-Australis, and Tillinghast Reflector Echelle Spectrograph, as well as near-infrared (NIR) RVs from CARMENES-NIR, CSHELL, IRD, iSHELL, NIRSPEC, and SPIRou, we provide a 5
σ
upper limit to the mass of AU Mic c of
M
c
≤ 20.13
M
⊕
and present a refined mass of AU Mic b of
M
b
=
20.12
−
1.57
+
1.72
M
⊕
. Used in our analyses is a new RV modeling toolkit to exploit the wavelength dependence of stellar activity present in our RVs via wavelength-dependent Gaussian processes. By obtaining near-simultaneous visible and near-infrared RVs, we also compute the temporal evolution of RV “color” and introduce a regressional method to aid in isolating Keplerian from stellar activity signals when modeling RVs in future works. Using a multiwavelength Gaussian process model, we demonstrate the ability to recover injected planets at 5
σ
significance with semi-amplitudes down to ≈10 m s
−1
with a known ephemeris, more than an order of magnitude below the stellar activity amplitude. However, we find that the accuracy of the recovered semi-amplitudes is ∼50% for such signals with our model.
Abstract
Giant planets on short-period orbits are predicted to be inflated and eventually engulfed by their host stars. However, the detailed timescales and stages of these processes are not well ...known. Here, we present the discovery of three hot Jupiters (
P
< 10 days) orbiting evolved, intermediate-mass stars (
M
⋆
≈ 1.5
M
⊙
, 2
R
⊙
<
R
⋆
< 5
R
⊙
). By combining TESS photometry with ground-based photometry and radial velocity measurements, we report masses and radii for these three planets of between 0.4 and 1.8
M
J
and 0.8 and 1.8
R
J
. TOI-2337b has the shortest period (
P
= 2.99432 ± 0.00008 days) of any planet discovered around a red giant star to date. Both TOI-4329b and TOI-2669b appear to be inflated, but TOI-2337b does not show any sign of inflation. The large radii and relatively low masses of TOI-4329b and TOI-2669b place them among the lowest density hot Jupiters currently known, while TOI-2337b is conversely one of the highest. All three planets have orbital eccentricities of below 0.2. The large spread in radii for these systems implies that planet inflation has a complex dependence on planet mass, radius, incident flux, and orbital properties. We predict that TOI-2337b has the shortest orbital decay timescale of any planet currently known, but do not detect any orbital decay in this system. Transmission spectroscopy of TOI-4329b would provide a favorable opportunity for the detection of water, carbon dioxide, and carbon monoxide features in the atmosphere of a planet orbiting an evolved star, and could yield new information about planet formation and atmospheric evolution.
Abstract
Mapping the orbital obliquity distribution of young planets is one avenue toward understanding mechanisms that sculpt the architectures of planetary systems. TOI-942 is a young field star, ...with an age of ∼60 Myr, hosting a planetary system consisting of two transiting Neptune-sized planets in 4.3 and 10.1 day period orbits. We observed the spectroscopic transits of the inner Neptune TOI-942b to determine its projected orbital obliquity angle. Through two partial transits, we find the planet to be in a prograde orbit, with a projected obliquity angle of
∣
λ
∣
=
1
−
33
+
41
deg. In addition, incorporating the light curve and the stellar rotation period, we find the true 3D obliquity to be
2
−
23
+
27
deg. We explored various sources of uncertainties specific to the spectroscopic transits of planets around young active stars, and showed that our reported obliquity uncertainty fully encompassed these effects. TOI-942b is one of the youngest planets to have its obliquity characterized, and one of even fewer residing in a multi-planet system. The prograde orbital geometry of TOI-942b is in line with systems of similar ages, none of which have yet been identified to be in strongly misaligned orbits.
We report on the discovery and characterization of three planets orbiting the F8 star HD 28109, which sits comfortably in TESS ’s continuous viewing zone. The two outer planets have periods of 56 . ...0067 ±0 . 0003 d and 84 . 2597 + 0 . 0010 −0 . 0008 d, which implies a period ratio very close to that of the first-order 3:2 mean motion resonance, exciting transit timing variations (TTVs) of up to 60 min. These two planets were first identified by TESS , and we identified a third planet in the TESS photometry with a period of 22 . 8911 ±0 . 0004 d. We confirm the planetary nature of all three planetary candidates using ground-based photometry from Hazelwood , ASTEP , and LCO , including a full detection of the ∼9 h transit of HD 28109 c from Antarctica. The radii of the three planets are R b = 2 . 199 + 0 . 098 −0 . 10 R ⊕, R c = 4 . 23 ±0 . 11 R ⊕, and R d = 3 . 25 ±0 . 11 R ⊕; we characterize their masses using TTVs and precise radial velocities from ESPRESSO and HARPS, and find them to be M b = 18 . 5 + 9 . 1 −7 . 6 M ⊕, M c = 7 . 9 + 4 . 2 −3 . 0 M ⊕, and M d = 5 . 7 + 2 . 7 −2 . 1 M ⊕, making planet b a dense, massive planet while c and d are both underdense. We also demonstrate that the two outer planets are ripe for atmospheric characterization using transmission spectroscopy, especially given their position in the CVZ of James Webb Space Telescope . The data obtained to date are consistent with resonant (librating) and non-resonant (circulating) solutions; additional observations will show whether the pair is actually locked in resonance or just near-resonant.
Abstract
While the population of confirmed exoplanets continues to grow, the sample of confirmed transiting planets around evolved stars is still limited. We present the discovery and confirmation of ...a hot Jupiter orbiting TOI-2184 (TIC 176956893), a massive evolved subgiant (
M
⋆
= 1.53 ± 0.12
M
⊙
,
R
⋆
= 2.90 ± 0.14
R
⊙
) in the Transiting Exoplanet Survey Satellite (TESS) Southern Continuous Viewing Zone. The planet was flagged as a false positive by the TESS Quick-Look Pipeline due to periodic systematics introducing a spurious depth difference between even and odd transits. Using a new pipeline to remove background scattered light in TESS Full Frame Image data, we combine space-based TESS photometry, ground-based photometry, and ground-based radial velocity measurements to report a planet radius of
R
p
= 1.017 ± 0.051
R
J
and mass of
M
p
= 0.65 ± 0.16
M
J
. For a planet so close to its star, the mass and radius of TOI-2184b are unusually well matched to those of Jupiter. We find that the radius of TOI-2184b is smaller than theoretically predicted based on its mass and incident flux, providing a valuable new constraint on the timescale of post-main-sequence planet inflation. The discovery of TOI-2184b demonstrates the feasibility of detecting planets around faint (TESS magnitude > 12) post-main-sequence stars and suggests that many more similar systems are waiting to be detected in the TESS FFIs, whose confirmation may elucidate the final stages of planetary system evolution.
ABSTRACT We report the discovery of a new Kepler transiting circumbinary planet (CBP). This latest addition to the still-small family of CBPs defies the current trend of known short-period planets ...orbiting near the stability limit of binary stars. Unlike the previous discoveries, the planet revolving around the eclipsing binary system Kepler-1647 has a very long orbital period (∼1100 days) and was at conjunction only twice during the Kepler mission lifetime. Due to the singular configuration of the system, Kepler-1647b is not only the longest-period transiting CBP at the time of writing, but also one of the longest-period transiting planets. With a radius of 1.06 0.01 RJup, it is also the largest CBP to date. The planet produced three transits in the light curve of Kepler-1647 (one of them during an eclipse, creating a syzygy) and measurably perturbed the times of the stellar eclipses, allowing us to measure its mass, 1.52 0.65 MJup. The planet revolves around an 11-day period eclipsing binary consisting of two solar-mass stars on a slightly inclined, mildly eccentric (ebin = 0.16), spin-synchronized orbit. Despite having an orbital period three times longer than Earth's, Kepler-1647b is in the conservative habitable zone of the binary star throughout its orbit.
We report the discovery of the first hot Jupiter in the Hyades open cluster. HD 285507b orbits a V = 10.47 K4.5V dwarf (M sub(*) = 0.734 M sub(middot in circle); R sub(*) = 0.656 R sub(middot in ...circle)) in a slightly eccentric (e = 0.086 super(+0.018) sub(-0.019) ) orbit with a period of 6.0881 super(+0.0019) sub(-0.0018) days. The induced stellar radial velocity corresponds to a minimum companion mass of M sub(p) sin i = 0.917 + or - 0.033 M sub(Jup). Line bisector spans and stellar activity measures show no correlation with orbital phase, and the radial velocity amplitude is independent of wavelength, supporting the conclusion that the variations are caused by a planetary companion. Follow-up photometry indicates with high confidence that the planet does not transit. HD 285507b joins a small but growing list of planets in open clusters, and its existence lends support to a planet formation scenario in which a high stellar space density does not inhibit giant planet formation and migration. We calculate the circularization timescale for HD 285507b to be larger than the age of the Hyades, which may indicate that this planet's non-zero eccentricity is the result of migration via interactions with a third body. We also demonstrate a significant difference between the eccentricity distributions of hot Jupiters that have had time to tidally circularize and those that have not, which we interpret as evidence against Type II migration in the final stages of hot Jupiter formation. Finally, the dependence of the circularization timescale on the planetary tidal quality factor, Q sub(p), allows us to constrain the average value for hot Jupiters to be log Q sub(p) = 6.14 super(+0.41) sub(-0.25).
Abstract We report the confirmation of a TESS-discovered transiting super-Earth planet orbiting a mid-G star, HD 307842 (TOI-784). The planet has a period of 2.8 days, and the radial velocity (RV) ...measurements constrain the mass to be 9.67 − 0.82 + 0.83 M ⊕ . We also report the discovery of an additional planet candidate on an outer orbit that is most likely nontransiting. The possible periods of the planet candidate are approximately 20–63 days, with the corresponding RV semiamplitudes expected to range from 3.2 to 5.4 m s −1 and minimum masses from 12.6 to 31.1 M ⊕ . The radius of the transiting planet (planet b) is 1.93 − 0.09 + 0.11 R ⊕ , which results in a mean density of 7.4 − 1.2 + 1.4 g cm − 3 suggesting that TOI-784 b is likely to be a rocky planet though it has a comparable radius to a sub-Neptune. We found TOI-784 b is located at the lower edge of the so-called “radius valley” in the radius versus insolation plane, which is consistent with the photoevaporation or core-powered mass-loss prediction. The TESS data did not reveal any significant transit signal of the planet candidate, and our analysis shows that the orbital inclinations of planet b and the planet candidate are 88.60 ° − 0.86 + 0.84 and ≤88.°3–89.°2, respectively. More RV observations are needed to determine the period and mass of the second object, and search for additional planets in this system.
Abstract
With data from the Transiting Exoplanet Survey Satellite (TESS), we showcase improvements to the MIT Quick Look Pipeline (QLP) through the discovery and validation of a multiplanet system ...around M dwarf TOI 4342 (
T
mag
= 11.032,
M
⋆
= 0.63
M
⊙
,
R
⋆
= 0.60
R
⊙
,
T
eff
= 3900 K,
d
= 61.54 pc). With updates to QLP, including a new multiplanet search, as well as faster cadence data from TESS’s First Extended Mission, we discovered two sub-Neptunes (
R
b
=
2.266
−
0.038
+
0.038
R
⊕
and
R
c
=
2.415
−
0.040
+
0.043
R
⊕
;
P
b
= 5.538 days and
P
c
= 10.689 days) and validated them with ground-based photometry, spectra, and speckle imaging. Both planets notably have high transmission spectroscopy metrics of 36 and 32, making TOI 4342 one of the best systems for comparative atmospheric studies. This system demonstrates how improvements to QLP, along with faster cadence full-frame images, can lead to the discovery of new multiplanet systems.
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