Space-based missions such as Kepler, and soon the Transiting Exoplanet Survey Satellite (TESS), provide large data sets that must be analyzed efficiently and systematically. Recent work by Shallue & ...Vanderburg successfully used state-of-the-art deep learning models to automatically classify Kepler transit signals as either exoplanets or false positives; our application of their model yielded 95.8% accuracy and 95.5% average precision. Here we expand upon that work by including additional scientific domain knowledge into the network architecture and input representations to significantly increase overall model performance to 97.5% accuracy and 98.0% average precision. Notably, we achieve 15%-20% gains in recall for the lowest signal-to-noise transits that can correspond to rocky planets in the habitable zone. We input into the network centroid time-series information derived from Kepler data plus key stellar parameters taken from the Kepler data release 25 catalog. We also implement data augmentation techniques to alleviate model over-fitting. These improvements allow us to drastically reduce the size of the model, while still maintaining improved performance; smaller models are better for generalization, for example from Kepler to TESS data. This Letter illustrates the importance of including expert domain knowledge in even state-of-the-art deep learning models when applying them to scientific research problems that seek to identify weak signals in noisy data. This classification tool will be especially useful for upcoming space-based photometry missions focused on finding small planets, such as TESS and PLATO.
KELT-9 b is an ultra-hot Jupiter transiting a rapidly rotating, oblate early-A-type star in a polar orbit. We model the effect of rapid stellar rotation on KELT-9 b's transit light curve using ...photometry from the Transiting Exoplanet Survey Satellite to constrain the planet's true spin-orbit angle and to explore how KELT-9 b may be influenced by stellar gravity darkening. We constrain the host star's equatorial radius to be 1.089 0.017 times as large as its polar radius and its local surface brightness to vary by ∼38% between its hot poles and cooler equator. We model the stellar oblateness and surface brightness gradient and find that it causes the transit light curve to lack the usual symmetry around the time of minimum light. We take advantage of the light-curve asymmetry to constrain KELT-9 b's true spin-orbit angle ( ), agreeing with Gaudi et al. that KELT-9 b is in a nearly polar orbit. We also apply a gravity-darkening correction to the spectral energy distribution model from Gaudi et al. and find that accounting for rapid rotation gives a better fit to available spectroscopy and yields a more reliable estimate for the star's polar effective temperature.
The Next Generation Transit Survey (NGTS) Wheatley, Peter J; West, Richard G; Goad, Michael R ...
Monthly notices of the Royal Astronomical Society,
04/2018, Volume:
475, Issue:
4
Journal Article
Peer reviewed
Open access
Abstract
We describe the Next Generation Transit Survey (NGTS), which is a ground-based project searching for transiting exoplanets orbiting bright stars. NGTS builds on the legacy of previous ...surveys, most notably WASP, and is designed to achieve higher photometric precision and hence find smaller planets than have previously been detected from the ground. It also operates in red light, maximizing sensitivity to late K and early M dwarf stars. The survey specifications call for photometric precision of 0.1 per cent in red light over an instantaneous field of view of 100 deg2, enabling the detection of Neptune-sized exoplanets around Sun-like stars and super-Earths around M dwarfs. The survey is carried out with a purpose-built facility at Cerro Paranal, Chile, which is the premier site of the European Southern Observatory (ESO). An array of twelve 20 cm f/2.8 telescopes fitted with back-illuminated deep-depletion CCD cameras is used to survey fields intensively at intermediate Galactic latitudes. The instrument is also ideally suited to ground-based photometric follow-up of exoplanet candidates from space telescopes such as TESS, Gaia and PLATO. We present observations that combine precise autoguiding and the superb observing conditions at Paranal to provide routine photometric precision of 0.1 per cent in 1 h for stars with I-band magnitudes brighter than 13. We describe the instrument and data analysis methods as well as the status of the survey, which achieved first light in 2015 and began full-survey operations in 2016. NGTS data will be made publicly available through the ESO archive.
Abstract
While secondary mass inferences based on single-lined spectroscopic binary (SB1) solutions are subject to
sin
i
degeneracies, this degeneracy can be lifted through the observations of ...eclipses. We combine the subset of Gaia Data Release 3 SB1 solutions consistent with brown dwarf-mass secondaries with the Transiting Exoplanet Survey Satellite (TESS) Object of Interest (TOI) list to identify three candidate transiting brown dwarf systems. Ground-based precision radial velocity follow-up observations confirm that TOI-2533.01 is a transiting brown dwarf with
M
=
72
−
3
+
3
M
Jup
=
0.069
−
0.003
+
0.003
M
⊙
orbiting TYC 2010-124-1 and that TOI-5427.01 is a transiting very low-mass star with
M
=
93
−
2
+
2
M
Jup
=
0.088
−
0.002
+
0.002
M
⊙
orbiting UCAC4 515-012898. We validate TOI-1712.01 as a very low-mass star with
M
=
82
−
7
+
7
M
Jup
=
0.079
−
0.007
+
0.007
M
⊙
transiting the primary in the hierarchical triple system BD+45 1593. Even after accounting for third light, TOI-1712.01 has a radius nearly a factor of 2 larger than predicted for isolated stars with similar properties. We propose that the intense instellation experienced by TOI-1712.01 diminishes the temperature gradient near its surface, suppresses convection, and leads to its inflated radius. Our analyses verify Gaia DR3 SB1 solutions in the low Doppler semiamplitude limit, thereby providing the foundation for future joint analyses of Gaia radial velocities and Kepler, K2, TESS, and PLAnetary Transits and Oscillations light curves for the characterization of transiting massive brown dwarfs and very low-mass stars.
Abstract
The fate of planets around rapidly evolving stars is not well understood. Previous studies have suggested that, relative to the main-sequence population, planets transiting evolved stars (
P
...< 100 days) tend to have more eccentric orbits. Here we present the discovery of TOI-4582 b, a
0.94
−
0.12
+
0.09
R
J
, 0.53 ± 0.05
M
J
planet orbiting an intermediate-mass subgiant star every 31.034 days. We find that this planet is also on a significantly eccentric orbit (
e
= 0.51 ± 0.05). We then compare the population of planets found transiting evolved (log
g
< 3.8) stars to the population of planets transiting main-sequence stars. We find that the rate at which median orbital eccentricity grows with period is significantly higher for evolved star systems than for otherwise similar main-sequence systems. In general, we observe that mean planet eccentricity 〈
e
〉 =
a
+
b
log
10
(
P
) for the evolved population with significant orbital eccentricity where
a
= −0.18 ± 0.08 and
b
= 0.38 ± 0.06, significantly distinct from the main-sequence planetary system population. This trend is seen even after controlling for stellar mass and metallicity. These systems do not appear to represent a steady evolution pathway from eccentric, long-period planetary orbits to circular, short-period orbits, as orbital model comparisons suggest that inspiral timescales are uncorrelated with orbital separation or eccentricity. Characterization of additional evolved planetary systems will distinguish effects of stellar evolution from those of stellar mass and composition.
ABSTRACT
We report the discovery of two exoplanets orbiting around HD 212729 (TOI 1052, TIC 317060587), a Teff = 6146 K star with V = 9.51 observed by TESS in Sectors 1 and 13. One exoplanet, ...TOI-1052b, is Neptune-mass and transits the star, and an additional planet TOI-1052c is observed in radial velocities but not seen to transit. We confirm the planetary nature of TOI-1052b using precise radial velocity observations from HARPS and determined its parameters in a joint RV and photometry analysis. TOI-1052b has a radius of $2.87^{+0.29}_{-0.24}$ R⊕, a mass of 16.9 ± 1.7 M⊕, and an orbital period of 9.14 d. TOI-1052c does not show any transits in the TESS data, and has a minimum mass of $34.3^{+4.1}_{-3.7}$ M⊕ and an orbital period of 35.8 d, placing it just interior to the 4:1 mean-motion resonance. Both planets are best fit by relatively high but only marginally significant eccentricities of $0.18^{+0.09}_{-0.07}$ for planet b and $0.24^{+0.09}_{-0.08}$ for planet c. We perform a dynamical analysis and internal structure model of the planets as well as deriving stellar parameters and chemical abundances. The mean density of TOI-1052b is $3.9^{+1.7}_{-1.3}$ g cm−3 consistent with an internal structure similar to Neptune. A nearby star is observed in Gaia DR3 with the same distance and proper motion as TOI-1052, at a sky projected separation of $\scriptstyle \sim$1500 au, making this a potential wide binary star system.
Abstract
We report the discovery and validation of two long-period giant exoplanets orbiting the early K dwarf TOI-4600 (
V
= 12.6,
T
= 11.9), first detected using observations from the Transiting ...Exoplanet Survey Satellite (TESS) by the TESS Single Transit Planet Candidate Working Group. The inner planet, TOI-4600 b, has a radius of 6.80 ± 0.31
R
⊕
and an orbital period of 82.69 days. The outer planet, TOI-4600 c, has a radius of 9.42 ± 0.42
R
⊕
and an orbital period of 482.82 days, making it the longest-period confirmed or validated planet discovered by TESS to date. We combine TESS photometry and ground-based spectroscopy, photometry, and high-resolution imaging to validate the two planets. With equilibrium temperatures of 347 K and 191 K, respectively, TOI-4600 b and c add to the small but growing population of temperate giant exoplanets that bridge the gap between hot/warm Jupiters and the solar system’s gas giants. TOI-4600 is a promising target for further transit and precise RV observations to measure the masses and orbits of the planets as well as search for additional nontransiting planets. Additionally, with Transit Spectroscopy Metric values of ∼30, both planets are amenable for atmospheric characterization with JWST. Together, these will lend insight into the formation and evolution of planet systems with multiple giant exoplanets.
ABSTRACT
Discovering transiting exoplanets with long orbital periods allows us to study warm and cool planetary systems with temperatures similar to the planets in our own Solar system. The ...Transiting Exoplanet Survey Satellite (TESS) mission has photometrically surveyed the entire Southern Ecliptic Hemisphere in Cycle 1 (2018 August–2019 July), Cycle 3 (2020 July–2021 June), and Cycle 5 (2022 September–2023 September). We use the observations from Cycle 1 and Cycle 3 to search for exoplanet systems that show a single transit event in each year, which we call duotransits. The periods of these planet candidates are typically in excess of 20 d, with the lower limit determined by the duration of individual TESS observations. We find 85 duotransit candidates, which span a range of host star brightnesses: 8 < Tmag < 14, transit depths between 0.1 per cent and 1.8 per cent, and transit durations between 2 and 10 h with the upper limit determined by our normalization function. Of these candidates, 25 are already known, and 60 are new. We present these candidates along with the status of photometric and spectroscopic follow-up.
Aims. The K2 mission has recently begun to discover new and diverse planetary systems. In December 2014, Campaign 1 data from the mission was released, providing high-precision photometry for ~22 000 ...objects over an 80-day timespan. We searched these data with the aim of detecting more important new objects. Methods. Our search through two separate pipelines led to the independent discovery of K2-19b and c, a two-planet system of Neptune-sized objects (4.2 and 7.2 R⊕), orbiting a K dwarf extremely close to the 3:2 mean motion resonance. The two planets each show transits, sometimes simultaneously owing to their proximity to resonance and the alignment of conjunctions. Results. We obtained further ground-based photometry of the larger planet with the NITES telescope, demonstrating the presence of large transit timing variations (TTVs), and used the observed TTVs to place mass constraints on the transiting objects under the hypothesis that the objects are near but not in resonance. We then statistically validated the planets through the PASTIS tool, independently of the TTV analysis.
Full text
Available for:
FMFMET, NUK, UL, UM, UPUK
ABSTRACT
The Transiting Exoplanet Survey Satellite has produced a large number of single-transit event candidates which are being monitored by the Next Generation Transit Survey (NGTS). We observed a ...second epoch for the TIC-231005575 system (Tmag = 12.06 and $T_{\rm eff} = 5500 \pm 85\, \mathrm{ K}$) with NGTS and a third epoch with Las Cumbres Observatory’s telescope in South Africa to constrain the orbital period ($P = 61.777\, \mathrm{ d}$). Subsequent radial velocity measurements with CORALIE revealed the transiting object has a mass of M2 = 0.128 ± 0.003 M⊙, indicating the system is a G-M binary. The radius of the secondary is R2 = 0.154 ± 0.008 R⊙ and is consistent with mesa models of stellar evolution to better than 1σ.
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