TESS News and Results

TOI-1842b: A Transiting Warm Saturn Undergoing Re-Inflation around an Evolving Subgiant

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The imminent launch of space telescopes designed to probe the atmospheres of exoplanets has prompted new efforts to prioritise the thousands of transiting planet candidates for follow-up characterisation. We report the detection and confirmation of TOI-1842b, a warm Saturn identified by TESS and confirmed with ground-based observations from Minerva-Australis, NRES, and the Las Cumbres Observatory Global Telescope. This planet has a radius of 1.04+0.06−0.05RJup, a mass of 0.214+0.040−0.038MJup, an orbital period of 9.5739+0.0002−0.0001 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 characterisation. As the host star is beginning to evolve off the main sequence, TOI-1842b presents an excellent opportunity to test models of gas giant re-inflation. The primary transit duration of only 4.3 hours also makes TOI-1842b an easily-schedulable target for further ground-based atmospheric characterisation.

Plus... the "Ironclad", a new really dense exoplanet in Vela

GJ 367b: A dense, ultrashort-period sub-Earth planet transiting a nearby red dwarf star

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The mass and radius of an exoplanet determine its mean density, which provides information about the possible interior structure. Lam et al. have identified a planet on a 7.7-hour orbit around a nearby red dwarf star. The authors determined the planet’s radius from the transit, then used radial velocity observations to measure the mass. They found a sub-Earth–sized planet with a density almost equivalent to pure iron. Its high surface temperature is close to the vaporization point of iron, suggesting that it is the iron core of a planet that has lost its outer mantle.

Aka TOI-731. Featuring in EPE before arXiv preprint.

UPDATE: now on Arxiv too.

There is artwork too!

Sirius_Alpha wrote:

A Super-Earth and two sub-Neptunes transiting the bright, nearby, and quiet M-dwarf TOI-270
https://arxiv.org/abs/1903.06107

Quote :

We report the Transiting Exoplanet Survey Satellite (TESS) discovery of three small planets transiting one of the brightest (K-mag 8.3) and nearest (22.5 parsec) M-dwarf hosts to date, TOI-270 (TIC 259377017). The system is observationally favourable, and can be exceptionally well characterised over the next few years. The M3V-type star is transited by the Super-Earth-sized TOI-270b (1.25 Rearth) and the sub-Neptune-sized exoplanets TOI-270 c (2.42 Rearth) and TOI-270 d (2.13 Rearth). The planet configuration is close to a mean-motion resonant chain, with the orbital periods (3.36, 5.66, and 11.38 days) near ratios of small integers (5:3 and 2:1). Notably, the equilibrium temperature of the outer planet (340 K) lies within the survivable range for extremophile organisms. TOI-270 will be a prime target for future studies since: 1) its near-resonance allows the detection of transit timing variations (TTVs) for precise mass measurements and detailed dynamical studies; 2) its brightness enables independent radial velocity (RV) mass measurements; 3) the outer planets are ideal for atmospheric characterisation via transmission spectroscopy with the James Webb Space Telescope (JWST); and 4) the quiet host star is well suited for future searches of terrestrial planets within the habitable zone. Altogether, very few systems with temperate small exoplanets are as suitable for complementary characterisation by TTVs, RVs and transmission spectroscopy as TOI-270.

An update for TOI-270 system

Transit Timings Variations in the three-planet system: TOI-270

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We present ground and space-based photometric observations of TOI-270 (L231-32), a system of three transiting planets consisting of one super-Earth and two sub-Neptunes discovered by TESS around a bright (K-mag=8.25) M3V dwarf. The planets orbit near low-order mean-motion resonances (5:3 and 2:1), and are thus expected to exhibit large transit timing variations (TTVs). Following an extensive observing campaign using 8 different observatories between 2018 and 2020, we now report a clear detection of TTVs for planets c and d, with amplitudes of ∼10 minutes and a super-period of ∼3 years, as well as significantly refined estimates of the radii and mean orbital periods of all three planets. Dynamical modeling of the TTVs alone puts strong constraints on the mass ratio of planets c and d and on their eccentricities. When incorporating recently published constraints from radial velocity observations, we obtain masses of Mb=1.48±0.18M⊕⁠, Mc=6.20±0.31M⊕ and Md=4.20±0.16M⊕ for planets b, c and d, respectively. We also detect small, but significant eccentricities for all three planets : eb = 0.0167 ± 0.0084, ec = 0.0044 ± 0.0006 and ed = 0.0066 ± 0.0020. Our findings imply an Earth-like rocky composition for the inner planet, and Earth-like cores with an additional He/H2O atmosphere for the outer two. TOI-270 is now one of the best-constrained systems of small transiting planets, and it remains an excellent target for atmospheric characterization.

An eccentric Brown Dwarf eclipsing an M dwarf

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We report the discovery of a M=67±2M_J brown dwarf transiting the early M dwarf TOI-2119 on an eccentric orbit (e=0.3362±0.0005) at an orbital period of 7.200861±0.000005 days. We confirm the brown dwarf nature of the transiting companion using a combination of ground-based and space-based photometry and high-precision velocimetry from the Habitable-zone Planet Finder. Detection of the secondary eclipse with TESS photometry enables a precise determination of the eccentricity and reveals the brown dwarf has a brightness temperature of 2100±80 K, a value which is consistent with an early L dwarf. TOI-2119 is one of the most eccentric known brown dwarfs with P<10 days, possibly due to the long circularization timescales for an object orbiting an M dwarf. We assess the prospects for determining the obliquity of the host star to probe formation scenarios and the possibility of additional companions in the system using Gaia EDR3 and our radial velocities.

Although dealing with a WASP planet, these results are from TESS...

Is there a WASP-4 c?

Characterizing the WASP-4 system with TESS and radial velocity data: Constraints on the cause of the hot Jupiter's changing orbit and evidence of an outer planet

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Orbital dynamics provide valuable insights into the evolution and diversity of exoplanetary systems. Currently, only one hot Jupiter, WASP-12b, is confirmed to have a decaying orbit. Another, WASP-4b, exhibits hints of a changing orbital period that could be caused by orbital decay, apsidal precession, or the acceleration of the system towards the Earth. We have analyzed all data sectors from NASA's Transiting Exoplanet Survey Satellite together with all radial velocity (RV) and transit data in the literature to characterize WASP-4b's orbit. Our analysis shows that the full RV data set is consistent with no acceleration towards the Earth. Instead, we find evidence of a possible additional planet in the WASP-4 system, with an orbital period of ~7000 days and Mcsin(i) of 5.47+0.44−0.43MJup. Additionally, we find that the transit timing variations of all of the WASP-4b transits cannot be explained by the second planet but can be explained with either a decaying orbit or apsidal precession, with a slight preference for orbital decay. Assuming the decay model is correct, we find an updated period of 1.338231587±0.000000022 days, a decay rate of -7.33±0.71 msec/year, and an orbital decay timescale of 15.77±1.57 Myr. If the observed decay results from tidal dissipation, we derive a modified tidal quality factor of Q′∗ = 5.1±0.9×104, which is an order of magnitude lower than values derived for other hot Jupiter systems. However, more observations are needed to determine conclusively the cause of WASP-4b's changing orbit and confirm the existence of an outer companion.

TOI 560 : Two Transiting Planets Orbiting a K Dwarf Validated with iSHELL, PFS and HIRES RVs
https://arxiv.org/abs/2112.13448

A pair of Sub-Neptunes transiting the bright K-dwarf TOI-1064 characterised with CHEOPS
https://arxiv.org/abs/2201.03570

TESS Giants Transiting Giants II: The hottest Jupiters orbiting evolved stars
https://arxiv.org/abs/2201.04140

The TESS-Keck Survey. VIII. Confirmation of a Transiting Giant Planet on an Eccentric 261 day Orbit with the Automated Planet Finder Telescope
https://arxiv.org/abs/2201.04146

Two gas giants transiting M dwarfs confirmed with HPF and NEID

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We confirm the planetary nature of two gas giants discovered by TESS. TOI-3714 (V=15.24, J=11.74) is an M2 dwarf hosting a hot Jupiter (Mp=0.70±0.03 MJ and Rp=1.01±0.03 RJ) on an orbital period of 2.154849±0.000001 days with a resolved white dwarf companion. TOI-3629 (V=14.63, J=11.42) is an M1 dwarf hosting a hot Jupiter (Mp=0.26±0.02 MJ and Rp=0.74±0.02 RJ) on an orbital period of 3.936551+0.000005−0.000006 days. We characterize both transiting companions using a combination of ground-based and space-based photometry, speckle imaging, and high-precision velocimetry from the Habitable-zone Planet Finder and the NEID spectrographs. These systems are amenable to additional characterization with transmission spectroscopy to probe atmospheric chemistry and, for TOI-3714, obliquity measurements to probe formation scenarios.

Several new TESS planets added at EPE lately:

Validation of 13 Hot and Potentially Terrestrial TESS Planets

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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 (Rp ∼ 0.6–2.0R⊕) and orbit stars of various magnitudes (Ks = 5.78–10.78, V = 8.4–15.69) and effective temperatures (Teff ∼ 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 Rp < 2 R⊕.

And what about adding TOI-2119 too?

Further confirmation of previously announced "TOIs" with two additions, TOI-1268 b and TOI-1442 b

TOI-1268b: the youngest hot Saturn-mass transiting exoplanet

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We report the discovery of TOI-1268b, a transiting Saturn-mass planet from the TESS space mission. With an age below one Gyr, derived from various age indicators, TOI-1268b is the youngest Saturn-mass planet known to date and contributes to the small sample of well characterised young planets. It has a slightly eccentric orbit (e=0.092±0.035), an orbital period of P=8.1577080±0.0000044 days, and transits an early K dwarf star with a mass of M⋆=0.96±0.04M⊙, a radius of R⋆=0.92±0.06R⊙, an effective temperature of Teff=5300±100 K, and a metallicity of 0.36±0.06 dex. By combining TESS photometry with high-resolution spectra acquired with the Tull spectrograph at McDonald observatory, and the high-resolution spectrographs at Tautenburg and Ondrejov observatories, we measured a planetary mass of Mp=96.4±8.3M⊕ and a radius of Rp=9.1±0.6R⊕. TOI-1268 is an ideal system to study the role of star-planet tidal interactions for non-inflated Saturn-mass planets. We used system parameters derived in this paper to constrain the planet tidal quality factor to the range of 104.5−4.9. When compared with the sample of other non-inflated Saturn-mass planets, TOI-1268b is one of the best candidates for transmission spectroscopy studies.

TOI-1442 b and TOI-2445 b: two ultra-short period super-Earths around M dwarfs

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Context. Exoplanets with orbital periods of less than one day are know as Ultra-short period (USP) planets. They are relatively rare products of planetary formation and evolution processes, but especially favourable to current planet detection methods. At the time of writing, 120 USP planets have already been confirmed. Aims. We aim to confirm the planetary nature of two new transiting planet candidates announced by the NASA's Transiting Exoplanet Survey Satellite (TESS), registered as TESS Objects of Interest (TOIs) TOI-1442.01 and TOI-2445.01. Methods. We use the TESS data, ground-based photometric light-curves and Subaru/IRD spectrograph radial velocity (RV) measurements to validate both planetary candidates and to establish their physical properties. Results. TOI-1442 b is a hot super-Earth with an orbital period of P=0.4090682±0.0000004d, a radius of Rp=1.27+0.50−0.44R⊕, equilibrium temperature of Tp,eq=1359+49−42K, and a mass Mp<18M⊕ at 3σ. TOI-2445 b is also a hot super-Earth/mini-Neptune with an orbital period of P=0.3711286±0.0000004d, a radius of Rp=1.52+1.20−0.26R⊕, equilibrium temperature of Tp,eq=1332+61−57K, and a mass Mp<38M⊕ at 3σ. Their physical properties align with current empirical trends and formation theories of USP planets. More RV measurements will be useful to constrain the planetary masses and mean densities, as well as the predicted presence of outer planetary companions.

The both have been listed at EPE but the latter, TOI-1442 b, as "candidate", yet authors state that it's confirmed. I don't understand...

A new Earth-sized (but not Earth-like) planet from TESS

Discovery and mass measurement of the hot, transiting, Earth-sized planet GJ 3929 b

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We report the discovery of GJ 3929 b, a hot Earth-sized planet orbiting the nearby M3.5 V dwarf star, GJ 3929 (G 180--18, TOI-2013). Joint modelling of photometric observations from TESS sectors 24 and 25 together with 73 spectroscopic observations from CARMENES and follow-up transit observations from SAINT-EX, LCOGT, and OSN yields a planet radius of Rb=1.150+/−0.040 Rearth, a mass of Mb=1.21+/−0.42 Mearth, and an orbital period of Pb=2.6162745+/−0.0000030 d. The resulting density of ρb=4.4+/−1.6 g/cm−3 is compatible with the Earth's mean density of about 5.5 g/cm−3. Due to the apparent brightness of the host star (J=8.7 mag) and its small size, GJ 3929 b is a promising target for atmospheric characterisation with the JWST. Additionally, the radial velocity data show evidence for another planet candidate with P[c]=14.303+/−0.035 d, which is likely unrelated to the stellar rotation period, Prot=122+/−13 d, which we determined from archival HATNet and ASAS-SN photometry combined with newly obtained TJO data.

A temperate sub-Neptune at TOI-1759

TOI-1759 b: a transiting sub-Neptune around a low mass star characterized with SPIRou and TESS
https://arxiv.org/abs/2202.01259

A transiting, temperate mini-Neptune orbiting the M dwarf TOI-1759 unveiled by TESS
https://arxiv.org/abs/2202.01240

TESS discoveries at almost daily rate, wow!

Moreover we're getting very close to 5,000 exoplanets.

(actually my own personal exoplanet list also including young BDs, rogue planets, timing detected circumbinary objects and degenerate WD/NS systems is already far beyond that threshold...).

TOIs with stellar companions

Stellar Companions to TESS Objects of Interest: A Test of Planet-Companion Alignment

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We present a catalog of stellar companions to host stars of TESS Objects of Interest (TOIs) identified from a marginalized likelihood ratio test that incorporates astrometric data from the Gaia Early Data Release 3 catalog (EDR3). The likelihood ratio is computed using a probabilistic model that incorporates parallax and proper motion covariances and marginalizes the distances and 3D velocities of stars in order to identify comoving stellar pairs. We find 172 comoving companions to 170 non-false positive TOI hosts, consisting of 168 systems with two stars and 2 systems with three stars. Amongst the 170 TOI hosts, 54 harbor confirmed planets that span a wide range of system architectures. We conduct an investigation of the mutual inclinations between the stellar companion and planetary orbits using Gaia EDR3, which is possible because transiting exoplanets must orbit within the line-of-sight, thus stellar companion kinematics can constrain mutual inclinations. While the statistical significance of the current sample is weak, we find that 73+14−20% of systems with Kepler-like architectures (RP ≤ 4 R⊕ and a < 1 AU) appear to favor a non-isotropic orientation between the planetary and companion orbits with a typical mutual inclination α of 35 ± 24∘. In contrast, 65+20−35% of systems with close-in giants (P < 10 days and RP > 4 R⊕) favor a perpendicular geometry (α= 89 ± 21∘) between the planet and companion. Moreover, the close-in giants with large stellar obliquities (planet-host misalignment) are also those that favor significant planet-companion misalignment.

Among planet candidates two confirmed systems (TOI-488 and TOI-1203) turn out to be double. But the latter one is unpublished, right?

Interesting paper also announcing a second planet in NGTS-11 system from TTV (and it seems to be transiting too being labelled and listed as TOI-1847.02)

TESS Transit Timing of Hundreds of Hot Jupiters

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We provide a database of transit times and updated ephemerides for 382 planets based on data from the NASA Transiting Exoplanet Survey Satellite (TESS) and previously reported transit times which were scraped from the literature in a semi-automated fashion. In total, our database contains 8,667 transit timing measurements for 382 systems. About 240 planets in the catalog are hot Jupiters (i.e. planets with mass >0.3MJup and period <10 days) that have been observed by TESS. The new ephemerides are useful for scheduling follow-up observations and searching for long-term period changes. WASP-12 remains the only system for which a period change is securely detected. We remark on other cases of interest, such as a few systems with suggestive (but not yet convincing) evidence for period changes, and the detection of a second transiting planet in the NGTS-11 system. The compilation of light curves, transit times, ephemerides, and timing residuals are made available online, along with the Python code that generated them.

Edasich wrote:

An eccentric Brown Dwarf eclipsing an M dwarf

Quote :

We report the discovery of a M=67±2M_J brown dwarf transiting the early M dwarf TOI-2119 on an eccentric orbit (e=0.3362±0.0005) at an orbital period of 7.200861±0.000005 days. We confirm the brown dwarf nature of the transiting companion using a combination of ground-based and space-based photometry and high-precision velocimetry from the Habitable-zone Planet Finder. Detection of the secondary eclipse with TESS photometry enables a precise determination of the eccentricity and reveals the brown dwarf has a brightness temperature of 2100±80 K, a value which is consistent with an early L dwarf. TOI-2119 is one of the most eccentric known brown dwarfs with P<10 days, possibly due to the long circularization timescales for an object orbiting an M dwarf. We assess the prospects for determining the obliquity of the host star to probe formation scenarios and the possibility of additional companions in the system using Gaia EDR3 and our radial velocities.

Seemingly repetita iuvant...

TOI-2119: A transiting brown dwarf orbiting an active M-dwarf from NASA's TESS mission

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We report the discovery of TOI-2119b, a transiting brown dwarf (BD) that orbits and is completely eclipsed by an active M-dwarf star. Using light curve data from the Transiting Exoplanet Survey Satellite mission and follow up high-resolution Doppler spectroscopic observations, we find the BD has a radius of Rb=1.08±0.03RJ, a mass of Mb=64.4±2.3MJ, an orbital period of P=7.200865±0.00002 days, and an eccentricity of e=0.337±0.002. The host star has a mass of M⋆=0.53±0.02M⊙, a radius of R⋆=0.50±0.01R⊙, an effective temperature of Teff=3621±48K, and a metallicity of [Fe/H]=+0.06±0.08. TOI-2119b joins an emerging population of transiting BDs around M-dwarf host stars, with TOI-2119 being the ninth such system. These M-dwarf--brown dwarf systems occupy mass ratios near q=Mb/M⋆≈0.1, which separates them from the typical mass ratios for systems with transiting substellar objects and giant exoplanets that orbit more massive stars. TOI-2119 is also one of the most active M-dwarf stars known to host a transiting brown dwarf. The nature of the secondary eclipse of the BD by the star enables us to estimate the effective temperature of the substellar object to be 2030±84K, which is consistent with predictions by substellar evolutionary models.

Plus a new entry

TESS discovery of a sub-Neptune orbiting a mid-M dwarf TOI-2136

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We present the discovery of TOI-2136b, a sub-Neptune planet transiting every 7.85 days a nearby M4.5V-type star, identified through photometric measurements from the TESS mission. The host star is located 33 pc away with a radius of R∗=0.34±0.02 R⊙, a mass of 0.34±0.02 M⊙ and an effective temperature of 3342±100 K. We estimate its stellar rotation period to be 75±5 days based on archival long-term photometry. We confirm and characterize the planet based on a series of ground-based multi-wavelength photometry, high-angular-resolution imaging observations, and precise radial velocities from CFHT/SPIRou. Our joint analysis reveals that the planet has a radius of 2.19±0.17 R⊕, and a mass measurement of 6.4±2.4 M⊕. The mass and radius of TOI2136b is consistent with a broad range of compositions, from water-ice to gas-dominated worlds. TOI-2136b falls close to the radius valley for low-mass stars predicted by the thermally driven atmospheric mass loss models, making it an interesting target for future studies of its interior structure and atmospheric properties.

Also here

Validation and atmospheric exploration of the sub-Neptune TOI-2136b around a nearby M3 dwarf

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The NASA space telescope TESS is currently in the extended mission of its all-sky search for new transiting planets. Of the thousands of candidates that TESS is expected to deliver, transiting planets orbiting nearby M dwarfs are particularly interesting targets since they provide a great opportunity to characterize their atmospheres by transmission spectroscopy. We aim to validate and characterize the new sub-Neptune sized planet candidate TOI-2136.01 orbiting a nearby M dwarf (d=33.36±0.02 pc, Teff=3373±108 K) with an orbital period of 7.852 days. We use TESS data, ground-based multi-color photometry, and radial velocity measurements with the InfraRed Doppler (IRD) instrument on the Subaru Telescope to validate the planetary nature of TOI-2136.01 and estimate the stellar and planetary parameters. We also conduct high-resolution transmission spectroscopy to search for helium in its atmosphere. We confirmed that TOI-2136.01 (now named as TOI-2136b) is a bona fide planet with a planetary radius of Rp=2.2±0.07 REarth and a mass of Mp=4.7+3.1−2.6 MEarth. We also search for helium 10830 Å absorption lines and place an upper limit on the equivalent width of < 7.8 mÅ (95 % confidence) and on the absorption signal of < 1.44 % (95 % confidence). TOI-2136b is a sub-Neptune transiting a nearby and bright star (J=10. and is a potential hycean planet, making it an excellent target for atmospheric studies to understand the formation, evolution, and habitability of the small planets.

Would be interesting find planets transiting this M dwarf brown dwarf binary systems.

Daniel wrote:

Would be interesting find planets transiting this M dwarf brown dwarf binary systems.

Sure it would. I also add a personal offtopic comment of mine about how challenging and interesting would be a new search for transiting circumbinary planets around OGLE, TrES, HATNet, Kepler, [whatever exoplanet search] program stars found to be eclipsing binaries.

The Puzzling Story of Flare Inactive Ultra Fast Rotating M dwarfs. II. Searching for radial velocity variations

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Observations made using TESS revealed a sample of low mass stars which show a periodic modulation on a period <0.2~d. Surprisingly many of these Ultra Fast Rotating (UFR) stars showed no evidence of flare activity which would be expected from such rapidly rotating stars. We present results from a spectroscopic survey of UFRs using the Nordic Optical Telescope to search for radial velocity variations which could reveal evidence for binarity. Our sample of 29 sources have a photometric period between 0.1-0.2d, cover spectral classes of M0-4V, and show no evidence for flares. We detect only one source with clear radial velocity shifts, with another two having Gaia RUWE values which suggests they are binaries. Further observations reveal the former star possibly contains a brown dwarf companion with a mass of M₂>58 M_Jup and probability P(M₂<90 M_Jup) = 50%. There is no evidence for the companion in our spectra, strengthening the case for a brown dwarf companion. We also examine the folded TESS light curves of all our targets, finding at least two are eclipsing binaries and one which has been contaminated by a spatially nearby δ Sct star. We estimate that around 1/4 of our targets may have been contaminated by short period variable stars. However, the majority of our targets are consistent with being single, low mass stars whose variability is due to starspots. We outline the possible reasons why they are not flare active despite being such rapid rotators.

The BD host is TIC 85407625 in Hercules (P_orb = 0.176 d, which for an assumed total mass of 0.56 M_Sol for the system means a 0.005 AUs separation).

Introducing TOI-203 b

On The Hydrosphere Stability of TESS Targets: Applications to 700 d, 256 b, and 203 b

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A main determinant of the habitability of exoplanets is the presence of stable liquid surface water. In an era of abundant possible targets, the potential to find a habitable world remains a driving force in prioritization. We present here a data-forward method to investigate the likelihood of a stable hydrosphere on the timescales of the formation of life, 1 Gyr, and beyond. As our primary application, we use this method to examine the potential hydrospheres of TESS Objects of Interest 700 d, 256 b, and 203 b. We first present our selection criteria, which is based on an implementation of the Earth Similarity Index, as well as the results of an initial investigation into the desiccation of the targets, which reveals that TOI 203 b is almost certainly desiccated based on TESS observations. We then describe the characterization of the remaining targets and their host stars from 2MASS, Gaia, and TESS data and the derivation of sampled probability distributions for their parameters. Following this, we describe our process of simulating the desiccation of the targets hydrospheres using the Virtual Planet Simulator, VPLanet, with inputs directly linked to the previously derived probability distributions. We find that 50.86 percent of the likely cases for TOI 700 d are desiccated and no modeled cases for TOI 256 b are without water. In addition, we calculate the remaining water inventory for the targets, the percentage of cases that are continuing to lose water, and the rate at which these cases are losing water.

TOI-1696: a nearby M4 dwarf with a 3R⊕ planet in the Neptunian desert

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We present the discovery and validation of a temperate sub-Neptune around the nearby mid-M dwarf TIC 470381900 (TOI-1696), with a radius of 3.09±0.11R⊕ and an orbital period of 2.5days, using a combination of TESS and follow-up observations using ground-based telescopes. Joint analysis of multi-band photometry from TESS, MuSCAT, MuSCAT3, Sinistro, and KeplerCam confirmed the transit signal to be achromatic as well as refined the orbital ephemeris. High-resolution imaging with Gemini/'Alopeke and high-resolution spectroscopy with the Subaru/IRD confirmed that there are no stellar companions or background sources to the star. The spectroscopic observations with IRD and IRTF/SpeX were used to determine the stellar parameters, and found the host star is an M4 dwarf with an effective temperature of Teff=3185±76K and a metallicity of [Fe/H] =0.336±0.060dex. The radial velocities measured from IRD set a 2-σ upper limit on the planetary mass to be 48.8M⊕. The large radius ratio (Rp/R⋆∼0.1) and the relatively bright NIR magnitude (J=12.2mag) make this planet an attractive target for further followup observations. TOI-1696b is one of the planets belonging to the Neptunian desert with the highest transmission spectroscopy metric discovered to date, making it an interesting candidate for atmospheric characterizations with JWST.

Uncovering the true periods of the young sub-Neptunes orbiting TOI-2076

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Context: TOI-2076 is a transiting three-planet system of sub-Neptunes orbiting a bright (G = 8.9 mag), young (340±80 Myr) K-type star. Although a validated planetary system, the orbits of the two outer planets were unconstrained as only two non-consecutive transits were seen in TESS photometry. This left 11 and 7 possible period aliases for each.
Aims: To reveal the true orbits of these two long-period planets, precise photometry targeted on the highest-probability period aliases is required. Long-term monitoring of transits in multi-planet systems can also help constrain planetary masses through TTV measurements.
Methods: We used the MonoTools package to determine which aliases to follow, and then performed space-based and ground-based photometric follow-up of TOI-2076 c and d with CHEOPS, SAINT-EX, and LCO telescopes.
Results: CHEOPS observations revealed a clear detection for TOI-2076 c at P=21.01538+0.00084−0.00074 d, and allowed us to rule out three of the most likely period aliases for TOI-2076 d. Ground-based photometry further enabled us to rule out remaining aliases and confirm the P=35.12537±0.00067 d alias. These observations also improved the radius precision of all three sub-Neptunes to 2.518±0.036, 3.497±0.043, and 3.232±0.063 R⊕. Our observations also revealed a clear anti-correlated TTV signal between planets b and c likely caused by their proximity to the 2:1 resonance, while planets c and d appear close to a 5:3 period commensurability, although model degeneracy meant we were unable to retrieve robust TTV masses. Their inflated radii, likely due to extended H-He atmospheres, combined with low insolation makes all three planets excellent candidates for future comparative transmission spectroscopy with JWST.

Going on with TESS updates

TOI-1670 b and c: An Inner Sub-Neptune with an Outer Warm Jupiter Unlikely to have Originated from High-Eccentricity Migration

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We report the discovery of two transiting planets around the bright ($V=9.9$ mag) main sequence F7 star TOI-1670 by the Transiting Exoplanet Survey Satellite. TOI-1670 b is a sub-Neptune ($R_\mathrm{b} = 2.06_{-0.15}^{+0.19}$ $R_\oplus$) on a 10.9-day orbit and TOI-1670 c is a warm Jupiter ($R_\mathrm{c} = 0.987_{-0.025}^{+0.025}$ $R_\mathrm{Jup}$) on a 40.7-day orbit. Using radial velocity observations gathered with the Tull coudé Spectrograph on the Harlan J. Smith telescope and HARPS-N on the Telescopio Nazionale Galileo, we find a planet mass of $M_\mathrm{c} = 0.63_{-0.08}^{+0.09}$ $M_\mathrm{Jup}$ for the outer warm Jupiter, implying a mean density of $\rho_c = 0.81_{-0.11}^{+0.13}$ g cm$^{-3}$. The inner sub-Neptune is undetected in our radial velocity data ($M_\mathrm{b} < 0.13$ $M_\mathrm{Jup}$ at the 99% confidence level). Multi-planet systems like TOI-1670 hosting an outer warm Jupiter on a nearly circular orbit ($e_\mathrm{c} = 0.09_{-0.04}^{+0.05}$) and one or more inner coplanar planets are more consistent with "gentle" formation mechanisms such as disk migration or $in$ $situ$ formation rather than high-eccentricity migration. Of the 11 known systems with a warm Jupiter and a smaller inner companion, 8 (73%) are near a low-order mean-motion resonance, which can be a signature of migration. TOI-1670 joins two other systems (27% of this subsample) with period commensurabilities greater than 3, a common feature of $in$ $situ$ formation or halted inward migration. TOI-1670 and the handful of similar systems support a diversity of formation pathways for warm Jupiters.

Cacciapuoti et al. (2022) "The TESS Triple-9 Catalog: 999 uniformly-vetted exoplanet candidates"
https://doi.org/10.1093/mnras/stac652

Excerpt from the abstract:

Quote :

More than 70 per cent of the TOIs listed in the TT9 pass our diagnostic tests, and are thus marked as true planetary candidates. We flagged 144 candidates as false positives, and identified 146 as potential false positives. At the time of writing, the TT9 catalog contains ∼20 per cent of the entire ExoFOP-TESS TOIs list

Edit: now on arXiv: https://arxiv.org/abs/2203.15826

A Close-In Puffy Neptune With Hidden Friends: The Enigma of TOI-620
http://arxiv.org/abs/2204.03108v1

Sirius_Alpha wrote:

A Close-In Puffy Neptune With Hidden Friends: The Enigma of TOI-620
http://arxiv.org/abs/2204.03108v1

So reading that, the c planet isn't confirmed, and the RVs don't detect planet b:

Quote :

Our model comparison (see Table 12) shows that the models that includes a second (“c”) planet candidate is the most favored, but any model including the b planet is disfavored and models without the “c” planet are not ruled out. In other words, the inclusion of a c planet in our RV model does not improve our recovery of a mass for TOI 620 b, nor are we statistically confident in the recovery of the c planet.

(emphasis mine)

I guess we wait and see what Gaia DR3 has to say about the substellar companion.