We report the discovery of 1SWASP J022916.91-395901.4 = GSC 07552-00389, a possible new VY Sculptoris variable in Eridanus, which is associated with the X-ray source 1RXS J022917.1-395851.
We present the discovery and characterization of HIP 33609 b, a transiting warm brown dwarf orbiting a late B star, discovered by NASA's Transiting Exoplanet Survey Satellite TESS as TOI-588 b. HIP ...33609 b is a large (R\(_{b}\) = 1.580\(_{-0.070}^{+0.074}\) R\(_{J}\)) brown dwarf on a highly eccentric (e = 0.560\(_{-0.031}^{+0.029}\)) orbit with a 39-day period. The host star is a bright (V = 7.3 mag), T\(_{eff}\) = 10,400\(_{-660}^{+800}\) K star with a mass of M\(_{*}\) = 2.383\(_{-0.095}^{+0.10}\) M\(_{\odot}\) and radius of R\(_{*}\) = 1.863\(_{-0.082}^{+0.087}\) R\(_{\odot}\), making it the hottest transiting brown dwarf host star discovered to date. We obtained radial velocity measurements from the CHIRON spectrograph confirming the companion's mass of M\(_{b}\) = 68.0\(_{-7.1}^{+7.4}\) M\(_{J}\) as well as the host star's rotation rate (\(vsini_{*} = 55.6 \pm 1.8\) km/s). We also present the discovery of a new comoving group of stars, designated as MELANGE-6, and determine that HIP 33609 is a member. We use a combination of rotation periods and isochrone models fit to the cluster members to estimate an age of 150 \(\pm\) 25 Myr. With a measured mass, radius, and age, HIP 33609 b becomes a benchmark for substellar evolutionary models.
We present the discovery and characterization of six short-period, transiting giant planets from NASA's Transiting Exoplanet Survey Satellite (TESS) -- TOI-1811 (TIC 376524552), TOI-2025 (TIC ...394050135), TOI-2145 (TIC 88992642), TOI-2152 (TIC 395393265), TOI-2154 (TIC 428787891), & TOI-2497 (TIC 97568467). All six planets orbit bright host stars (8.9 <G< 11.8, 7.7 <K< 10.1). Using a combination of time-series photometric and spectroscopic follow-up observations from the TESS Follow-up Observing Program (TFOP) Working Group, we have determined that the planets are Jovian-sized (R\(_{P}\) = 1.00-1.45 R\(_{J}\)), have masses ranging from 0.92 to 5.35 M\(_{J}\), and orbit F, G, and K stars (4753 \(<\) T\(_{eff}\) \(<\) 7360 K). We detect a significant orbital eccentricity for the three longest-period systems in our sample: TOI-2025 b (P = 8.872 days, \(e\) = \(0.220\pm0.053\)), TOI-2145 b (P = 10.261 days, \(e\) = \(0.182^{+0.039}_{-0.049}\)), and TOI-2497 b (P = 10.656 days, \(e\) = \(0.196^{+0.059}_{-0.053}\)). TOI-2145 b and TOI-2497 b both orbit subgiant host stars (3.8 \(<\) \(\log\) g \(<\)4.0), but these planets show no sign of inflation despite very high levels of irradiation. The lack of inflation may be explained by the high mass of the planets; \(5.35^{+0.32}_{-0.35}\) M\(_{\rm J}\) (TOI-2145 b) and \(5.21\pm0.52\) M\(_{\rm J}\) (TOI-2497 b). These six new discoveries contribute to the larger community effort to use {\it TESS} to create a magnitude-complete, self-consistent sample of giant planets with well-determined parameters for future detailed studies.
We present the discovery of two exoplanets transiting TOI-836 (TIC 440887364) using data from TESS Sector 11 and Sector 38. TOI-836 is a bright (\(T = 8.5\) mag), high proper motion (\(\sim\,200\) ...mas yr\(^{-1}\)), low metallicity (Fe/H\(\approx\,-0.28\)) K-dwarf with a mass of \(0.68\pm0.05\) M\(_{\odot}\) and a radius of \(0.67\pm0.01\) R\(_{\odot}\). We obtain photometric follow-up observations with a variety of facilities, and we use these data-sets to determine that the inner planet, TOI-836 b, is a \(1.70\pm0.07\) R\(_{\oplus}\) super-Earth in a 3.82 day orbit, placing it directly within the so-called 'radius valley'. The outer planet, TOI-836 c, is a \(2.59\pm0.09\) R\(_{\oplus}\) mini-Neptune in an 8.60 day orbit. Radial velocity measurements reveal that TOI-836 b has a mass of \(4.5\pm0.9\) M\(_{\oplus}\) , while TOI-836 c has a mass of \(9.6\pm2.6\) M\(_{\oplus}\). Photometric observations show Transit Timing Variations (TTVs) on the order of 20 minutes for TOI-836 c, although there are no detectable TTVs for TOI-836 b. The TTVs of planet TOI-836 c may be caused by an undetected exterior planet.
We present the discovery of TOI-1518b -- an ultra-hot Jupiter orbiting a bright star \(V = 8.95\). The transiting planet is confirmed using high-resolution optical transmission spectra from EXPRES. ...It is inflated, with \(R_p = 1.875\pm0.053\,R_{\rm J}\), and exhibits several interesting properties, including a misaligned orbit (\({240.34^{+0.93}_{-0.98}}\) degrees) and nearly grazing transit (\(b =0.9036^{+0.0061}_{-0.0053}\)). The planet orbits a fast-rotating F0 host star (\(T_{\mathrm{eff}} \simeq 7300\) K) in 1.9 days and experiences intense irradiation. Notably, the TESS data show a clear secondary eclipse with a depth of \(364\pm28\) ppm and a significant phase curve signal, from which we obtain a relative day-night planetary flux difference of roughly 320 ppm and a 5.2\(\sigma\) detection of ellipsoidal distortion on the host star. Prompted by recent detections of atomic and ionized species in ultra-hot Jupiter atmospheres, we conduct an atmospheric cross-correlation analysis. We detect neutral iron (\({5.2\sigma}\)), at \(K_p = 157^{+68}_{-44}\) km s\(^{-1}\) and \(V_{\rm sys} = -16^{+2}_{-4}\) km s\(^{-1}\), adding another object to the small sample of highly irradiated gas-giant planets with Fe detections in transmission. Detections so far favor particularly inflated gas giants with radii \(\gtrsim 1.78\,R_{\rm J}\); although this may be due to observational bias. With an equilibrium temperature of \(T_{\rm eq}=2492\pm38\) K and a measured dayside brightness temperature of \(3237\pm59\) K (assuming zero geometric albedo), TOI-1518b is a promising candidate for future emission spectroscopy to probe for a thermal inversion.
Astronomers do not have a complete picture of the effects of wide-binary companions (semimajor axes greater than 100 AU) on the formation and evolution of exoplanets. We investigate these effects ...using new data from Gaia EDR3 and the TESS mission to characterize wide-binary systems with transiting exoplanets. We identify a sample of 67 systems of transiting exoplanet candidates (with well-determined, edge-on orbital inclinations) that reside in wide visual binary systems. We derive limits on orbital parameters for the wide-binary systems and measure the minimum difference in orbital inclination between the binary and planet orbits. We determine that there is statistically significant difference in the inclination distribution of wide-binary systems with transiting planets compared to a control sample, with the probability that the two distributions are the same being 0.0037. This implies that there is an overabundance of planets in binary systems whose orbits are aligned with those of the binary. The overabundance of aligned systems appears to primarily have semimajor axes less than 700 AU. We investigate some effects that could cause the alignment and conclude that a torque caused by a misaligned binary companion on the protoplanetary disk is the most promising explanation.
Close-in gas giants present a surprising range of stellar obliquity, the angle between a planet's orbital axis and its host star's spin axis. It is unclear whether the obliquities reflect the ...planets' dynamical history (e.g., aligned for in situ formation or disk migration versus misaligned for high-eccentricity tidal migration) or whether other mechanisms (e.g., primordial misalignment or planet-star interactions) are more important in sculpting the obliquity distribution. Here we present the stellar obliquity measurement of TOI-1268 (TIC-142394656, \(V_{\rm mag} {\sim} 10.9\)), a young K-type dwarf hosting an 8.2-day period, Saturn-sized planet. TOI-1268's lithium abundance and rotation period suggest the system age between the ages of Pleiades cluster (\({\sim}120\) Myr) and Praesepe cluster (\({\sim}670\) Myr). Using the newly commissioned NEID spectrograph, we constrain the stellar obliquity of TOI-1268 via the Rossiter-McLaughlin (RM) effect from both radial velocity (RV) and Doppler Tomography (DT) signals. The 3\(\sigma\) upper bounds of the projected stellar obliquity \(|\lambda|\) from both models are below 60\(^\circ\). The large host star separation (\(a/R_\star {\sim} 17\)), combined with the system's young age, makes it unlikely that the planet has realigned its host star. The stellar obliquity measurement of TOI-1268 probes the architecture of a young gas giant beyond the reach of tidal realignment (\(a/R_\star {\gtrsim} 10\)) and reveals an aligned or slightly misaligned system.
We report the discovery of ten short-period giant planets (TOI-2193A b, TOI-2207 b, TOI-2236 b, TOI-2421 b, TOI-2567 b, TOI-2570 b, TOI-3331 b, TOI-3540A b, TOI-3693 b, TOI-4137 b). All of the ...planets were identified as planet candidates based on periodic flux dips observed by NASA's Transiting Exoplanet Survey Satellite (TESS). The signals were confirmed to be from transiting planets using ground-based time-series photometry, high angular resolution imaging, and high-resolution spectroscopy coordinated with the TESS Follow-up Observing Program. The ten newly discovered planets orbit relatively bright F and G stars (\(G < 12.5\),~\(T_\mathrm{eff}\) 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-2421 b is notable for being a Saturn-mass planet and TOI-2567 b for being a ``sub-Saturn'', with masses of \(0.322\pm 0.073\) and \(0.195\pm 0.030\) Jupiter masses, respectively. In most cases, we have little information about the orbital eccentricities. Two exceptions are TOI-2207 b, which has an 8-day period and a detectably eccentric orbit (\(e = 0.17\pm0.05\)), and TOI-3693 b, a 9-day planet for which we can set an upper limit of \(e < 0.052\). The ten planets described here are the first new planets resulting from an effort to use TESS data to unify and expand on the work of previous ground-based transit surveys in order to create a large and statistically useful sample of hot Jupiters.
We present the discovery of a highly irradiated and moderately inflated ultra-hot Jupiter, TOI-1431b/MASCARA-5b (HD 201033b), first detected by NASA's Transiting Exoplanet Survey Satellite mission ...(TESS) and the Multi-site All-Sky CAmeRA (MASCARA). The signal was established to be of planetary origin through radial velocity measurements obtained using SONG, SOPHIE, FIES, NRES, and EXPRES, which show a reflex motion of \(K=294.1\pm1.1\) m s\(^{-1}\). A joint analysis of the TESS and ground-based photometry and radial velocity measurements reveals that TOI-1431b has a mass of \(M_{p}=3.12\pm0.18\) \(\rm{M_J}\) (\(990\pm60\) M\(_{\oplus}\)), an inflated radius of \(R_{p}=1.49\pm0.05\) \(\rm{R_J}\) (\(16.7\pm0.6\) R\(_{\oplus}\)), and an orbital period of \(P=2.650237\pm0.000003\) d. Analysis of the spectral energy distribution of the host star reveals that the planet orbits a bright (\(\mathrm{V}=8.049\) mag) and young (\(0.29^{+0.32}_{-0.19}\) Gyr) Am type star with \(T_{\rm eff}=7690^{+400}_{-250}\) \(\rm{K}\), resulting in a highly irradiated planet with an incident flux of \(\langle F \rangle=7.24^{+0.68}_{-0.64}\times\)10\(^9\) erg s\(^{-1}\) cm\(^{-2}\) (\(5300^{+500}_{-470}\mathrm{S_{\oplus}}\)) and an equilibrium temperature of \(T_{eq}=2370\pm70\) K. TESS photometry also reveals a secondary eclipse with a depth of \(127^{+4}_{-5}\)ppm as well as the full phase curve of the planet's thermal emission in the red-optical. This has allowed us to measure the dayside and nightside temperature of its atmosphere as \(T_\mathrm{day}=3004\pm64\) K and \(T_\mathrm{night}=2583\pm63\) K, the second hottest measured nightside temperature. The planet's low day/night temperature contrast (\(\sim\)420 K) suggests very efficient heat transport between the dayside and nightside hemispheres.
We report the discovery of TOI-2180 b, a 2.8 \(M_{\rm J}\) giant planet orbiting a slightly evolved G5 host star. This planet transited only once in Cycle 2 of the primary Transiting Exoplanet Survey ...Satellite (TESS) mission. Citizen scientists identified the 24 hr single-transit event shortly after the data were released, allowing a Doppler monitoring campaign with the Automated Planet Finder telescope at Lick Observatory to begin promptly. The radial velocity observations refined the orbital period of TOI-2180 b to be 260.8\(\pm\)0.6 days, revealed an orbital eccentricity of 0.368\(\pm\)0.007, and discovered long-term acceleration from a more distant massive companion. We conducted ground-based photometry from 14 sites spread around the globe in an attempt to detect another transit. Although we did not make a clear transit detection, the nondetections improved the precision of the orbital period. We predict that TESS will likely detect another transit of TOI-2180 b in Sector 48 of its extended mission. We use giant planet structure models to retrieve the bulk heavy-element content of TOI-2180 b. When considered alongside other giant planets with orbital periods over 100 days, we find tentative evidence that the correlation between planet mass and metal enrichment relative to stellar is dependent on orbital properties. Single-transit discoveries like TOI-2180 b highlight the exciting potential of the TESS mission to find planets with long orbital periods and low irradiation fluxes despite the selection biases associated with the transit method.
