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Register a new userThe obliquity and atmosphere of the ultra-hot Jupiter TOI-1431b (MASCARA-5b): A misaligned orbit and no signs of atomic ormolecular absorptions
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Ultra-hot Jupiters are defined as giant planets with equilibrium temperatures larger than 2000 K. Most of them are found orbiting bright A-F type stars, making them extremely suitable objects to study their atmospheres using high-resolution spectroscopy. Recent studies show a variety of atoms and molecules detected in the atmospheres of this type of planets. Here we present our analysis of the newly discovered ultra-hot Jupiter TOI-1431b/MASCARA-5b, using two transit observations with the HARPS-N spectrograph and one transit observation with the EXPRES spectrograph. Analysis of the Rossiter-McLaughlin effect shows that the planet is in a polar orbit, with a projected obliquity $ lambda = -155^{+20}_{-10}$ degrees. Combining the nights and applying both cross-correlation methods and transmission spectroscopy, we find no evidences of CaI, FeI, FeII, MgI, NaI, VI, TiO, VO or H$alpha$ in the atmosphere of the planet. Our most likely explanation for the lack of atmospheric features is the large surface gravity of the planet.
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We present the discovery of a highly irradiated and moderately inflated ultra-hot Jupiter, TOI-1431b/MASCARA-5b (HD 201033b), first detected by NASAs 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 $K=294.1pm1.1$ m s$^{-1}$. A joint analysis of TESS, MuSCAT2, and LCOGT photometry, radial velocity measurements, and the spectral energy distribution of the host star reveals that TOI-1431b has a mass of $M_{p}=3.14_{-0.18}^{+0.19}$ $rm{M_J}$ ($1000pm60$ M$_{oplus}$), an inflated radius of $R_{p}=1.51pm0.06$ $rm{R_J}$ ($16.9_{-0.6}^{+0.7}$ R$_{oplus}$), and an orbital period of $P=2.65022pm0.00001$ d. 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 $T_{eq}=2370pm100$ K. TESS photometry also reveals a secondary eclipse with a depth of $124pm5$ppm as well as the full phase curve of the planets thermal emission in the red-optical. This has allowed us to measure the dayside and nightside temperature of its atmosphere as $T_mathrm{day}=2983^{+63}_{-68}$ K and $T_mathrm{night}=2556^{+62}_{-65}$ K, the second hottest measured nightside temperature. The planets low day/night temperature contrast ($sim$400 K) suggests very efficient heat transport between the dayside and nightside hemispheres.
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 $R_p = 1.875pm0.053,R_{rm J}$, 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 $364pm28$ 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 (${5.2sigma}$), 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 $T_{rm eq}=2492pm38$ K and a measured dayside brightness temperature of $3237pm59$ K (assuming zero geometric albedo), TOI-1518b is a promising candidate for future emission spectroscopy to probe for a thermal inversion.
MASCARA-4 b is a hot Jupiter in a highly-misaligned orbit around a rapidly-rotating A3V star that was observed for 54 days by the Transiting Exoplanet Survey Satellite (tess). We perform two analyses of MASCARA-4 b using a stellar gravity-darkened model. First, we measure MASCARA-4 bs misaligned orbital configuration by modeling its tess~photometric light curve. We take advantage of the asymmetry in MASCARA-4 bs transit due to its host stars gravity-darkened surface to measure MASCARA-4 bs true spin-orbit angle to be $104^{circ+7^circ}_{-13^circ}$. We also detect a $sim4sigma$ secondary eclipse at $0.491pm0.007$ orbital phase, proving that the orbit is slightly eccentric. Second, we model MASCARA-4 bs insolation including gravity-darkening and find that the planets received XUV flux varies by $4$% throughout its orbit. MASCARA-4 bs short-period, polar orbit suggests that the planet likely underwent dramatic orbital evolution to end up in its present-day configuration and that it receives a varying stellar irradiance that perpetually forces the planet out of thermal equilibrium. These findings make MASCARA-4 b an excellent target for follow-up characterization to better understand orbital evolution and current-day of planets around high-mass stars.
We report the discovery of MASCARA-1 b, the first exoplanet discovered with the Multi-site All-Sky CAmeRA (MASCARA). It is a hot Jupiter orbiting a bright $m_V=8.3$, rapidly rotating ($vsin i_star > 100~rm{km~s}^{-1}$) A8 star with a period of $2.148780pm8times10^{-6} ~rm{days}$. The planet has a mass and radius of $3.7pm0.9~rm{M}_{rm{Jup}}$ and $1.5pm0.3~rm{R}_{rm{Jup}}$, respectively. As with most hot Jupiters transiting early-type stars we find a misalignment between the planet orbital axis and the stellar spin axis, which may be signature of the formation and migration histories of this family of planets. MASCARA-1 b has a mean density of $1.5pm0.9~rm{g~cm^{-3}}$ and an equilibrium temperature of $2570^{+50}_{-30}~rm{K}$, one of the highest temperatures known for a hot Jupiter to date. The system is reminiscent of WASP-33, but the host star lacks apparent delta-scuti variations, making the planet an ideal target for atmospheric characterization. We expect this to be the first of a series of hot Jupiters transiting bright early-type stars that will be discovered by MASCARA.
We report a spin-orbit misalignment for the hot-Jupiter HATS-14b, measuring a projected orbital obliquity of |lambda|= 76 -5/+4 deg. HATS-14b orbits a high metallicity, 5400 K G dwarf in a relatively short period orbit of 2.8 days. This obliquity was measured via the Rossiter-McLaughlin effect, obtained with observations from Keck-HIRES. The velocities were extracted using a novel technique, optimised for low signal-to-noise spectra, achieving a high precision of 4 m/s point-to-point scatter. However, we caution that our uncertainties may be underestimated. Due to the low rotational velocity of the star, the detection significance is dependent on the vsini prior that is imposed in our modelling. Based on trends observed in the sample of hot Jupiters with obliquity measurements, it has been suggested that these planets modify the spin axes of their host stars, with an efficiency that depends on the stellar type and orbital period of the system. In this framework, short-period planets around stars with surface convective envelopes, like HATS-14b, are expected to have orbits that are aligned with the spin axes of their host stars. HATS-14b, however, is a significant outlier from this trend, challenging the effectiveness of the tidal realignment mechanism.
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