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Register a new userGravity-Darkening Analysis of Misaligned Hot Jupiter MASCARA-4 b
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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.
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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.
In this paper, we aim to characterize a transiting planetary candidate in the southern skies found in the combined MASCARA and bRing data sets of HD 85628, an A3V star of V = 8.2 mag at a distance 172 pc, to confirm its planetary nature. The candidate was originally detected in data obtained jointly with the MASCARA and bRing instruments using a BLS search for transit events. Further photometry was taken by the 0.7 m CHAT, and radial velocity measurements with FIDEOS on the ESO 1.0 m Telescope. High resolution spectra during a transit were taken with CHIRON on the SMARTS 1.5 m telescope to target the Doppler shadow of the candidate. We confirm the existence of a hot Jupiter transiting the bright A3V star HD 85628, which we co-designate as MASCARA-4b and bRing-1b. It is in a 2.824 day orbit, with an estimated planet radius of $1.53 ^{0.07}_{0.04}$ $R_{rm{Jup}}$ and an estimated planet mass of $3.1 pm 0.9$ $M_{rm{Jup}}$, putting it well within the planet mass regime.. The CHAT observations show a partial transit, reducing the probability that the transit was around a faint background star. The CHIRON observations show a clear Doppler shadow, implying that the transiting object is in a retrograde orbit with $|lambda| = 247.5 pm 1.6 $textdegree. The planet orbits at at a distance of 0.047 $pm$ 0.004 AU from the star and has a zero-albedo equilibrium temperature of 2100 $pm$ 100 K. In addition, we find that HD 85628 has a previously unreported stellar companion star in the Gaia DR2 data demonstrating common proper motion and parallax at 4.3 arcsecond separation (projected separation $sim$740 AU), and with absolute magnitude consistent with being a K/M dwarf.
In this paper we present MASCARA-2 b, a hot Jupiter transiting the $m_V=7.6$ A2 star HD 185603. Since early 2015, MASCARA has taken more than 1.6 million flux measurements of the star, corresponding to a total of almost 3000 hours of observations, revealing a periodic dimming in the flux with a depth of $1.3%$. Photometric follow-up observations were performed with the NITES and IAC80 telescopes and spectroscopic measurements were obtained with the Hertzsprung SONG telescope. We find MASCARA-2 b orbits HD 185603 with a period of $3.474119^{+0.000005}_{-0.000006}~rm{days}$ at a distance of $0.057 pm 0.006~rm{AU}$, has a radius of $1.83 pm 0.07~rm{R}_{rm{J}}$ and place a $99%$ upper limit on the mass of $< 17~rm{M}_{rm{J}}$. HD 185603 is a rapidly rotating early-type star with an effective temperature of $8980^{+90}_{-130}~rm{K}$ and a mass and radius of $1.89^{+0.06}_{-0.05}~M_odot$, $1.60 pm 0.06~R_odot$, respectively. Contrary to most other hot Jupiters transiting early-type stars, the projected planet orbital axis and stellar spin axis are found to be aligned with $lambda=0.6 pm 4^circ$. The brightness of the host star and the high equilibrium temperature, $2260 pm 50~rm{K}$, of MASCARA-2 b make it a suitable target for atmospheric studies from the ground and space. Of particular interest is the detection of TiO, which has recently been detected in the similarly hot planets WASP-33 b and WASP-19 b.
Ultra-hot Jupiters offer interesting prospects for expanding our theories on dynamical evolution and the properties of extremely irradiated atmospheres. In this context, we present the analysis of new optical spectroscopy for the transiting ultra-hot Jupiter WASP-121b. We first refine the orbital properties of WASP-121b, which is on a nearly polar (obliquity $psi^{rm North}$=88.1$pm$0.25$^{circ}$ or $psi^{rm South}$=91.11$pm$0.20$^{circ}$) orbit, and exclude a high differential rotation for its fast-rotating (P$<$1.13 days), highly inclined ($i_mathrm{star}^{rm North}$=8.1$stackrel{+3.0}{_{-2.6}}^{circ}$ or $i_mathrm{star}^{rm South}$=171.9$stackrel{+2.5}{_{-3.4}}^{circ}$) star. We then present a new method that exploits the reloaded Rossiter-McLaughlin technique to separate the contribution of the planetary atmosphere and of the spectrum of the stellar surface along the transit chord. Its application to HARPS transit spectroscopy of WASP-121b reveals the absorption signature from metals, likely atomic iron, in the planet atmospheric limb. The width of the signal (14.3$pm$1.2 km/s) can be explained by the rotation of the tidally locked planet. Its blueshift (-5.2$pm$0.5 km/s) could trace strong winds from the dayside to the nightside, or the anisotropic expansion of the planetary thermosphere.
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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