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SOPHIE velocimetry of <i>Kepler</i> transit candidates
摘要： The exoplanet KOI-142b (Kepler-88b) shows transit timing variations (TTVs) with a semi-amplitude of ～12 h, which earned it the nickname “king of transit variations”. Only the transit of planet b was detected in the Kepler data with an orbital period of ～10.92 days and a radius of ～0.36 RJup. The TTVs together with the transit duration variations of KOI-142b were analysed recently, ?nding a unique solution for a companion-perturbing planet. An outer non-transiting companion was predicted, KOI-142c, with a mass of 0.626 ± 0.03 MJup and a period of 22.3397+0.0021 ?0.0018 days, which is close to the 2:1 mean-motion resonance with the inner transiting planet. We report an independent con?rmation of KOI-142c using radial velocity observations with the SOPHIE spectrograph at the Observatoire de Haute-Provence. We derive an orbital period of 22.10 ± 0.25 days and a minimum planetary mass of 0.76+0.32 0.16 MJup, both in good agreement with the predictions by previous transit timing analysis. Therefore, this is the ?rst radial velocity con?rmation of a non-transiting planet discovered with TTVs, providing an independent validation of the TTVs technique.
关键词： techniques: spectroscopic,stars: fundamental parameters,stars: individual: Kepler-88,planetary systems,stars: individual: KIC5446285,techniques: radial velocities
更新于2025-09-09 09:28:46
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Large Binocular Telescope view of the atmosphere of GJ1214b
摘要： The atmospheric composition and vertical structure of the super-Earth GJ1214b has been a subject of debate since its discovery in 2009. Recent studies have indicated that high-altitude clouds might mask the lower layers. However, some data points that were gathered at different times and facilities do not fit this picture, probably because of a combination of stellar activity and systematic errors. We observed two transits of GJ1214b with the Large Binocular Camera, the dual-channel camera at the Large Binocular Telescope. For the first time, we simultaneously measured the relative planetary radius k = Rp/R* at blue and red optical wavelengths (B + R), thus constraining the Rayleigh scattering on GJ1214b after correcting for stellar activity effects. To the same purpose, a long-term photometric follow-up of the host star was carried out with WiFSIP at STELLA, revealing a rotational period that is significantly longer than previously reported. Our new unbiased estimates of k yield a flat transmission spectrum extending to shorter wavelengths, thus confirming the cloudy atmosphere scenario for GJ1214b.
关键词： stars: individual: GJ1214,planetary systems,techniques: photometric
更新于2025-09-09 09:28:46
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Tracking Advanced Planetary Systems (TAPAS) with HARPS-N
摘要： Context. Lithium-rich giant stars are rare objects. For some of them, Li enrichment exceeds the abundance of this element found in solar system meteorites, suggesting that these stars have gone through a Li enhancement process. Aims. We identi?ed a Li-rich giant HD 107028 with A(Li) > 3.3 in a sample of evolved stars observed within the PennState Toru′n Planet Search. In this work we study di?erent enhancement scenarios and we try to identify the one responsible for Li enrichment in HD 107028. Methods. We collected high-resolution spectra with three di?erent instruments, covering di?erent spectral ranges. We determined stellar parameters and abundances of selected elements with both equivalent width measurements and analysis, and spectral synthesis. We also collected multi-epoch high-precision radial velocities in an attempt to detect a companion. Results. Collected data show that HD 107028 is a star at the base of the red giant branch (RGB). Except for high Li abundance, we have not identi?ed any other anomalies in its chemical composition, and there is no indication of a low-mass or stellar companion. We exclude Li production at the luminosity function bump on the RGB as the e?ective temperature and luminosity suggest that the evolutionary state is much earlier than the RGB bump. We also cannot con?rm the Li enhancement by contamination as we do not observe any anomalies that are associated with this scenario. Conclusions. After evaluating various scenarios of Li enhancement we conclude that the Li-overabundance of HD 107028 originates from main-sequence evolution, and may be caused by di?usion processes.
关键词： stars: fundamental parameters,planetary systems,stars: atmospheres,techniques: spectroscopic,stars: individual: HD 107028,stars: late-type
更新于2025-09-04 15:30:14
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A CRIRES-search for H <sub/>3</sub><sup>+</sup> emission from the hot Jupiter atmosphere of HD 209458 b
摘要： Close-in extrasolar giant planets are expected to cool their thermospheres by producing H+3 emission in the near-infrared (NIR), but simulations predict H+3 emission intensities that differ in the resulting intensity by several orders of magnitude. We want to test the observability of H+3 emission with CRIRES at the Very Large Telescope (VLT), providing adequate spectral resolution for planetary atmospheric lines in NIR spectra. We search for signatures of planetary H+3 emission in the L' band, using spectra of HD 209458 obtained during and after secondary eclipse of its transiting planet HD 209458 b. We searched for H+3 emission signatures in spectra containing the combined light of the star and, possibly, the planet. With the information on the ephemeris of the transiting planet, we derive the radial velocities at the time of observation and search for the emission at the expected line positions. We also apply a cross-correlation test to search for planetary signals and use a shift and add technique combining all observed spectra taken after secondary eclipse to calculate an upper emission limit. We do not find signatures of atmospheric H+3 emission in the spectra containing the combined light of HD 209458 and its orbiting planet. We calculate the emission limit for the H+3 line at 3953.0 nm [Q(1, 0)] to be 8.32 × 1018 W and a limit of 5.34 × 1018 W for the line at 3985.5 nm [Q(3, 0)]. Comparing our emission limits to the theoretical predictions suggests that we lack 1 to 3 magnitudes of sensitivity to measure H+3 emission in our target object. We show that under more favorable weather conditions the data quality can be improved significantly, reaching 5 × 1016 W for star-planet systems that are close to Earth. We estimate that pushing the detection limit down to 1015 W will be possible with ground-based observations with future instrumentation, for example, the European Extremly Large Telescope.
关键词： planetary systems,infrared: stars,stars: individual: HD 209458
更新于2025-09-04 15:30:14
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Characterizing HR?3549?B using SPHERE
摘要： Aims. In this work, we characterize the low-mass companion of the A0 field star HR 3549. Methods. We observed HR 3549B in imaging mode with the near-infrared branch (IFS and IRDIS) of SPHERE at the VLT, with IFS in Y J mode and IRDIS in the H band. We also acquired a medium-resolution spectrum with the IRDIS long-slit spectroscopy mode. The data were reduced using the dedicated SPHERE GTO pipeline, which is custom-designed for this instrument. We employed algorithms such as PCA and TLOCI to reduce the speckle noise. Results. The companion was clearly visible with both IRDIS and IFS. We obtained photometry in four different bands and also the astrometric position for the companion. Based on our astrometry, we confirm that it is a bound object and set constraints on its orbit. Although several uncertainties still remain, we estimate an age of ～100–150 Myr for this system, yielding a most probable mass for the companion of 40–50 MJup and Teff ～ 2300?2400 K. Compared with template spectra, this points to a spectral type between M9 and L0 for the companion, commensurate with its position on the color–magnitude diagram.
关键词： techniques: imaging spectroscopy,planetary systems,methods: data analysis,instrumentation: spectrographs
更新于2025-09-04 15:30:14
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The SHARDDS survey: First resolved image of the HD?114082 debris disk in the Lower Centaurus Crux with SPHERE
摘要： We present the first resolved image of the debris disk around the 16 ± 8 Myr old star, HD 114082. The observation was made in the H-band using the SPHERE instrument. The star is at a distance of 92 ± 6 pc in the Lower Centaurus Crux association. Using a Markov chain Monte Carlo analysis, we determined that the debris is likely in the form of a dust ring with an inner edge of 27.7+2.8?3.5 au, position angle –74.3?+0.5?0.4. The disk imaged in scattered light has a surface density that is declining with radius of ～r?4, which is steeper than expected for grain blowout by radiation pressure. We find only marginal evidence (2σ) of eccentricity and rule out planets more massive than 1.0 MJup orbiting within 1 au of the inner edge of the ring, since such a planet would have disrupted the disk. The disk has roughly the same fractional disk luminosity (Ldisk/L? = 3.3 × 10?3) as HR 4796 A and β Pictoris, however it was not detected by previous instrument facilities most likely because of its small angular size (radius ～0.4′′), low albedo (～0.2), and low scattering efficiency far from the star due to high scattering anisotropy. With the arrival of extreme adaptive optics systems, such as SPHERE and GPI, the morphology of smaller, fainter, and more distant debris disks are being revealed, providing clues to planet-disk interactions in young protoplanetary systems.
关键词： stars: individual: HD 114082,planetary systems,techniques: high angular resolution
更新于2025-09-04 15:30:14
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The GAPS programme with HARPS-N at TNG
摘要： Aims. For more than 1.5 years we spectroscopically monitored the star KELT-6 (BD+31 2447), which is known to host the transiting hot-Saturn KELT-6 b, because a previously observed long-term trend in radial velocity time series suggested that there is an outer companion. Methods. We collected a total of 93 new spectra with the HARPS-N and TRES spectrographs. A spectroscopic transit of KELT-6 b was observed with HARPS-N, and simultaneous photometry was obtained with the IAC-80 telescope. Results. We proved the existence of an outer planet with a mininum mass Mpsin i = 3.71 ± 0.21 MJup and a moderately eccentric orbit (e = 0.21+0.039 ?0.036) of period P ～ 3.5 years. We improved the orbital solution of KELT-6 b and obtained the ?rst measurement of the Rossiter-McLaughlin effect, showing that the planet has a likely circular, prograde, and slightly misaligned orbit with a projected spin-orbit angle of λ = ?36 ± 11 degrees. We improved the KELT-6 b transit ephemeris from photometry and provide new measurements of the stellar parameters. KELT-6 appears as an interesting case for studying the formation and evolution of multi-planet systems.
关键词： techniques: photometric,planetary systems,techniques: radial velocities,stars: individual: KELT-6
更新于2025-09-04 15:30:14
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Maximum Angular Separation Epochs for Exoplanet Imaging Observations
摘要： Direct imaging of exoplanets presents both significant challenges and significant gains. The advantages primarily lie in receiving emitted and, with future instruments, reflected photons at phase angles not accessible by other techniques, enabling the potential for atmospheric studies and the detection of rotation and surface features. The challenges are numerous and include coronagraph development and achieving the necessary contrast ratio. Here, we address the specific challenge of determining epochs of maximum angular separation for the star and planet. We compute orbital ephemerides for known transiting and radial velocity planets, taking Keplerian orbital elements into account. We provide analytical expressions for angular star–planet separation as a function of the true anomaly, including the locations of minimum and maximum. These expressions are used to calculate uncertainties for maximum angular separation as a function of time for the known exoplanets, and we provide strategies for improving ephemerides with application to proposed and planned imaging missions.
关键词： planetary systems,techniques: radial velocities,techniques: high angular resolution
更新于2025-09-04 15:30:14
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Detecting Ocean Glint on Exoplanets Using Multiphase Mapping
摘要： Rotational mapping and specular reflection (glint) are two proposed methods to directly detect liquid water on the surface of habitable exoplanets. However, false positives for both methods may prevent the unambiguous detection of exoplanet oceans. We use simulations of Earth as an exoplanet to introduce a combination of multiwavelength, multiphase, time-series direct-imaging observations and accompanying analyses that may improve the robustness of exoplanet ocean detection by spatially mapping the ocean glint signal. As the planet rotates, the glint spot appears to “blink” as Lambertian scattering continents interrupt the specular reflection from the ocean. This manifests itself as a strong source of periodic variability in crescent-phase disk-integrated reflected light curves. We invert these light curves to constrain the longitudinal slice maps and apparent albedo of multiple surfaces at both quadrature and crescent phase. At crescent phase, the retrieved apparent albedo of ocean-bearing longitudinal slices is increased by a factor of 5, compared to the albedo at quadrature phase, due to the contribution from glint. The land-bearing slices exhibit no significant change in apparent albedo with phase. The presence of forward-scattering clouds in our simulated observation increases the overall reflectivity toward crescent, but we find that clouds do not correlate with any specific surfaces, thereby allowing for the phase-dependent glint effect to be interpreted as distinct from cloud scattering. Retrieving the same longitudinal map at quadrature and crescent phases may be used to tie changes in the apparent albedo with phase back to specific geographic surfaces (or longstanding atmospheric features), although this requires ideal geometries. We estimate that crescent-phase time-dependent glint measurements are feasible for between 1 and 10 habitable zone exoplanets orbiting the nearest G, K, and M dwarfs using a space-based, high-contrast, direct-imaging telescope with a diameter between 6 and 15 m.
关键词： planets and satellites: oceans,astrobiology,planetary systems,planets and satellites: terrestrial planets,planets and satellites: surfaces
更新于2025-09-04 15:30:14
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SCExAO/CHARIS Near-infrared Direct Imaging, Spectroscopy, and Forward-Modeling of <i>κ</i> And b: A Likely Young, Low-gravity Superjovian Companion
摘要： We present SCExAO/CHARIS high-contrast imaging/JHK integral field spectroscopy of κ And b, a directly imaged low-mass companion orbiting a nearby B9V star. We detect κ And b at a high signal-to-noise ratio and extract high-precision spectrophotometry using a new forward-modeling algorithm for (A-)LOCI complementary to KLIP-FM developed by Pueyo et al. κ And b’s spectrum best resembles that of a low-gravity L0–L1 dwarf (L0–L1γ). Its spectrum and luminosity are very well matched by 2MASS J0141-4633 and several other 12.5–15 MJ free-floating members of the 40 Myr old Tuc–Hor Association, consistent with a system age derived from recent interferometric results for the primary, a companion mass at/near the deuterium-burning limit (12 MJ), and a companion-to-primary mass ratio characteristic of other directly imaged planets (q～0.005). We did not unambiguously identify additional, more closely orbiting companions brighter and more massive than κ And b down to ρ～0 3 (15 au). SCExAO/CHARIS and complementary Keck/NIRC2 astrometric points reveal clockwise orbital motion. Modeling points toward a likely eccentric orbit: a subset of acceptable orbits include those that are aligned with the star’s rotation axis. However, κ And b’s semimajor axis is plausibly larger than 55 au and in a region where imaging of κ And and low-resolution disk instability could form massive companions. Deeper high-contrast spectroscopy from extreme adaptive optics systems such as SCExAO/CHARIS and higher-resolution spectroscopy from Keck/OSIRIS or, later, IRIS on the Thirty Meter Telescope could help to clarify κ And b’s chemistry and whether its spectrum provides an insight into its formation environment.
关键词： stars: individual: (HD 222439),planetary systems,techniques: high angular resolution,stars: early-type
更新于2025-09-04 15:30:14