We present the discovery and characterisation of two transiting planets observed by the Transiting Exoplanet Survey Satellite (TESS) orbiting the nearby (d⋆ ≈ 22 pc), bright (J ≈ 9 mag) M3.5 dwarf ...LTT 3780 (TOI–732). We confirm both planets and their association with LTT 3780 via ground-based photometry and determine their masses using precise radial velocities measured with the CARMENES spectrograph. Precise stellar parameters determined from CARMENES high-resolution spectra confirm that LTT 3780 is a mid-M dwarf with an effective temperature of T(eff) = 3360 ± 51 K, a surface gravity of log g⋆ = 4.81 ± 0.04 (cgs), and an iron abundance of Fe/H = 0.09 ± 0.16 dex, with an inferred mass of M⋆ = 0.379 ± 0.016M⊙ and a radius of R⋆ = 0.382 ± 0.012R⊙. The ultra-short-period planet LTT 3780 b (P(b) = 0.77 d) with a radius of 1.35(−0.06,+0.06) R⊕, a mass of 2.34(−0.23,+0.24) M⊕, and a bulk density of 5.24(−0.81,+0.94) g/cu.cm joins the population of Earth-size planets with rocky, terrestrial composition. The outer planet, LTT 3780 c, with an orbital period of 12.25 d, radius of 2.42(−0.10,+0.10) R⊕, mass of 6.29(−0.61,+0.63) M⊕, and mean density of 2.45(−0.37,+0.44) g/cu.cm belongs to the population of dense sub-Neptunes. With the two planets located on opposite sides of the radius gap, this planetary system is an excellent target for testing planetary formation, evolution, and atmospheric models. In particular, LTT 3780 c is an ideal object for atmospheric studies with the James Webb Space Telescope (JWST).
We observed two transits of the iconic gas giant HD 209458b between 380 and 780 nm, using the high-resolution ESPRESSO spectrograph. The derived planetary transmission spectrum exhibits features at ...all wavelengths where the parent star shows strong absorption lines, for example, Na
I
, Mg
I
, Fe
I
, Fe
II
, Ca
I
, V
I
, H
α
, and K
I
. We interpreted these features as the signature of the deformation of the stellar line profiles due to the Rossiter-McLaughlin effect, combined with the centre-to-limb effects on the stellar surface, which is in agreement with similar reports recently presented in the literature. We also searched for species that might be present in the planetary atmosphere but not in the stellar spectra, such as TiO and VO, and obtained a negative result. Thus, we find no evidence of any planetary absorption, including previously reported Na
I
, in the atmosphere of HD 209458b. The high signal-to-noise ratio in the transmission spectrum (~1700 at 590 nm) allows us to compare the modelled deformation of the stellar lines in assuming different one-dimensional stellar atmospheric models. We conclude that the differences among various models and observations remain within the precision limits of the data. However, the transmission light curves are better explained when the centre-to-limb variation is not included in the computation and only the Rossiter-McLaughlin deformation is considered. This demonstrates that ESPRESSO is currently the best facility for spatially resolving the stellar surface spectrum in the optical range using transit observations and carrying out empirical validations of stellar models.
Context.
The CARMENES instrument, installed at the 3.5 m telescope of the Calar Alto Observatory in Almería, Spain, was conceived to deliver high-accuracy radial velocity (RV) measurements with ...long-term stability to search for temperate rocky planets around a sample of nearby cool stars. Moreover, the broad wavelength coverage was designed to provide a range of stellar activity indicators to assess the nature of potential RV signals and to provide valuable spectral information to help characterise the stellar targets.
Aims.
We describe the CARMENES guaranteed time observations (GTO), spanning from 2016 to 2020, during which 19 633 spectra for a sample of 362 targets were collected. We present the CARMENES Data Release 1 (DR1), which makes public all observations obtained during the GTO of the CARMENES survey.
Methods.
The CARMENES survey target selection was aimed at minimising biases, and about 70% of all known M dwarfs within 10 pc and accessible from Calar Alto were included. The data were pipeline-processed, and high-level data products, including 18 642 precise RVs for 345 targets, were derived. Time series data of spectroscopic activity indicators were also obtained.
Results.
We discuss the characteristics of the CARMENES data, the statistical properties of the stellar sample, and the spectroscopic measurements. We show examples of the use of CARMENES data and provide a contextual view of the exoplanet population revealed by the survey, including 33 new planets, 17 re-analysed planets, and 26 confirmed planets from transiting candidate follow-up. A subsample of 238 targets was used to derive updated planet occurrence rates, yielding an overall average of 1.44 ± 0.20 planets with 1
M
⊕
<
M
pl
sin
i <
1000
M
⊕
and 1 day <
P
orb
< 1000 days per star, and indicating that nearly every M dwarf hosts at least one planet. All the DR1 raw data, pipeline-processed data, and high-level data products are publicly available online.
Conclusions.
CARMENES data have proven very useful for identifying and measuring planetary companions. They are also suitable for a variety of additional applications, such as the determination of stellar fundamental and atmospheric properties, the characterisation of stellar activity, and the study of exoplanet atmospheres.
The GAPS Programme at TNG Sicilia, D; Scandariato, G; Guilluy, G ...
Astronomy and astrophysics (Berlin),
07/2024, Letnik:
687
Journal Article
Recenzirano
Odprti dostop
Context. HAT-P-67 b is one of the lowest-density gas giants known to date, making it an excellent target for atmospheric characterisation through the transmission spectroscopy technique. Aims. In the ...framework of the GAPS large programme, we collected four transit events of HAT-P-67 b with the aim of studying the exoplanet atmosphere and deriving the orbital projected obliquity. Methods. We exploited the high-precision GIARPS (GIANO-B + HARPS-N) observing mode of the Telescopio Nazionale Galileo (TNG) along with additional archival TESS photometry to explore the activity level of the host star. We performed transmission spec-troscopy, both in the visible (VIS) and in the near-infrared (NIR) wavelength range, and we analysed the Rossiter–McLaughlin (RML) effect when fitting both the radial velocities and the Doppler shadow. Based on the TESS photometry, we redetermined the transit parameters of HAT-P-67 b. Results. By modelling the RML effect, we derived a sky-projected obliquity of (2.2 ± 0.4)°, indicating an aligned planetary orbit. The chromospheric activity index log R′HK, the CCF profile, and the variability in the transmission spectrum of the Hα line suggest that the host star shows signatures of stellar activity and/or pulsation. We found no evidence of atomic or molecular species in the optical transmission spectra, with the exception of pseudo-signals corresponding to Cr I, Fe I, Ha, Na I, and Ti I. In the NIR range, we found an absorption signal of the He I triplet of 5.56−0.30+0.29% (19.0σ), corresponding to an effective planetary radius of ~3 Rp (where Rp ~ 2 RJ), which extends beyond the planet’s Roche lobe radius. Conclusions. Owing to the stellar variability and the high uncertainty of the model, we could not confirm the planetary origin of the signals found in the optical transmission spectrum. On the other hand, we were able to confirm previous detections of the infrared He I triplet, providing a 19.0σ detection. Our finding indicates that the planet’s atmosphere is evaporating.
We report on the precise radial velocity follow-up of TOI-544 (HD 290498),ã bright K star ( V = 10.8), which hostsã small transiting planet recently disco v ered by the Trãnsiting Exoplanet Survey ...Satellite (TESS) . We collected 122 high-resolution High Accuracy Radial velocity Planet Searcher (HARPS)ãnd HARPS-N spectra to spectroscopically confirm the transiting planetãnd measure its mass. The nearly 3-yr baseline of our follow-upãllowed us to unveil the presence ofãnãdditional, non-transiting, longer-period companion planet. We derivedã radiusãnd mass for the inner planet, TOI-544 b, of 2.018 ±0.076 R⊙and 2.89 ±0.48 M⊙, respectively, which givesã bulk density of 1 . 93 + 0 . 30 -0 . 25 g cm -3 . TOI-544 c hasã minimum mass of 21.5 ±2.0 M⊙and orbital period of 50.1 ±0.2 d. The low density of planet-b implies that it has eitherãn Earth-like rocky core withã hydrogenãtmosphere, orã composition which harboursã significant fraction of water. The composition interpretation is degenerate depending on the specific choice of planet interior models used. Additionally, TOI-544 b hasãn orbital period of 1.55 dãnd equilibrium temperature of 999 ±14 K, placing it within the predicted location of the radius valley, where few planetsãre expected. TOI-544 b isã top target for futureãtmospheric observations, for example with JWST , which would enable better constraints of the planet composition.
The GAPS Programme at TNG Guilluy, G.; D’Arpa, M. C.; Bonomo, A. S. ...
Astronomy and astrophysics (Berlin),
06/2024, Letnik:
686
Journal Article
Recenzirano
Context . Atmospheric escape plays a fundamental role in shaping the properties of exoplanets. The metastable near-infrared (nIR) helium triplet at 1083.3 nm (He I ) is a powerful proxy of extended ...and evaporating atmospheres. Aims . We used the GIARPS (GIANO-B + HARPS-N) observing mode of the Telescopio Nazionale Galileo to search for He I absorption in the upper atmospheres of five close-in giant planets hosted by the K and M dwarf stars of our sample, namely WASP-69 b, WASP-107 b, HAT-P-11 b, GJ 436 b, and GJ 3470 b. Methods . We focused our analysis on the nIR He I triplet, performing high-resolution transmission spectroscopy by comparing the in-transit and out-of-transit observations. In instances where nightly variability in the He I absorption signal was identified, we investigated the potential influence of stellar magnetic activity on the planetary absorption signal by searching for variations in the H α transmission spectrum. Results . We spectrally resolve the He I triplet and confirm the published detections for WASP-69 b (3.91 ± 0.22%, 17.6 σ ), WASP-107 b (8.17 −0.76 +0.80 %, 10.5 σ ), HAT-P-11 b (1.36 ± 0.17%, 8.0 σ ), and GJ 3470 b (1.75 −0.36 +0.39 %, 4.7 σ ). We do not find evidence of extra absorption for GJ 436 b. We observe night-to-night variations in the He I absorption signal for WASP-69 b, associated with variability in H α , which likely indicates the influence of pseudo-signals related to stellar activity. Additionally, we find that the He I signal of GJ 3470 b originates from a single transit observation, thereby corroborating the discrepancies found in the existing literature. An inspection of the H α line reveals an absorption signal during the same transit event. Conclusions . By combining our findings with previous analyses of GIANO-B He I measurements of planets orbiting K dwarfs, we explore potential trends with planetary and stellar parameters that are thought to affect the absorption of metastable He I . Our analysis is unable to identify clear patterns, thus emphasising the necessity for additional measurements and the exploration of potential additional parameters that may be important in controlling He I absorption in planetary upper atmospheres.
Context.
Ultra-hot Jupiters, with their high equilibrium temperatures and resolved spectral lines, have emerged as a perfect testbed for new analysis techniques in the study of exoplanet atmospheres. ...In particular, the resolved sodium doublet as a resonant line has proven a powerful indicator to probe the atmospheric structure over a wide pressure range.
Aims.
We aim to explore an atmospheric origin of the observed blueshifted feature next to the sodium doublet of the ultra-hot Jupiter WASP-121 b using a partial transit obtained with the 4-UT mode of ESPRESSO. We intend to study its atmospheric dynamics visible across the terminator by splitting the data into mid-transit and egress.
Methods.
We explored the impact of the Rossiter-McLaughlin effect on the line shape of the sodium doublet. The partial transit is separated into one dataset centred around mid-transit and one dataset comprising the second part of the transit and egress. Lastly, the atmospheric retrieval code, Multinested Eta Retrieval Code (MERC), was applied to both datasets in order to study the imprint of atmospheric dynamics on the line shape of the sodium doublet.
Results.
We determine that the blueshifted high-velocity absorption component is generated only during the egress part of the transit when a larger fraction of the day side of the planet is visible. For the egress data, MERC retrieves the blueshifted high-velocity absorption component as an equatorial day-to-night side wind across the evening limb, with no zonal winds visible on the morning terminator with weak evidence compared to a model with only vertical winds. For the mid-transit data, the observed line broadening is attributed to a vertical, radial wind.
Conclusions.
We attribute the equatorial day-to-night-side wind over the evening terminator to a localised jet and restrain its existence between the substellar point and up to 10° to the terminator in longitude, an opening angle of the jet of at most 60° in latitude, and a lower boundary in altitude between 1.08, 1.15
R
p
. As a hypothesis, we propose that the jet is produced by the excitation of standing planetary scale Rossby waves by stellar irradiation and subsequently broken by Kelvin-Helmholtz instabilities. Due to the partial nature of the transit, we cannot make any statements on whether the jet is truly super-rotational and one-sided or part of a symmetric day-to-night-side atmospheric wind from the hotspot.
The GAPS Programme at TNG Sicilia, D.; Scandariato, G.; Guilluy, G. ...
Astronomy and astrophysics (Berlin),
07/2024, Letnik:
687
Journal Article
Recenzirano
Context . HAT-P-67 b is one of the lowest-density gas giants known to date, making it an excellent target for atmospheric characterisation through the transmission spectroscopy technique. Aims . In ...the framework of the GAPS large programme, we collected four transit events of HAT-P-67 b with the aim of studying the exoplanet atmosphere and deriving the orbital projected obliquity. Methods . We exploited the high-precision GIARPS (GIANO-B + HARPS-N) observing mode of the Telescopio Nazionale Galileo (TNG) along with additional archival TESS photometry to explore the activity level of the host star. We performed transmission spec-troscopy, both in the visible (VIS) and in the near-infrared (NIR) wavelength range, and we analysed the Rossiter–McLaughlin (RML) effect when fitting both the radial velocities and the Doppler shadow. Based on the TESS photometry, we redetermined the transit parameters of HAT-P-67 b. Results . By modelling the RML effect, we derived a sky-projected obliquity of (2.2 ± 0.4)°, indicating an aligned planetary orbit. The chromospheric activity index log R ′ HK , the CCF profile, and the variability in the transmission spectrum of the H α line suggest that the host star shows signatures of stellar activity and/or pulsation. We found no evidence of atomic or molecular species in the optical transmission spectra, with the exception of pseudo-signals corresponding to Cr I , Fe I , Ha, Na I , and Ti I . In the NIR range, we found an absorption signal of the He I triplet of 5.56 −0.30 +0.29 % (19.0 σ ), corresponding to an effective planetary radius of ~3 R p (where R p ~ 2 R J ), which extends beyond the planet’s Roche lobe radius. Conclusions . Owing to the stellar variability and the high uncertainty of the model, we could not confirm the planetary origin of the signals found in the optical transmission spectrum. On the other hand, we were able to confirm previous detections of the infrared He I triplet, providing a 19.0 σ detection. Our finding indicates that the planet’s atmosphere is evaporating.
The GAPS Programme at TNG Basilicata, M.; Giacobbe, P.; Bonomo, A. S. ...
Astronomy & astrophysics,
6/2024, Letnik:
686
Journal Article
Recenzirano
Odprti dostop
Context. The atmospheric characterisation of hot and warm Neptune-size exoplanets is challenging mainly due to their relatively small radius and atmospheric scale height, which reduce the amplitude ...of atmospheric spectral features. The warm-Neptune HAT-P-11 b is a remarkable target for atmospheric characterisation because of the large brightness of its host star ( V = 9.46 mag; H = 7.13 mag). Aims. The aims of this work are to review the main physical and architectural properties of the HAT-P-11 planetary system, and to probe the presence of eight molecular species in the atmosphere of HAT-P-11 b through near-infrared (NIR) high-resolution transmission spectroscopy. Methods. We reviewed the physical and architectural properties of the HAT-P-11 planetary system by analysing transits and occultations of HAT-P-11 b from the Kepler data set as well as HIRES at Keck archival radial-velocity data. We modelled the latter with Gaussian-process regression and a combined quasi-periodic and squared-exponential kernel to account for stellar variations on both (short-term) rotation and (long-term) activity-cycle timescales. In order to probe the atmospheric composition of HAT-P-11 b, we observed four transits of this target with the NIR GIANO-B at TNG spectrograph and cross-correlated the data with template atmospheric transmission spectra. Results. We find that the long-period radial-velocity signal previously attributed to the HAT-P-11 c planet ( P ~ 9.3 yr; M p sin i ~ 1.6 M J ; e ~ 0.6) is more likely due to the stellar magnetic activity cycle. Nonetheless, the H IPPARCOS - Gaia difference in the proper-motion anomaly suggests that an outer-bound companion might still exist. For HAT-P-11 b, we measure a radius of R p = 0.4466 ± 0.0059 R J , a mass of M p = 0.0787 ± 0.0048 M J , a bulk density of ρ p = 1.172 ± 0.085 g cm −3 , and an orbital eccentricity of e = 0.2577 −0.0025 +0.0033 . These values are compatible with those from the literature. Probing its atmosphere, we detect the presence of two molecular species, H 2 O and NH 3 , with a S/N of 5.1 and 5.3, and a significance of 3.4 σ and 5.0 σ , respectively. We also tentatively detect the presence of CO 2 and CH 4 , with a S/N of 3.0 and 4.8, and a significance of 3.2 σ and 2.6 σ , respectively. Conclusions. We revisit the HAT-P-11 planetary system, confirm the presence of H 2 O, and report the detection of NH 3 in the atmosphere of HAT-P-11 b, also finding hints for the presence of CO 2 and CH 4 that need to be confirmed by further observations.
During the first billion years of their life, exoplanet atmospheres are modified by different atmospheric escape phenomena that can strongly affect the shape and morphology of the exoplanet itself. ...These processes can be studied with Lyalpha , Halpha , and/or He i triplet observations. We present high-resolution spectroscopy observations from CARMENES and GIARPS checking for He i and Halpha signals in 20 exoplanetary atmospheres: V1298\,Tau\,c, K2-100\,b, HD\,63433\,b, HD\,63433\,c, HD\,73583\,b, HD\,73583\,c, K2-77\,b, TOI-2076\,b, TOI-2048\,b, HD\,235088\,b, TOI-1807\,b, TOI-1136\,d, TOI-1268\,b, TOI-1683\,b, TOI-2018\,b, MASCARA-2\,b, WASP-189\,b, TOI-2046\,b, TOI-1431\,b, and HAT-P-57\,b. We report two new high-resolution spectroscopy He i detections for TOI-1268\,b and TOI-2018\,b, and a Halpha detection for TOI-1136\,d. Furthermore, we detect hints of He i for HD\,63433\,b, and Halpha for HD\,73583\,b and c, which need to be confirmed. The aim of the Measuring Out-flows in Planets orbiting Young Stars (MOPYS) project is to understand the evaporating phenomena and test their predictions from the current observations. We compiled a list of 70 exoplanets with He i and/or Halpha observations, from this work and the literature, and we considered the He i and Halpha results as proxy for atmospheric escape. Our principal results are that 0.1--1Gyr planets do not exhibit more He i or Halpha detections than older planets, and evaporation signals are more frequent for planets orbiting sim 1--3\,Gyr stars. We provide new constraints to the cosmic shoreline, the empirical division between rocky planets and planets with atmosphere, by using the evaporation detections and we explore the capabilities of a new dimensionless parameter He /R_ Hill $, to explain the He i triplet detections. Furthermore, we present a statistically significant upper boundary for the He i triplet detections in the $T_ eq $ versus $ p $ parameter space. Planets located above that boundary are unlikely to show He i absorption signals.
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