93 research outputs found
Large Interferometer For Exoplanets (LIFE): VIII. Where is the phosphine? Observing exoplanetary PH3 with a space based MIR nulling interferometer
Phosphine could be a key molecule in the understanding of exotic chemistry
happening in (exo)planetary atmospheres. While it has been detected in the
Solar System's giant planets, it has not been observed in exoplanets yet. In
the exoplanetary context however it has been theorized as a potential
biosignature molecule. The goal of our study is to identify which illustrative
science cases for PH3 chemistry are observable with a space-based mid-infrared
nulling interferometric observatory like the LIFE (Large Interferometer For
Exoplanets) concept. We identified a representative set of scenarios for PH3
detections in exoplanetary atmospheres varying over the whole dynamic range of
the LIFE mission. We used chemical kinetics and radiative transfer calculations
to produce forward models of these informative, prototypical observational
cases for LIFEsim, our observation simulator software for LIFE. In a detailed,
yet first order approximation it takes a mission like LIFE: (i) about 1h to
find phosphine in a warm giant around a G star at 10 pc, (ii) about 10 h in H2
or CO2 dominated temperate super-Earths around M star hosts at 5 pc, (iii) and
even in 100h it seems very unlikely that phosphine would be detectable in a
Venus-Twin with extreme PH3 concentrations at 5 pc. Phosphine in concentrations
previously discussed in the literature is detectable in 2 out of the 3 cases
and about an order of magnitude faster than comparable cases with JWST. We show
that there is a significant number of objects accessible for these classes of
observations. These results will be used to prioritize the parameter range for
the next steps with more detailed retrieval simulations. They will also inform
timely questions in the early design phase of a mission like LIFE and guide the
community by providing easy-to-scale first estimates for a large part of
detection space of such a mission.Comment: In press. Accepted for publication in Astrobiology on 02 November
2022. 26 pages, 5 figures and 8 table
Large interferometer for exoplanets: VIII. Where is the phosphine? Observing exoplanetary PH3 with a space-based mid-infrared nulling interferometer
Stars and planetary system
The GAPS Programme at TNG. XXVIII. A pair of hot-Neptunes orbiting the young star TOI-942
Context. Young stars and multi-planet systems are two types of primary objects that allow us to study, understand, and constrain planetary formation and evolution theories. Aims: We validate the physical nature of two Neptune-sized planets transiting TOI-942 (TYC 5909-319-1), a previously unacknowledged young star (50-20+30 Myr) observed by the TESS space mission in Sector 5. Methods: Thanks to a comprehensive stellar characterization, TESS light curve modeling and precise radial-velocity measurements, we validated the planetary nature of the TESS candidate and detected an additional transiting planet in the system on a larger orbit. Results: From photometric and spectroscopic observations we performed an exhaustive stellar characterization and derived the main stellar parameters. TOI-942 is a relatively active K2.5V star (log R'HK = -4.17 ± 0.01) with rotation period Prot = 3.39 ± 0.01 days, a projected rotation velocity v sin i⋆ = 13.8 ± 0.5 km s-1, and a radius of ~0.9 R⊙. We found that the inner planet, TOI-942 b, has an orbital period Pb = 4.3263 ± 0.0011 days, a radius Rb = 4.242-0.313+0.376 R⊕, and a mass upper limit of 16 M⊕ at 1σ confidence level. The outer planet, TOI-942 c, has an orbital period Pc = 10.1605-0.0053+0.0056 days, a radius Rc = 4.793-0.351+0.410 R⊕, and a mass upper limit of 37 M⊕ at 1σ confidence level. Based on observations made with the Italian Telescopio Nazionale Galileo (TNG) operated by the Fundación Galileo Galilei (FGG) of the Istituto Nazionale di Astrofisica (INAF) at the Observatorio del Roque de los Muchachos (La Palma, Canary Islands, Spain). The authors became aware of a parallel effort on the characterization of TOI-942 by Zhou et al. (2021) in the late stages of the manuscript preparations. The submissions are coordinated, and no analyses or results were shared prior to submission
The GAPS Programme at TNG. XXI. A GIARPS case study of known young planetary candidates: confirmation of HD 285507 b and refutation of AD Leonis b
Context. The existence of hot Jupiters is still not well understood. Two main channels are thought to be responsible for their current location: a smooth planet migration through the protoplanetary disk or the circularization of an initial highly eccentric orbit by tidal dissipation leading to a strong decrease in the semimajor axis. Different formation scenarios result in different observable effects, such as orbital parameters (obliquity and eccentricity) or frequency of planets at different stellar ages. Aims: In the context of the GAPS Young Objects project, we are carrying out a radial velocity survey with the aim of searching and characterizing young hot-Jupiter planets. Our purpose is to put constraints on evolutionary models and establish statistical properties, such as the frequency of these planets from a homogeneous sample. Methods: Since young stars are in general magnetically very active, we performed multi-band (visible and near-infrared) spectroscopy with simultaneous GIANO-B + HARPS-N (GIARPS) observing mode at TNG. This helps in dealing with stellar activity and distinguishing the nature of radial velocity variations: stellar activity will introduce a wavelength-dependent radial velocity amplitude, whereas a Keplerian signal is achromatic. As a pilot study, we present here the cases of two known hot Jupiters orbiting young stars: HD 285507 b and AD Leo b. Results: Our analysis of simultaneous high-precision GIARPS spectroscopic data confirms the Keplerian nature of the variation in the HD 285507 radial velocities and refines the orbital parameters of the hot Jupiter, obtaining an eccentricity consistent with a circular orbit. Instead, our analysis does not confirm the signal previously attributed to a planet orbiting AD Leo. This demonstrates the power of the multi-band spectroscopic technique when observing active stars. Photometry, RV, and time series are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/638/A5 Based on observations made with the Italian Telescopio Nazionale Galileo (TNG) operated by the Fundación Galileo Galilei (FGG) of the Istituto Nazionale di Astrofisica (INAF) at the Observatorio del Roque de los Muchachos (La Palma, Canary Islands, Spain). Partly based on data obtained with the STELLA robotic telescopes in Tenerife, an AIP facility jointly operated by AIP and IAC
Large interferometer for exoplanets (LIFE). I. Improved exoplanet detection yield estimates for a large mid-infrared space-interferometer mission
Stars and planetary system
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