Search

The recently-computed ExoMol line lists for isotopologues of AlH are used to analyse the blue spectrum (4000-4500 {\AA}) of Proxima Cen (M5.5 V). Comparison of the observed and computed spectra enables the identification of a large number of 27AlH lines of the A1{\Pi} - X1{\Sigma}+ band system: the spectral range covering 1-0, 0-0 and 1-1 bands is dominated by clearly resolved AlH lines. We reveal the diffuse nature of transitions close to the dissociation limit which appears in the form of increasingly wider(up to 5 {\AA}) and shallower (up to the continuum confusion limit) AlH line profiles. The predicted wavelengths of AlH diffuse lines are systematically displaced. The effect broadening by pre-dissociation states on the line profiles is included by increasing the radiative damping rate by up to 5 orders of magnitude. We determine empirical values of damping rates for a number of the clean 0-0 Q-branch transitions by comparing the observed and synthetic stellar spectra. We find excellent agreement between our damping rates and lifetimes available in the literature. A comparison of 27Al1H ExoMol and REALH spectra shows that the observed spectrum is better described by the ExoMol line list. A search for 26Al1H lines in the Proxima Cen spectrum does not reveal any notable features; giving an upper limit of 27Al1H/26Al1H {>} 100., Comment: 22 pages, 6 tables, 10 figs, accepted by MNRAS

Context. Although the number of exoplanets reported in the literature exceeds 5000 so far, only a few dozen of them are young planets (≤900 Myr). However, a complete characterization of these young planets is key to understanding the current properties of the entire population. Hence, it is necessary to constrain the planetary formation processes and the timescales of dynamical evolution by measuring the masses of exoplanets transiting young stars. Aims. We characterize and measure the masses of two transiting planets orbiting the 400 Myr old solar-type star HD 63433, which is a member of the Ursa Major moving group. Methods. We analysed precise photometric light curves of five sectors of the TESS mission with a baseline of ~750 days and obtained ~150 precise radial velocity measurements with the visible and infrared arms of the CARMENES instrument at the Calar Alto 3.5 m telescope in two different campaigns of ~500 days. We performed a combined photometric and spectroscopic analysis to retrieve the planetary properties of two young planets. The strong stellar activity signal was modelled by Gaussian regression processes. Results. We have updated the transit parameters of HD 63433 b and c and obtained planet radii of Rpb = 2.140 ± 0.087 R⊕ and Rpc = 2.692 ± 0.108 R⊕. Our analysis allowed us to determine the dynamical mass of the outer planet with a 4σ significance (Mpc = 15.54 ± 3.86 M⊕) and set an upper limit on the mass of the inner planet at 3σ (Mpb < 21.76 M⊕). According to theoretical models, both planets are expected to be sub-Neptunes, whose interiors mostly consist of silicates and water with no dominant composition of iron, and whose gas envelopes are lower than 2% in the case of HD 63433 c. The envelope is unconstrained in HD 63433 b.

Current theories of planetary evolution predict that infant giant planets have large radii and very low densities before they slowly contract to reach their final size after about several hundred million years1,2. These theoretical expectations remain untested so far as the detection and characterization of very young planets is extremely challenging due to the intense stellar activity of their host stars3,4. Only the recent discoveries of young planetary transiting systems allow initial constraints to be placed on evolutionary models5,6,7. With an estimated age of 20 million years, V1298 Tau is one of the youngest solar-type stars known to host transiting planets; it harbours a system composed of four planets, two Neptune-sized, one Saturn-sized and one Jupiter-sized8,9. Here we report a multi-instrument radial velocity campaign of V1298 Tau, which allowed us to determine the masses of two of the planets in the system. We find that the two outermost giant planets, V1298 Tau b and e (0.64 ± 0.19 and 1.16 ± 0.30 Jupiter masses, respectively), seem to contradict our knowledge of early-stages planetary evolution. According to models, they should reach their mass–radius combination only hundreds of millions of years after formation. This result suggests that giant planets can contract much more quickly than usually assumed. © 2021, The Author(s), under exclusive licence to Springer Nature Limited., A.S.M. acknowledges financial support from the Spanish Ministry of Science and Innovation (MICINN) under the 2019 Juan de la Cierva Programme. J.I.G.H. acknowledges financial support from the Spanish MICINN under the 2013 Ramón y Cajal programme RYC-2013-14875. A.S.M., J.I.G.H., R.R., B.T.-P., N.L., M.R.Z.O., E.G.-A., J.A.C., P.J.A. and I.R. acknowledge financial support from the Spanish Ministry of Science and Innovation through projects AYA2017-86389-P, PID2019-109522GB-C53, PID2019-109522GB-C51, AYA2016-79425-C3-3-P, PID2019-109522GB-C52 and PGC2018-098153-B-C33. M.D. acknowledges financial support from the FP7-SPACE Project ETAEARTH (GA no. 313014). A.M., D.L., G.M., A.S. and S.D. acknowledge partial contribution from the agreement ASI-INAF no. 2018-16-HH.0. S.B., D.L., G.M. and D.T. acknowledge partial contribution from the agreement ASI-INAF no. 2021-5-HH.0. P.J.A. acknowledges financial support from the project SEV-2017-0709. S.D., V.D., S.B. and D.T. acknowledge support from the PRIN-INAF 2019 ‘Planetary systems at young ages’ (PLATEA). D.S.A. thanks the Leverhulme Trust for financial support. I.R. acknowledges the support of the Generalitat de Catalunya/CERCA programme. E.G.-A acknowledges support from the Spanish State Research Agency (AEI) project no. MDM-2017-0737 Unidad de Excelencia ‘María de Maeztu’ Centro de Astrobiología (CAB, CSIC/INTA). D.T. acknowledges the support of the Italian National Institute of Astrophysics (INAF) through the INAF Main Stream project ‘Ariel and the astrochemical link between circumstellar discs and planets’ (CUP: C54I19000700005). E.E.-B. acknowledges financial support from the European Union and the State Agency of Investigation of the Spanish Ministry of Science and Innovation (MICINN) under grant PRE2020-093107 of the Pre-Doc Program for the Training of Doctors (FPI-SO) through FEDER, FSE and FDCAN funds. This work is 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). CARMENES is an instrument at the Centro Astronómico Hispano-Alemán (CAHA) at Calar Alto (Almería, Spain), operated jointly by the Junta de Andalucía and the Instituto de Astrofísica de Andalucía (CSIC). This work is based on data obtained with the STELLA robotic telescopes in Tenerife, an AIP facility jointly operated by AIP and IAC. This work makes use of observations from the LCOGT network.

This is an Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited., We report the discovery and characterisation of two Earth-mass planets orbiting in the habitable zone of the nearby M-dwarf GJ 1002 based on the analysis of the radial-velocity (RV) time series from the ESPRESSO and CARMENES spectrographs. The host star is the quiet M5.5 V star GJ 1002 (relatively faint in the optical, V ~ 13.8 mag, but brighter in the infrared, J ~ 8.3 mag), located at 4.84 pc from the Sun. We analyse 139 spectroscopic observations taken between 2017 and 2021. We performed a joint analysis of the time series of the RV and full-width half maximum (FWHM) of the cross-correlation function (CCF) to model the planetary and stellar signals present in the data, applying Gaussian process regression to deal with the stellar activity. We detect the signal of two planets orbiting GJ 1002. GJ 1002 b is a planet with a minimum mass mp sin i of 1.08 ± 0.13 M⊕ with an orbital period of 10.3465 ± 0.0027 days at a distance of 0.0457 ± 0.0013 au from its parent star, receiving an estimated stellar flux of 0.67 F⊕. GJ 1002 c is a planet with a minimum mass mp sin i of 1.36 ± 0.17 M⊕ with an orbital period of 20.202 ± 0.013 days at a distance of 0.0738 ± 0.0021 au from its parent star, receiving an estimated stellar flux of 0.257 F⊕. We also detect the rotation signature of the star, with a period of 126 ± 15 days. We find that there is a correlation between the temperature of certain optical elements in the spectrographs and changes in the instrumental profile that can affect the scientific data, showing a seasonal behaviour that creates spurious signals at periods longer than ~200 days. GJ 1002 is one of the few known nearby systems with planets that could potentially host habitable environments. The closeness of the host star to the Sun makes the angular sizes of the orbits of both planets (~9.7 mas and ~15.7 mas, respectively) large enough for their atmosphere to be studied via high-contrast high-resolution spectroscopy with instruments such as the future spectrograph ANDES for the ELT or the LIFE mission. © The Authors 2023., A.S.M. acknowledges financial support from the Spanish Ministry of Science and Innovation (MICINN) under 2018 Juan de la Cierva program IJC2018-035229-I. A.S.M., V.M.P., J.I.G.H., C.A.P. and R.R. acknowledge financial support from the Spanish MICINN project PID2020-117493GB-I00. A.S.M., V.M.P., J.I.G.H. and R.R. acknowledge financial support from the Government of the Canary Islands project ProID2020010129. J.P.F. is supported in the form of a work contract funded by national funds through FCT with reference DL 57/2016/CP1364/CT0005. C.J.M. acknowledges FCT and POCH/FSE (EC) support through Investigador FCT Contract 2021.01214.CEECIND/CP1658/CT0001. This work was supported by FCT - Fundação para a Ciência e a Tecnologia through national funds and by FEDER through COMPETE2020 – Programa Operacional Competitividade e Internacionalização by these grants: UIDB/04434/2020; UIDP/04434/2020. A.M.S acknowledges support from the Fundação para a Ciência e a Tecnologia (FCT) through the Fellowship 2020.05387.BD. and POCH/FSE (EC). This work was supported by FCT – Fundação para a Ciência e a Tecnologia through national funds and by FEDER through COMPETE2020– Programa Operacional Competitividade e Inter-nacionalização by these grants: UIDB/04434/2020; UIDP/04434/2020; PTDC/FIS-AST/32113/2017 & POCI-01-0145-FEDER-032113; PTDC/FIS-AST/28953/2017 & POCI-01-0145-FEDER-028953. The INAF authors acknowledge financial support of the Italian Ministry of Education, University, and Research with PRIN 201278X4FL and the “Progetti Premiali” funding scheme. J.B.D. acknowledges financial support from the Swiss National Science Foundation (SNSF). This work has, in part, been carried out within the framework of the National Centre for Competence in Research PlanetS supported by SNSF. CARMENES is an instrument for the Centro Astronómico Hispano en Andalucía (CAHA) at Calar Alto (Almería, Spain), operated jointly by the Junta de Andalucía and the Instituto de Astrofísica de Andalucía (CSIC). CARMENES was funded by the Max-Planck-Gesellschaft (MPG), the Consejo Superior de Investigaciones Científicas (CSIC), the Ministerio de Economía y Competitividad (MINECO) and the European Regional Development Fund (ERDF) through projects FICTS-2011-02, ICTS-2017-07-CAHA-4, and CAHA16-CE-3978, and the members of the CARMENES Consortium (Max-Planck-Institut für Astronomie, Instituto de Astrofísica de Andalucía, Landessternwarte Königstuhl, Institut de Ciències de l’Espai, Institut für Astrophysik Göttingen, Universidad Complutense de Madrid, Thüringer Landessternwarte Tautenburg, Instituto de Astrofísica de Canarias, Hamburger Sternwarte, Centro de Astrobiología and Centro Astronómico Hispano en Andalucía), with additional contributions by the MINECO, the Deutsche Forschungsgemeinschaft through the Major Research Instrumentation Programme and Research Unit FOR2544 “Blue Planets around Red Stars”, the Klaus Tschira Stiftung, the states of Baden-Württemberg and Niedersachsen, and by the Junta de Andalucía. This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www. cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. Manuscript written using Overleaf. Main analysis performed in Python3 (Van Rossum & Drake 2009) running on Ubuntu (Sobell 2015) systems and MS. Windows running the Windows subsystem for Linux (WLS). Radial velocities and selected activity indicators extracted with SERVAL (Zechmeister et al. 2018). Second RV extraction with S-BART (Silva et al. 2022). Extensive use of the DACE platform https://dace.unige.ch/ Extensive usage of Numpy (van der Walt et al. 2011). Extensive usage of Scipy (Virtanen et al. 2020). All figures built with Matplotlib (Hunter 2007). Periodograms and phase folded curves built using Pyastronomy (Czesla et al. 2019). Gaussian processes modelled with S+LEAF (Delisle et al. 2022), Celerite2 (Foreman-Mackey et al. 2017) and George (Foreman-Mackey et al. 2013). Nested sampling with Dynesty (Speagle 2020). Selected operations accelerated with Numba (Lam et al. 2015). Keplerian function adapted from Pytransit (Parviainen 2015). Selected calculations made in Excel (Microsoft Corporation 2018). TESS target pixel file plot done with tpfplotter (Aller et al. 2020). Aperture photometry performed with AstroImageJ (Collins et al. 2017). The bulk of the analysis was performed on desktop PC with an AMD RyzenTM 9 3950X (16 cores, 2 threads per core, 3.5–4.7 GHz) and a server hosting 2 x Intel(R) Xeon(R) Gold 5218 (2x16 cores, 2 threads per core, 2.3-3.9 GHz)., With funding from the Spanish government through the "Severo Ochoa Centre of Excellence" accreditation (CEX2021-001131-S).

We present radial velocity follow-up obtained with ESPRESSO of the M-type star LTT 1445A (TOI-455), for which a transiting planet b with an orbital period of~5.4 days was detected by TESS. We report the discovery of a second transiting planet (LTT 1445A c) and a third non-transiting candidate planet (LTT 1445A d) with orbital periods of 3.12 and 24.30 days, respectively. The host star is the main component of a triple M-dwarf system at a distance of 6.9 pc. We used 84 ESPRESSO high-resolution spectra to determine accurate masses of 2.3$\pm$0.3 $\mathrm{M}_\oplus$ and 1.0$\pm$0.2 $\mathrm{M}_\oplus$ for planets b and c and a minimum mass of 2.7$\pm$0.7 $\mathrm{M}_\oplus$ for planet d. Based on its radius of 1.43$\pm0.09$ $\mathrm{R}_\oplus$ as derived from the TESS observations, LTT 1445A b has a lower density than the Earth and may therefore hold a sizeable atmosphere, which makes it a prime target for the James Webb Space Telescope. We used a Bayesian inference approach with the nested sampling algorithm and a set of models to test the robustness of the retrieved physical values of the system. There is a probability of 85$\%$ that the transit of planet c is grazing, which results in a retrieved radius with large uncertainties at 1.60$^{+0.67}_{-0.34}$ $\mathrm{R}_\oplus$. LTT 1445A d orbits the inner boundary of the habitable zone of its host star and could be a prime target for the James Webb Space Telescope., 31 pages, 20 figures Accepted A&A

HE 0107$-$5240 is a hyper metal-poor star with $\rm [Fe/H]=-5.39$. We performed high-res observations with the ESPRESSO spectrograph at the VLT to constrain the kinematical properties of the binary system HE 0107$-$5240 and to probe the binarity of the sample of 8 most metal-poor stars with $\rm [Fe/H], 15 pages, 7 Figures. Accepted for publication in A&A

This paper reports on the detailed characterisation of the K2-111 planetary system with K2, WASP, and ASAS-SN photometry as well as high-resolution spectroscopic data from HARPS-N and ESPRESSO. The host, K2-111, is confirmed to be a mildly evolved ($\log g=4.17$), iron-poor ([Fe/H]$=-0.46$), but alpha-enhanced ([$\alpha$/Fe]$=0.27$), chromospherically quiet, very old thick disc G2 star. A global fit, performed by using PyORBIT shows that the transiting planet, K2-111b, orbits with a period $P_b=5.3518\pm0.0004$ d, and has a planet radius of $1.82^{+0.11}_{-0.09}$ R$_\oplus$ and a mass of $5.29^{+0.76}_{-0.77}$ M$_\oplus$, resulting in a bulk density slightly lower than that of the Earth. The stellar chemical composition and the planet properties are consistent with K2-111b being a terrestrial planet with an iron core mass fraction lower than the Earth. We announce the existence of a second signal in the radial velocity data that we attribute to a non-transiting planet, K2-111c, with an orbital period of $15.6785\pm 0.0064$ days, orbiting in near-3:1 mean-motion resonance with the transiting planet, and a minimum planet mass of $11.3\pm1.1$ M$_\oplus$. Both planet signals are independently detected in the HARPS-N and ESPRESSO data when fitted separately. There are potentially more planets in this resonant system, but more well-sampled data are required to confirm their presence and physical parameters., Comment: Accepted for publication in MNRAS on 28 Sept 2020. Paper is 18 pages with an additional 12 pages of supplementary material. Data is available at https://vizier.u-strasbg.fr/viz-bin/VizieR?-source=J/MNRAS/499/5004

Despite the discovery of thousands of exoplanets, the mechanisms of planet formation and evolution have not been well tested with observations, mainly because the lack of a complete photometric and spectroscopic characterization of young planets, which presents a big challenge due to the high stellar activity of young stars. By determining the masses of young exoplanets, we can establish their composition, and investigate their evolution with age. For these observations, we can deduce if they were formed without gas (rocky planets) from their origin, or if they are born as small gaseous planets that lose their atmosphere rapidly (~tens of Myr) by photoevaporation (Murray-Clay et al. 2019) or slowly (~1 Gyr) by core-powered mass loss (Ginzburg et al. 2018). HD63433 is a very bright and fast rotating (6.46 days) solar-type star of the young (~400Myr) Ursa Major moving group hosting two transiting mini-Neptune-size exoplanets (Mann et al. 2020) with orbital periods of 7.11 (HD63433 b) and 20.55 (HD63433 c) days. We have collected 150 Radial Velocity (RV) measurements of HD63433 with CARMENES spectrograph over 1.4 years to determine the mass of the planets (Mallorquín et al. 2022, in prep). We have jointly modeled the transits, the keplerian planetary signal, and stellar activity with Gaussian Processes combining the TESS photometry and the CARMENES RV dataset. Our results reveal that the outer planet is detected in the CARMENES time series with an amplitude of 4.1+-1.0 m/s at the level of 4-sigma, which correspond to an absolute mass of Mp=17.4+-4.3 mass of the Earth for HD63433 c, making it the smallest planet with a robust mass determination at young ages. We report an upper limit of Mp

Current theories predict that very young giant planets have large radii and very low densities before they slowly contract to reach their final size after several hundred million years. Open stellar clusters and young moving groups of stars offer a unique opportunity to study exoplanets at their infant stages because of the well-constrained ages. The extreme stellar activity of young stars makes measuring the masses of their planets a very challenging task. Planet-induced radial velocity signals are typically smaller in amplitude and at lower frequencies than stellar-induced signals. These situations place very demanding requirements for RV observation campaigns and puts us in a worst-case scenario for the standard methods of stellar activity modelling. With an estimated age of 20 million years, V1298 Tau is one of the youngest solar-type stars known to host transiting planets; it harbours a system composed of four planets, two Neptune-sized, one Saturn-sized and one Jupiter-sized. Using more than 200 radial velocity measurements, condensed into a 4-month period, we were able to measure the radial velocity amplitude induced by the planet V1298 Tau b, and to pick up a second signal that was suspected to be linked to V1298 Tau e. The analysis required the combination of radial velocities, ground-based photometry contemporary to the RV campaign, and K2 photometry. The result obtained indicated that V1298 Tau might have contracted much faster than predicted by theoretical models, highlighting the importance of attempting these difficult cases.

Ground-based high-resolution spectrographs are key instruments for several astrophysical domains. Unfortunately, the observed spectra are contaminated by the Earth's atmosphere. While different techniques exist to correct for telluric lines in exoplanet atmospheric studies, in radial velocity (RV) studies, telluric lines with an absorption depth of >2% are generally masked, which poses a problem for faint targets and M dwarfs as most of their RV content is present where telluric contamination is important. We propose a simple telluric model to be embedded in the ESPRESSO DRS. The goal is to provide telluric-free spectra and enable RV measurements, including spectral ranges where telluric lines fall. The model is a line-by-line radiative transfer code that assumes a single atmospheric layer. We use the sky conditions and the physical properties of the lines from HITRAN to create the telluric spectrum. A subset of selected telluric lines is used to robustly fit the spectrum through a Levenberg-Marquardt minimization algorithm. When applied to stellar spectra from A0- to M5-type stars, the residuals of the strongest H2O lines are below 2% for all spectral types, with the exception of M dwarfs, which are within the pseudo-continuum. We then determined the RVs from the telluric-corrected ESPRESSO spectra of Tau Ceti and Proxima. We created telluric-free masks and compared the obtained RVs with the DRS RVs. In the case of Tau Ceti, we identified that micro-telluric lines introduce systematics up to an amplitude of 58 cm/s and with a period of one year. For Proxima, the gain in spectral content at redder wavelengths is equivalent to a gain of 25% in photon noise. This leads to better constraints on the semi-amplitude and eccentricity of Proxima d. We showcase that our model can be applied to other molecules, and thus to other wavelength regions observed by other spectrographs, such as NIRPS., 18 pages, 18 figures, accepted to A&A

The discovery of a planetary candidate orbiting the habitable zone of our closest neighbor, Proxima Centauri (Gl 551), shook the planetary community as few other discoveries have done in recent years. It not only showed that the nearest star to the Sun could host a planetary system but also that, given the right conditions, it could host a habitable rocky planet. 2020 brought back the attention to Proxima with the announcement of a second planetary candidate in the system, the confirmation of Proxima b, using ESPRESSO, and the suggestion of a third, very low mass. Now, after an intense observational campaign, we can confidently say there’s a third companion with just one quarter of the mass of the Earth. Proxima d is one of the lightest exoplanets known to date. It orbits its parent star at 0.029 AU, with a period of 5.12 days. It’s induced RV semi-amplitude, of just 39 cm/s on a V-mag 11 star, highlights the capabilities of the ESPRESSO spectrograph, installed at the VLT telescope array of the Paranal observatory. The signal has an amplitude that is just 1/5 of the amplitude of the activity-induced radial velocity signal, which shows that, under the right conditions, current techniques can detect planetary signals much smaller than activity signals. The discovery of Proxima d opens the door to the characterization of the population of very low mass planets of the solar neighborhood. It shows that radial velocity studies are now capable of detecting exoplanets with masses similar to the Earth and much smaller.&nbsp

This review talk will include observational aspects as well as theoretical aspects, describing the processes which are involved for M dwarfs when conducting RV measurements. Additionally, it will outline the variety of approaches that have so far been implemented by the community, both in the visible, but also in the IR (CARMENES, GIANO-B, SPIROU).

Atmospheric studies at high spectral resolution have shown the presence of molecules, neutral and ionised metals, and hydrogen in the transmission spectrum of ultra-hot Jupiters, and have started to probe the dynamics of their atmospheres. We analyse the transmission spectrum of MASCARA-1b, one of the densest ultra-hot Jupiters orbiting a bright (V=8.3) star. We focus on the CaII H&K, NaI, LiI, H$\alpha$, and KI D1 spectral lines and on the cross-correlated FeI, FeII, CaI, YI, VI, VII, CaH, and TiO lines. For those species that are not present in the stellar spectrum, no detections are reported, but we measure upper limits with an excellent precision ($\sim10$ ppm for particular species). For those species that are present in the stellar spectrum and whose planet-occulted spectral lines induce spurious features in the planetary transmission spectrum, an accurate modelling of the Rossiter-McLaughlin effect (RM) and centre-to-limb variations (CLV) is necessary to recover possible atmospheric signals. In the case of MASCARA-1b, this is difficult due to the overlap between the radial velocities of the stellar surface regions occulted by MASCARA-1b and the orbital track along which the planet atmospheric signal is expected to be found. To try to disentangle a possible planetary signal, we compare our results with models of the RM and CLV effects, and estimate the uncertainties of our models depending on the different system parameters. Unfortunately, more precise measurements of the spin-orbit angle are necessary to better constrain the planet-occulted track and correct for the transit effects in the transmission spectrum with enough precision to be able to detect or discard possible planetary absorptions. Finally, we discuss the possibility that non-detections are related to the low absorption expected for a high surface gravity planet such as MASCARA-1b., Comment: Accepted

Since the discovery in 1995 of 51 Peg b, radial velocity searches have proven to be one of the most effective ways of finding new extrasolar planets, in particular extrasolar planets orbiting nearby stars, where transits are often not detected. Back when the first exoplanet orbiting a Sun-like star was discovered, it was possible to detect the presence of a Jupiter-like planet in a close orbit to its star. Today, high-precision radial velocity measurements, obtained using high-resolution spectrographs, allow us to find Earth-mass planets that orbit inside, or close to, the habitable zone of their host stars. In some cases, with new-generation instruments such as ESPRESSO, it is possible to detect the presence of planets much lighter than the Earth. There was a time in which it was impossible to detect the presence of exoplanets by measuring radial velocity variations. There was a time in which it was expected that large stellar activity variations (assumed to be of the order of 20 m/s for quiet stars) could prevent us from detecting low-mass exoplanets. Increasingly more precise instrumentation and the advancement of the analysis techniques radically changed the situation and opened the door to the complete characterization of the low-mass exoplanetary population of the solar vicinity. Here, will embark in a short journey on the history of the radial velocity technique as a mean to detect extrasolar planets. From the early concept of spectrographs dedicated to the measurement of stellar velocities, to the detection of a planet with 1/4 the mass of the Earth orbiting Proxima Centauri.

Since the discovery in 1995 of 51 Peg b, radial velocity searches have proven to be one of the most effective ways of finding new extrasolar planets, in particular extrasolar planets orbiting nearby stars, where transits are often not detected. Back when the first exoplanet orbiting a Sun-like star was discovered, it was possible to detect the presence of a Jupiter-like planet in a close orbit to its star. Today, high-precision radial velocity measurements, obtained using high-resolution spectrographs, allow us to find Earth-mass planets that orbit inside, or close to, the habitable zone of their host stars. In some cases, with new-generation instruments such as ESPRESSO, it is possible to detect the presence of planets much lighter than the Earth. At these levels of precision, signals induced by stellar activity in the RV curves become the most important limiting factor, even in the case of magnetically quiet stars. Stellar activity can induce apparent Doppler shifts of the stellar spectrum, which cause periodic signals that range from less than one to dozens of meters per second. The correct detection and characterization of the different star-induced signals and their effect in the RVs is one of the most important steps to detect and properly characterize low-mass exoplanets, and its importance increases with increased precision as, even in the case of the quietest stars, these activity-induced signals can be the dominant signals in the data. Here, will embark in a short journey on the history of the radial velocity technique as a mean to detect extrasolar planets. From the early concept of spectrographs dedicated to the measurement of stellar velocities, to the detection of a planet with 1/4 the mass of the Earth orbiting Proxima Centauri.

Dynamical scalar fields in an effective four-dimensional field theory are naturally expected to couple to the rest of the theory's degrees of freedom, unless some new symmetry is postulated to suppress these couplings. In particular, a coupling to the electromagnetic sector will lead to spacetime variations of the fine-structure constant, $\alpha$. Astrophysical tests of the space-time stability of $\alpha$ are therefore a powerful probe of new physics. Here we use ESPRESSO and other contemporary measurements of $\alpha$, together with background cosmology data, local laboratory atomic clock and Weak Equivalence Principle measurements, to place stringent constraints on the simplest examples of the two broad classes of varying $\alpha$ models: Bekenstein models and quintessence-type dark energy models, both of which are parametric extensions of the canonical $\Lambda$CDM model. In both cases, previously reported constraints are improved by more than a factor of ten. This improvement is largely due to the very strong local constraints, but astrophysical measurements can help to break degeneracies between cosmology and fundamental physics parameters., Comment: 8 pages, 2 figures, 2 tables; in press at Phys. Rev. D

Current theories predict that very young giant planets have large radii and very low densities before they slowly contract to reach their final size after several hundred million years. Open stellar clusters and young moving groups of stars offer a unique opportunity to study exoplanets at their infant stages because of the well-constrained ages. The extreme stellar activity of young stars makes measuring the masses of their planets a very challenging task. Planet-induced radial velocity signals are typically smaller in amplitude and at lower frequencies than stellar-induced signals. These situations place very demanding requirements for RV observation campaigns and puts us in a worst-case scenario for the standard methods of stellar activity modelling. With an estimated age of 20 million years, V1298 Tau is one of the youngest solar-type stars known to host transiting planets; it harbours a system composed of four planets, two Neptune-sized, one Saturn-sized and one Jupiter-sized. Using more than 200 radial velocity measurements, condensed into a 4-month period, we were able to measure the radial velocity amplitude induced by the planet V1298 Tau b, and to pick up a second signal that was suspected to be linked to V1298 Tau e. The analysis required the combination of radial velocities, ground-based photometry contemporary to the RV campaign, and K2 photometry. The result obtained indicated that V1298 Tau might have contracted much faster than predicted by theoretical models, highlighting the importance of attempting these difficult cases.

Presentation of the IACSAT-1 project.&nbsp