Search For Exoplanets Research Articles

Stellar magnetic activity in Earth 2.0 candidates based on LAMOST DR10

Aims. Stellar chromospheric activity can impact the search for exoplanets. Earth 2.0 (ET 2.0) is a space telescope designed for exoplanet detection. In this work, we survey the stellar chromospheric activity in the ET 2.0 target regions to enhance the detection rate of exoplanets. Methods. This work uses Hα and mbox Ca ii H K lines as indicators of chromospheric activity and conducts a survey of stellar chromospheric activity in the ET 2.0 target regions using LAMOST low- and medium-resolution spectra. After cross-referencing with the ET 2.0 input catalog, we obtained over 349,000 low-resolution spectra and over 30,000 medium-resolution spectra from LAMOST. We quantified the chromospheric activity intensity for all spectra and selected the results for those with a signal-to-noise ratio (S/N) above 10 for further studies of the chromospheric activity. The quantification standards include equivalent width (EW) and the ratio of bolometric luminosity to the corresponding spectral line luminosity (L_Hα/L_bol, L_CaH/L_bol, L_CaK/L_bol, L_HK/L_bol). Results. Utilizing Hα and mbox Ca ii H K lines, we evaluated the chromospheric activity for over 320,000 and 110,000 spectra based on LAMOST low-resolution spectra, respectively. In addition, we evaluated chromospheric activity for 34,000 spectra using Hα lines based on medium-resolution spectra. We selected samples that are suitable for exoplanet studies, based on Hα and mbox Ca ii H K lines. Additionally, we explored the relationship between stellar activity observed by LAMOST and rotation periods obtained from Kepler and TESS surveys. Our findings confirm the presence of two distinct regions in terms of their relationship between stellar activity and Rossby number (Ro), namely: saturated and unsaturated. We determined a critical Ro in the range of 0.09 to 0.12 using the r-band spectra of 11,921 stars and u-band spectra of 6,120 stars. Moreover, we observe that mbox Ca ii H K lines exhibit greater sensitivity to Ro in the unsaturated region, compared to Hα line measurements. Lastly, we have established positive correlations between various activity indicators, including R'_CaK, R'_CaH, R'_HK, and R'_Hα.

Detection and characterization of giant planets with Gaia astrometry

ABSTRACT Astrometric observations with Gaia are expected to play a valuable role in future exoplanet surveys. With current data from Gaia’s third data release (DR3), we are sensitive to periods from less than 1 yr to more than 4 yr but, unlike radial velocity (R.V.) are not as restricted by the orbital inclination of a potential planet. The presence and potential properties of a companion affect the primary’s renormalized unit weight error (RUWE) making this a valuable quantity in the search for exoplanets. Using this value and the fitted astrometric tracks from Gaia, we use Bayesian inference to constrain the mass and orbital parameters of companions in known systems. Combining this with R.V. measurements, we show it is possible to independently measure mass and inclination and suggest HD 66141 b is a possible brown dwarf with maximum mass 23.9$^{+7.2}_{-6.4}$ $\mathrm{ M}_{\mathrm{J}}$. We show how this method may be applied to directly imaged planets in the future, using $\beta$-Pictoris c as an example but note that the host star is bright and active, making it difficult to draw clear conclusions. We show how the next Gaia data release, which will include epoch astrometry, will allow us to accurately constrain orbital parameters from astrometric data alone, revolutionizing future searches for exoplanets. Combining predicted observational limits on planet mass with theoretical distributions, we estimate the probability that a star with a given RUWE will host a detectable planet, which will be highly valuable in planning future surveys.

The CARMENES search for exoplanets around M dwarfs

Context. Radial velocity (RV) jitter represents an intrinsic limitation on the precision of Doppler searches for exoplanets that can originate from both instrumental and astrophysical sources. Aims. We aim to determine the RV jitter floor in M dwarfs and investigate the stellar properties that lead to RV jitter induced by stellar activity. Methods. We determined the RV jitter in 239 M dwarfs from the CARMENES survey that are predominantly of mid to late spectral type and solar metallicity. We also investigated the correlation between stellar rotation and magnetic fields with RV jitter. Results. The median jitter in the CARMENES sample is 3.1 m s−1, and it is 2.3 m s−1 for stars with an upper limit of 2 km s−1 on their projected rotation velocities. We provide a relation between the stellar equatorial rotation velocity and RV jitter in M dwarfs based on a subsample of 129 well-characterized CARMENES stars. RV jitter induced by stellar rotation dominates for stars with equatorial rotation velocities greater than 1 km s−1. A jitter floor of 2 m s−1 dominates in stars with equatorial rotation velocities below 1 km s−1. This jitter floor likely contains contributions from stellar jitter, instrumental jitter, and undetected companions. We study the impact of the average magnetic field and the distributions of magnetic filling factors on the RV jitter. We find a series of stars with excess RV jitter and distinctive distributions of magnetic filling factors. These stars are characterized by a dominant magnetic field component between 2 to 4 kG. Conclusions. An RV jitter floor can be distinguished from RV jitter induced by activity and rotation based on the stellar equatorial rotation velocity. RV jitter induced by activity and rotation primarily depends on the equatorial rotation velocity. This RV jitter is also related to the distribution of magnetic filling factors, and this emphasizes the role of the magnetic field in the generation of RV jitter.

Revisiting the conundrum of the sub-Jovian and Neptune desert

Context. The search for exoplanets has led to the identification of intriguing patterns in their distributions, one of which is the so-called sub-Jovian and Neptune desert. The occurrence rate of Neptunian exoplanets with an orbital period P ≲ 4 days sharply decreases in this region in period-radius and period-mass space. Aims. We present a novel approach to delineating the sub-Jovian and Neptune desert by considering the incident stellar flux F on the planetary surface as a key parameter instead of the traditional orbital period of the planets. Through this change of perspective, we demonstrate that the incident flux still exhibits a paucity of highly irradiated Neptunes, but also captures the proximity to the host star and the intensity of stellar radiation. Methods. Leveraging a dataset of confirmed exoplanets, we performed a systematic analysis to map the boundaries of the sub-Jovian and Neptune desert in the (F, Rp) and (F, Mp) diagrams, with Rp and Mp corresponding to the planetary radius and mass, respectively. By using statistical techniques and fitting procedures, we derived analytical expressions for these boundaries that offer valuable insights into the underlying physical mechanisms governing the dearth of Neptunian planets in close proximity to their host stars. Results. We find that the upper and lower bounds of the desert are well described by a power-law model in the (F, Rp) and (F, Mp) planes. We also obtain the planetary mass-radius relations for each boundary by combining the retrieved analytic expressions in the two planes. This work contributes to advancing our knowledge of exoplanet demographics and to refining theoretical models of planetary formation and evolution within the context of the sub-Jovian and Neptune desert.

Confirming the Tidal Tails of the Young Open Cluster Blanco 1 with TESS Rotation Periods

Blanco 1 is an ≈130 Myr open cluster located 240 pc from the Sun, below the Galactic plane. Recent studies have reported the existence of diffuse tidal tails extending 50–60 pc from the cluster center based on the positions and velocities measured by Gaia. To independently assess the reality and extent of this structure, we used light curves generated from TESS full-frame images to search for photometric rotation periods of stars in and around Blanco 1. We detected rotation periods down to a stellar effective temperature of ≈3100 K in 347 of the 603 cluster member candidates for which we have light curves. For cluster members in the core and candidate members in the tidal tails, both within a temperature range of 4400–6200 K, 74% and 72% of the rotation periods, respectively, are consistent with the single-star gyrochronological sequence. In contrast, a comparison sample of field stars yielded gyrochrone-consistent rotation periods for only 8.5% of the stars. The tidal tail candidates’ overall conformance to the core members’ gyrochrone sequence implies that their contamination ratio is consistent with zero and <0.33 at the 2σ level. This result confirms the existence of Blanco 1 tidal tails and doubles the number of Blanco 1 members for which there are both spatio-kinematic and rotation-based cluster membership verification. Extending the strategy of using TESS light curves for gyrochronology to other nearby young open clusters and stellar associations may provide a viable strategy for mapping out their dissolution and broadening the search for young exoplanets.

Searching for GEMS: TOI-6383Ab, a Giant Planet Transiting an M3-dwarf Star in a Binary System* *Based on observations obtained with the Hobby–Eberly Telescope (HET), which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Ludwig-Maximillians-Universitaet Muenchen, and Georg-August Universitaet Goettingen. The HET is named in honor of its principal benefactors, William P. Hobby and

We report on the discovery of a transiting giant planet around the 3500 K M3-dwarf star TOI-6383A located 172 pc from Earth. It was detected by the Transiting Exoplanet Survey Satellite and confirmed by a combination of ground-based follow-up photometry and precise radial velocity measurements. This planet has an orbital period of ∼1.791 days, a mass of 1.040 ± 0.094 M J , and a radius of 1.008−0.033+0.036RJ , resulting in a mean bulk density of 1.26−0.17+0.18 g cm−3. TOI-6383A has an M dwarf companion star, TOI-6383B, which has a stellar effective temperature of T eff ∼ 3100 K and a projected orbital separation of 3126 au. TOI-6383A is a low-mass dwarf star hosting a giant planet and is an intriguing object for planetary evolution studies due to its high planet-to-star mass ratio. This discovery is part of the Searching for Giant Exoplanets around M-dwarf Stars (GEMS) Survey, intending to provide robust and accurate estimates of the occurrence of GEMS and the statistics on their physical and orbital parameters. This paper presents an interesting addition to the small number of confirmed GEMS, particularly notable since its formation necessitates massive, dust-rich protoplanetary discs and high accretion efficiency (>10%).

Tracking the influence of a very close secondary star on planetary growth and evolution

Abstract This work investigated the dynamics of planets in binary systems and provided insights into the stability and evolution of these systems. We explored the influence of a nearby secondary star on planetary growth and evolution, focusing on S-type configurations. We tracked the orbits of the planets and analyzed their stability over long timescales, considering various parameters such as mass, eccentricity, and inclination. Our results show that the presence of a secondary star can significantly impact the growth and evolution of planets, leading to changes in their orbits and potential ejection from the system, however, it was possible to identify stable planets even in systems experiencing multiple disturbances. One of the most significant results of the work was the analysis of the increased material in the disc near the primary star, which contributes to planet growth, driven by the density spirals influenced by the binary star.These findings have important implications for the search for habitable exoplanets and emphasize the need for further studies of planetary systems in binary star environments.

The Search for Exoplanets: Methods and History

The discovery of exoplanets, planets beyond the solar system, has raised key questions about extraterrestrial life and the technology needed to find it. While considerable progress in exoplanet detection has been achieved over the past three decades, the methods currently in use still face notable limitations. Indeed, the detection of exoplanets has come a long way since its first confirmation in 1992. At first, these celestial objects were considered as figment of movies and science fiction, but it is credible today that Radial Velocity, Transit, Gravitational Microlensing, Direct Imaging, and Astrometry approaches have found these planetary bodies. While each of the methods works well, all techniques possess specific systematic errors depending on orbital radius, planetary size, and so on. For the past few decades, missions like Hubble, Spitzer as well as Kepler have delivered the fundamental catalogs and enormously improved the knowledge in the field of exoplanets. Recent developments, specifically with the JWST, have provided new ideas with indications of biosignatures on planet exoplanet K2-18b. The future prospects for exoplanet discovery also look good, for example, with the help of the machine learning for analysis and planned instruments like Nancy Grace Roman Space Telescope and the concept of Habitable Worlds Observatory. These observatories are oriented towards the search of potentially habitable exoplanets and for exploration of other universal enigmatic processes. In this paper, the advancement of technique in identifying exoplanets is outlined with specific focus on significant accomplishments, trends, technologies, and future outlook, which shows a fairly promising field that holds great potential for finding more habitable planets.

Magnetized Winds of M-type Stars and Star–Planet Magnetic Interactions: Uncertainties and Modeling Strategy

M-type stars are the most common stars in the Universe. They are ideal hosts for the search of exoplanets in the habitable zone (HZ), as their small size and low temperature make the HZ much closer-in than their solar twins. Harboring very deep convective layers, they also usually exhibit very intense magnetic fields. Understanding their environment, in particular their coronal and wind properties, is thus very important, as they might be very different from what is observed in the solar system. The mass-loss rate of M-type stars is poorly known observationally, and recent attempts to estimate it for some of them (e.g., TRAPPIST-1 and Proxima Centauri) can vary by an order of magnitude. In this work, we revisit the stellar wind properties of M dwarfs in the light of the latest estimates of Ṁ through Lyα absorption at the astropause and slingshot prominences. We outline a modeling strategy to estimate the mass-loss rate, radiative loss, and wind speed, with uncertainties, based on an Alfvén-wave-driven stellar wind model. We find that it is very likely that several TRAPPIST-1 planets lie within the Alfvén surface, which implies that these planets experience star–planet magnetic interactions (SPMIs). We also find that SPMIs between Proxima Cen b and its host star could be the reason for recently observed radio emissions.

Tunable 30 GHz laser frequency comb for astronomical spectrograph characterization and calibration.

The search for Earth-like exoplanets with the Doppler radial velocity (RV) technique is an extremely challenging and multifaceted precision spectroscopy problem. Currently, one of the limiting instrumental factors in reaching the required long-term 10-10 level of radial velocity precision is the defect-driven subpixel quantum efficiency (QE) variations in the large-format detector arrays used by precision echelle spectrographs. Tunable frequency comb calibration sources that can fully map the point spread function (PSF) across a spectrograph's entire bandwidth are necessary for quantifying and correcting these detector artifacts. In this work, we demonstrate a combination of laser frequency and mode spacing control that allows full and deterministic tunability of a 30 GHz electro-optic comb together with its filter cavity. After supercontinuum generation, this gives access to any optical frequency across 700-1300 nm. Our specific implementation is intended for the comb deployed at the Habitable-Zone Planet Finder (HPF) spectrograph and its near-infrared Hawaii-2RG array, but the techniques apply to all laser frequency combs (LFCs) used for precision astronomical spectrograph calibration and other applications that require broadband tuning.

The use of visualization technologies in the study of the probability of life on exoplanets

Abstract The modern generation receives a significant amount of information from various sources daily. The information received should be perceived and analyzed, and conclusions drawn. Young people prefer visual technologies that allow them to obtain and analyse dynamic details quickly. The educational process should not lag; on the contrary, it should prepare a thinking, creative person who can easily use modern digital technologies. This paper discusses the use of the Universal Sandbox 2 universe simulator in the study of astronomy, namely the search for exoplanets and the study of the conditions necessary for the existence of life on them.

The CARMENES search for exoplanets around M dwarfs

We present the abundances of magnesium (Mg) and silicon (Si) for 314 dwarf stars with spectral types in the interval K7.0–M5.5 (Teff range ≈ 4200–3050 K) observed with the CARMENES high-resolution spectrograph at the 3.5 m telescope at the Calar Alto Observatory. Our analysis employs the BT-Settl model atmospheres, the radiative transfer code Turbospectrum, and a state-of-the-art selection of atomic and molecular data. These Mg and Si abundances are critical for understanding both the chemical evolution and assembly of the Milky Way and the formation and composition of rocky planets. Our chemical abundances show a line-to-line scatter at the level of 0.1 dex for all studied spectral types. The typical error bar of our chemical abundance measurements is ± 0.11 dex (Mg) and ± 0.16 dex (Si) for all spectral types based on the comparison of the results obtained for stellar components of multiple systems. The derived abundances are consistent with the galactic evolution trends and observed chemical abundance distribution of earlier FGK-type stars in the solar neighbourhood. Besides, our analysis provides compatible abundances for stars in multiple systems. In addition, we studied the abundances of different galactic stellar populations. In this paper, we also explore the relation of the Mg and Si abundances of stars with and without known planets.

Confrontation between modelled solar integrated observables and direct observations

Context. Stellar variability strongly impacts the search for low-mass exoplanets with radial velocity techniques. Two types of planet-free time series can be used to quantify this impact: models and direct solar observations after a subtraction of the Solar System planetary contribution. Making a comparison among these approaches is necessary to improve the models, which can then be used for blind tests across a broad range of conditions. Aims. Our objective is therefore to validate the amplitude of the convective blueshift in plages used in our previous works, particularly in blind tests, with HARPS-N solar data. Methods. We applied our model to the structures observed at the time of HARPS-N observations and established a direct comparison between the radial velocity time series. To complete our diagnosis, we also studied the observed radial velocities separately for each diffraction order derived from the individual cross-correlation functions, as well as our line-by-line radial velocities. Results. We find that our previous model had been underestimating the amplitude of the convective blueshift inhibition by a factor of about 2. A direct estimation of the convective blueshift in the spectra, which is shown to be correlated with the plage filling factor, allows us to explain the difference with previous estimations obtained with MDI/SOHO Dopplergrams, based on the specific properties of the Ni line used in this mission. In addition, we identified several instrumental systematics, in particular, the presence of a 2 m s−1 peak-to-peak signal with a period of about 200 days in radial velocity and bisector. This signal could be due to periodic detector warmups, a systematic dependence of the long-term trend on wavelength that is possibly related to the variability of the continuum over time, and/or an offset in radial velocity after the interruption of several months in October 2017. Conclusions. A large amplitude in the convective blueshift inhibition of (360 ms−1, namely twice more than in our previous works) must be used when building synthetic times series for blind tests. The presence of instrumental systematics should also be taken into account when using sophisticated methods based on line properties to mitigate stellar activity when searching for very weak signals.

The CARMENES search for exoplanets around M dwarfs. Revisiting the GJ 581 multi-planetary system with new Doppler measurements from CARMENES, HARPS, and HIRES

GJ\,581 is a nearby M dwarf known to host a packed multiple planet system composed of two super-Earths and a Neptune-mass planet. We present new orbital analyses of the GJ\,581 system, utilizing recent radial velocity (RV) data obtained from the CARMENES spectrograph combined with newly reprocessed archival data from the HARPS and HIRES spectrographs. Our aim was to analyze the post-discovery spectroscopic data of GJ\,581, which were obtained with CARMENES. In addition, we used publicly available HIRES and HARPS spectroscopic data to seek evidence of the known and disputed exoplanets in this system. We aimed to investigate the stellar activity of GJ\,581 and update the planetary system's orbital parameters using state-of-the-art numerical models and techniques. We performed a periodogram analysis of the available precise CARMENES, HIRES, and HARPS RVs and of stellar activity indicators. We conducted detailed orbital analyses by testing various orbital configurations consistent with the RV data. We studied the posterior probability distribution of the parameters fit to the data and we explored the long-term stability and overall orbital dynamics of the GJ\,581 system. We refined the orbital parameters of the GJ\,581 system using the most precise and complete set of Doppler data available. Consistent with the existing literature, our analysis confirms that the system is unequivocally composed of only three planets detectable in the present data, dismissing the putative planet GJ\,581\,d as an artifact of stellar activity. Our N-body fit reveals that the system's inclination is $i = $\,deg, which implies that the planets could be up to 30&lt;!PCT!&gt; more massive than their previously reported minimum masses. Furthermore, we report that the GJ\,581 system exhibits long-term stability, as indicated by the posterior probability distribution, characterized by secular dynamical interactions without the involvement of mean motion resonances.

A search for non-transiting exoplanets with optical light phase curves from TESS Southern ecliptic sectors

ABSTRACT Phased photometric variation provides a method for discovering potential non-transiting exoplanets in high-precision time-series photometry. Applying a Lomb–Scargle algorithm, we search for phased photometric variation in a selection of 140 000 bright dwarf stars with full-frame image light curves from the Southern ecliptic hemisphere of the Transiting Exoplanet Survey Satellite (TESS) mission. We fit the phased photometric variation signal for these candidates using a three-component model comprised of atmospheric reflection/emission, tidal ellipsoidal distortion, and Doppler beaming contributions. We find 27 candidate signals that can be attributed to short-period, massive planets. Our candidates have periods ranging from 0.74 to 1.98 d, and photometric variations with amplitudes ranging from 94 to 528 ppm. The host stars are all bright (9 &amp;lt; T &amp;lt; 11) F- and G-type dwarf stars. We estimate the radial velocity semi-amplitudes to be in excess of 60 m s−1 for each candidate, easily within reach of current high-precision spectrographs. If confirmed, these candidates would be the first non-transiting exoplanets discovered with TESS.

The First High-contrast Images of Near High-mass X-Ray Binaries with Keck/NIRC2

Although the study of X-ray binaries has led to major breakthroughs in high-energy astrophysics, their circumbinary environment at scales of ∼100–10,000 au has not been thoroughly investigated. In this paper, we undertake a novel and exploratory study by employing direct and high-contrast imaging techniques on a sample of X-ray binaries, using adaptive optics and the vortex coronagraph on Keck/NIRC2. High-contrast imaging opens up the possibility to search for exoplanets, brown dwarfs, circumbinary companion stars, and protoplanetary disks in these extreme systems. Here we present the first near-infrared high-contrast images of 13 high-mass X-ray binaries located within ∼2–3 kpc. The key results of this campaign involve the discovery of several candidate circumbinary companions ranging from substellar (brown dwarf) to stellar masses. By conducting an analysis based on Galactic population models, we discriminate sources that are likely background/foreground stars and isolate those that have a high probability (≳60%–99%) of being gravitationally bound to the X-ray binary. This paper seeks to establish a preliminary catalog for future analyses of proper motion and subsequent observations. With our preliminary results, we calculate the first estimate of the companion frequency and the multiplicity frequency for X-ray binaries: ≈0.6 and 1.8 ± 0.9, respectively, considering only the sources that are most likely bound to the X-ray binary. In addition to extending our comprehension of how brown dwarfs and stars can form and survive in such extreme systems, our study opens a new window to our understanding of the formation of X-ray binaries.

Searching for Giant Exoplanets around M-dwarf Stars (GEMS) I: Survey Motivation

Recent discoveries of transiting giant exoplanets around M-dwarf stars (GEMS), aided by the all-sky coverage of TESS, are starting to stretch theories of planet formation through the core-accretion scenario. Recent upper limits on their occurrence suggest that they decrease with lower stellar masses, with fewer GEMS around lower-mass stars compared to solar-type. In this paper, we discuss existing GEMS both through confirmed planets, as well as protoplanetary disk observations, and a combination of tests to reconcile these with theoretical predictions. We then introduce the Searching for GEMS survey, where we utilize multidimensional nonparameteric statistics to simulate hypothetical survey scenarios to predict the required sample size of transiting GEMS with mass measurements to robustly compare their bulk-density with canonical hot Jupiters orbiting FGK stars. Our Monte Carlo simulations predict that a robust comparison requires about 40 transiting GEMS (compared to the existing sample of ∼15) with 5σ mass measurements. Furthermore, we discuss the limitations of existing occurrence estimates for GEMS and provide a brief description of our planned systematic search to improve the occurrence rate estimates for GEMS.

Analysis of the public HARPS/ESO spectroscopic archive

Context. Magnetic activity is currently the primary limiting factor in radial velocity (RV) exoplanet searches. Even inactive stars, such as the Sun, exhibit RV jitter of the order of a few m s−1 due to active regions on their surfaces. Time series of chromospheric activity indicators, such as the Ca II H&amp;K lines, can be utilized to reduce the impact of such activity phenomena on exoplanet search programmes. In addition, the identification and correction of instrumental effects can improve the precision of RV exoplanet surveys. Aims. We aim to update the HARPS -RVBANK RV database and include an additional 3.5 yr of time series and Ca II H&amp;K lines (R′HK) chromospheric activity indicators. This additional data will aid in the analysis of the impact of stellar magnetic activity on the RV time series obtained with the HARPS instrument. Our updated database aims to provide a valuable resource for the exoplanet community in understanding and mitigating the effects of such stellar magnetic activity on RV measurements. Methods. The new HARPS-RVBANK database includes all stellar spectra obtained with the HARPS instrument prior to January 2022. The RVs corrected for small but significant nightly zero-point variations were calculated using an established method. The R′HK estimates were determined from both individual spectra and co-added template spectra with the use of model atmospheres. As input for our derivation of R′HK, we derived stellar parameters from co-added, high signal-to-noise ratio templates for a total of 3230 stars using the stellar parameter code SPECIES. Results. The new version of the HARPS RV database has a total of 252 615 RVs of 5239 stars. Of these, 195 387 have R′HK values, which corresponds to 77% of all publicly available HARPS spectra. Currently, this is the largest public database of high-precision (down to ~1 m s−1) RVs, and the largest compilation of R′HK measurements. We also derived lower limits for the RV jitter of F-, G-, and K-type stars as a function of R′HK.

Distinguishing exoplanet companions from field stars in direct imaging using Gaia astrometry

Direct imaging searches for exoplanets around stars detect many spurious candidates that are in fact background field stars. To help distinguish these from genuine companions, multi-epoch astrometry can be used to identify a common proper motion with the host star. Although this is frequently done, many approaches lack an appropriate model for the motions of the background population, or do not use a statistical framework to properly quantify the results. For this study we used Gaia astrometry combined with 2MASS photometry to model the parallax and proper motion distributions of field stars around exoplanet host stars as a function of candidate magnitude. We developed a likelihood-based method that compares the positions of a candidate at multiple epochs with the positions expected under both this field star model and a co-moving companion model. Our method propagates the covariances in the Gaia astrometry and the candidate positions. True companions are assumed to have long periods compared to the observational baseline, so we currently neglect orbital motion. We applied our method to a sample of 23 host stars with 263 candidates identified in the B-Star Exoplanet Abundance Study (BEAST) survey on VLT/SPHERE. We identified seven candidates in which the odds ratio favours the co-moving companion model by a factor of 100 or more. Most of these detections are based on only two or three epochs separated by less than three years, so further epochs should be obtained to reassess the companion probabilities. Our method is publicly available as an open-source python package from 1em

The CARMENES search for exoplanets around M dwarfs

Light from celestial objects interacts with the molecules of the Earth’s atmosphere, resulting in the production of telluric absorption lines in ground-based spectral data. Correcting for these lines, which strongly affect red and infrared wavelengths, is often needed in a wide variety of scientific applications. Here, we present the template division telluric modeling (TDTM) technique, a method for accurately removing telluric absorption lines in stars that exhibit numerous intrinsic features. Based on the Earth’s barycentric motion throughout the year, our approach is suited for disentangling telluric and stellar spectral components. By fitting a synthetic transmission model, telluric-free spectra are derived. We demonstrate the performance of the TDTM technique in correcting telluric contamination using a high-resolution optical spectral time series of the feature-rich M3.0 dwarf star Wolf 294 that was obtained with the CARMENES spectrograph. We apply the TDTM approach to the CARMENES survey sample, which consists of 382 targets encompassing 22 357 optical and 20 314 near-infrared spectra, to correct for telluric absorption. The corrected spectra are coadded to construct template spectra for each of our targets. This library of telluric-free, high signal-to-noise ratio, high-resolution (ℛ &gt; 80 000) templates comprises the most comprehensive collection of spectral M-dwarf data available to date, both in terms of quantity and quality, and is available at the project website.