Very Low Mass Stars, Brown Dwarfs and Planets

    Description

    Our goal is to study the processes that lead to the formation of low mass stars, brown dwarfs and planets and to characterize the physical properties of these objects in various evolutionary stages. Low mass stars and brown dwarfs are likely the most numerous type of objects in our Galaxy but due to their low intrinsic luminosity they are not so well known. We aim to study the frequency, multiplicity and spatial distribution of these objects in the solar neighbourhood and in nearby star forming regions and stellar clusters in order to better understand the mechanism of formation, characterise their optical and infrared properties and establish the relation between spectral properties, mass and luminosity.. Most of our effort will be dedicated to push toward lower mass limits the detection of these astros either bounded to stars and brown dwarfs and/or free-floating in interstellar space. The lowest mass objects display a lower intrinsic luminosity and cooler effective temperatures thus they are remarkably difficult to detect using direct imaging techniques. However, these techniques allow a full photometric and spectroscopic characterization and a best determination of their physical and chemical properties. We also aim to investigate the presence of planets around low mass stars using radial velocity measurements and techniques for high spatial resolution imaging. We will develop ultrastable spectrographs for large telescopes and systems for ultrafast imaging. With the spectrographs it would be possible to detect planets of similar mass to the Earth around G, K and M-type stars. The goal is to establish the frequency of these planets in stars of the solar neighbourhood and characterise the properties of the associated planetary systems.

    1. The optical and near-infrared sequence of 10 Myr-old L dwarfs in the nearest OB association to the Sun, Upper Scorpius
    2. The lithium depletion boundary of the Hyades cluster.

    Related publications

    • TOI-2285b: A 1.7 Earth-radius planet near the habitable zone around a nearby M dwarf

      We report the discovery of TOI-2285b, a sub-Neptune-sized planet transiting a nearby (42 pc) M dwarf with a period of 27.3 d. We identified the transit signal from the Transiting Exoplanet Survey Satellite photometric data, which we confirmed with ground-based photometric observations using the multiband imagers MuSCAT2 and MuSCAT3. Combining these

      Fukui, Akihiko et al.

      Advertised on:

      12
      2021
    • Rapid contraction of giant planets orbiting the 20-million-year-old star V1298 Tau

      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

      Suárez Mascareño, A. et al.

      Advertised on:

      12
      2021
    • GTC/CanariCam Deep Mid-infrared Imaging Survey of Northern Stars within 5 pc

      In this work we present the results of a direct imaging survey for brown dwarf companions around the nearest stars at the mid-infrared 10 micron range (λ c = 8.7 μm, Δλ = 1.1 μm) using the CanariCam instrument on the 10.4 m Gran Telescopio Canarias (GTC). We imaged the 25 nearest stellar systems within 5 pc of the Sun at declinations δ > -25° (at

      Gauza, Bartosz et al.

      Advertised on:

      12
      2021
    • TOI-1201 b: A mini-Neptune transiting a bright and moderately young M dwarf

      We present the discovery of a transiting mini-Neptune around TOI-1201, a relatively bright and moderately young early M dwarf (J ≈ 9.5 mag, ~600-800 Myr) in an equal-mass ~8 arcsecond-wide binary system, using data from the Transiting Exoplanet Survey Satellite, along with follow-up transit observations. With an orbital period of 2.49 d, TOI-1201 b

      Kossakowski, D. et al.

      Advertised on:

      12
      2021
    • Diving Beneath the Sea of Stellar Activity: Chromatic Radial Velocities of the Young AU Mic Planetary System

      We present updated radial-velocity (RV) analyses of the AU Mic system. AU Mic is a young (22 Myr) early-M dwarf known to host two transiting planets-P b ~ 8.46 days, ${R}_{b}={4.38}_{-0.18}^{+0.18}\ {R}_{\oplus }$ , P c ~ 18.86 days, ${R}_{c}={3.51}_{-0.16}^{+0.16}\ {R}_{\oplus }$ . With visible RVs from Calar Alto high-Resolution search for M

      Cale, Bryson L. et al.

      Advertised on:

      12
      2021
    • A young spectroscopic binary in a quintuple system part of the Local Association

      Context. Double-lined spectroscopic (SB2) binaries allow us to obtain a direct determination of the masses of their components, which is essential to test stellar models. Although these objects only provide a lower limit for the mass, they are more abundant than their eclipsing counterparts as they are not as strongly limited by the inclination of

      Cardona Guillén, Carlos et al.

      Advertised on:

      10
      2021
    • Is the orbit of the exoplanet WASP-43b really decaying? TESS and MuSCAT2 observations confirm no detection

      Up to now, WASP-12b is the only hot Jupiter confirmed to have a decaying orbit. The case of WASP-43b is still under debate. Recent studies preferred or ruled out the orbital decay scenario, but further precise transit timing observations are needed to definitively confirm or refute the period change of WASP-43b. This possibility is given by the

      Garai, Z. et al.

      Advertised on:

      12
      2021
    • The Rossiter-McLaughlin effect revolutions: an ultra-short period planet and a warm mini-Neptune on perpendicular orbits

      Comparisons of the alignment of exoplanets with a common host star and each other can be used to distinguish among concurrent evolution scenarios for the star and the planets. However, multi-planet systems usually host mini-Neptunes and super-Earths, whose sizes make orbital architecture measurements challenging. We introduce the Rossiter

      Bourrier, V. et al.

      Advertised on:

      10
      2021
    • HD 22496 b: The first ESPRESSO stand-alone planet discovery

      Context. The ESPRESSO spectrograph is a new powerful tool developed to detect and characterize extrasolar planets. Its design allows an unprecedented radial velocity precision (down to a few tens of cm s−1) and long-term thermomechanical stability. Aims: We present the first stand-alone detection of an extrasolar planet by blind radial velocity

      Lillo-Box, J. et al.

      Advertised on:

      10
      2021
    • A large sub-Neptune transiting the thick-disk M4 V TOI-2406

      Context. Large sub-Neptunes are uncommon around the coolest stars in the Galaxy and are rarer still around those that are metal-poor. However, owing to the large planet-to-star radius ratio, these planets are highly suitable for atmospheric study via transmission spectroscopy in the infrared, such as with JWST. Aims: Here we report the discovery

      Wells, R. D. et al.

      Advertised on:

      9
      2021
    • Into the storm: diving into the winds of the ultra-hot Jupiter WASP-76 b with HARPS and ESPRESSO

      Context. Despite swift progress in the characterisation of exoplanet atmospheres in composition and structure, the study of atmospheric dynamics has not progressed at the same speed. While theoretical models have been developed to describe the lower layers of the atmosphere, and independently, the exosphere, little is known about the intermediate

      Seidel, J. V. et al.

      Advertised on:

      9
      2021
    • The CARMENES search for exoplanets around M dwarfs. Spectroscopic orbits of nine M-dwarf multiple systems, including two triples, two brown dwarf candidates, and one close M-dwarf-white dwarf binary

      Context. M dwarfs are ideal targets for the search of Earth-size planets in the habitable zone using the radial velocity method, and are attracting the attention of many ongoing surveys. One of the expected results of these surveys is that new multiple-star systems have also been found. This is the case also for the CARMENES survey, thanks to which

      Baroch, D. et al.

      Advertised on:

      9
      2021
    • Warm terrestrial planet with half the mass of Venus transiting a nearby star

      In recent years, the advent of a new generation of radial velocity instruments has allowed us to detect planets with increasingly lower mass and to break the one Earth-mass barrier. Here we report a new milestone in this context by announcing the detection of the lowest-mass planet measured so far using radial velocities: L 98-59 b, a rocky planet

      Demangeon, O. D. S. et al.

      Advertised on:

      9
      2021
    • Wide companions to M and L subdwarfs with Gaia and the Virtual Observatory

      Aims: The aim of the project is to identify wide common proper motion companions to a sample of spectroscopically confirmed M and L metal-poor dwarfs (also known as subdwarfs) to investigate the impact of metallicity on the binary fraction of low-mass metal-poor binaries and to improve the determination of their metallicity from the higher-mass

      González-Payo, J. et al.

      Advertised on:

      6
      2021
    • The CARMENES search for exoplanets around M dwarfs. Mapping stellar activity indicators across the M dwarf domain

      Context. Stellar activity poses one of the main obstacles for the detection and characterisation of small exoplanets around cool stars, as it can induce radial velocity (RV) signals that can hide or mimic the presence of planetary companions. Several indicators of stellar activity are routinely used to identify activity-related signals in RVs, but

      Lafarga, M. et al.

      Advertised on:

      8
      2021
    • HADES RV programme with HARPS-N at TNG. XIV. A candidate super-Earth orbiting the M-dwarf GJ 9689 with a period close to half the stellar rotation period

      Context. It is now well-established that small, rocky planets are common around low-mass stars. However, the detection of such planets is challenged by the short-term activity of host stars. Aims: The HARPS-N red Dwarf Exoplanet Survey programme is a long-term project at the Telescopio Nazionale Galileo aimed at monitoring nearby, early-type, M

      Maldonado, J. et al.

      Advertised on:

      7
      2021
    • Simultaneous photometric and CARMENES spectroscopic monitoring of fast-rotating M dwarf GJ 3270. Discovery of a post-flare corotating feature

      Context. Active M dwarfs frequently exhibit large flares, which can pose an existential threat to the habitability of any planet in orbit in addition to making said planets more difficult to detect. M dwarfs do not lose angular momentum as easily as earlier-type stars, which maintain the high levels of stellar activity for far longer. Studying

      Johnson, E. N. et al.

      Advertised on:

      7
      2021
    • The CARMENES search for exoplanets around M dwarfs. Two terrestrial planets orbiting G 264-012 and one terrestrial planet orbiting Gl 393

      We report the discovery of two planetary systems, namely G 264-012, an M 4.0 dwarf with two terrestrial planets (Mb sin i=2.50−0.30+0.29 M⊕ and Mc sin i=3.75−0.47+0.48 M⊕), and Gl 393, a bright M 2.0 dwarf with one terrestrial planet (Mb sini = 1.71 ± 0.24M⊕). Although both stars were proposed to belong to young stellar kinematic groups, we

      Amado, P. J. et al.

      Advertised on:

      6
      2021
    • An ultra-short-period transiting super-Earth orbiting the M3 dwarf TOI-1685

      Dynamical histories of planetary systems, as well as the atmospheric evolution of highly irradiated planets, can be studied by characterizing the ultra-short-period planet population, which the TESS mission is particularly well suited to discover. Here, we report on the follow-up of a transit signal detected in the TESS sector 19 photometric time

      Bluhm, P. et al.

      Advertised on:

      6
      2021
    • ESPRESSO mass determination of TOI-263b: an extreme inhabitant of the brown dwarf desert

      The TESS mission has reported a wealth of new planetary systems around bright and nearby stars amenable for detailed characterizations of planet properties and atmospheres. However, not all interesting TESS planets orbit around bright host stars. TOI-263 b is a validated ultra-short-period substellar object in a 0.56-day orbit around a faint (V =

      Palle, E. et al.

      Advertised on:

      6
      2021

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