Very Low Mass Stars, Brown Dwarfs and Planets

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Organizational Unit

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.

Publications related

  • New Isolated Planetary-mass Objects and the Stellar and Substellar Mass Function of the σ Orionis Cluster

    We report on our analysis of the VISTA Orion ZY JHKs photometric data (completeness magnitudes of Z = 22.6 and J = 21.0 mag) focusing on a circular area of 2798.4 arcmin2 around the young σ Orionis star cluster (~3 Myr, ~352 pc, and solar metallicity). The combination of the VISTA photometry with optical, WISE and Spitzer data allows us to identify

    Peña-Ramírez, K. et al.

    Advertised on:

  • Polarisation of very-low-mass stars and brown dwarfs. I. VLT/FORS1 optical observations of field ultra-cool dwarfs

    Context: Ultra-cool dwarfs of the L spectral type (T_eff = 1400-2200 K) are known to have dusty atmospheres. Asymmetries of the dwarf surface may arise from rotationally-induced flattening and dust-cloud coverage, and may result in non-zero linear polarisation through dust scattering. Aims: We aim to study the heterogeneity of ultra-cool dwarfs'

    Goldman, B. et al.

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  • Further investigation of white dwarfs in the open clusters NGC 2287 and NGC 3532

    We report the results of a CCD imaging survey, complemented by astrometric and spectroscopic follow-up studies, that aims to probe the fate of heavy-weight intermediate-mass stars by unearthing new, faint, white dwarf members of the rich, nearby, intermediate-age open clusters NGC 3532 and NGC 2287. We identify a total of four white dwarfs with

    Dobbie, P. D. et al.

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