Brown dwarfs

  title={Brown dwarfs},
  author={France Allard and Derek Homeier},
According to theory, an object that has a mass of less than about 8 percent of the mass of the sun cannot sustain significant nuclear fusion reactions in its core. This marks the dividing line between red dwarf stars and brown dwarfs. When brown dwarfs are very young, they generate some energy from the fusion of heavy hydrogen, or deuterium, into helium nuclei, but this supply is used up in a few tens of millions of years. After that brown dwarfs glow because of the heat generated by the… 

Possible nuclear fusion of deuteron in the cores of Earth, Jupiter, Saturn, and brown dwarfs

Many brown dwarfs have recently been discovered as sub-stellar objects in which deuteron thermonuclear fusion is taking place. Although Jupiter and Saturn emit nearly twice as much heat as they

Photometric and spectroscopic studies of very low mass YSOs and young Brown Dwarfs in S106

  • Y. Oasa
  • Physics, Geology
    Proceedings of the International Astronomical Union
  • 2006
Young brown dwarfs have been identified in a significant population in various star forming regions. Some deep surveys have yielded less massive objects with planetary-mass (e.g., Oasa et al. 1999;

A Substellar Mass Function for Alpha Per ⋆

. We present a deep, wide-field optical survey of the young stellar cluster Alpha Per, in which we have discovered a large population of candidate brown dwarfs. Subsequent infrared photometric

Formation, Evolution and Multiplicity of Brown Dwarfs and Giant Exoplanets

This proceeding summarizes the talk of the awardee of the Spanish Astronomical Society award to the best Spanish thesis in Astronomy and Astrophysics in the two-year period 2006–2007. The thesis

A deep survey of brown dwarfs in Orion with Gemini

We report the results of a deep near infrared (JHK) survey of the outer parts of the Trapezium Cluster with Gemini South/Flamingos. 396 sources were detected in a 26 arcmin 2 area, including 138

The formation of stars

We review the process of star formation, detailing the theories underlying the stability of molecular clouds and their collapse to protostars, and discussing the empirical evidence and models which

X-ray emission of brown dwarfs: towards constraining the dependence on age, luminosity, and temperature

Aims. We observed brown dwarfs in different evolutionary stages with the Chandra X-ray Observatory with the aim to disentangle the influence of different stellar parameters on the X-ray emission of


The CM Draconis system comprises two eclipsing mid-M dwarfs of nearly equal mass in a 1.27 day orbit. This well-studied eclipsing binary has often been used for benchmark tests of stellar models,

The Least Massive (Sub)Stellar Component of the Milky Way

This review presents a panorama of the research topics that are currently being developed by our strategic research group at the IAC in the field of very low-mass stars, brown dwarfs, extrasolar



Looking for Very Low-Mass Pre-Main Sequence Objects with SDSS

Determining the process(es) by which brown dwarfs form is key to understanding their intrinsic nature. If their origins are within circumstellar disks they are akin to giant planets. If, on the other

Variability of L Dwarfs in the Near Infrared

. We have obtained series of images in the near infrared J and K; bands for seven L-type dwarfs with a duration of 3 to 6 hours. We present results on: 1) the amplitude of variability associated with

Modeling of Optical and IR Spectra of M and Brown Dwarfs

. Procedure and results of computation of optical and infrared spectra of ultracool (1000 < Teff < 3000 K) objects are discussed. LTE synthetic spectra and spectral energy distributions in wide

Surveying the solar neighborhood for brown dwarf companions with the ECLIPSE Discovery mission

The proposed Eclipse Discovery mission is an optical space telescope designed to provide a thousandfold reduction in scattered light near bright stars in comparison to any Hubble Space Telescope

Methane and the Spectra of T Dwarfs

We have updated our PHOENIX model atmospheres and theoretical spectra for ultracool dwarfs with new opacity data for methane based on line strength predictions with the STDS software. By extending

Evolution of Brown Dwarf Atmospheres: Investigating Physical Parameters from Near-IR Spectra

We obtained near-infrared spectra of a sample of very low mass objects as a function of age in order to investigate the temperature and surface gravity sensitivity of several features in the J and K

Model atmospheres and spectra: The role of dust

Brown dwarf atmospheres form molecules, then high temperature condensates (corundum, titanates, silicates, and iron compounds), and then low temperature condensates (ices) as they cool down over

A Deep Large Scale Survey for Intermediate Age Brown Dwarfs in the Praesepe Cluster

We present a 1.4 square degree survey of the Praesepe open cluster complete to I = 21.3 and Z = 20.2. This corresponds to masses down to 0.06 M ⊙ and 0.075 M ⊙ for an assumed cluster age of 1.0 or

X-ray emission from old and intermediate age brown dwarfs

We report on two recent XMM-Newton observations of Brown Dwarfs in the Pleiades cluster and in the field aiming to constrain the age dependence of X-ray emission from substellar objects.

The Classification of L Dwarfs: Is It Based on Clouds or Temperature?

A continuous L dwarf classification sequence requires the combined use of far optical (visible) and near infrared spectral indices. However, the visible and near infrared indices currently in use