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A SUBSTELLAR SAFARI NIALL DEACON (MPIA)
A SUBSTELLAR SAFARI NIALL DEACON (MPIA)
Ejected from formation site? Form in disks? Density fluctuations in forming cloud?
THE RUNTS OF THE LITTER Bate 2008
As expected in the optical
Why so odd in the near-IR?
WHAT DO THEY LOOK LIKE? Credit: JPL
OBAFGKM (LT)
SPECTRAL ODDITY
Cushing 2005 Rayner 2009
BROWN DWARFS ARE DIRECTLY OBSERVABLE EXOPLANET ANALOGUES
HR 8799 PLANETS Four planets (e closer in) around a ≈30Myr old A star
B component is under-luminous in near-IR and red for spectral type
Marois 2008
Binary brown dwarf spanning L/T transition at 2pc
B component is variable due to patchy cloud coverage
A FANTASTIC BENCHMARK SYSTEM
Luhman 2013
Crossfield et al. 2014
Luhman 2014 225-260K 2.2pc 3-20MJ
A 250K BROWN DWARF
2010
2014
THE BIG QUESTIONS Low mass end of star formation
Initial Mass Function
Multiple systems
Atmospheres Ultracool atmospheres similar to young giant planets
Low gravity, young objects best analogues
Variability due to clouds
THE IMF AT LOW MASSES dn = Am -Γ
dlog10m
Bastian 2010
Collaborators: N. Lodieu, N. Hambly, S. Boudrealt
THE IMF IS LOGNORMAL IN CLUSTERS
Lodieu 2012 Lodieu 2012 Boudrealt 2012
BUT DECLINES FASTER IN THE FIELD?
Burningham 2012 Burningham 2010 Pinfield 2008 Deacon 2006
Collaborators: B. Burningham, D. Pinfield, A. Day-Jones, UKIDSS CDSWG
Γ=-0.5 Γ=-1.0 Γ=-1.5
Γ=-2.0
Cruz/Reid 2MASS
Burgasser Kirkpatrick 2MASS
SDSS CFHT
WISE
UKIDSS
PanSTARRS 1
Credit: Dwarf Archives
Wide-field 1.8m telescope doing multiple surveys
Surveying ¾ of the sky four times per year in 5 filters
PAN-STARRS1 Collaborators: M. Liu, E.A Magnier, W. Best, K. Aller, B. Bowler, PS1 KP3
OUR INITIAL SELECTION WAS A BIT MESSY Using Pan-STARRS and 2MASS astrometry & photometry
UKIRT CLEARED THINGS UP
IRTF SPEX SPECTRA >90% success rate Deacon 2011
Liu 2011 Liu in prep
WE’RE FILLING OUT THE MID-T DWARFS
STILL ADDING L/T OBJECTS WITHIN 25 PC Seven within 15pc to appear in Best et al. (2013) Detected using PS1+WISE colours
Three L and T dwarfs identified due to parallax (Magnier et al., in prep.)
First ever blind survey to identify targets from parallax
THE FIRST BLIND PARALLAX SURVEY
Member of the 12-25 Myr beta Pictorus association Spectral type L7 Same mass (≈6mJ), luminosity and colour as directly imaged planets
PSO 318-22: A FREE-FLOATING PLANETARY-MASS OBJECT
Liu et al 2013
BENCHMARK SYSTEMS
Wide companions to main sequence stars Age, distance and metallicity determined from primary Formation mechanism for wide binaries uncertain
2MASS J
Deacon et al. ApJ submitted
NEW ATMOSPHERIC MODELS REPRODUCE TEMPERATURES WELL
Deacon et al 2012
SUMMARY Brown dwarfs probe the low mass end of the star formation process
Apparent discrepancy between MF in clusters and field Pan-STARRS1 is completing the substellar census
Big increase in the wide L companion population
Finding new L/T objects within 15pc
Brown dwarfs are directly observable exoplanet analogues
Benchmark systems can constrain atmospheric properties Euclid will be an ideal tool for brown dwarf characterisation
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