Observations of irradiated brown dwarfs

Department of Physics & Astronomy

Observations of irradiated brown

dwarfs

S.L. Casewell, M.R. Burleigh, P. Maxted, K.A.

Lawrie, P. Rimmer, H. Melin, M. Marley, P.Steele

• www.le.ac.uk

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Evolution

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Systems

GD1400

WD+L6

0.67M sun + 60 M Jup

P=9.98 hours

WD Teff=11000K

WD0137-349

WD+L6-L8

0.4M sun + 53 M Jup

P=116 Min

WD Teff= 16500 K

NLTT5306

WD+L4-L7

0.44M sun +56

M jup

P=101.88 min

WD Teff=7756 K

WD0837+185

WD+>T8

0.8M sun + ~30M Jup

P=4.2 hours

WD Teff= 15000 K

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Heating? NLTT5306

15.84

15.85

15.86

Magnitude

15.87

15.88

15.89

15.9

0 0.2 0.4 0.6 0.8 1

Orbital Phase

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Heating? WD0837

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WD0137-349

WD H Absorption lines

BD H emission feature

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Heating?

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Irradiation

Blue J

Light Blue H

Red K

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Irradiation

Blue [3.6]

Black [4.5]

Red [5.8]

Light Blue [8.0]

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GNIRS spectrum

J

H

WD+L6

WD+L8

WD+T2

WD+T5

WD

K

2

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Orbit phase 0.05

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Orbit phase 0.2

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Orbit phase 0.3

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Orbit phase 0.4

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Orbit phase 0.6

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Orbit phase 0.7

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Orbit phase 0.8

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Orbit phase 0.9

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Orbit phase 0.05

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Spectral shape

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2

10 -18

0.9

0.9

H2O

CO

CH4

1.5

0.7

10 -19

CO/CH 4

0

Ratio

1

10 -20

Cross section

0.5

10 -21

2.1 2.15 2.2 2.25 2.3 2.35 2.4 2.45 2.5

10 -22

Wavelength (um)

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H 2 fluorescence

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H 3 +

Red line: Model of Jupiter broadened to ISAAC resolution

Grey line: ISAAC data when irradiated hemisphere faces us

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Conclusions

• 3 of the 4 BDs in known systems are being irradiated

• H 3 + seen when irradiated hemisphere faces us

• Possibility of H 2 fluorescence – pumping?

• Possibility of additional photochemistry

• These objects can be used as testbeds for exoplanets