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The infrared overluminosity of young, ultracool substellar objectsMaría Rosa Zapatero Osorio
(CAB, CSIC-INTA)
Collaborators: R. Rebolo (IAC), V. J. S. Béjar (IAC), J. Caballero (CAB), G. Bihain (IAC), C. Álvarez (GTC, IAC)
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Tuesday, October 5, 2010
Bihain et al. (2010)
Near-infrared spectra (NICS/TNG) of Pleiades late-M and L-type brown dwarfs.
Some show the “triangular” shape at around 1.6 µm even at the age of 120
Myr, a feature believed to be caused by a low-gravity atmosphere.
The Pleiades (120 Myr)
Tuesday, October 5, 2010
Cruz et al. (2009)
LiI
>550 L dwarfs known in the field. About 5-10% appear to have less than 300 Myr.
Tuesday, October 5, 2010
Rebolo et al. (1998)
G 196-3B, a young L3-type dwarf with lithium
Small proper motion companion located at 16” from a low-mass (M2.5)
star with significant X-ray emission.
Tuesday, October 5, 2010
Rebolo et al. (1998)
G 196-3B, a young L3-type dwarf with lithium
Small proper motion companion located at 16” from a low-mass (M2.5)
star with significant X-ray emission.
The M2.5 star, G 19-3A, has spectroscopic
properties resembling those of young stars
members of a Per (~80 Myr) and the Pleiades (120 Myr). Likely age of the system < 300 Myr.
Tuesday, October 5, 2010
Rebolo et al. (1998)
G 196-3B, a young L3-type dwarf with lithium
Small proper motion companion located at 16” from a low-mass (M2.5)
star with significant X-ray emission.
The M2.5 star, G 19-3A, has spectroscopic
properties resembling those of young stars
members of a Per (~80 Myr) and the Pleiades (120 Myr). Likely age of the system < 300 Myr.
ALFOSC/NOT spectrum confirmed the ultracool
nature of G 196-3B (Teff = 1870 K). We determined a
probable mass in the range 10-40 Mjup.
Tuesday, October 5, 2010
Cruz et al. (2009)
Optical spectroscopy (Keck and Gemini
data) of the young, field L-type dwarfs.
The atomic feature due to KI is very
sensitive to gravity. High gravity (≈ high
atmospheric pressure) produces
deeper alkaline lines.
It is believed these objects have ages in the interval 10-300
Myr.
Tuesday, October 5, 2010
2MASS J1146345+223053 (L3)
Kelu 1 (L2)
G 196 3B
KI H O2 FeH H O2KI COH O2
VOCrH,FeH
NaI
FeH
H O2
FeH H O2
Zapatero Osorio et al. (2010)
G 196-3B, a young L3-type dwarf with lithium
There are also gravity-sensitive spectral
features in the near-infrared wavelengths, like the “triangular” shape of the H-band, and the stronger H2O band at around 1.2 µm.
Tuesday, October 5, 2010
M5 L5L0
G196 3B
M5 L5L0
G 196-3B
In the visible, young and “old” field dwarfs show similar photometric properties.
The infrared overluminosity of young, ultracool substellar objects
Tuesday, October 5, 2010
M5 L0 L5M5 L0 L5
It is in the near- and mid-infrared wavelengths where we find discrepancies: the young field objects show redder colors than “old” dwarfs of similar spectral
classification.
G 196-3B
G 196-3A
G 196-3B
Other young sources
High-gravity dwarfs
The infrared overluminosity of young, ultracool substellar objects
Tuesday, October 5, 2010
M5 L0 L5 M5 L0 L5
It is in the near- and mid-infrared wavelengths where we find discrepancies: the young field objects show redder colors than “old” dwarfs of similar spectral
classification.
G 196-3B G 196-3B
High-gravity dwarfs
The infrared overluminosity of young, ultracool substellar objects
Tuesday, October 5, 2010
The infrared overluminosity of young, ultracool substellar objects
G 196-3B
With disk
Without disk
Zapatero Osorio et al. (2007)
G 196-3B
Tuesday, October 5, 2010
M5 L0 L5
G 196-3B
Other young sources
The infrared overluminosity of young, ultracool substellar objects
This behavior is NOT reproduce by current theory of model atmospheres.
Lyon models
1 Myr10 Myr
100 Myr
500 Myr1 Gyr
L5L1M8
Tuesday, October 5, 2010
120 Myr 3 Myr
L0 L5 L0 L0L5 L5
??? Myr
The infrared overluminosity of young, ultracool substellar objects
Tuesday, October 5, 2010
G 196-3BField L2-L3BB 1800K
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J
I
KH
4.5
3.6
8.0
5.8
24
The infrared overluminosity of young, ultracool substellar objects: G 196-3B.
The spectral energy distribution of G 196-3B is that of an L2-L3 source up to the H-band, but it is clearly overluminous at longer wavelengths.
Zapatero Osorio et al. (2010)
Tuesday, October 5, 2010
Combined fluxField L2 L3G 196 3B
Black body 1400 K
The infrared overluminosity of young, ultracool substellar objects: G 196-3B.
The spectral energy distribution of G 196-3B is reasonably modeled by the combined flux of a field L2-L3 source (~2000 K) and a single-temperature
black-body of 1400 K with the same luminosity than the L2-L3 source.
Zapatero Osorio et al. (2010)
Tuesday, October 5, 2010
Combined fluxField L2 L3G 196 3B
Black body 1400 K
The infrared overluminosity of young, ultracool substellar objects: G 196-3B.
The spectral energy distribution of G 196-3B is reasonably modeled by the combined flux of a field L2-L3 source (~2000 K) and a single-temperature
black-body of 1400 K with the same luminosity than the L2-L3 source.
A possible scenario: a low-gravity atmosphere with enshrouded upper atmospheric layers and/or a warm
dusty disk/envelope.
Zapatero Osorio et al. (2010)
Tuesday, October 5, 2010
The infrared overluminosity of young, ultracool substellar objects
We are measuring the parallax of 10 of these young, field L dwarfs. Distance is a key parameter to break the degeneracy between age, mass, and luminosity.
Our sample is expected to lie at distances 10-50 pc.
Tuesday, October 5, 2010
G 196-3B, a young L3-type dwarf with lithium
For G 196-3, distance is fundamental to test evolutionary models (e.g., one single
isochrone must reproduce both the star and the substellar companion). Our preliminary
parallax measurement “sets” G 196-3A and B very close to the 20-50 Myr isochrones ( ). At these young ages, the mass of G 196-3B is close to the planetary borderline, i.e., 12
Mjup.
G 196-3B
G 196-3A
Tuesday, October 5, 2010
The infrared overluminosity of young, ultracool substellar objects
Conclusions:
Young (20-300 Myr), field L0-L5 dwarfs (very likely brown dwarfs with M = 10-40 Mjup) show infrared flux excesses, which are not explained by theory.
Distance is a critical parameter to determine the age and mass of these objects and to establish their properties.
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Tuesday, October 5, 2010
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