SIMBAD references

2011MNRAS.412.2071C - Mon. Not. R. Astron. Soc., 412, 2071-2078 (2011/April-2)

Methane band and Spitzer mid-IR imaging of l and T dwarf candidates in the Pleiades.

CASEWELL S.L., JAMESON R.F., BURLEIGH M.R., DOBBIE P.D., ROY M., HODGKIN S.T. and MORAUX E.

Abstract (from CDS):

We present Spitzer observations at [3.6] and [4.5] µm together with the methane short (1.58 µm) - methane long (1.69 µm) colour for three cool dwarfs in the Pleiades, PLZJ23, PLZJ93 and PLZJ100. We determine the effective temperatures of PLZJ23 and PLZJ93 to be ≈1200 and ≈1100 K. From the broad-band photometry we place an upper limit of 1100 K on the effective temperature of PLZJ100 but lack the data required to determine the value more precisely. These temperatures are in the T dwarf regime, yet the methane colours indicate no methane is present. We attribute this to youth/low gravity in line with theoretical expectations. However, we find even less methane is present than predicted by the models.

PLZJ23 and PLZJ93 are also very bright in the [3.6] µm waveband (PLZJ100 is not measured) compared to field brown dwarfs which can also be explained by this lack of methane.

The definition of the T spectral class is the appearance of methane absorption, so strictly, via this definition, PLZJ93 and PLZJ100 cannot be described as T dwarfs. The colours of these two objects are, however, not compatible with those of L dwarfs. Thus we have a classification problem and cannot assign these objects a (photometric) spectral type.


Abstract Copyright: 2011 The Authors Monthly Notices of the Royal Astronomical Society2011 RAS

Journal keyword(s): brown dwarfs - stars: low-mass - open clusters and associations: individual: Pleiades

Simbad objects: 26

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2019.12.15-22:10:55

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