Bibcode
Zapatero Osorio, M. R.; Béjar, V. J. S.; Goldman, B.; Caballero, J. A.; Rebolo, R.; Acosta-Pulido, J. A.; Manchado, A.; Peña-Ramírez, K.
Referencia bibliográfica
The Astrophysical Journal, Volume 740, Issue 1, article id. 4 (2011).
Fecha de publicación:
10
2011
Revista
Número de citas
25
Número de citas referidas
23
Descripción
We report on near-infrared J- and H-band linear polarimetric photometry
of eight ultracool dwarfs (two late-M, five L0-L7.5, and one T2.5) with
known evidence for photometric variability due to dust clouds, anomalous
red infrared colors, or low-gravity atmospheres. The polarimetric data
were acquired with the LIRIS instrument on the William Herschel
Telescope. We also provide mid-infrared photometry in the interval
3.4-24 μm for some targets obtained with Spitzer and WISE, which has
allowed us to confirm the peculiar red colors of five sources in the
sample. We can impose modest upper limits of 0.9% and 1.8% on the linear
polarization degree for seven targets with a confidence of 99%. Only one
source, 2MASS J02411151-0326587 (L0), appears to be strongly
polarized (P ~ 3%) in the J band with a significance level of
P/σ P ~ 10. The likely origin of its linearly
polarized light and rather red infrared colors may reside in a
surrounding disk with an asymmetric distribution of grains. Given its
proximity (66 ± 8 pc), this object becomes an excellent target
for the direct detection of the disk.