Related papers: Spitzer Variability Properties of Low-Gravity L Dw…
We present the results of a program to acquire photometry for eighty-six late-M, L, and T dwarfs using the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. We examine the behavior of these cool dwarfs in various color-color and…
Up to now, most planet search projects have concentrated on F to K stars. In order to considerably widen the view, we have stated a survey for planets of old, nearby brown dwarfs and very low mass stars. Using UVES, we have observed 26…
Observations of variability can provide valuable information about the processes of cloud formation and dissipation in brown dwarf atmospheres. Here we report the results of an independent analysis of archival data from the Brown dwarf…
We present first results from a targeted search for brown dwarfs with unusual red colors indicative of peculiar atmospheric characteristics. These include objects with low surface gravities or with unusual dust content or cloud properties.…
We present the discovery of rapid photometric variability in three ultra-cool dwarfs from long-duration monitoring with the Spitzer Space Telescope. The T7, L3.5, and L8 dwarfs have the shortest photometric periods known to date:…
We aim to study the optical and near-infrared linear polarimetric properties of a sample of young M7-L7 dwarfs ($\approx$1-500 Myr) with spectroscopic signatures of low- and intermediate-gravity atmospheres. We collected optical ($RIZ$) and…
Heterogeneous clouds or temperature perturbations in rotating brown dwarfs produce variability in the observed flux. We report time-resolved simultaneous observations of the variable T6.5 brown dwarf 2MASSJ22282889-431026 over the…
We present high-precision photometry on 107 variable low-mass stars and brown dwarfs in the ~3 Myr Sigma Orionis open cluster. We have carried out I-band photometric monitoring within two fields, encompassing 153 confirmed or candidate…
The transition from the L to the T spectral type of brown dwarfs is marked by a very rapid transition phase, remarkable brightening in the J-band and a higher binary frequency. Despite being an active area of inquiry, this transition regime…
Photometric I band light curves of 21 ultra cool M and L dwarfs are presented. Variability with amplitudes of 0.01 to 0.055 magnitudes (RMS) with typical timescales of an hour to several hours are discovered in half of these objects.…
Models of brown dwarf atmospheres suggest they exhibit complex physical behaviour. Observations have shown that they are indeed dynamic, displaying small photometric variations over timescales of hours. Here I report results of infrared…
In our effort to complete the census of low-mass stars and brown dwarfs in the immediate Solar Neighborhood, we present spectra, photometry, proper motions, and distance estimates for forty-two low-mass star and brown dwarf candidates…
We present the results of photometric and spectroscopic follow-ups of the lowest mass member candidates in the nearest OB association, Upper Scorpius (5-10 Myr; 145+/-17 pc), with the Gran Telescopio de Canarias (GTC) and European Southern…
We report the initial results of the Brown Dwarf Spectroscopic Survey Gravity Project, to study gravity sensitive features as indicators of youth in brown dwarfs. Low-resolution (R~2000) J-band and optical (R~1000) observations using…
Deep optical imaging is used to study time-domain properties of young brown dwarfs in sigma Orionis over typical rotational time-scales and to search for new substellar and planetary-mass cluster members. We used VIMOS at the VLT to monitor…
Optical and near-infrared spectroscopy of the newly discovered peculiar L dwarf 2MASS J11263991-5003550 are presented. Folkes et al. identified this source as a high proper motion L9+/-1 dwarf based on its strong H2O absorption at 1.4…
We used the optical and near-infrared imagers located on the Liverpool, the IAC80, and the William Herschel telescopes to monitor 18 M7$-$L9.5 dwarfs with the objective of measuring their rotation periods. We achieved accuracies typically…
We explore the rotation and activity of very low mass (VLM) objects by means of a photometric variability study. Our targets in the vicinity of Epsilon Ori belong to the OriOB1b population in the Orion star-forming complex. In this region…
We present spectroscopic and imaging observations of the active T dwarf 2MASS 1237+6526, intended to investigate the emission mechanism of this cool brown dwarf. The H$\alpha$ emission line first detected in 1999 July appears to be…
We present observations of a circumstellar disk that is inclined close to edge-on around a young brown dwarf in the Taurus star-forming region. Using data obtained with SpeX at the NASA Infrared Telescope Facility, we find that the slope of…