Related papers: Probing Disk Accretion in Young Brown Dwarfs
We present accretion rates for a large number of solar-type stars in the Cep OB2 region, based on U band observations. Our study comprises 95 members of the ~4 Myr-old cluster Tr 37 (including 20 "transition" objects; TO), as well as the…
We present precise measurements of radial (RV) and projected rotational ($v\sin{i}$) velocities, effective temperatures, and surface gravities of a sample of 258 M6 to L2 dwarfs with multi-epoch, high-resolution ($\lambda/\Delta\lambda$ =…
Using the Hectochelle multifiber spectrograph, we have obtained high-resolution (R~34,000) spectra in the Halpha region for a large number of stars in the 4 Myr-old cluster Tr 37, containing 146 previously known members and 26 newly…
The $K2$ Mission has photometrically monitored thousands of stars at high precision and cadence in a series of $\sim$80-day campaigns focused on sections of the ecliptic plane. During its second campaign, $K2$ targeted over 1000 young…
Advances in high-resolution imaging have revealed H$\alpha$ emission separated from the host star. It is generally believed that the emission is associated with forming planets in protoplanetary disks. However, the nature of this emission…
We have examined the relationship between rotation and activity in 14 late-type (M6-M7) M dwarfs, using high resolution spectra taken at the W.M. Keck Observatory and flux-calibrated spectra from the Sloan Digital Sky Survey. Most were…
We have analyzed a broad-band optical and near-infrared spectrum of FU Tau A, a presumed young brown dwarf in the Taurus star forming region that has intrigued both theorists and observers by its over-luminosity in the HR diagram with…
In this work, we introduce the use of H I Pfund-beta (4.6538 micron) as a tracer of mass accretion from protoplanetary disks onto young stars. Pf-beta was serendipitously observed in NIRSPEC and CRIRES surveys of CO fundamental emission,…
We present results from the volume-complete spectroscopic survey of 0.1-0.3M$_\odot$ M dwarfs within 15pc. This work discusses the active sample without close binary companions, providing a comprehensive picture of these 123 stars with…
By comparing near-infrared spectra with atmosphere models, we infer the effective temperature, surface gravity, projected rotational velocity, and radial velocity for 21 very-low-mass stars and brown dwarfs. The unique sample consists of…
(Abridged) We present the results of the first unbiased survey for metal pollution among H-atmosphere (DA) white dwarfs with cooling ages of 20-200 Myr and 17000K < Teff < 27000K, using HST COS in the far UV between 1130 and 1435 A. The…
In the framework of the GIARPS@TNG High-resolution Observations of T Tauri stars (GHOsT) project, we study the accretion properties of 37 Classical T Tauri Stars of the Taurus-Auriga star forming region (SFR) with the aim of characterizing…
Using the near-infrared spectrometer SpeX and its slit-viewing camera at the IRTF, I have resolved a low-mass member of the Upper Scorpius OB association into a double star. From K-band images of the pair, DENIS-P J161833.2-251750.4 A and…
Infrared excesses around metal polluted white dwarfs have been associated with the accretion of dusty, planetary material. This work analyses the available infrared data for an unbiased sample of white dwarfs and demonstrates that no more…
Although the Orion Nebula Cluster is one of the most studied clusters in the solar neighborhood, the evolution of the very low-mass members ($M_* < 0.25 \, M_\odot$) has not been fully addressed due to their faintness. Our goal is to verify…
We have used 3.5 to 8 micron data from the Cores to Disks (c2d) Legacy survey and our own deep IJHKs images of a 0.5 square degree portion of the c2d fields in Ophiuchus to produce a sample of candidate young objects with probable masses…
We aim to characterize the U-band variability of young brown dwarfs in the Taurus Molecular Cloud and discuss its origin. We used the XMM-Newton Extended Survey of the Taurus Molecular Cloud, where a sample of 11 young bona fide brown…
Observations of planetary material polluting the atmospheres of white dwarfs are an important probe of the bulk composition of exoplanetary material. Medium- and high-resolution optical and ultraviolet spectroscopy of seven white dwarfs…
There are only a handful of known short-period pre-main sequence spectroscopic binaries with significant accretion rates (Class II sources). AK Sco stands out in this list because the system is composed of two equal mass F5 stars in a…
Young stars and planetary systems form in molecular clouds. For classical T Tauri stars (CTTS, F-K type precursors) the accretion disk does not reach down to the central star, but it is truncated near the co-rotation radius. The inner edge…