Related papers: Brown Dwarfs as Galactic Chronometers
We present Spitzer IRAC photometry of twelve very late-type T dwarfs; nine have [3.6], [4.5], [5.8] and [8.0] photometry and three have [3.6] and [4.5] photometry only. We investigate trends with type and color for the planning and…
Irradiated brown dwarfs (BDs) provide natural laboratories to test our understanding of substellar and irradiated atmospheres. A handful of short-period BDs around white dwarfs (WDs) have been observed, but the uniquely intense UV-dominated…
The aim of the Degenerate Objects around Degenerate Objects (DODO) survey is to search for very low mass brown dwarfs and extrasolar planets in wide orbits around white dwarfs via direct imaging. The direct detection of such companions…
Using WFPC2 on the Hubble Space Telescope, we have isolated a sample of 258 white dwarfs (WDs) in the Galactic globular cluster M4. Fields at three radial distances from the cluster center were observed and sizeable WD populations were…
We present astrometric measurements of eleven nearby ultracool brown dwarfs of spectral types Y and late-T, based on imaging observations from a variety of space-based and ground-based telescopes. These measurements have been used to…
Studies of cool white dwarfs in the solar neighbourhood have placed a limit on the age of the Galactic disk of 8-9 billion years. However, determining their cooling ages requires the knowledge of their effective temperatures, masses, radii,…
We use Kepler/K2 lightcurves to measure rotation periods of brown dwarfs and very low mass stars in the Upper Scorpius star-forming region. Our sample comprises a total of 104 periods. Depending on the assumed age of Upper Scorpius, about a…
Brown dwarfs may have such low masses because they are prematurely ejected from small unstable multiple systems, while the members are still actively building up their masses. We demonstrate that this scenario is consistent with all…
White dwarfs are a class of stars with unique physical properties. They present many challenging problems whose solution requires the application of advanced theories of dense matter, state-of-the-art experimental techniques, and extensive…
Over the past couple of decades, researchers have predicted more than a dozen super-Chandrasekhar white dwarfs from the detections of over-luminous type Ia supernovae. It turns out that magnetic fields and rotation can explain such massive…
Dwarf galaxies make ideal laboratories to test galaxy evolution paradigms and cosmological models. Detailed studies of dwarfs across the spectrum allow us to gauge the efficacy of astrophysical processes at play in the lowest mass halos…
The census of solar neighbours is still complemented by new discoveries, mainly of very low-mass, faint dwarfs, close to or within the substellar domain. These discoveries contribute to a better understanding of the field population; its…
In a perturbed Universe, comoving tracers on a two-dimensional surface of constant observed redshift are at different proper time since the Big Bang. For tracers whose age is known independently, one can measure these perturbations of the…
We consider the limiting case for orbital stability of the companions to HR 8799. This case is only consistent with ages for the system of ~100 Myr, not with the 1 Gyr age proposed from astroseismology. The discrepancy probably arises…
This White Paper, submitted to the National Academy of Sciences' Astro2010 Decadal Review Committee, focuses on 2 central themes in the study of young brown dwarfs -- their formation mechanism and disk characteristics -- which are of direct…
Astrophysical objects below the stellar mass limit but well above the mass of Jupiter eluded discovery for nearly three decades after Kumar first proposed their existence, and for two decades after Tarter proposed the name "brown dwarfs."…
It is possible to reliably identify white dwarfs (WDs) without recourse to spectra, instead using photometric and astrometric measurements to distinguish them from Main Sequence stars and quasars. WDs' colours can also be used to infer…
Brown dwarfs bridge the gap between the stellar and planetary mass regimes. Evolving from conditions very similar to the lowest-mass stars, the atmospheres of older brown dwarfs closely resemble those expected in close-in extrasolar giant…
We summarize recent improvements in model atmosphere and internal structure of faint white dwarfs. We derive an analytical cooling theory which illustrates the effects of various physical processes on the energy budget and the cooling…
A detailed analysis of halo white dwarf candidates is presented, which is based on model atmosphere fits to observed energy distributions built from photoelectric or photographic magnitudes. Most of the candidates identified in reduced…