Related papers: Most white dwarfs with detectable dust discs show …

Since 2003, the Spitzer Space Telescope has provided groundbreaking views of Galactic star formation in bands from 3.6 past 24 microns. During the cryogenic mission (the first 5.5 years), variability of young stars at these bands was noted,…

We assume a scenario in which transition discs (i.e. discs around young stars that have signatures of cool dust but lack significant near infra-red emission from warm dust) are associated with the presence of planets (or brown dwarfs).…

With the launch of the {\em Wide-field Infrared Survey Explorer} ({\em WISE}), a new era of detecting planetary debris and brown dwarfs around white dwarfs (WDs) has begun with the {\em WISE} InfraRed Excesses around Degenerates (WIRED)…

Studies of debris disks around white dwarfs (WDs) have focused on infrared wavelengths because debris disks are much colder than the star and are believed to contribute to the spectrum only at longer wavelengths. Nevertheless, these disks…

We present the results of a multi-wavelength multi-epoch survey of five evolved protoplanetary disks in the IC 348 cluster that show significant infrared variability. Using 3-8micron and 24micron photometry along with 5-40micron…

White dwarf planetary science is a rapidly growing field of research featuring a diverse set of observations and theoretical explorations. Giant planets, minor planets, and debris discs have all been detected orbiting white dwarfs. The…

We examine 14 hot white dwarfs for signs of infrared excess using the Spitzer Space Telescope. Twelve of the objects are massive white dwarfs which have been suggested to be the result of binary mergers. The remaining two objects are…

The presence of planetary material in white dwarf atmospheres, thought to be accreted from a dusty debris disc produced via the tidal disruption of a planetesimal, is common. Approximately five per cent of these discs host a co-orbital…

I present the results of a program to spectrophotometrically monitor the L1.5 dwarf 2MASSW J1145572+231730 to identify the cause of photospheric variability in ultra cool dwarfs. Plausible candidates are magnetically-induced star spots and…

We present a spectral analysis of the FUSE spectra of EM Cygni, a Z Cam DN system. The FUSE spectrum, obtained in quiescence, consists of 4 individual exposures (orbits): two exposures, at orbital phases phi ~ 0.65 and phi ~ 0.90, have a…

The coldest brown dwarf, WISE 0855, is the closest known planetary-mass, free-floating object and has a temperature nearly as cold as the solar system gas giants. Like Jupiter, it is predicted to have an atmosphere rich in methane, water,…

We present the results of a search of infrared excess candidates in a comprehensive (29\,000 stars) magnitude limited sample of dwarf stars, spanning the spectral range F2-K0, and brighter than V$=$15 mag. We searched the sample within the…

Spectroscopic observations of white dwarfs reveal that many of them are polluted by exoplanetary material, whose bulk composition can be uniquely probed this way. We present a spectroscopic and photometric analysis of the DA white dwarf…

Most of the radio-loud narrow-line Seyfert 1 (NLS1) galaxies resemble compact steep-spectrum sources. However, the extremely radio-loud ones show blazar-like characteristics, like flat radio spectra, compact radio cores, substantial…

White dwarfs (WDs) are powerful tools to study the evolutionary history of stars and binaries in the Galaxy. But do we understand their multiplicity from a theoretical point of view? This can be tested by a comparison with the sample of WDs…

Debris disks around single white dwarfs are thought to be the remains of planetary bodies disrupted by tidal forces. Ongoing accretion of the hereby produced dust allows to detect the planetary material in the white dwarf photosphere and to…

Circumstellar disks of planetary debris are now known or suspected to closely orbit hundreds of white dwarf stars. To date, both data and theory support disks that are entirely contained within the preceding giant stellar radii, and hence…

Recent monitoring programs of ultra cool field M and L dwarfs (low mass stars or brown dwarfs) have uncovered low amplitude photometric I-band variations which may be associated with an inhomogeneous distribution of photospheric…

We predict the existence of dusty disks and possibly CO planets around massive white dwarfs. We show that the thermal emission from these disks should be detectable in the infrared. The planets may also be detectable either by direct IR…

A sample of 4 thousands Gaia sources with apparent $G$-band magnitudes of $<17$ and trigonometric parallaxes of $>3.33$ milli-arcseconds were cross-matched to the Transiting Exoplanet Survey high level science products and the Full-Frame…