Related papers: Two Beyond-Primitive Extrasolar Planetesimals
Spitzer observations reveal the presence of warm debris from a tidally destroyed rocky and possibly icy planetary body orbiting the white dwarf GD 61. Ultraviolet and optical spectroscopy of the metal-contaminated stellar photosphere reveal…
The spectra of the planetary nebula M1-42 is reanalysed using spectral measurements made in the mid-infrared with the Spitzer Space Telescope. The aim is to determine the chemical composition of this object. We also make use of ISO, IUE and…
The connection between helium-rich hot subdwarfs of spectral types O and B (He-sdB) has been relatively unexplored since the latter were found in significant numbers in the 1980's. In order to explore this connection further, we have…
We present spectroscopic observations of the dust- and gas-enshrouded, polluted, single white dwarf star SDSSJ104341.53+085558.2 (hereafter SDSSJ1043+0855). Hubble Space Telescope Cosmic Origins Spectrograph far-ultraviolet spectra combined…
The recently discovered hypervelocity white dwarf LP 40-65 (aka GD 492) has been suggested as the outcome of the failed disruption of a white dwarf in a sub-luminous Type Ia supernova (SN Ia). We present new observations confirming GD 492…
A correlation between giant-planet mass and atmospheric heavy elemental abundance was first noted in the past century from observations of planets in our own Solar System, and has served as a cornerstone of planet formation theory. Using…
The results of new spectroscopic analyses of 20 recently reported extrasolar planet parent stars are presented. The companion of one of these stars, HD 10697, has recently been shown to have a mass in the brown dwarf regime; we find [Fe/H]…
The study of high-redshift galaxies provides critical insights into the early stages of cosmic evolution, particularly during the so-called 'cosmic noon', when star formation activity reached its peak. Within this context, the origin of the…
We explore different evolutionary scenarios to explain the helium deficiency observed in H1504+65, the most massive known PG1159 star. We concentrate mainly on the possibility that this star could be the result of mass loss shortly after…
We present high-precision multi-band photometry for the globular cluster (GC) M2. We combine the analysis of the photometric data obtained from the Hubble Space Telescope UV Legacy Survey of Galactic GCs GO-13297, with chemical abundances…
PG1159-035 is the prototype of the PG1159 spectral class which consists of extremely hot hydrogen-deficient (pre-) white dwarfs. It is also the prototype of the GW Vir variables, which are non-radial g-mode pulsators. The study of PG1159…
The presence of a planetary system can shield a planetesimal disk from the secular gravitational perturbations due to distant outer massive objects (planets or stellar companions). As the host star evolves off the main sequence to become a…
Observations of heavy metal pollution in white dwarf stars indicate that metal-rich planetesimals are frequently scattered into star-grazing orbits, tidally disrupted, and accreted onto the white dwarf surface, offering direct insight into…
The accretion of icy and rocky solids during the formation of a gas giant planet is poorly constrained and challenging to model. Refractory species, like sulfur, are only present in solids in the protoplanetary disk where planets form.…
With four giant planets ($m\sim5-10~M_{\rm Jup}$, $T_\rm{eff}\sim900-1200$ K) orbiting between 15-70 au, HR 8799 provides an unparalleled testbed for studying giant planet formation and probing compositional trends across the protoplanetary…
We present a series of systematic abundance measurements for 89 hot DA white dwarfs drawn from the FUSE observation archive. These stars span the temperature range ~ 20000-70000K, and form the largest sample to-date, exceeding our earlier…
Between 30 - 50% of white dwarfs (WDs) show heavy elements in their atmospheres. This "pollution" is thought to arise from the accretion of planetesimals perturbed by outer planet(s) to within the WD's tidal disruption radius. A small…
HD~20794 is a nearby, bright, metal-poor G-type dwarf hosting a compact planetary system, including a super-Earth near the habitable zone. Its low stellar activity and the availability of precise radial-velocity and photometric data make it…
The metal budgets in some white dwarf (WD) atmospheres reveal that volatile-rich circumstellar bodies must both exist in extrasolar systems and survive the giant branch phases of stellar evolution. The resulting behaviour of these active…
The presence of heavy elements in the atmospheres of the hottest H-rich DA white dwarfs has been the subject of considerable interest. While theoretical calculations can demonstrate that radiative forces, counteracting the effects of…