A5013191138- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Astro and Planetary Science
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- Astrophysics and Cosmic Phenomena
- Pulsars and Gravitational Waves Research
- High-pressure geophysics and materials
- History and Developments in Astronomy
- Galaxies: Formation, Evolution, Phenomena
- Geophysics and Gravity Measurements
- Atmospheric Ozone and Climate
- Solar and Space Plasma Dynamics
- Adaptive optics and wavefront sensing
- Cosmology and Gravitation Theories
- Scientific Research and Discoveries
- SAS software applications and methods
- Relativity and Gravitational Theory
- Real-time simulation and control systems
- Geological and Geophysical Studies
- Traditional Chinese Medicine Studies
- Phytoestrogen effects and research
- Firm Innovation and Growth
European Southern Observatory
2018-2025
European Space Astronomy Centre
2021-2025
European Space Agency
2025
University of Warwick
2015-2020
Centro de Estudios de Física del Cosmos de Aragón
2018
Universitat Politècnica de Catalunya
2018
University of Göttingen
2017
University of California, Santa Barbara
2017
Astronomical Observatory of Capodimonte
2017
Villanova University
2017
Abstract Galactic compact binaries with orbital periods shorter than a few hours emit detectable gravitational waves (GWs) at low frequencies. Their GW signals can be detected the future Laser Interferometer Space Antenna (LISA). Crucially, they may useful in early months of mission operation helping to validate LISA's performance comparison prelaunch expectations. We present an updated list 55 candidate LISA-detectable measured properties, for which we derive distances based on Gaia Data...
Abstract We present volume-limited samples of cataclysmic variables (CVs) and AM CVn binaries jointly selected from SRG/eROSITA eRASS1 Gaia DR3 using an X-ray + optical color–color diagram (the “X-ray Main Sequence”). This tool identifies all CV subtypes, including magnetic low-accretion rate systems, in contrast to most previous surveys. find 23 CVs, 3 which are CVns, out 150 pc the Western Galactic Hemisphere. Our sample is spectroscopically verified complete down L X = 1.3 × 10 29 erg s...
We present the first volume-limited sample of cataclysmic variables (CVs), selected using accurate parallaxes provided by second data release (DR2) ESA $\mathit{Gaia}$ space mission. The is composed 42 CVs within $150\,$pc, including two new systems discovered data, and $(77 \pm 10)\,$per cent complete. use this to study intrinsic properties Galactic CV population. In particular, density we derive, $\rho=(4.8^{+0.6}_{-0.8}) \times10^{-6}\,\mathrm{pc}^{-3}$, lower than predicted most binary...
Debris discs which orbit white dwarfs are signatures of remnant planetary systems. We present 12 yr optical spectroscopy the metal-polluted dwarf SDSS J1228+1040, shows a steady variation in morphology 8600 Å Ca ii triplet line profiles from gaseous component its debris disc. identify additional emission lines O i, Mg ii, Fe and deep co-added spectra. These features (including H & K) exhibit wide range strength with respect to each other triplet, indicating different intensity distributions...
We present a detailed study of the metal-polluted DB white dwarf SDSS J0845+2257 (Ton 345). Using high-resolution Hubble Space Telescope/Cosmic Origins Spectrograph and Very Large Telescope spectroscopy, we have detected hydrogen 11 metals in atmosphere dwarf. The origin these is almost certainly circumstellar disc dusty gaseous debris from tidally disrupted planetesimal, accreting at rate 1.6 × 1010 g s−1. Studying chemical abundances accreted material demonstrates that planetesimal had...
We report on the masses ($M_\mathrm{WD}$), effective temperatures ($T_\mathrm{eff}$) and secular mean accretion rates ($\langle \dot{M} \rangle$) of 43 cataclysmic variable (CV) white dwarfs, 42 which were obtained from combined analysis their $\mathit{Hubble~Space~Telescope}$ ultraviolet data with parallaxes provided by Early Third Data Release $\mathit{Gaia}$ space mission, one dwarf gravitational redshift. Our results double number CV dwarfs an accurate mass measurement, bringing total...
ABSTRACT We present a catalogue of 507 cataclysmic variables (CVs) observed in SDSS I to IV including 70 new classifications collated from multiple archival data sets. This represents the largest sample CVs with high-quality and homogeneous optical spectroscopy. have used this derive unbiased space densities period distributions for major sub-types CVs. also report on some peculiar CVs, bouncers exhibiting large changes accretion rates. 59 periods, 178 unpublished spectra, 262 or updated...
We present HST spectroscopy for 45 cataclysmic variables (CVs), observed with HST/COS and HST/STIS. For 36 CVs, the white dwarf is recognisable through its broad Ly α absorption profile we measure effective temperatures (Teff) by fitting data assuming log g = 8.35, which corresponds to average mass CV dwarfs (≃0.8 M⊙). Our results nearly double number of an accurate temperature measurement. find that CVs above period gap have, on average, higher (〈Teff〉 ≃ 23 000 K) exhibit much more scatter...
A handful of white dwarfs with helium-dominated atmospheres contain exceptionally large masses hydrogen in their convection zones, the metal-polluted dwarf GD 16 being one earliest recognized examples. We report discovery a similar star: coincidentally named 17. obtained medium-resolution spectroscopy both and 17 calculated abundances accretion rates photospheric H, Mg, Ca, Ti, Fe Ni. The metal abundance ratios indicate that two stars recently accreted debris, which is Mg-poor compared to...
ABSTRACT We present the first population synthesis of synchronous magnetic cataclysmic variables, called polars, taking into account effect white dwarf (WD) field on angular momentum loss. implemented reduced braking (MB) model proposed by Li, Wu & Wickramasinghe Binary Stellar Evolution (bse) code recently calibrated for variable (CV) evolution. then compared separately our predictions polars and non-magnetic CVs with a large homogeneous sample observed from Sloan Digital Sky Survey....
We report the discovery of three stars that, along with prototype LP40-365, form a distinct class chemically peculiar runaway that are survivors thermonuclear explosions. Spectroscopy four confirmed LP 40-365 finds ONe-dominated atmospheres enriched remarkably similar amounts nuclear ashes partial O- and Si-burning. Kinematic evidence is consistent ejection from binary supernova progenitor; at least two have rest-frame velocities indicating they unbound to Galaxy. With masses radii ranging...
The infrared dust emission from the white dwarf GD 56 is found to rise and fall by 20 per cent peak-to-peak over 11.2 yr, consistent with ongoing production depletion. It hypothesized that produced via collisions associated an evolving disc, temporarily increasing emitting surface of warm debris, subsequently destroyed or assimilated within a few years. variations are debris does not change temperature, indicating depleted fixed range orbital radii. Gas in may rapidly re-condense onto...
WD J204713.76-125908.9 is a new addition to the small class of white dwarfs with helium-dominated photospheres that exhibit strong Balmer absorption lines and atmospheric metal pollution. The exceptional abundances hydrogen observed in these stars may be result accretion water-rich rocky bodies. We obtained far-ultraviolet optical spectroscopy using Cosmic Origin Spectrograph on-board Hubble Space Telescope X-shooter on Very Large Telescope, identify photospheric nine metals: C, O, Mg, Si,...
ABSTRACT Close white dwarf binaries play an important role across a range of astrophysics, including thermonuclear supernovae, the Galactic low-frequency gravitational wave signal, and chemical evolution Galaxy. Progress in developing detailed understanding complex, multithreaded evolutionary pathways these systems is limited by lack statistically sound observational constraints on relative fractions various sub-populations their physical properties. The available samples are small,...
White dwarfs with emission lines from gaseous debris discs are among the rarest examples of planetary remnant hosts, but at same time they key objects for studying final evolutionary stage systems. Making use large number white identified in Gaia DR2, we conducting a survey remnants and here present first results our search: six discs. This publication focuses on main observational properties these highlights their most unique features. Three systems particular stand out:...
White dwarf photospheric parameters are usually obtained by means of spectroscopic or photometric analysis. These results not always consistent with each other, the published values often including just statistical uncertainties. The differences more dramatic for white dwarfs helium-dominated photospheres, so to obtain realistic uncertainties we have analysed a sample 13 these dwarfs, applying both techniques up three different and data sets star. We found mean standard deviations < $\sigma...
Abstract V498 Hya (SDSS J084555.07+033929.2) was identified as a short-period cataclysmic variable (CV) by the Catalina Real-Time Transient Survey (CRTS) in 2008. The superhump period measured during detected single superoutburst of Hya. quiescent spectrum subsequently taken SDSS-V Milky Way Mapper survey suggested that CV donor may be brown dwarf. We present time-resolved follow-up spectroscopy quiescence, obtained with GTC OSIRIS spectrograph, from which we derived 86.053 min spectroscopic...
V498 Hya (SDSS J084555.07+033929.2) was identified as a short-period cataclysmic variable (CV) by the Catalina Real-Time Transient Survey (CRTS) in 2008. The superhump period measured during detected single superoutburst of Hya. quiescent spectrum subsequently taken \SDSSV\ Milky Way Mapper survey suggested that CV donor may be brown dwarf. We present time-resolved follow-up spectroscopy quiescence, obtained with GTC OSIRIS spectrograph, from which we derived 86.053 min spectroscopic period,...
The age-metallicity relation (AMR) is a fundamental observational constraint for understanding how the Galactic disc formed and evolved chemically in time. However, there not yet an agreement on properties of AMR solar neighbourhood, primarily due to difficulty obtaining accurate stellar ages individual field stars. We have started campaign providing much needed input by using wide white dwarf-main sequence (WDMS) binaries. White dwarfs are natural clocks can be used derive ages....
We present time-resolved optical and ultraviolet spectroscopy photometry of V1460~Her, an eclipsing cataclysmic variable with a 4.99\,h orbital period overluminous K5-type donor star. The spectra show emission lines from accretion disc along absorption the donor. use these to measure radial velocities, which, together constraints upon inclination photometry, imply masses $M_1=0.869\pm0.006\,\mathrm{M}_\odot$ $M_2=0.295\pm0.004\,\mathrm{M}_\odot$ for white dwarf radius donor,...
We report the discovery of an extremely close white dwarf plus F main-sequence star in a 12 h binary identified by combining data from Radial Velocity Experiment survey and Galaxy Evolution Explorer survey. A combination spectral energy distribution fitting optical Hubble Space Telescope ultraviolet spectroscopy allowed us to place fairly precise constraints on physical parameters binary. The system, TYC 6760-497-1, consists hot Teff ∼ 20 000 K, |$M_\rm{WD}\sim 0.6 {\rm{M_{{\odot }}}}$| F8...
While highly evolved cataclysmic variables (CVs) with brown dwarf donors, often called "period bouncers", are predicted to make up $\simeq40-70$ % of the Galactic CV population, only a handful such systems currently known. The identification and characterization additional period bouncers is therefore important probe this poorly understood phase evolution. We investigate evolution QZ Lib following its 2004 super-outburst using multi-epoch spectroscopy. From time-resolved spectroscopic...
The upcoming NASA Transiting Exoplanet Survey Satellite (TESS) will obtain space-based uninterrupted light curves for a large sample of bright white dwarfs distributed across the entire sky, providing very rich resource asteroseismological studies and search transits from planetary debris. We have compiled an all-sky catalogue ultraviolet, optical, infrared photometry as well proper motions, which we propose essential tool preliminary identification characterisation potential targets....
We report the identification of SDSS J121929.45+471522.8 as third apparently isolated magnetic (B~18.5+/-1.0,MG) white dwarf exhibiting Zeeman-split Balmer emission lines. The star shows coherent variability at optical wavelengths with an amplitude ~0.03mag and a period 15.26h, which we interpret spin dwarf. Modelling spectral energy distribution Gaia parallax, derive temperature 7500+/-148K, mass 0.649+/-0.022Msun, cooling age 1.5+/-0.1Gyr, well upper limit on sub-stellar or giant planet...