A5026713556- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Gamma-ray bursts and supernovae
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Astrophysical Phenomena and Observations
- Adaptive optics and wavefront sensing
- Calibration and Measurement Techniques
- Galaxies: Formation, Evolution, Phenomena
- Water Quality Monitoring and Analysis
- History and Developments in Astronomy
- Geological and Geophysical Studies
- Planetary Science and Exploration
- Spectroscopy Techniques in Biomedical and Chemical Research
- Geomagnetism and Paleomagnetism Studies
- Solar and Space Plasma Dynamics
- Geophysics and Gravity Measurements
- High-pressure geophysics and materials
- Pulsars and Gravitational Waves Research
- Transportation Planning and Optimization
- Space Exploration and Technology
- Medical Imaging Techniques and Applications
- Superconducting and THz Device Technology
- Atmospheric Ozone and Climate
Friedrich-Alexander-Universität Erlangen-Nürnberg
2018-2024
Universitat Politècnica de Catalunya
2018-2024
Institut d'Estudis Espacials de Catalunya
2022-2023
University of Warwick
2014-2020
Centro de Estudios de Física del Cosmos de Aragón
2018
Max Planck Institute for Radio Astronomy
2016
Max Planck Society
2016
University of Hertfordshire
2011-2014
We present a catalogue of white dwarf candidates selected from the second data release Gaia (DR2). used sample spectroscopically confirmed dwarfs Sloan Digital Sky Survey (SDSS) to map entire space spanned by these objects in Hertzsprung–Russell diagram. then defined set cuts absolute magnitude, colour, and number quality flags remove majority contaminating objects. Finally, we adopt method analogous one presented our earlier SDSS photometric catalogues calculate probability being (PWD) for...
We describe the Next Generation Transit Survey (NGTS), which is a ground-based project searching for transiting exoplanets orbiting bright stars. NGTS builds on legacy of previous surveys, most notably WASP, and designed to achieve higher photometric precision hence find smaller planets than have previously been detected from ground. It also operates in red light, maximizing sensitivity late K early M dwarf The survey specifications call 0.1 per cent light over an instantaneous field view...
The VST Photometric Halpha Survey of the Southern Galactic Plane and Bulge (VPHAS+) is surveying southern Milky Way in u, g, r, i at 1 arcsec angular resolution. Its footprint spans latitude range -5 < b +5 all longitudes south celestial equator. Extensions around Centre to latitudes +/-10 bring much Bulge. This ESO public survey, begun on 28th December 2011, reaches down 20th magnitude (10-sigma) will provide single-epoch digital optical photometry for 300 million stars. observing strategy...
WEAVE, the new wide-field, massively multiplexed spectroscopic survey facility for William Herschel Telescope, will see first light in late 2022. WEAVE comprises a 2-degree field-of-view prime-focus corrector system, nearly 1000-multiplex fibre positioner, 20 individually deployable 'mini' integral field units (IFUs), and single large IFU. These systems feed dual-beam spectrograph covering wavelength range 366$-$959\,nm at $R\sim5000$, or two shorter ranges $R\sim20\,000$. After summarising...
Abstract A complete accounting of nearby objects—from the highest-mass white dwarf progenitors down to low-mass brown dwarfs—is now possible, thanks an almost set trigonometric parallax determinations from Gaia, ground-based surveys, and Spitzer follow-up. We create a census objects within Sun-centered sphere 20 pc radius check published literature decompose each binary or higher-order system into its separate components. The result is volume-limited ∼3600 individual star formation products...
We present photometry and spectroscopy for 27 pulsating hydrogen-atmosphere white dwarfs (DAVs; a.k.a. ZZ Ceti stars) observed by the Kepler space telescope up to K2 Campaign 8, an extensive compilation of observations with unprecedented duration (>75 days) duty cycle (>90%). The space-based reveals pulsation properties previously inaccessible ground-based observations. observe a sharp dichotomy in oscillation mode line widths at roughly 800 s, such that dwarf pulsations periods exceeding s...
The INT/WFC Photometric H-Alpha Survey of the Northern Galactic Plane (IPHAS) is a 1800 square degrees imaging survey covering latitudes |b| < 5 deg and longitudes l = 30 to 215 in r, i H-alpha filters using Wide Field Camera (WFC) on 2.5-metre Isaac Newton Telescope (INT) La Palma. We present first quality-controlled globally-calibrated source catalogue derived from survey, providing single-epoch photometry for 219 million unique sources across 92% footprint. observations were carried out...
We revisit the properties and astrophysical implications of field white dwarf mass distribution in preparation Gaia applications. Our study is based on two samples with best established completeness most precise atmospheric parameters, volume-complete survey within 20 pc Sloan Digital Sky Survey (SDSS) magnitude-limited sample. explore modelling observed distributions Monte Carlo simulations, but find that it difficult to constrain independently initial function (IMF), initial-to-final-mass...
We present the discovery of NGTS-1b, a hot-Jupiter transiting an early M-dwarf host ($T_{eff}=3916^{+71}_{-63}~K$) in P=2.674d orbit discovered as part Next Generation Transit Survey (NGTS). The planet has mass $0.812^{+0.066}_{-0.075}~M_{J}$, making it most massive ever M-dwarf. radius is $1.33^{+0.61}_{-0.33}~R_{J}$. Since transit grazing, we determine this by modelling data and placing prior on density from population known gas giant planets. NGTS-1b third found around M-dwarf,...
The cool white dwarf SDSS J124231.07+522626.6 exhibits photospheric absorption lines of eight distinct heavy elements in medium resolution optical spectra, notably including oxygen. Teff = 13 000 K atmosphere is helium-dominated, but the convection zone contains significant amounts hydrogen and four most common rock-forming (O, Mg, Si, Fe) account for almost all accreted mass, totalling at least 1.2 × 1024 g, similar to mass Ceres. time-averaged accretion rate 2 1010 g s−1, one highest rates...
Based on data from the ESA Gaia Data Release 2 (DR2) and several ground-based, multi-band photometry surveys we have compiled an all-sky catalogue of 39 800 hot subluminous star candidates selected in DR2 by means colour, absolute magnitude, reduced proper motion cuts. We expect majority to be subdwarf stars spectral type B O, followed blue horizontal branch late B-type (HBB), post-AGB stars, central planetary nebulae. The contamination cooler should about 10%. is magnitude limited G < 19...
A low-mass planet around a white dwarf Numerous exoplanets have been detected Sun-like stars. These stars end their lives as dwarfs, which should inherit any surviving planetary systems. Manser et al. found periodic shifts in emission lines from disc of gas orbiting (see the Perspective by Fossati). They used numerical simulations to show that most likely explanation for spectral is within disc. The must be unusually small and dense avoid being ripped apart tidal forces. authors speculate it...
We present a three dimensional map of extinction in the Northern Galactic Plane derived using photometry from IPHAS survey. The has fine angular ($\sim 10$ arcmin) and distance (100 pc) sampling allied to significant depth ($\gtrsim 5$ kpc). construct method based on hierarchical Bayesian model as previously described by Sale (2012). In addition mean extinction, we also measure differential which arises fractal nature ISM, show that it will be dominant source uncertainty estimates some...
We present the discovery of strongly variable emission lines from a gaseous disc around DA white dwarf SDSS J1617+1620, star previously found to have an infrared excess indicative dusty debris formed by tidal disruption rocky planetary body. Time-series spectroscopy obtained during period 2006-2014 has shown appearance strong double-peaked Ca II in 2008. The were weak, at best, earlier observations, and monotonically faded through remainder our monitoring. Our observations represent...
We present a spectroscopic survey of 230 white dwarf candidates within 40 pc the Sun from William Herschel Telescope and Gran Telescopio Canarias. All were selected $\textit{Gaia}$ Data Release 2 (DR2) in almost all cases had no prior classifications. find total 191 confirmed dwarfs 39 main-sequence star contaminants. The majority stellar remnants sample are relatively cool ($\langle T_{\rm eff} \rangle$ = 6200 K), showing either hydrogen Balmer lines or featureless spectrum, corresponding...
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...
White dwarf stars are the most common end point of stellar evolution. Of special interest ultramassive white dwarfs, as they related to type Ia Supernovae explosions, merger events, and Fast Radio Bursts. Ultramassive dwarfs expected harbour oxygen-neon (ONe) cores a result single standard However, fraction them could have carbon-oxygen (CO) cores. Recent studies, based on new observations provided by {\it Gaia} space mission, indicate that small experience strong delay in their cooling,...
We present a spectroscopic survey of 248 white dwarf candidates within 40 pc the Sun; these 244 are in southern hemisphere. Observations were performed mostly with Very Large Telescope (X-Shooter) and Southern Astrophysical Research Telescope. Almost all selected from $\textit{Gaia}$ Data Release 3 (DR3). find total 246 confirmed dwarfs, 209 which had no previously published spectra, two main-sequence star contaminants. Of these, 100 dwarfs display hydrogen Balmer lines, 69 have featureless...
ABSTRACT White dwarfs with an F, G, or K type companion represent the last common ancestor for a plethora of exotic systems throughout galaxy, though to this point very few them have been fully characterized in terms orbital period and component masses, despite fact several thousand identified. Gaia data release 3 has examined many hundreds thousands systems, as such we can use this, conjunction our previous UV excess catalogues, perform spectral energy distribution fitting order obtain...
White dwarf masses are among the most important properties used to constrain their past and future evolution. Direct estimates of white crucial for assessing validity theoretical evolutionary models methods analysis. The main goal this work was measure radii dwarfs that belong widely separated, common proper-motion binaries with non-degenerate companions. These can be assessed, independently from mass-radius relations, through measurements gravitational redshifts photometric radii. We...
We report the discovery of a peculiar L dwarf from United Kingdom Infrared Deep Sky Survey Large Area Survey, ULAS J222711−004547. The very red infrared photometry (MKO J − K = 2.79 ± 0.06, WISE W1−W2 0.65 0.05) J222711−004547 makes it one reddest brown dwarfs discovered so far. obtained moderate resolution spectrum this target using XSHOOTER spectrograph on Very Telescope, and we classify as L7pec, confirming its nature. Comparison to theoretical models suggests that object could be...
The Gaia Data Release 1 (DR1) sample of white dwarf parallaxes is presented, including 6 directly observed degenerates and 46 dwarfs in wide binaries. This data set combined with spectroscopic atmospheric parameters to study the mass-radius relationship (MRR). G magnitudes are used derive model atmosphere dependent radii, which can then be compared predictions a theoretical MRR. We find good agreement between DR1 parallaxes, published effective temperatures (Teff) surface gravities (log g),...
ABSTRACT The age–metallicity relation (AMR) is a fundamental tool for constraining the chemical evolution of Galactic disc. In this work, we analyse observational properties using binary stars that have not interacted consisting white dwarf (WD) – from which can derive total age system and main sequence (MS) star metallicity as traced by [Fe/H] abundances. Our sample consists 46 widely separated, but unresolved spectroscopic binaries identified within Sloan Digital Sky Survey, 189 WD plus MS...
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,...