Results 11 to 20 of about 437,426 (252)
Missing metals in DQ stars: A simple explanation
Astronomy & Astrophysics, 2022 Classical DQ stars are white dwarfs whose atmospheres contain detectable traces of carbon brought up to the surface by a convective dredge-up process. Intriguingly, unlike other white dwarf spectral classes, DQ stars virtually never show signs of external pollution by elements heavier than carbon.
Simon Blouin
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Missing metals in DQ stars: a compelling clue to their origin [PDF]
Monthly Notices of the Royal Astronomical SocietyABSTRACT White dwarf stars frequently experience external pollution by heavy elements, and yet the intrinsically carbon-enriched DQ spectral class members fail to exhibit this phenomenon, representing a decades-old conundrum. This study reports a high-resolution spectroscopic search for Ca ii in classical DQ white dwarfs, finding that ...
J Farihi, P Dufour, T G Wilson
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The Astrophysical Journal, 2022 Abstract We continue our comprehensive theoretical investigation of the spectral evolution of white dwarfs based on sophisticated simulations of element transport. In this paper, we focus on the transformation of PG 1159 stars into DO/DB white dwarfs due to the gravitational settling of heavy elements and then into DQ white dwarfs ...
A. Bédard, P. Bergeron, P. Brassard
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Modelling and observations of molecules in discs around young stars [PDF]
, 2013 This thesis contains a study of molecules within circumstellar discs around young stars. Firstly, the chemistry of a disc around a young, Class 0 protostar is modelled.
Ilee, John David
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INVESTIGATIONS OF LONG-PERIOD DQ HERCULIS STARS.
, 1986 The magnetic rotator model has long been the favored explanation for coherent photometric modulations in the DQ Herculis class of cataclysmic variables. However, to date, all evidence supporting this model has been of the indirect variety.
PENNING, WILLIAM ROY.
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Rapid Evolution of the White Dwarf Pulsar AR Scorpii
The Astrophysical Journal Letters, 2023 Analysis of AR Sco optical light curves spanning 9 yr shows a secular change in the relative amplitudes of the beat pulse pairs generated by the two magnetic poles of its rotating white dwarf.
Peter Garnavich +6 more
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A Hot DQ White Dwarf in the Open Star Cluster M35 [PDF]
The Astrophysical Journal, 2006 We report the discovery of a hot DQ white dwarf, NGC 2168:LAWDS 28, that is a likely member of the 150-Myr old cluster NGC 2168 (Messier 35). The spectrum of the white dwarf is dominated by CII features. The effective temperature is difficult to estimate but likely > 20,000 K based on the temperatures of hot DQs with similar spectra.
Williams, Kurtis A. +3 more
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, 2022 HLA-DQ donor-specific antibodies (DSA) are the most prevalent type of DSA after renal transplantation and have been associated with eplet mismatches between donor and recipient HLA. Eplets are theoretically defined configurations of surface exposed amino
Cynthia S. M. Kramer (11917436) +10 more
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The Astrophysical Journal, 2023 DQ Tau is a unique young high-eccentricity binary system that exhibits regular magnetic reconnection flares and pulsed accretion near periastron. We conducted NuSTAR, Swift, and Chandra observations during the 2022 July 30 periastron to characterize X ...
Konstantin V. Getman +5 more
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Recurring millimeter flares as evidence for star-star magnetic reconnection events in the DQ Tauri PMS binary system [PDF]
Astronomy and Astrophysics, 2010 Observations of the T Tauri spectroscopic binary DQ Tau in April 2008 captured an unusual flare at 3 mm, which peaked at an observed max flux of 0.5 Jy (about 27x the quiescent value). Here we present follow-up mm observations that demonstrate a periodicity to the phenomenon.
Salter, D. M. +7 more
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