Effective temperatures of cataclysmic-variable white dwarfs as a probe of their evolution
| Autor: | Paula Szkody, Matthias R. Schreiber, Dean M. Townsley, Peter Nelson, D. de Martino, Anna F. Pala, Daisaku Nogami, Christian Knigge, Knox S. Long, D. Rodriguez Perez, M. J. Cook, K. M. Ivarsen, B. Monard, Tom Marsh, Edward M. Sion, Arto Oksanen, Patrick Godon, J. B. Haislip, Rod Stubbings, Jeremy Shears, Monica Zorotovic, Daniel E. Reichart, J. P. Moore, Ivan Hubeny, A. A. Henden, Roger D. Pickard, Aaron P. LaCluyze, S. Kafka, David Boyd, Gary Poyner, G. Myers, Boris T. Gänsicke |
|---|---|
| Přispěvatelé: | GBR |
| Rok vydání: | 2016 |
| Předmět: |
Physics
010504 meteorology & atmospheric sciences European research FOS: Physical sciences White dwarf Astronomy Cataclysmic variable star Astronomy and Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics Astrophysics 01 natural sciences Astrophysics - Solar and Stellar Astrophysics Space and Planetary Science 0103 physical sciences Astrophysics::Solar and Stellar Astrophysics 010303 astronomy & astrophysics QC Astrophysics::Galaxy Astrophysics Solar and Stellar Astrophysics (astro-ph.SR) 0105 earth and related environmental sciences |
| Zdroj: | Monthly Notices of the Royal Astronomical Society. 466:2855-2878 |
| ISSN: | 1365-2966 0035-8711 |
| DOI: | 10.1093/mnras/stw3293 |
| Popis: | 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$\alpha$ absorption profile and we measure the white dwarf effective temperatures ($T_{\mathrm{eff}}$) by fitting the HST data assuming $\log\,g=8.35$, which corresponds to the average mass for CV white dwarfs ($\simeq\,0.8\,\mathrm{M}_\odot$). Our results nearly double the number of CV white dwarfs with an accurate temperature measurement. We find that CVs above the period gap have, on average, higher temperatures ($\langle T_{\mathrm{eff}} \rangle \simeq 23\,000\,$K) and exhibit much more scatter compared to those below the gap ($\langle T_{\mathrm{eff}} \rangle \simeq 15\,000\,$K). While this behaviour broadly agrees with theoretical predictions, some discrepancies are present: (i) all our new measurements above the gap are characterised by lower temperatures ($T_{\mathrm{eff}} \simeq 16\,000 - 26\,000\,$K) than predicted by the present day CV population models ($T_{\mathrm{eff}} \simeq 38\,000 - 43\,000\,$K); (ii) our results below the gap are not clustered in the predicted narrow track and exhibit in particular a relatively large spread near the period minimum, which may point to some shortcomings in the CV evolutionary models. Finally, in the standard model of CV evolution, reaching the minimum period, CVs are expected to evolve back towards longer periods with mean accretion rates $\dot{M}\lesssim 2 \times 10^{-11}\,\mathrm{M}_\odot\,\mathrm{yr}^{-1}$, corresponding to $T_\mathrm{eff}\lesssim 11\,500\,$K. We do not unambiguously identify any such system in our survey, suggesting that this major component of the predicted CV population still remains elusive to observations. Comment: 26 pages, 21 figures. Published in MNRAS |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|