Hubble space telescope STIS spectroscopy of VW hydri during early quiescence following a superoutburst

Edward M. Sion, Fu Hua Cheng, Paula Szkody, Boris Gänsicke, Warren M. Sparks, Ivan - Hubeny

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

Hubble Space Telescope Space Telescope Imaging Spectrograph (STIS) observations of VW Hydri 2 and 7 days after the end of a superoutburst reveal a heated white dwarf with deep broad Lyα, narrow metallic absorption features and evidence of a hotter Keplerian-broadened component. We confirm the existence of enhanced abundances of odd-numbered nuclear species P, Mn, and Al as well as an N/C ratio indicative of CNO H-burning thermonuclear processing. Our best single-temperature white dwarf reduced χ2 fit to the first spectrum reveals (1) a DAZQ white dwarf with Teff = 22,500 ± 500 K, log g = 8.0, and photospheric abundances C = 0.3 solar, N = 3.0 solar, O = 3.0 solar, Si = 0.3 solar, Al = 2 solar, Fe = 0.5 solar, Mg = 3.0 solar, Mn = 50 solar, Ni = 0.3 solar, P = 15 solar, and Ti = 0.1 solar. The best-fit white dwarf + accretion belt composite model yields a large improvement in the reduced χ2 value. The accretion belt temperature is 32,000 K and covers a fractional area of 3%, contributing 11% of the flux. The second spectrum 5 days later reveals slightly increased metal abundances except that P is elevated to 20 times solar while Fe has declined to 0.05 times solar. The white dwarf has cooled by ≈1000 K, the belt temperature is 32,000 K, and the fractional area and flux contribution of the belt are 5% and 20%, respectively. These STIS observations confirm that a past (prehistoric?) thermonuclear runaway has occurred on the white dwarf in VW Hyi. It is expected that the thermonuclear runaway would be strong enough to produce a nova outburst. Therefore, these two classes of close binaries, namely, dwarf novae and classical novae, are linked and can overlap.

Original languageEnglish (US)
JournalAstrophysical Journal
Volume561
Issue number1 PART 2
DOIs
StatePublished - Nov 1 2001
Externally publishedYes

Fingerprint

Hubble Space Telescope
spectrographs
spectroscopy
telescopes
accretion
dwarf novae
novae
temperature
outburst
composite materials
metal
metals

Keywords

  • Accretion, accretion disks
  • Stars: abundances
  • Stars: dwarf novae
  • Stars: individual (VW hydri)
  • White dwarfs

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Hubble space telescope STIS spectroscopy of VW hydri during early quiescence following a superoutburst. / Sion, Edward M.; Cheng, Fu Hua; Szkody, Paula; Gänsicke, Boris; Sparks, Warren M.; Hubeny, Ivan -.

In: Astrophysical Journal, Vol. 561, No. 1 PART 2, 01.11.2001.

Research output: Contribution to journalArticle

Sion, Edward M. ; Cheng, Fu Hua ; Szkody, Paula ; Gänsicke, Boris ; Sparks, Warren M. ; Hubeny, Ivan -. / Hubble space telescope STIS spectroscopy of VW hydri during early quiescence following a superoutburst. In: Astrophysical Journal. 2001 ; Vol. 561, No. 1 PART 2.
@article{ef4726bf43de4a2db597ea99a08cbe2c,
title = "Hubble space telescope STIS spectroscopy of VW hydri during early quiescence following a superoutburst",
abstract = "Hubble Space Telescope Space Telescope Imaging Spectrograph (STIS) observations of VW Hydri 2 and 7 days after the end of a superoutburst reveal a heated white dwarf with deep broad Lyα, narrow metallic absorption features and evidence of a hotter Keplerian-broadened component. We confirm the existence of enhanced abundances of odd-numbered nuclear species P, Mn, and Al as well as an N/C ratio indicative of CNO H-burning thermonuclear processing. Our best single-temperature white dwarf reduced χ2 fit to the first spectrum reveals (1) a DAZQ white dwarf with Teff = 22,500 ± 500 K, log g = 8.0, and photospheric abundances C = 0.3 solar, N = 3.0 solar, O = 3.0 solar, Si = 0.3 solar, Al = 2 solar, Fe = 0.5 solar, Mg = 3.0 solar, Mn = 50 solar, Ni = 0.3 solar, P = 15 solar, and Ti = 0.1 solar. The best-fit white dwarf + accretion belt composite model yields a large improvement in the reduced χ2 value. The accretion belt temperature is 32,000 K and covers a fractional area of 3{\%}, contributing 11{\%} of the flux. The second spectrum 5 days later reveals slightly increased metal abundances except that P is elevated to 20 times solar while Fe has declined to 0.05 times solar. The white dwarf has cooled by ≈1000 K, the belt temperature is 32,000 K, and the fractional area and flux contribution of the belt are 5{\%} and 20{\%}, respectively. These STIS observations confirm that a past (prehistoric?) thermonuclear runaway has occurred on the white dwarf in VW Hyi. It is expected that the thermonuclear runaway would be strong enough to produce a nova outburst. Therefore, these two classes of close binaries, namely, dwarf novae and classical novae, are linked and can overlap.",
keywords = "Accretion, accretion disks, Stars: abundances, Stars: dwarf novae, Stars: individual (VW hydri), White dwarfs",
author = "Sion, {Edward M.} and Cheng, {Fu Hua} and Paula Szkody and Boris G{\"a}nsicke and Sparks, {Warren M.} and Hubeny, {Ivan -}",
year = "2001",
month = "11",
day = "1",
doi = "10.1086/324558",
language = "English (US)",
volume = "561",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "1 PART 2",

}

TY - JOUR

T1 - Hubble space telescope STIS spectroscopy of VW hydri during early quiescence following a superoutburst

AU - Sion, Edward M.

AU - Cheng, Fu Hua

AU - Szkody, Paula

AU - Gänsicke, Boris

AU - Sparks, Warren M.

AU - Hubeny, Ivan -

PY - 2001/11/1

Y1 - 2001/11/1

N2 - Hubble Space Telescope Space Telescope Imaging Spectrograph (STIS) observations of VW Hydri 2 and 7 days after the end of a superoutburst reveal a heated white dwarf with deep broad Lyα, narrow metallic absorption features and evidence of a hotter Keplerian-broadened component. We confirm the existence of enhanced abundances of odd-numbered nuclear species P, Mn, and Al as well as an N/C ratio indicative of CNO H-burning thermonuclear processing. Our best single-temperature white dwarf reduced χ2 fit to the first spectrum reveals (1) a DAZQ white dwarf with Teff = 22,500 ± 500 K, log g = 8.0, and photospheric abundances C = 0.3 solar, N = 3.0 solar, O = 3.0 solar, Si = 0.3 solar, Al = 2 solar, Fe = 0.5 solar, Mg = 3.0 solar, Mn = 50 solar, Ni = 0.3 solar, P = 15 solar, and Ti = 0.1 solar. The best-fit white dwarf + accretion belt composite model yields a large improvement in the reduced χ2 value. The accretion belt temperature is 32,000 K and covers a fractional area of 3%, contributing 11% of the flux. The second spectrum 5 days later reveals slightly increased metal abundances except that P is elevated to 20 times solar while Fe has declined to 0.05 times solar. The white dwarf has cooled by ≈1000 K, the belt temperature is 32,000 K, and the fractional area and flux contribution of the belt are 5% and 20%, respectively. These STIS observations confirm that a past (prehistoric?) thermonuclear runaway has occurred on the white dwarf in VW Hyi. It is expected that the thermonuclear runaway would be strong enough to produce a nova outburst. Therefore, these two classes of close binaries, namely, dwarf novae and classical novae, are linked and can overlap.

AB - Hubble Space Telescope Space Telescope Imaging Spectrograph (STIS) observations of VW Hydri 2 and 7 days after the end of a superoutburst reveal a heated white dwarf with deep broad Lyα, narrow metallic absorption features and evidence of a hotter Keplerian-broadened component. We confirm the existence of enhanced abundances of odd-numbered nuclear species P, Mn, and Al as well as an N/C ratio indicative of CNO H-burning thermonuclear processing. Our best single-temperature white dwarf reduced χ2 fit to the first spectrum reveals (1) a DAZQ white dwarf with Teff = 22,500 ± 500 K, log g = 8.0, and photospheric abundances C = 0.3 solar, N = 3.0 solar, O = 3.0 solar, Si = 0.3 solar, Al = 2 solar, Fe = 0.5 solar, Mg = 3.0 solar, Mn = 50 solar, Ni = 0.3 solar, P = 15 solar, and Ti = 0.1 solar. The best-fit white dwarf + accretion belt composite model yields a large improvement in the reduced χ2 value. The accretion belt temperature is 32,000 K and covers a fractional area of 3%, contributing 11% of the flux. The second spectrum 5 days later reveals slightly increased metal abundances except that P is elevated to 20 times solar while Fe has declined to 0.05 times solar. The white dwarf has cooled by ≈1000 K, the belt temperature is 32,000 K, and the fractional area and flux contribution of the belt are 5% and 20%, respectively. These STIS observations confirm that a past (prehistoric?) thermonuclear runaway has occurred on the white dwarf in VW Hyi. It is expected that the thermonuclear runaway would be strong enough to produce a nova outburst. Therefore, these two classes of close binaries, namely, dwarf novae and classical novae, are linked and can overlap.

KW - Accretion, accretion disks

KW - Stars: abundances

KW - Stars: dwarf novae

KW - Stars: individual (VW hydri)

KW - White dwarfs

UR - http://www.scopus.com/inward/record.url?scp=0035511195&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0035511195&partnerID=8YFLogxK

U2 - 10.1086/324558

DO - 10.1086/324558

M3 - Article

VL - 561

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 1 PART 2

ER -