Observations of the bright novalike variable IX Velorum with the Hopkins ultraviolet telescope

Knox S. Long, Richard A. Wade, William P. Blair, Arthur F. Davidsen, Ivan - Hubeny

Research output: Contribution to journalArticle

46 Citations (Scopus)

Abstract

The Hopkins Ultraviolet Telescope, an experiment flown on the Space Shuttle as part of the Astro-1 mission, was used to obtain a spectrum of the novalike variable IX Vel (= CPD -48° 1577) in the wavelength range 830-1860 Å. The observation revealed a rich absorption-line and continuum spectrum that peaks near 1050 Å at a flux of 1.6 × 10-11 ergs cm-2 s-1 Å-1. In the sub-Lyman-α region, some of the more prominent absorption lines are S VI λλ933, 945, C III λ977, Lyman-β, O VIi λλ1032, 1038, P V λλ1118, 1128, and C III λ1176. No emission was detected below the Lyman limit. The overall continuum shape of IX Vel in the FUV can be approximated using models of an optically thick accretion disk in which the integrated spectrum has been constructed by summing model stellar atmospheres or proper disk model spectra. However, if the distance to IX Vel is ∼95 pc, standard disk models without reddening cannot simultaneously reproduce the color and flux in the UV. While interstellar reddening can reconcile this difference, the amount of reddening appears inconsistent with the absence of a 2200 Å bump in the spectrum and the very low H I column density measured along the line of sight. Improved fits to the data can be obtained by modifying the accretion disk structure within three white dwarf radii. None of the models reproduces the profiles of the Li- and Na-like ions, which are observed as strong but relatively narrow absorption lines, and which are almost surely due to a wind above the disk.

Original languageEnglish (US)
Pages (from-to)704-715
Number of pages12
JournalAstrophysical Journal
Volume426
Issue number2
StatePublished - May 10 1994
Externally publishedYes

Fingerprint

ultraviolet telescopes
accretion disks
accretion
continuums
interstellar extinction
stellar atmospheres
space shuttles
space shuttle
erg
line of sight
line spectra
wavelength
absorption spectra
color
radii
ion
atmosphere
profiles
wavelengths
ions

Keywords

  • Binaries: close
  • Novae, cataclysmic variables
  • Stars: individual (IX Velorum)
  • Ultraviolet: stars

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Observations of the bright novalike variable IX Velorum with the Hopkins ultraviolet telescope. / Long, Knox S.; Wade, Richard A.; Blair, William P.; Davidsen, Arthur F.; Hubeny, Ivan -.

In: Astrophysical Journal, Vol. 426, No. 2, 10.05.1994, p. 704-715.

Research output: Contribution to journalArticle

Long, KS, Wade, RA, Blair, WP, Davidsen, AF & Hubeny, I 1994, 'Observations of the bright novalike variable IX Velorum with the Hopkins ultraviolet telescope', Astrophysical Journal, vol. 426, no. 2, pp. 704-715.
Long, Knox S. ; Wade, Richard A. ; Blair, William P. ; Davidsen, Arthur F. ; Hubeny, Ivan -. / Observations of the bright novalike variable IX Velorum with the Hopkins ultraviolet telescope. In: Astrophysical Journal. 1994 ; Vol. 426, No. 2. pp. 704-715.
@article{addda196dda7401896b374cf9c275933,
title = "Observations of the bright novalike variable IX Velorum with the Hopkins ultraviolet telescope",
abstract = "The Hopkins Ultraviolet Telescope, an experiment flown on the Space Shuttle as part of the Astro-1 mission, was used to obtain a spectrum of the novalike variable IX Vel (= CPD -48° 1577) in the wavelength range 830-1860 {\AA}. The observation revealed a rich absorption-line and continuum spectrum that peaks near 1050 {\AA} at a flux of 1.6 × 10-11 ergs cm-2 s-1 {\AA}-1. In the sub-Lyman-α region, some of the more prominent absorption lines are S VI λλ933, 945, C III λ977, Lyman-β, O VIi λλ1032, 1038, P V λλ1118, 1128, and C III λ1176. No emission was detected below the Lyman limit. The overall continuum shape of IX Vel in the FUV can be approximated using models of an optically thick accretion disk in which the integrated spectrum has been constructed by summing model stellar atmospheres or proper disk model spectra. However, if the distance to IX Vel is ∼95 pc, standard disk models without reddening cannot simultaneously reproduce the color and flux in the UV. While interstellar reddening can reconcile this difference, the amount of reddening appears inconsistent with the absence of a 2200 {\AA} bump in the spectrum and the very low H I column density measured along the line of sight. Improved fits to the data can be obtained by modifying the accretion disk structure within three white dwarf radii. None of the models reproduces the profiles of the Li- and Na-like ions, which are observed as strong but relatively narrow absorption lines, and which are almost surely due to a wind above the disk.",
keywords = "Binaries: close, Novae, cataclysmic variables, Stars: individual (IX Velorum), Ultraviolet: stars",
author = "Long, {Knox S.} and Wade, {Richard A.} and Blair, {William P.} and Davidsen, {Arthur F.} and Hubeny, {Ivan -}",
year = "1994",
month = "5",
day = "10",
language = "English (US)",
volume = "426",
pages = "704--715",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "2",

}

TY - JOUR

T1 - Observations of the bright novalike variable IX Velorum with the Hopkins ultraviolet telescope

AU - Long, Knox S.

AU - Wade, Richard A.

AU - Blair, William P.

AU - Davidsen, Arthur F.

AU - Hubeny, Ivan -

PY - 1994/5/10

Y1 - 1994/5/10

N2 - The Hopkins Ultraviolet Telescope, an experiment flown on the Space Shuttle as part of the Astro-1 mission, was used to obtain a spectrum of the novalike variable IX Vel (= CPD -48° 1577) in the wavelength range 830-1860 Å. The observation revealed a rich absorption-line and continuum spectrum that peaks near 1050 Å at a flux of 1.6 × 10-11 ergs cm-2 s-1 Å-1. In the sub-Lyman-α region, some of the more prominent absorption lines are S VI λλ933, 945, C III λ977, Lyman-β, O VIi λλ1032, 1038, P V λλ1118, 1128, and C III λ1176. No emission was detected below the Lyman limit. The overall continuum shape of IX Vel in the FUV can be approximated using models of an optically thick accretion disk in which the integrated spectrum has been constructed by summing model stellar atmospheres or proper disk model spectra. However, if the distance to IX Vel is ∼95 pc, standard disk models without reddening cannot simultaneously reproduce the color and flux in the UV. While interstellar reddening can reconcile this difference, the amount of reddening appears inconsistent with the absence of a 2200 Å bump in the spectrum and the very low H I column density measured along the line of sight. Improved fits to the data can be obtained by modifying the accretion disk structure within three white dwarf radii. None of the models reproduces the profiles of the Li- and Na-like ions, which are observed as strong but relatively narrow absorption lines, and which are almost surely due to a wind above the disk.

AB - The Hopkins Ultraviolet Telescope, an experiment flown on the Space Shuttle as part of the Astro-1 mission, was used to obtain a spectrum of the novalike variable IX Vel (= CPD -48° 1577) in the wavelength range 830-1860 Å. The observation revealed a rich absorption-line and continuum spectrum that peaks near 1050 Å at a flux of 1.6 × 10-11 ergs cm-2 s-1 Å-1. In the sub-Lyman-α region, some of the more prominent absorption lines are S VI λλ933, 945, C III λ977, Lyman-β, O VIi λλ1032, 1038, P V λλ1118, 1128, and C III λ1176. No emission was detected below the Lyman limit. The overall continuum shape of IX Vel in the FUV can be approximated using models of an optically thick accretion disk in which the integrated spectrum has been constructed by summing model stellar atmospheres or proper disk model spectra. However, if the distance to IX Vel is ∼95 pc, standard disk models without reddening cannot simultaneously reproduce the color and flux in the UV. While interstellar reddening can reconcile this difference, the amount of reddening appears inconsistent with the absence of a 2200 Å bump in the spectrum and the very low H I column density measured along the line of sight. Improved fits to the data can be obtained by modifying the accretion disk structure within three white dwarf radii. None of the models reproduces the profiles of the Li- and Na-like ions, which are observed as strong but relatively narrow absorption lines, and which are almost surely due to a wind above the disk.

KW - Binaries: close

KW - Novae, cataclysmic variables

KW - Stars: individual (IX Velorum)

KW - Ultraviolet: stars

UR - http://www.scopus.com/inward/record.url?scp=12044249187&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=12044249187&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:12044249187

VL - 426

SP - 704

EP - 715

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 2

ER -