X-ray spectra of cataclysmic variables from the Einstein Observatory

Michael Eracleous, Jules Halpern, Joseph Patterson

Research output: Contribution to journalArticle

74 Citations (Scopus)

Abstract

We determine X-ray spectral parameters of 32 cataclysmic variables observed with the Einstein imaging proportional counter, by fitting an optically thin, thermal bremsstrahlung spectrum to the final, reprocessed version of the raw data. The conclusions of earlier studies, based on the first processing of the data, are not substantially changed. Most of the stars show temperatures in the range 1-5 keV, while a few exhibit harder spectra with temperatures in excess of 10 keV. Estimated 0.1-3.5 keV luminosities are generally in the range 1030-1032 ergs s-1. The results are consistent with the X-rays originating in a disk/white dwarf boundary layer of nonmagnetic systems, or in a hot, postshock region in the accretion column of DQ Her stars. Contribution to the X-ray luminosity from the corona of the companion is probably negligible as the luminosities found are well above the upper limits recently determined for the X-ray luminosities of late-type main-sequence stars. In a few objects we find column densities that are unusually high for interstellar material, suggesting that the absorption occurs in the system itself, and very likely within the Roche lobe of the primary. Absorption of X-rays in the outer parts of the accretion disk seems to be a plausible explanation, especially since the systems displaying highly absorbed spectra are known to have high inclinations.

Original languageEnglish (US)
Pages (from-to)290-300
Number of pages11
JournalAstrophysical Journal
Volume382
Issue number1
DOIs
StatePublished - Nov 20 1991

Fingerprint

HEAO 2
cataclysmic variables
observatory
luminosity
x rays
accretion
stars
main sequence stars
proportional counters
accretion disks
lobes
bremsstrahlung
erg
coronas
inclination
corona
boundary layers
boundary layer
temperature

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Eracleous, Michael ; Halpern, Jules ; Patterson, Joseph. / X-ray spectra of cataclysmic variables from the Einstein Observatory. In: Astrophysical Journal. 1991 ; Vol. 382, No. 1. pp. 290-300.
@article{be781ade7fd7472699814b7b348502cb,
title = "X-ray spectra of cataclysmic variables from the Einstein Observatory",
abstract = "We determine X-ray spectral parameters of 32 cataclysmic variables observed with the Einstein imaging proportional counter, by fitting an optically thin, thermal bremsstrahlung spectrum to the final, reprocessed version of the raw data. The conclusions of earlier studies, based on the first processing of the data, are not substantially changed. Most of the stars show temperatures in the range 1-5 keV, while a few exhibit harder spectra with temperatures in excess of 10 keV. Estimated 0.1-3.5 keV luminosities are generally in the range 1030-1032 ergs s-1. The results are consistent with the X-rays originating in a disk/white dwarf boundary layer of nonmagnetic systems, or in a hot, postshock region in the accretion column of DQ Her stars. Contribution to the X-ray luminosity from the corona of the companion is probably negligible as the luminosities found are well above the upper limits recently determined for the X-ray luminosities of late-type main-sequence stars. In a few objects we find column densities that are unusually high for interstellar material, suggesting that the absorption occurs in the system itself, and very likely within the Roche lobe of the primary. Absorption of X-rays in the outer parts of the accretion disk seems to be a plausible explanation, especially since the systems displaying highly absorbed spectra are known to have high inclinations.",
author = "Michael Eracleous and Jules Halpern and Joseph Patterson",
year = "1991",
month = "11",
day = "20",
doi = "10.1086/170716",
language = "English (US)",
volume = "382",
pages = "290--300",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "1",

}

X-ray spectra of cataclysmic variables from the Einstein Observatory. / Eracleous, Michael; Halpern, Jules; Patterson, Joseph.

In: Astrophysical Journal, Vol. 382, No. 1, 20.11.1991, p. 290-300.

Research output: Contribution to journalArticle

TY - JOUR

T1 - X-ray spectra of cataclysmic variables from the Einstein Observatory

AU - Eracleous, Michael

AU - Halpern, Jules

AU - Patterson, Joseph

PY - 1991/11/20

Y1 - 1991/11/20

N2 - We determine X-ray spectral parameters of 32 cataclysmic variables observed with the Einstein imaging proportional counter, by fitting an optically thin, thermal bremsstrahlung spectrum to the final, reprocessed version of the raw data. The conclusions of earlier studies, based on the first processing of the data, are not substantially changed. Most of the stars show temperatures in the range 1-5 keV, while a few exhibit harder spectra with temperatures in excess of 10 keV. Estimated 0.1-3.5 keV luminosities are generally in the range 1030-1032 ergs s-1. The results are consistent with the X-rays originating in a disk/white dwarf boundary layer of nonmagnetic systems, or in a hot, postshock region in the accretion column of DQ Her stars. Contribution to the X-ray luminosity from the corona of the companion is probably negligible as the luminosities found are well above the upper limits recently determined for the X-ray luminosities of late-type main-sequence stars. In a few objects we find column densities that are unusually high for interstellar material, suggesting that the absorption occurs in the system itself, and very likely within the Roche lobe of the primary. Absorption of X-rays in the outer parts of the accretion disk seems to be a plausible explanation, especially since the systems displaying highly absorbed spectra are known to have high inclinations.

AB - We determine X-ray spectral parameters of 32 cataclysmic variables observed with the Einstein imaging proportional counter, by fitting an optically thin, thermal bremsstrahlung spectrum to the final, reprocessed version of the raw data. The conclusions of earlier studies, based on the first processing of the data, are not substantially changed. Most of the stars show temperatures in the range 1-5 keV, while a few exhibit harder spectra with temperatures in excess of 10 keV. Estimated 0.1-3.5 keV luminosities are generally in the range 1030-1032 ergs s-1. The results are consistent with the X-rays originating in a disk/white dwarf boundary layer of nonmagnetic systems, or in a hot, postshock region in the accretion column of DQ Her stars. Contribution to the X-ray luminosity from the corona of the companion is probably negligible as the luminosities found are well above the upper limits recently determined for the X-ray luminosities of late-type main-sequence stars. In a few objects we find column densities that are unusually high for interstellar material, suggesting that the absorption occurs in the system itself, and very likely within the Roche lobe of the primary. Absorption of X-rays in the outer parts of the accretion disk seems to be a plausible explanation, especially since the systems displaying highly absorbed spectra are known to have high inclinations.

UR - http://www.scopus.com/inward/record.url?scp=0009223695&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0009223695&partnerID=8YFLogxK

U2 - 10.1086/170716

DO - 10.1086/170716

M3 - Article

AN - SCOPUS:0009223695

VL - 382

SP - 290

EP - 300

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 1

ER -