Hubble Space Telescope Far-UV Spectroscopy of the Short Orbital Period Recurrent Nova CI Aql: Implications for White Dwarf Mass Evolution

Edward M. Sion, R. E. Wilson, Patrick Godon, Sumner Starrfield, Robert E. Williams, M. J. Darnley

    Research output: Contribution to journalArticle

    Abstract

    An Hubble Space Telescope Cosmic Object Spectrograph Far UV spectrum (1170 to 1800) was obtained for the short orbital period recurrent novae (T Pyxidis subclass), CI Aquilae. CI Aql is the only classical Cataclysmic variable (CV) known to have two eclipses of a sensible depth per orbit cycle and also to have pre- and post-outburst light curves that are steady enough to allow estimates of mass and orbital period changes. Our far-ultraviolet (FUV) spectral analysis with model accretion disks and non-LTE high-gravity photospheres, together with the Gaia parallax, reveal that CI Aql's FUV light is dominated by an optically thick accretion disk with an accretion rate of the order of 4 × 10 -8 M yr -1 . Its database of light curves, radial velocity curves, and eclipse timings is among the best for any CV. Its orbit period (P), dP/dt, and reference time are rederived via a simultaneous analysis of the three data types, giving a dimensionless post-outburst dP/dt of (-2.49 ± 0.95) × 10 -10 . The lack of information on the loss of orbital to rotational angular momentum leads to some uncertainty in the translation of dP/dt to the white dwarf (WD) mass change rate, dM 1 /dt, but within the modest range of to +7.8 × 10 -8 . The estimated WD mass change through outburst for CI Aql, based on simple differencing of its pre- and post-outburst orbit period, is unchanged from the previously published . At the WD's estimated mass increase rate, it will terminate as a Type Ia supernova within 10 million years.

    Original languageEnglish (US)
    Article number68
    JournalAstrophysical Journal
    Volume872
    Issue number1
    DOIs
    StatePublished - Feb 10 2019

    Fingerprint

    Hubble Space Telescope
    outburst
    spectroscopy
    orbitals
    cataclysmic variables
    eclipses
    orbits
    accretion disks
    light curve
    accretion
    high gravity environments
    novae
    parallax
    photosphere
    ultraviolet radiation
    radial velocity
    spectrographs
    spectrum analysis
    supernovae
    angular momentum

    Keywords

    • cataclysmic variables
    • Novae

    ASJC Scopus subject areas

    • Astronomy and Astrophysics
    • Space and Planetary Science

    Cite this

    Hubble Space Telescope Far-UV Spectroscopy of the Short Orbital Period Recurrent Nova CI Aql : Implications for White Dwarf Mass Evolution. / Sion, Edward M.; Wilson, R. E.; Godon, Patrick; Starrfield, Sumner; Williams, Robert E.; Darnley, M. J.

    In: Astrophysical Journal, Vol. 872, No. 1, 68, 10.02.2019.

    Research output: Contribution to journalArticle

    Sion, Edward M. ; Wilson, R. E. ; Godon, Patrick ; Starrfield, Sumner ; Williams, Robert E. ; Darnley, M. J. / Hubble Space Telescope Far-UV Spectroscopy of the Short Orbital Period Recurrent Nova CI Aql : Implications for White Dwarf Mass Evolution. In: Astrophysical Journal. 2019 ; Vol. 872, No. 1.
    @article{c2ec6bfeffd34b5fb2b23cfcf9801d7d,
    title = "Hubble Space Telescope Far-UV Spectroscopy of the Short Orbital Period Recurrent Nova CI Aql: Implications for White Dwarf Mass Evolution",
    abstract = "An Hubble Space Telescope Cosmic Object Spectrograph Far UV spectrum (1170 to 1800) was obtained for the short orbital period recurrent novae (T Pyxidis subclass), CI Aquilae. CI Aql is the only classical Cataclysmic variable (CV) known to have two eclipses of a sensible depth per orbit cycle and also to have pre- and post-outburst light curves that are steady enough to allow estimates of mass and orbital period changes. Our far-ultraviolet (FUV) spectral analysis with model accretion disks and non-LTE high-gravity photospheres, together with the Gaia parallax, reveal that CI Aql's FUV light is dominated by an optically thick accretion disk with an accretion rate of the order of 4 × 10 -8 M yr -1 . Its database of light curves, radial velocity curves, and eclipse timings is among the best for any CV. Its orbit period (P), dP/dt, and reference time are rederived via a simultaneous analysis of the three data types, giving a dimensionless post-outburst dP/dt of (-2.49 ± 0.95) × 10 -10 . The lack of information on the loss of orbital to rotational angular momentum leads to some uncertainty in the translation of dP/dt to the white dwarf (WD) mass change rate, dM 1 /dt, but within the modest range of to +7.8 × 10 -8 . The estimated WD mass change through outburst for CI Aql, based on simple differencing of its pre- and post-outburst orbit period, is unchanged from the previously published . At the WD's estimated mass increase rate, it will terminate as a Type Ia supernova within 10 million years.",
    keywords = "cataclysmic variables, Novae",
    author = "Sion, {Edward M.} and Wilson, {R. E.} and Patrick Godon and Sumner Starrfield and Williams, {Robert E.} and Darnley, {M. J.}",
    year = "2019",
    month = "2",
    day = "10",
    doi = "10.3847/1538-4357/aafb0b",
    language = "English (US)",
    volume = "872",
    journal = "Astrophysical Journal",
    issn = "0004-637X",
    publisher = "IOP Publishing Ltd.",
    number = "1",

    }

    TY - JOUR

    T1 - Hubble Space Telescope Far-UV Spectroscopy of the Short Orbital Period Recurrent Nova CI Aql

    T2 - Implications for White Dwarf Mass Evolution

    AU - Sion, Edward M.

    AU - Wilson, R. E.

    AU - Godon, Patrick

    AU - Starrfield, Sumner

    AU - Williams, Robert E.

    AU - Darnley, M. J.

    PY - 2019/2/10

    Y1 - 2019/2/10

    N2 - An Hubble Space Telescope Cosmic Object Spectrograph Far UV spectrum (1170 to 1800) was obtained for the short orbital period recurrent novae (T Pyxidis subclass), CI Aquilae. CI Aql is the only classical Cataclysmic variable (CV) known to have two eclipses of a sensible depth per orbit cycle and also to have pre- and post-outburst light curves that are steady enough to allow estimates of mass and orbital period changes. Our far-ultraviolet (FUV) spectral analysis with model accretion disks and non-LTE high-gravity photospheres, together with the Gaia parallax, reveal that CI Aql's FUV light is dominated by an optically thick accretion disk with an accretion rate of the order of 4 × 10 -8 M yr -1 . Its database of light curves, radial velocity curves, and eclipse timings is among the best for any CV. Its orbit period (P), dP/dt, and reference time are rederived via a simultaneous analysis of the three data types, giving a dimensionless post-outburst dP/dt of (-2.49 ± 0.95) × 10 -10 . The lack of information on the loss of orbital to rotational angular momentum leads to some uncertainty in the translation of dP/dt to the white dwarf (WD) mass change rate, dM 1 /dt, but within the modest range of to +7.8 × 10 -8 . The estimated WD mass change through outburst for CI Aql, based on simple differencing of its pre- and post-outburst orbit period, is unchanged from the previously published . At the WD's estimated mass increase rate, it will terminate as a Type Ia supernova within 10 million years.

    AB - An Hubble Space Telescope Cosmic Object Spectrograph Far UV spectrum (1170 to 1800) was obtained for the short orbital period recurrent novae (T Pyxidis subclass), CI Aquilae. CI Aql is the only classical Cataclysmic variable (CV) known to have two eclipses of a sensible depth per orbit cycle and also to have pre- and post-outburst light curves that are steady enough to allow estimates of mass and orbital period changes. Our far-ultraviolet (FUV) spectral analysis with model accretion disks and non-LTE high-gravity photospheres, together with the Gaia parallax, reveal that CI Aql's FUV light is dominated by an optically thick accretion disk with an accretion rate of the order of 4 × 10 -8 M yr -1 . Its database of light curves, radial velocity curves, and eclipse timings is among the best for any CV. Its orbit period (P), dP/dt, and reference time are rederived via a simultaneous analysis of the three data types, giving a dimensionless post-outburst dP/dt of (-2.49 ± 0.95) × 10 -10 . The lack of information on the loss of orbital to rotational angular momentum leads to some uncertainty in the translation of dP/dt to the white dwarf (WD) mass change rate, dM 1 /dt, but within the modest range of to +7.8 × 10 -8 . The estimated WD mass change through outburst for CI Aql, based on simple differencing of its pre- and post-outburst orbit period, is unchanged from the previously published . At the WD's estimated mass increase rate, it will terminate as a Type Ia supernova within 10 million years.

    KW - cataclysmic variables

    KW - Novae

    UR - http://www.scopus.com/inward/record.url?scp=85062025811&partnerID=8YFLogxK

    UR - http://www.scopus.com/inward/citedby.url?scp=85062025811&partnerID=8YFLogxK

    U2 - 10.3847/1538-4357/aafb0b

    DO - 10.3847/1538-4357/aafb0b

    M3 - Article

    VL - 872

    JO - Astrophysical Journal

    JF - Astrophysical Journal

    SN - 0004-637X

    IS - 1

    M1 - 68

    ER -