Classical novae in outburst: The early evolution of the ultraviolet continuum

Cassatella, A.; Altamore, A.; González‐Riestra, R.

doi:10.1051/0004-6361:20020107

Cited by 36 publications

(88 citation statements)

References 36 publications

(28 reference statements)

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“…The progressive hardening of the UV spectrum stops after day 10, when the C(1455-2885) color index stabilizes around a value of zero. Both these features are a common property of the novae studied by Cassatella et al (2002). Figure 3 reports, as a function of time, the observed flux in the most prominent UV emission lines, as measured by us from the available IUE low-resolution spectra.…”

Section: Evolution Of the Uv Continuummentioning

confidence: 73%

“…This approximation is reasonably accurate in a very narrow wavelength range around UV 1455 Å flux (Cassatella et al 2002; Paper III) near its peak. IR and optical fluxes are calculated from free-free emission by using physical values of our wind solutions.…”

Section: Optically Thick Wind Modelmentioning

confidence: 85%

“…These results imply that the duration of a UV nova outburst can be used as a useful tool to estimate the WD mass in nova systems. In Figure 14, we compare the theoretical relation of t FWHM versus WD mass (Hachisu & Kato 2006) with those obtained from the measured values of t FWHM (Cassatella et al 2002) and from the WD masses of seven classical novae, including V838 Her, estimated from the previous works (namely, from Paper I for V1668 Cyg and V1974 Cyg; from for V351 Pup, OS And, and V693 CrA, and from this paper for V838 Her). We recall that the masses of these novae were determined by using the light-curve fitting method not only on the UV 1455 Å light curve, but also on the optical, IR, and supersoft X-ray light curves.…”

Section: Mass Determination From the Duration Of The 1455 å Maximummentioning

confidence: 94%

“…We have measured the mean flux in two narrow bands 20 Å wide centered at 1455 Å and 2855 Å, selected to best represent the UV continuum because it is little affected by emission lines (Cassatella et al 2002). Figure 2 shows the time evolution of the F (1455 Å) and F (2885 Å) fluxes and of the UV color index C(1455-2885) = −2.5 log[F (1455 Å)/F (2885 Å)].…”

Section: Evolution Of the Uv Continuummentioning

confidence: 99%

See 3 more Smart Citations

A Universal Decline Law of Classical Novae. Iv. V838 Her (1991): A Very Massive White Dwarf

Kato

Hachisu

Cassatella

2009

ApJ

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We present a unified model of optical and ultraviolet (UV) light curves for one of the fastest classical novae, V838 Herculis (Nova Herculis 1991), and estimate its white dwarf (WD) mass. Based on an optically thick wind theory of nova outbursts, we model the optical light curves with free-free emission and the UV 1455 Å light curves with blackbody emission. Our models of 1.35 ± 0.02 M WD simultaneously reproduce the optical and UV 1455 Å observations. The mass lost by the wind is ΔM wind ∼ 2 × 10 −6 M . We provide new determinations of the reddening, E(B − V ) = 0.53 ± 0.05, and of the distance, 2.7 ± 0.5 kpc.

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Section: Evolution Of the Uv Continuummentioning

confidence: 73%

Section: Optically Thick Wind Modelmentioning

confidence: 85%

Section: Mass Determination From the Duration Of The 1455 å Maximummentioning

confidence: 94%

Section: Evolution Of the Uv Continuummentioning

confidence: 99%

See 2 more Smart Citations

A Universal Decline Law of Classical Novae. Iv. V838 Her (1991): A Very Massive White Dwarf

Kato

Hachisu

Cassatella

2009

ApJ

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“…Their time-normalized light curves are almost independent of the WD mass, chemical composition of ejecta, and wavelength. also found that their UV 1455 Å model light curves (Cassatella et al 2002), interpreted as photospheric blackbody emission, are also time-normalized by the same factor as in the optical and NIR light curves. Using the fact that the time-scaling factor is closely related to the WD mass, the authors determined the WD mass and other parameters for a number of well-observed novae (e.g., , 2010Hachisu et al 2008;).…”

Section: Introductionmentioning

confidence: 84%

Light curve analysis of classical novae: free-free emission vs photospheric emission

Hachisu¹,

Kato²

2017

Proceedings of the Golden Age of Cataclysmic Variables and Related Objects - III — PoS(Golden2015)

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We analyzed light curves of seven relatively slower novae, PW Vul, V705 Cas, GQ Mus, RR Pic, V5558 Sgr, HR Del, and V723 Cas, based on an optically thick wind theory of nova outbursts. For fast novae, free-free emission dominates the spectrum in optical bands rather than photospheric emission and nova optical light curves follow the universal decline law. Faster novae blow stronger winds with larger mass loss rates. Since the brightness of free-free emission depends directly on the wind mass loss rate, faster novae show brighter optical maxima. In slower novae, however, we must take into account photospheric emission because of their lower wind mass loss rates. We calculated three model light curves of free-free emission, photospheric emission, and the sum of them for various WD masses with various chemical compositions of their envelopes, and fitted reasonably with observational data of optical, near-IR (NIR), and UV bands. From light curve fittings of the seven novae, we estimated their absolute magnitudes, distances, and WD masses. In PW Vul and V705 Cas, free-free emission still dominates the spectrum in the optical and NIR bands. In the very slow novae, RR Pic, V5558 Sgr, HR Del, and V723 Cas, photospheric emission dominates the spectrum rather than free-free emission, which makes a deviation from the universal decline law. We have confirmed that the absolute brightnesses of our model light curves are consistent with the distance moduli of four classical novae with known distances (GK Per, V603 Aql, RR Pic, and DQ Her). We also discussed the reason why the very slow novae are about ∼ 1 mag brighter than the proposed maximum magnitude vs. rate of decline relation.

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Spectral evolution of the two classical novae PW Vul and V1668 Cyg using International Ultraviolet Explorer low‐resolution spectra

et al. 2018

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We studied the evolution of the normalized flux of selected ultraviolet (UV) emission lines of two classical novae (PW Vul and V1668 Cyg) using International Ultraviolet Explorer (IUE) short wavelength observations. Different phases of the outburst are studied. Emission lines covering a wide range of ionization states are investigated. We use the calculated fluxes to estimate the mass accretion rates during quiescence of both novae. We found average values of the UV luminosity for PW Vul to be of 1.0 ± 0.1 × 10 35 erg s −1 , and the corresponding value for V1668 Cyg is 4.0 ± 0.2 × 10 35 erg s −1 . In quiescence, we obtained average values for the mass accretion ratesṀ acc of 8.7 ± 0.4 × 10 −10 M ⊙ year −1 and 1.8 ± 0.1 × 10 −10 M ⊙ year −1 , respectively. We attribute the spectral behavior of the two systems to the variation of the optical thickness and temperature of the envelope during the different phases of the outburst. Our results demonstrate the effect of the white dwarf mass on the evolution of the nova. The results of IUE observations are consistent with the theoretical CO models of classical nova of.

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Classical novae in outburst: The early evolution of the ultraviolet continuum

Cited by 36 publications

References 36 publications

A Universal Decline Law of Classical Novae. Iv. V838 Her (1991): A Very Massive White Dwarf

A Universal Decline Law of Classical Novae. Iv. V838 Her (1991): A Very Massive White Dwarf

Light curve analysis of classical novae: free-free emission vs photospheric emission

Spectral evolution of the two classical novae PW Vul and V1668 Cyg using International Ultraviolet Explorer low‐resolution spectra

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