The UBV Color Evolution of Classical Novae. III. Time-stretched Color–Magnitude Diagram of Novae in Outburst

Hachisu, Izumi; Kato, Mariko

doi:10.3847/1538-4365/ab0202

Cited by 13 publications

(18 citation statements)

References 95 publications

(341 reference statements)

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“…Therefore, Hachisu & Kato (2006) calculated free-free emission model light curves with F ν ∝ Ṁ 2 wind /(v 2 ph R ph ), where F ν is the flux at the frequency ν. These model light curves well reproduce many nova light curves (e.g., Hachisu & Kato 2006, 2010, 2018, 2019a.…”

Section: Introductionsupporting

confidence: 59%

“…where M V [t] is the original absolute V brightness and M ′ V [t ′ ] is the time-normalized brightness after timenormalization of t ′ = t/f s . This property was calibrated on many novae (e.g., , 2018, 2019a. Hachisu & Kato (2010) also presented a theoretical explanation of the MMRD relation based on the universal decline law and Equation (1).…”

Section: Introductionmentioning

confidence: 99%

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A Theory for the Maximum Magnitude versus Rate of Decline (MMRD) Relation of Classical Novae

Hachisu,

Saio,

Kato

et al. 2020

Preprint

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We propose a theory for the MMRD relation of novae, using free-free emission model light curves built on the optically thick wind theory. We calculated (t 3 , M V,max ) for various sets of ( Ṁacc , M WD ), where M V,max is the peak absolute V magnitude, t 3 is the 3-mag decay time from the peak, and Ṁacc is the mass accretion rate on to the white dwarf (WD) of mass M WD . The model light curves are uniquely characterized by x ≡ M env /M sc , where M env is the hydrogen-rich envelope mass and M sc is the scaling mass at which the wind has a certain wind mass-loss rate. For a given ignition mass M ig , we can specify the first point x 0 = M ig /M sc on the model light curve, and calculate the corresponding peak brightness and t 3 time from this first point. Our (t 3 , M V,max ) points cover well the distribution of existing novae. The lower the mass accretion rate, the brighter the peak. The maximum brightness is limited to M V,max −10.4 by the lowest mass-accretion rate of Ṁacc 1 × 10 −11 M ⊙ yr −1 . A significant part of the observational MMRD trend corresponds to the Ṁacc ∼ 5 × 10 −9 M ⊙ yr −1 line with different WD masses. A scatter from the trend line indicates a variation in their mass-accretion rates. Thus, the global trend of an MMRD relation does exist, but its scatter is too large for it to be a precision distance indicator of individual novae.

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Section: Introductionsupporting

confidence: 59%

Section: Introductionmentioning

confidence: 99%

A Theory for the Maximum Magnitude versus Rate of Decline (MMRD) Relation of Classical Novae

Hachisu,

Saio,

Kato

et al. 2020

Preprint

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“…The mass estimate in the theoretical light curve fittings indicates ∼ 1.35 M⊙ for the both novae. See figure 48 of Hachisu & Kato (2019a) for V2491 Cyg, and figure 3 of for RS Oph.…”

Section: Observational Properties Of V2491 Cyg and Rs Ophmentioning

confidence: 99%

“…Page et al (2010) and Pagnotta & Schaefer (2014) discussed that V2491 Cyg is possibly a recurrent nova (see, also, Tomov et al (2008)). Hachisu & Kato (2019a) compared the light curves of V2491 Cyg and RS Oph, both of which show a similar X-ray emergence time (see their figure 16). These similarities suggest that both RS Oph and V2491 Cyg host a massive WD (∼ 1.35 M⊙: see the next section).…”

Section: Introductionmentioning

confidence: 98%

A light curve model of V2491 Cyg: Classical nova outburst on a cool and massive white dwarf

Kato,

Saio,

Hachisu

2021

Preprint

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The classical nova V2491 Cyg was once suggested to be a recurrent nova. We have broadly reproduced the light curve of V2491 Cyg by a nova outburst model on a cold 1.36 M ⊙ white dwarf (WD), which strongly suggests that V2491 Cyg is a classical nova outbursting on a cold very massive WD rather than a recurrent nova outbursting on a warmer WD like the recurrent nova RS Oph. In a long-term evolution of a cataclysmic binary, an accreting WD has been settled down to a thermal equilibrium state with the balance of gravitational energy release and neutrino loss. The central temperature of the WD is uniquely determined by the energy balance. The WD is hot (cold) for a high (low) mass-accretion rate. We present the central temperatures, ignition masses, ignition radii, and recurrence periods for various WD masses and mass-accretion rates. In a classical nova, which corresponds to a low mass-accretion rate, the WD is cool and strongly degenerated and the ignition mass is large, which result in a strong nova outburst. In a recurrent nova, the WD is relatively warmer because of a high mass accretion rate and the outburst is relatively weaker. The gravitational energy release substantially contributes to the luminosity during the recurrent nova outbursts. We compare physical properties between classical novae and recurrent novae and discuss the essential differences between them.

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“…Then, the V − I color turns to the blue. No X-ray data of V496 Sct are available, but the nova should enter the SSS phase when it declined to M I > 0 as shown in Figures 50 and 52 of Hachisu & Kato (2019a).…”

Section: − I Color: Evidence 1 Of An Irradiatedmentioning

confidence: 99%

ASASSN-16oh: A Nova Outburst with No Mass Ejection—A New Type of Supersoft X-Ray Source in Old Populations

Kato

Saio

Hachisu

2020

ApJ

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ASASSN-16oh is a peculiar transient supersoft X-ray source without a mass ejection signature in the field of the Small Magellanic Cloud. Maccarone et al. (2019) concluded that ASASSN-16oh is the first dwarf nova with supersoft X-ray that originated from an equatorial accretion belt on a white dwarf (WD). Hillman et al. (2019) proposed a thermonuclear runaway model that both the X-rays and V /I photons are emitted from the hot WD. We calculated the same parameter models as Hillman et al.'s and found that they manipulated on/off the mass-accretion, and their best fit V light curves are 6 mag fainter, and decay about 10 times slower, than that of ASASSN-16oh. We propose a nova model induced by a high rate of mass-accretion during a dwarf nova outburst, i.e., the X-rays originate from the surface of the hydrogen-burning WD whereas the V /I photons are from the irradiated disk. Our model explains the main observational properties of ASASSN-16oh. We also obtained thermonuclear runaway models with no mass ejection for a wide range of parameters of the WD mass and massaccretion rates including both natural and forced novae in low-metal environments of Z = 0.001 and Z = 0.0001. They are a new type of periodic supersoft X-ray sources with no mass ejection, and also a bright transient in V /I bands if they have a large disk. We suggest that such objects are candidates of Type Ia supernova progenitors because its mass is increasing at a very high efficiency (∼ 100%).

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The UBV Color Evolution of Classical Novae. III. Time-stretched Color–Magnitude Diagram of Novae in Outburst

Cited by 13 publications

References 95 publications

A Theory for the Maximum Magnitude versus Rate of Decline (MMRD) Relation of Classical Novae

A Theory for the Maximum Magnitude versus Rate of Decline (MMRD) Relation of Classical Novae

A light curve model of V2491 Cyg: Classical nova outburst on a cool and massive white dwarf

ASASSN-16oh: A Nova Outburst with No Mass Ejection—A New Type of Supersoft X-Ray Source in Old Populations

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