A Light Curve Analysis of Gamma-ray Nova V959 Mon -- Distance and White Dwarf Mass

Abstract

V959 Mon is one of the gamma-ray detected novae. It was optically discovered about 50 days after the gamma-ray detection due to proximity to the Sun. The nova speed class is unknown because of lack of the earliest half of optical light curve and short supersoft X-ray phase due to eclipse by the disk rim. Using the universal decline law and time-stretching method, we analyzed the data of V959 Mon and obtained nova parameters. We estimated the distance modulus in the V band to be (m-M)_V=13.15\pm0.3 for the reddening of E(B-V)=0.38\pm0.01 by directly comparing with the similar type of novae, LV Vul, V1668 Cyg, IV Cep, and V1065 Cen. The distance to V959 Mon is 2.5\pm0.5 kpc. If we assume that the early phase light curve of V959 Mon is the same as that of time-stretched light curves of LV Vul, our model light curve fitting suggests that the white dwarf (WD) mass is 0.9-1.15 M_sun, being consistent with a neon nova identification. At the time of gamma-ray detection the photosphere of nova envelope extends to 5-8 R_sun (about two or three times the binary separation) and the wind mass-loss rate is (3-4)\times 10^{-5} M_sun yr^{-1}. The period of hard X-ray emission is consistent with the time of appearance of the companion star from the nova envelope. The short supersoft X-ray turnoff time is consistent with the epoch when the WD photosphere shrank to behind the elevating disk rim, that occurs 500 days before nuclear burning turned off.

18 pages including 9 figures, to appear in the Astrophysical Journal

References in corpus (16)

• A Three-Dimensional Map of Milky-Way Dust
• Fermi Establishes Classical Novae as a Distinct Class of Gamma-Ray Sources
• A Universal Decline Law of Classical Novae
• A 3D extinction map of the Northern Galactic Plane based on IPHAS photometry
• Optical and Supersoft X-ray Light Curve Models of Classical Nova V2491 Cygni: A New Clue to the Secondary Maximum
• Light Curve Analysis of Neon Novae
• A Light Curve Analysis of Classical Novae: Free-free Emission vs. Photospheric Emission
• Multi-wavelength Light Curve Model of the One-year Recurrence Period Nova M31N 2008-12a
• A Universal Decline Law of Classical Novae. III. GQ Mus 1983
• A Hubble Space Telescope Survey for Novae in M87. II. Snuffing out the Maximum Magnitude - Rate of Decline Relation for Novae as a Non-Standard Candle, and a Prediction of the Existence of Ultrafast Novae
• The UBV Color Evolution of Classical Novae. II. Color-Magnitude Diagram
• The Distance to Nova V959 Mon from VLA Imaging
• V5116 Sgr, an Eclipsing Supersoft Post-Outburst Nova?
• The Distances of the Galactic Novae
• Distance and Reddening of the Enigmatic Gamma-ray-Detected Nova V1324 Sco
• The supersoft X-ray source in V5116 Sgr I. The high resolution spectra

Cited by in corpus (8)

• A Light Curve Analysis of 32 Recent Galactic Novae --- Distances and White Dwarf Masses
• A strong shock during a nova outburst: an origin of multiple velocity systems in optical spectra and of high-energy emissions
• Physics of nova outbursts: A theoretical model of classical nova outbursts with self-consistent wind mass loss
• The $UBV$ Color Evolution of Classical Novae. III. Time-Stretched Color-Magnitude Diagram of Novae in Outburst
• The $UBV$ Color Evolution of Classical Novae. IV. Time-Stretched $(U-B{)}_0$-$(M_B-2.5\log f_{\mathrm{s}})$ and $(V-I{)}_0$-$(M_I-2.5\log f_{\mathrm{s}})$ Color-Magnitude Diagrams of Novae in Outburst
• A multiwavelength light curve analysis of the classical nova YZ Ret: An extension of the universal decline law to the nebular phase
• Supersoft X-Ray Phases of Recurrent Novae as an Indicator of their White Dwarf Masses
• A light curve model of V2491 Cyg: Classical nova outburst on a cool and massive white dwarf