NUCLEAR THERMOMETERS FOR CLASSICAL NOVAE

• Published in: The Astrophysical journal Vol. 762; no. 2; pp. 1 - 11
• Main Authors: Downen, Lori N, Iliadis, Christian, Jose, Jordi, Starrfield, Sumner
• Format: Journal Article
• Language: English
• Published: United States 10.01.2013
• Subjects: ALUMINIUM; Aluminum; ASTRONOMY; ASTROPHYSICS; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPARATIVE EVALUATIONS; COMPUTERIZED SIMULATION; ELEMENT ABUNDANCE; HYDRODYNAMICS; MAIN SEQUENCE STARS; NEON; Nova; NOVAE; Outbursts; OXYGEN; PHOSPHORUS 30 TARGET; PROTON REACTIONS; SENSITIVITY; Simulation; SODIUM; SULFUR 31; TEMPERATURE DEPENDENCE; TEMPERATURE MEASUREMENT; Thermometers; THERMONUCLEAR REACTIONS; WHITE DWARF STARS
• ISSN: 0004-637X; 1538-4357
• DOI: 10.1088/0004-637X/762/2/105

Classical novae are stellar explosions occurring in binary systems, consisting of a white dwarf and a main-sequence companion. Thermonuclear runaways on the surface of massive white dwarfs, consisting of oxygen and neon, are believed to reach peak temperatures of several hundred million kelvin. These temperatures are strongly correlated with the underlying white dwarf mass. The observational counterparts of such models are likely associated with outbursts that show strong spectral lines of neon in their shells (neon novae). The goals of this work are to investigate how useful elemental abundances are for constraining the peak temperatures achieved during these outbursts and determine how robust "nova thermometers" are with respect to uncertain nuclear physics input. We present updated observed abundances in neon novae and perform a series of hydrodynamic simulations for several white dwarf masses. We find that the most useful thermometers, N/O, N/Al, O/S, S/Al, O/Na, Na/Al, O/P, and P/Al, are those with the steepest monotonic dependence on peak temperature. The sensitivity of these thermometers to thermonuclear reaction rate variations is explored using post-processing nucleosynthesis simulations. The ratios N/O, N/Al, O/Na, and Na/Al are robust, meaning they are minimally affected by uncertain rates. However, their dependence on peak temperature is relatively weak. The ratios O/S, S/Al, O/P, and P/Al reveal sttong dependences on temperature and the poorly known super(30)P(p, [gamma]) super(31)S rate. We compare our model predictions to neon nova observations and obtain the following estimates for the underlying white dwarf masses: 1.34-1.35 M sub([middot in circle]) (V838 Her), 1.18-1.21 M sub([middot in circle]) (V382 Vel), [< or =, slant]1.3 M sub([middot in circle]) (V693 CrA), [< or =, slant]1.2 M sub([middot in circle]) (LMC 1990#1), and [< or =, slant] 1.2 M sub([middot in circle]) (QU Vul).