TY - JOUR
T1 - On the Raman O VI and related lines in classical novae
AU - Shore, Steven N.
AU - De Gennaro Aquino, Ivan
AU - Scaringi, Simone
AU - Van Winckel, Hans
N1 - Funding Information:
Based on observations made with the Mercator Telescope, operated on the island of La Palma by the Flemish Community, at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofsica de Canarias. Further based on observations obtained with the HERMES spectrograph, which is supported by the Fund for Scientific Research of Flanders (FWO), Belgium, the Research Council of K.U.Leuven, Belgium, the Fonds National de la Recherche Scientifique (F.R.S.-FNRS), Belgium, the Royal Observatory of Belgium, the Observatoire de Genève, Switzerland, and the Thüringer Landessternwarte Tautenburg, Germany. S.N.S. warmly thanks Elena Mason, Greg Schwarz, Sumner Starrfield, Francois Teyssier, and Patrick Woudt for invaluable discussions and exchanges. S.S. acknowledges funding from the FWO Pegasus Marie Curie fellowship program. We thank Alejandra Sans Fuentes, Roy Stensen, and Maria Suveges for carrying out some of the observations. We thank the referee, Bob Williams, for very helpful suggestions.
Publisher Copyright:
© 2014 ESO.
PY - 2014/10/1
Y1 - 2014/10/1
N2 - We critically examine the recent claimed detection of Raman-scattered O VI at around 6830 Å in the iron curtain stage spectra of the classical CO nova V339 Del. The observed line variations are compatible in the profile and timing of emission line strength with an excited state transition of neutral carbon. Line formation in classical nova ejecta is physically very different from what it is in symbiotic binaries, in which the O VI emission line is formed within the wind of the companion red giant at low differential velocity. The ejecta velocity and density structure prevent the scattering from producing analogous features. High velocity gradient outflows, such as winds, are subject to the same constraints. There might, however, be a broadband spectropolarimetric signature of the Raman process and also Rayleigh scattering at some stage in the expansion. We show that the neutral carbon spectrum, hitherto underexploited for novae, is especially useful as a probe of the structure of the ejecta during the early, optically thick stages of the expansion.
AB - We critically examine the recent claimed detection of Raman-scattered O VI at around 6830 Å in the iron curtain stage spectra of the classical CO nova V339 Del. The observed line variations are compatible in the profile and timing of emission line strength with an excited state transition of neutral carbon. Line formation in classical nova ejecta is physically very different from what it is in symbiotic binaries, in which the O VI emission line is formed within the wind of the companion red giant at low differential velocity. The ejecta velocity and density structure prevent the scattering from producing analogous features. High velocity gradient outflows, such as winds, are subject to the same constraints. There might, however, be a broadband spectropolarimetric signature of the Raman process and also Rayleigh scattering at some stage in the expansion. We show that the neutral carbon spectrum, hitherto underexploited for novae, is especially useful as a probe of the structure of the ejecta during the early, optically thick stages of the expansion.
KW - Atomic processes
KW - Novae, cataclysmic variables
KW - Radiation mechanisms: general
KW - Stars: winds, outflows
UR - http://www.scopus.com/inward/record.url?scp=84907938666&partnerID=8YFLogxK
U2 - 10.1051/0004-6361/201424786
DO - 10.1051/0004-6361/201424786
M3 - Article
AN - SCOPUS:84907938666
SN - 0004-6361
VL - 570
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
M1 - L4
ER -