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Title: MID-INFRARED SPECTROSCOPIC OBSERVATIONS OF THE DUST-FORMING CLASSICAL NOVA V2676 OPH

Abstract

The dust-forming nova V2676 Oph is unique in that it was the first nova to provide evidence of C{sub 2} and CN molecules during its near-maximum phase and evidence of CO molecules during its early decline phase. Observations of this nova have revealed the slow evolution of its lightcurves and have also shown low isotopic ratios of carbon ({sup 12}C/{sup 13}C) and nitrogen ({sup 14}N/{sup 15}N) in its envelope. These behaviors indicate that the white dwarf (WD) star hosting V2676 Oph is a CO-rich WD rather than an ONe-rich WD (typically larger in mass than the former). We performed mid-infrared spectroscopic and photometric observations of V2676 Oph in 2013 and 2014 (respectively 452 and 782 days after its discovery). No significant [Ne ii] emission at 12.8 μ m was detected at either epoch. These provided evidence for a CO-rich WD star hosting V2676 Oph. Both carbon-rich and oxygen-rich grains were detected in addition to an unidentified infrared feature at 11.4 μ m originating from polycyclic aromatic hydrocarbon molecules or hydrogenated amorphous carbon grains in the envelope of V2676 Oph.

Authors:
; ;  [1];  [2];  [3]
  1. Koyama Astronomical Observatory, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555 (Japan)
  2. Department of Earth Science and Astronomy, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902 (Japan)
  3. Department of Physics, Faculty of Science, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555 (Japan)
Publication Date:
OSTI Identifier:
22666286
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astronomical Journal (Online); Journal Volume: 153; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTROPHYSICS; CARBON 12; CARBON 13; CARBON MONOXIDE; CARBON NITRIDES; COSMIC DUST; COSMOCHEMISTRY; CYANIDES; HYDROGENATION; INTERMEDIATE INFRARED RADIATION; ISOTOPE RATIO; MOLECULES; NITROGEN 14; NITROGEN 15; NOVAE; POLYCYCLIC AROMATIC HYDROCARBONS; WHITE DWARF STARS

Citation Formats

Kawakita, Hideyo, Arai, Akira, Shinnaka, Yoshiharu, Ootsubo, Takafumi, and Nagashima, Masayoshi, E-mail: kawakthd@cc.kyoto-su.ac.jp. MID-INFRARED SPECTROSCOPIC OBSERVATIONS OF THE DUST-FORMING CLASSICAL NOVA V2676 OPH. United States: N. p., 2017. Web. doi:10.3847/1538-3881/153/2/74.
Kawakita, Hideyo, Arai, Akira, Shinnaka, Yoshiharu, Ootsubo, Takafumi, & Nagashima, Masayoshi, E-mail: kawakthd@cc.kyoto-su.ac.jp. MID-INFRARED SPECTROSCOPIC OBSERVATIONS OF THE DUST-FORMING CLASSICAL NOVA V2676 OPH. United States. doi:10.3847/1538-3881/153/2/74.
Kawakita, Hideyo, Arai, Akira, Shinnaka, Yoshiharu, Ootsubo, Takafumi, and Nagashima, Masayoshi, E-mail: kawakthd@cc.kyoto-su.ac.jp. Wed . "MID-INFRARED SPECTROSCOPIC OBSERVATIONS OF THE DUST-FORMING CLASSICAL NOVA V2676 OPH". United States. doi:10.3847/1538-3881/153/2/74.
@article{osti_22666286,
title = {MID-INFRARED SPECTROSCOPIC OBSERVATIONS OF THE DUST-FORMING CLASSICAL NOVA V2676 OPH},
author = {Kawakita, Hideyo and Arai, Akira and Shinnaka, Yoshiharu and Ootsubo, Takafumi and Nagashima, Masayoshi, E-mail: kawakthd@cc.kyoto-su.ac.jp},
abstractNote = {The dust-forming nova V2676 Oph is unique in that it was the first nova to provide evidence of C{sub 2} and CN molecules during its near-maximum phase and evidence of CO molecules during its early decline phase. Observations of this nova have revealed the slow evolution of its lightcurves and have also shown low isotopic ratios of carbon ({sup 12}C/{sup 13}C) and nitrogen ({sup 14}N/{sup 15}N) in its envelope. These behaviors indicate that the white dwarf (WD) star hosting V2676 Oph is a CO-rich WD rather than an ONe-rich WD (typically larger in mass than the former). We performed mid-infrared spectroscopic and photometric observations of V2676 Oph in 2013 and 2014 (respectively 452 and 782 days after its discovery). No significant [Ne ii] emission at 12.8 μ m was detected at either epoch. These provided evidence for a CO-rich WD star hosting V2676 Oph. Both carbon-rich and oxygen-rich grains were detected in addition to an unidentified infrared feature at 11.4 μ m originating from polycyclic aromatic hydrocarbon molecules or hydrogenated amorphous carbon grains in the envelope of V2676 Oph.},
doi = {10.3847/1538-3881/153/2/74},
journal = {Astronomical Journal (Online)},
number = 2,
volume = 153,
place = {United States},
year = {Wed Feb 01 00:00:00 EST 2017},
month = {Wed Feb 01 00:00:00 EST 2017}
}
  • We present a high spatial (diffraction-limited) resolution ({approx}0.''3) mid-infrared (MIR) spectroscopic study of the nuclei and star-forming regions of four local luminous infrared galaxies (LIRGs) using T-ReCS on the Gemini South telescope. We investigate the spatial variations of the features seen in the N-band spectra of LIRGs on scales of {approx}100 pc, which allow us to resolve their nuclear regions and separate the active galactic nucleus (AGN) emission from that of the star formation (SF). We compare (qualitatively and quantitatively) our Gemini T-ReCS nuclear and integrated spectra of LIRGs with those obtained with Spitzer IRS. Star-forming regions and AGNs showmore » distinct features in the MIR spectra, and we spatially separate these, which is not possible using the Spitzer data. The 9.7 {mu}m silicate absorption feature is weaker in the nuclei of the LIRGs than in the surrounding regions. This is probably due to the either clumpy or compact environment of the central AGN or young, nuclear starburst. We find that the [Ne II]12.81 {mu}m luminosity surface density is tightly and directly correlated with that of Paalpha for the LIRG star-forming regions (slope of 1.00 +- 0.02). Although the 11.3 {mu}m PAH feature shows also a trend with Paalpha, this is not common for all the regions and the slope is significantly lower. We also find that the [Ne II]12.81 {mu}m/Paalpha ratio does not depend on the Paalpha equivalent width (EW), i.e., on the age of the ionizing stellar populations, suggesting that, on the scales probed here, the [Ne II]12.81 {mu}m emission line is a good tracer of the SF activity in LIRGs. On the other hand, the 11.3 {mu}m PAH/Paalpha ratio increases for smaller values of the Paalpha EW (increasing ages), indicating that the 11.3 {mu}m PAH feature can also be excited by older stars than those responsible for the Paalpha emission. Finally, more data are needed in order to address the different physical processes (age of the stellar populations, hardness and intensity of the radiation field, mass of the star-forming regions) affecting the energetics of the polycyclic aromatic hydrocarbon features in a statistical way. Additional high spatial resolution observations are essential to investigating the SF in local LIRGs at the smallest scales and determining ultimately whether they share the same physical properties as high-z LIRGs, ULIRGs, and submillimiter galaxies and therefore belong to the same galaxy population.« less
  • We present optical spectrophotometric and near-infrared (NIR) photometric observations of the nova V2676 Oph covering the period from 2012 March 29 through 2015 May 8. The optical spectra and photometry of the nova have been taken from SMARTS and Asiago; the NIR photometry was obtained from SMARTS and Mt. Abu. The spectra were dominated by strong H i lines from the Balmer series, Fe ii, N i, and [O i] lines in the initial days, typical of an Fe ii type nova. The measured FWHM for the H β and H α lines was 800–1200 km s{sup −1}. There wasmore » pronounced dust formation starting 90 days after the outburst. The J − K color was the largest among recent dust-forming novae.« less
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