We present infrared spectroscopy of the classical nova V339 Del, obtained over an ∼2-yr period. The infrared emission lines were initially symmetrical, with half width half-maximum velocities of 525 km s−1. In later (t ≳ 77 d, where t is the time from outburst) spectra, however, the lines displayed a distinct asymmetry, with a much stronger blue wing, possibly due to obscuration of the receding component by dust. Dust formation commenced at approximately day 34.75 at a condensation temperature of 1480 ± 20 K, consistent with graphitic carbon. Thereafter, the dust temperature declined with time as Td ∝ t−0.346, also consistent with graphitic carbon. The mass of dust initially rose, as a result of an increase in grain size and/or number, peaked at approximately day 100, and then declined precipitously. This decline was most likely caused by grain shattering due to electrostatic stress after the dust was exposed to X-radiation. The appendix summarizes Planck means for carbon and the determination of grain mass and radius for a carbon dust shell.
Bibliographical noteFunding Information:
RDG acknowledges support from the National Aeronautics and Space Administration (NASA) and the United States Air Force. VARMR acknowledges financial support from the Radboud Excellence Initiative. CEW acknowledges partial support from NASA (HST-GO-13828.008-A). SS gratefully acknowledges partial support from both NASA and NSF grants to ASU. The research work at the Physical Research Laboratory is supported by the Department of Space, Government of India. DS is a visiting astronomer at the Infrared Telescope Facility, which is operated by the University of Hawaii under contract NNH14CK55B with NASA.
- Cataclysmic variables
- Circumstellar matter
- Infrared: stars
- Line: profiles
- Stars: individual: V339 Del