[en] We present results of our dense spectroscopic monitoring of Nova V5668 Sgr. Starting on March 19 in 2015, only a few days after discovery, we have obtained a series of spectra with the TIGRE telescope and its HEROS echelle spectrograph which offers a resolution of R = 20,000 and covers the optical wavelength range from 3800 to 8800 {\AA}. We performed a line identification of the discernible features for four spectra which are representative for the respective phases in the light curve evolution of that nova. By simultaneously analysing the variations in the visual light curve and the corresponding spectra of Nova V5668 Sgr, we found that during the declining phases of the nova the absorption features in all hydrogen and many other lines had shifted to higher expansion velocities of -2000 km s^-1. Conversely, during the rise towards the following maximum, these observed absorption features had returned to lower expansion velocities.We found that the absorption features of some Fe II lines displayed the same behaviour, but in addition disappeared for a few days during some declining phases. Features of several N I lines also disappeared while new N II lines appeared in emission for a few days during some of the declining phases of the light curve of Nova V5668 Sgr. The shape of the emission features is changing during the evolution and shows a clear double peak structure after the deep minimum.
Research center :
STAR - Space sciences, Technologies and Astrophysics Research - ULiège
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Jack, D.
Robles Pérez, J. De J.
De Gennaro Aquino, I.
Schröder, K.-P.
Wolter, U.
Eenens, P.
Schmitt, J. H. M. M.
Mittag, M.
Hempelmann, A.
González-Pérez, J. N.
Rauw, Grégor ; Université de Liège > Groupe d'astrophysique des hautes énergies (GAPHE)
Hauschildt, P. H.
Language :
English
Title :
Study of the variability of Nova V5668 Sgr, based on high-resolution spectroscopic monitoring
Banerjee, D. P. K., Ashok, N. M., & Srivastava, M. (2015). Near-infrared observations: Dust enshrouds Nova Sgr 2015b. The Astronomer's Telegram, 7748, 1.
Banerjee, D. P. K., Ashok, N. M., Venkataraman, V., & Srivastava, M. (2015). CO detected strongly in emission in Nova Sgr 2015 #2. The Astronomer's Telegram, 7303, 1.
Banerjee, D. P. K., Joshi, V., Srivastava, M. K., & Ashok, N. M. (2016). Dust and fire in nova V5668 Sgr (Nova Sgr 2015#2). The Astronomer's Telegram, 8753, 1.
Banerjee, D. P. K., Srivastava, M. K., Ashok, N. M., & Venkataraman, V. (2016). Near-infrared studies of the carbon monoxide and dust-forming Nova V5668. Monthly Notices of the Royal Astronomical Society, 455, L109–L113.
Bode, M. F. (2010). The outbursts of classical and recurrent novae. Astronomical Notes, 331, 160–168.
Bode, M. F., & Evans, A. (2008). Classical novae: Cambridge University Press, Cambridge, United Kingdom.
Cheung, C. C., Jean, P., Collaboration, F. L. A. T., & Shore, S. N. (2015). Fermi-LAT Gamma-ray Observations of Nova Sagittarii 2015 No. 2. The Astronomer's Telegram, 7283, 1.
Cheung, C. C., Jean, P., & Shore, S. N. (2015). Further Fermi-LAT Gamma-ray Observations of Nova Sagittarii 2015. The Astronomer's Telegram, 7315, 1.
De Gennaro Aquino, I., Schröder, K.-P., Mittag, M., Wolter, U., Jack, D., Eenens, P., … Rauw, G. (2015). High spectral resolution monitoring of Nova V339 Delphini with TIGRE. Astronomy & Astrophysics, 581, A134, 1–79.
della Valle, M., & Livio, M. (1995). The Calibration of Novae as Distance Indicators. Astrophysical Journal, 452, 704–709.
Gallagher, J. S., & Starrfield, S. (1978). Theory and observations of classical novae. Annual Review of Astronomy & Astrophysics, 16, 171–214.
Gaposchkin, S. (1956). Photographic and visual light curves of Nova Herculis 1934 (DQ Her). Astronomical Journal, 61, 36–39.
Harvey, E., Berdyugin, A., & Redman, M. (2015). WHT, DIPOL-2 polarimetry of Nova Sgr 2015b. The Astronomer's Telegram, 7986.
Jack, D., Mittag, M., Schröder, K.-P., Schmitt, J. H. M. M., Hempelmann, A., González-Pérez, J. N., … Cabrera Sixto, J. M. (2015). Time series of high-resolution spectra of SN 2014J observed with the TIGRE telescope. Monthly Notices of the Royal Astronomical Society, 451, 4104–4113.
Kazarovets, E. V., & Samus, N. N. (2015). Novae and Nova-like Stars in the 81th Name-list of Variable Stars: Official Announcement of GCVS Names. Peremennye Zvezdy, 35, 3.
Kuin, P., Page, K., Osborne, J., Shore, S., Schwarz, G., & Walter, F. (2015). Initial results from the HST STIS spectrum of Nova V5668 Sgr (2015 #2). The Astronomer's Telegram, 8275.
Kuiper, G., & Greenstein, J. (1960). Stars and stellar systems: Stellar atmospheres (Vol. 6): University of Chicago Press, Chicago, USA.
McLaughlin, D. B. (1943). On the spectra of novae. Publications of Michigan Observatory, 8, 149–194.
McLaughlin, D. B. (1944). The spectral changes of a typical nova. Popular Astronomy, 52, 109–122.
Page, K. L., Beardmore, A. P., & Osborne, J. P. (2015). A 71 second oscillation in the super-soft X-ray flux of V5668 Sgr (Nova Sgr 2015 No. 2). The Astronomer's Telegram, 8133.
Page, K. L., Kuin, N. P. M., Beardmore, A. P., Osborne, J. P., & Schwarz, G. J. (2015). Nova V5668 Sgr (N Sgr 2015 no. 2) enters the super-soft X-ray phase. The Astronomer's Telegram, 8054.
Page, K. L., Kuin, N. P. M., Osborne, J. P., & Schwarz, G. J. (2015). The slowly rising X-ray flux of Nova V5668 Sgr (N Sgr 2015 no. 2). The Astronomer's Telegram, 7953.
Payne-Gaposchkin, C. (1964). The galactic novae: Dover Publications, New York, USA.
Schmitt, J. H. M. M., Schröder, K.-P., Rauw, G., Hempelmann, A., Mittag, M., González-Pérez, J. N., … Trinidad, M. A. (2014). TIGRE: A new robotic spectroscopy telescope at Guanajuato, Mexico. Astronomical Notes, 335, 787–796.
Strope, R. J., Schaefer, B. E., & Henden, A. A. (2010). Catalog of 93 Nova Light Curves: Classification and Properties. Astronomical Journal, 140, 34–62.
Tajitsu, A., Sadakane, K., Naito, H., Arai, A., Kawakita, H., & Aoki, W. (2016). The 7Be ii Resonance Lines in Two Classical Novae V5668 Sgr and V2944 Oph. Astrophysical Journal, 818, 191.
Wagner, R. M., Woodward, C. E., Starrfield, S., Ilyin, I., Strassmeier, K. G., Page, K., & Beardmore, A. P. (2016). Optical Spectroscopy of the Classical Novae V339 Del (2013) and V5668 Sgr (2015 No. 2). In American Astronomical Society Meeting Abstracts (Vol. 227, p. 239.10).
Walter, F. M. (2015). Formation of Dust in Nova Sgr 2015b. The Astronomer's Telegram, 7643, 1.
Williams, S. C., Darnley, M. J., & Bode, M. F. (2015). Spectroscopic Observation of PNV J18365700-2855420 with the Liverpool Telescope. The Astronomer's Telegram, 7230, 1.
