Continuing optical spectroscopy of V339 Del = Nova Del 2013 with the Nordic Optical Telescope and the ARAS Group
ATel #5378; S. N. Shore (Univ. of Pisa, INFN-Pisa), K. Alton, D. Antao, E. Barbotin, P. Berardi, P. Bohlsen, F. Boubault, D. Boyd, J. Briol, C. Buil, S. Charbonnel, P. Dubreuil, M. Dubs, J. Edlin, T. de France, A. Favaro, O. Garde, K. Graham, D. Greenan, J. Guarro, T. Hansen, D. Hyde, T. Lemoult, R. Leadbeater, G. Martineau, Y. Buchet, J. P. Masviel, J. Montier, E. Pollmann, J. Ribeiro, O. Thizy, ,J.-N. Terry, F. Teyssier (contributing participants, ARAS)
on 9 Sep 2013; 04:22 UT
Distributed as an Instant Email Notice Transients
Credential Certification: S. N. Shore (shore@df.unipi.it)
Since our first report (ATel#5312) we have been continuing nightly, almost hourly spectroscopic observations of V339 Del = Nova Del 2013 = PNV J20233073+2046041). Here we report the state at approximately the t_3 point in the photometric decline (see also ATel#5370). Spectra have been obtained with the 2.6 m Nordic Optical Telecope FIbre-fed Echelle Spectrograph (FIES) (R ~ 67000), the Ondrejov Observatory 2m Zeiss coude spectrograph (R = 18000), and a variety of grating and echelle spectrographs of the ARAS group with resolutions ranging from 580 - 11000. The ARAS spectra (565 between Aug. 14 and Sept. 7) are publicly available at the consortium website; a major development is that now spectrophotometrically calibrated spectra are also included using standards and photometry. The Balmer absorption components are still present on H-gamma, H-delta, Fe II 5018A, Ca II H and K. On the NOT spectrum from Sept. 8, the components Na I D1 and D2 at vrad ~ -1200,-900,-700 km/S with many fine components on both doublet members (widths of < 100 km/s); since roughly Sep. 2 these have appeared against an increasingly strong Na I emission line (with possible He II). The components on Fe II 5018 are more distinct: -1275, -1200, -970, -890, -830. The Na I D line now shows a complex absorption trough, possibly with components of both the D1 and D2 lines at -850 and -600 km/s. The [O I] 5577, 6300, and O I 6354, 8446 emission remain among the strongest lines in the spectra from Aug. 18 on. An strong, isolated absorption line at 5826A is compatible with Fe I 5052A. In the red, a previously un-noticed feature appears at 6726 that we identify with O I that showed a detached absorption on Sep. 18 that subsequently disappeared. The same is found for a line at 7115 that we identify as C I; an absorption component was present until Sep. 22 at -500 km/s. The structure is compatible with bipolar models with 2:1 or 3:1 axial ratios and moderate (45+/-20 degree) inclinations but this remains preliminary.
Interstellar absorption is detected on Na I and Ca II strongly at -4.9, +1.1, with weak features at +19.2, and +31.7 km/s (uncertainty +/-0.1A). Interstellar DIBs, Na I, and H I 21 cm measurements along the line of sight confirm the low extinction (E(B-V) ~ 0.18) (ATel #5297). Absorption is detected at CH+ 4232A at the main Na I and Ca II velocities. There is no detectable CH 4300A. CN 3883, 4216 never appeared in the spectra during this reporting period.
The changes are now relatively slower than during the first two weeks. The lack of He I/II and any higher ions (no N II, C II at this writing (the only ions are Fe-group, no [N II]) indicates that the ejecta remain optically thick in the UV and may explain the lack of radio emission. All emission lines show the same multiple-peaked line profile. On Aug. 28, the integrated flux (3600 - 7400A) was approximately (2.7+/-0.1)E-8 erg/s/cm^2; on Sep. 8 it was (2.3+/-0.1)E-8. The last, corrected for E(B-V)~0.18, is 4.1E-8 erg/c/cm^2.
We will continue to follow this nova with this dense coverage for as long as possible with the small telescopes, and continuing observatons are planned for the NOT and Ondrejov.
ARAS database for Nova Del 2013
