[IAUC] CBET 906: 20070325 : V2615 OPHIUCHI

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                                                  Electronic Telegram No. 906
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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CBAT en CFA.HARVARD.EDU (science)
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V2615 OPHIUCHI
     U. Munari, A. Siviero, and M. Valentini, Istituto Nazionale di
Astrofisica, Padova Astronomical Observatory; and P. Ochner and S.
Dallaporta, ANS ("Asiago Novae and Symbiotic stars") Collaboration,
report that absolutely fluxed optical spectra (ranges 390-780 nm at 0.423
nm/pixel and 639-704 nm at 0.061 nm/pixel) of N Oph 2007 (cf. CBET 900;
IAUC 8824) were obtained on Mar. 22.17 and 24.18 UT with the Asiago 1.82-m
telescope (+ AFOSC).  Large changes are seen to have occurred between
these two dates:  mainly a marked reduction in equivalent width of
emission lines and reduction in outflow velocity of absorption components
of P-Cyg profiles.  On Mar. 22.17, the spectrum was characterized by
emission lines of weak intensity, all displaying a P-Cyg profile.  The
strongest emission lines were due to Fe II multiplets 27, 28, 37, 38, 42,
48, 49, 55, and 74; Si II multiplets 2, 3, 4 and 5; N I multiplet 3; Ca
II H and K; Na I D1 and D2; and O I 777.2-nm (the O I being the second
strongest emission after H_alpha).  The spectrum showed a large Balmer
decrement, the observed H_alpha:H_beta:H_gamma emission ratio being
15.8:1.0:0.08.  The integrated flux of the H_beta emission line was 3.2
x 10^(-12) erg cm^(-2) s^(-1).  The emission component of H_alpha was
gaussian in shape, with a FWHM of 940 km/s and an equivalent width of
3.73 nm.  The absorption component had a flat bottom extending for 240
km/s, a width at half intensity of 540 km/s, and an equivalent width of
0.55 nm.  With respect to the peak of the H_alpha emission, the
absorption terminal velocity was -1415 km/s, and the mean velocity -910
km/s.
     In the Mar. 24.18 spectra, the lines have profoundly changed their
appearance, with emission components of the P-Cyg profiles being just
barely visible, and absorption components of Fe II lines having their
equivalent widths reduced by 20 percent.  The only emission lines apparent
on a cursory inspection of the Mar. 24.18 spectra were O I 777.2-nm and
H_alpha.  The emission component of H_alpha shrank to 580 km/s in FWHM and
to 0.75 nm in equivalent width.  The terminal velocity of the absorption
component remained stable around -1400 km/s, but its mean value slowed to
-650 km/s, again with respect to the peak of the emission component.  The
H_alpha absorption component showed now a multi-component profile and,
contrary to what is seen with the Fe II lines, the H_alpha component was
not reduced in equivalent width, still holding at 0.55 nm.  Diffuse
interstellar bands were observed at 442.8, 578.0 (equivalent width 0.085
nm), 628.4 (0.27), and 661.4 (0.021) nm.  CCD photometry for Mar. 22.16
gives V = 9.46 (+/- 0.02) and B-V = +0.89 (+/- 0.02).


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
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                         (C) Copyright 2007 CBAT
2007 March 25                    (CBET 906)               Daniel W. E. Green