CBET 2202 March 13, 2010

Electronic Telegram No. 2202

Central Bureau for Astronomical Telegrams

INTERNATIONAL ASTRONOMICAL UNION

CBAT Director: Daniel W. E. Green; Room 209; Dept. of Earth and Planetary

Sciences; Harvard University; 20 Oxford St.; Cambridge, MA 02138; U.S.A.

e-mail: cbat@iau.org; cbatiau@eps.harvard.edu

URL http://www.cfa.harvard.edu/iau/cbat.html

V1413 AQUILAE

U. Munari and A. Siviero, Istituto Nazionale di Astrofisica,

Astronomical Observatory of Padova; and S. Dallaporta and P. Valisa, "Asiago

Novae and Symbiotic Stars" (ANS) collaboration, write that, in 1978, the

symbiotic nova V1413 Aql (= AS 338) began a not-yet-concluded outburst,

characterized by two broad maxima at V = 11 in 1982-1983 and in 1995-1996.

Since then, V1413 Aql has been exponentially declining, reaching mean

brightness levels of B = 14.6, V = 13.6, V-R_c = +0.91, and V-I_c = +2.17 in

2008 -- still appreciably brighter than the quiescence level. In April last

year, Munari et al. (CBET 1761) detected the beginning of a re-brightening.

V1413 Aql was closely monitored during all of 2009 and measured at mean

values B = 13.80, V = 12.79, V-R_c = +0.88, V-I_c = +1.90. At that time,

they predicted that the 2009 event could mark the beginning of a long ascent

to a third maximum that, extrapolating from the previous two peaks, could be

reached at V = 11 in about one year. That is precisely what it seems to

have now occurred. As soon as V1413 Aql re-emerged from seasonal

conjunction with the sun, Munari et al. resumed observations and found it

shining at B = 11.74, V = 10.90, V-R_c = +0.70, V-I_c = +1.39 (mean values

for the nights 2010 Mar. 6-9). The three maxima so far observed during the

symbiotic-nova outburst of V1413 Aql are regularly spaced by about 14 years.

The previous two maxima were marked by spectacularly deep eclipses of the

outbursting companion following the orbital period of 434.1 days derived by

Munari (1992, A.Ap. 257, 163), and this will presumably occur also during

the current third maximum. The center of the next eclipse will be on May

15, and it will offer a great opportunity to derive an accurate radius for

the outbursting component. A flat bottom of the eclipse should occur,

lasting for about 25 days. Following eclipse analysis by Siviero et al.

(2007, Baltic Astronomy 16, 55), the ingress should soon begin (depending

upon the inflated dimension of the outbursting component). The last

measurement of Munari et al. on Mar. 13.15 UT (B = 11.837, V = 11.009,

V-R_c = +0.728, V-I_c = +1.423) could actually mark the start of the

ingress phase. Absolutely fluxed, low-resolution spectra of V1413 Aql were

obtained on Mar. 13.16 UT with the Asiago 1.22-m telescope (range 325-753

nm; 0.23 nm/pixel) and the Varese 0.6-m telescope (range 380-840 nm; 0.21

nm/pixel). The blue spectrum of the outbursting component completely

overwhelms the molecular absorption spectrum of the M 5 III companion over

the whole optical range. The Balmer continuum is in emission, and the only

significant absorption features are the interstellar Na I D1/D2 and Ca II K

lines. Compared to 2009, the emission-line spectrum has become very rich

and characterized by low-ionization and low-velocity conditions, with no

P-Cyg profile visible, disappearance of [O III] lines, and emergence of a

forest of Fe II lines. The strongest emission lines belong to the Balmer

series, He I, and Fe II multiplets 27, 28, 37, 38, 42, 46, 48, 49, 55, 73,

and 74. The H_beta flux is 4.0 x 10**(-12) erg cm**(-2) s**(-1), and the

flux ratio (H_alpha):(H_beta):(He I 587.6-nm):(Fe II 468.6-nm) is

6.41:1.00:0.18:0.14.

NOTE: These 'Central Bureau Electronic Telegrams' are sometimes

superseded by text appearing later in the printed IAU Circulars.

2010 March 13 (CBET 2202) Daniel W. E. Green