Development of discrete velocity components in the optical spectrum of T Pyx
ATel #3376; S. N. Shore (Pisa), T. Augusteijn (NOT), A. Ederoclite (IAC), H. Uthas (Columbia University)
on 24 May 2011; 16:14 UT
Distributed as an Instant Email Notice Novae
Credential Certification: S. N. Shore (shore@df.unipi.it)
We have continued out high resolution optical spectroscopy of the
latest outburst of T Pyx with the FIES fiber-fed echelle (R ~ 67000)
as first reported in ATel 3306. Here we describe the changes in the
optical resonance and Fe II lines. The first observation,
obtained on 2011 Apr. 15.92 UT, shows a pre-maximum spectrum (e.g.
McLaughlin, D. B. 1964, Ann.Ap., 27, 450, now identified as the
so-called fireball stage) showing only Balmer series and He I/II with
P Cyg components extending to -3000 km/s, and a complex blend at C
III/ N II 4640 A. The second spectrum, Apr. 23.9 UT, shows no He II
and only weak He I, and the 4640 A feature had vanished. Instead,
weak emission and possible P Cyg absorption was detected at Na I
5889,5895 and on Ca II 3933,3964 A with P Cyg profiles on Fe II RMT 42
but not other lines arising from the same level. The P Cyg absorption
became more evident on the next spectrum, May 6.9 UT, for all of these
transitions showing detached components at progressively higher
velocities. The Na I D line illustrates this evolution (Na I P Cyg profiles and
their changes have been noted for only a few other novae, notably V705 Cas 1993):
May 6.88 UT, -1900, -1160, -660 (weak); May 15.90 UT, -2000, -1350, -820;
May 21.87 UT: -2200 with numerous narrower components. The highest
velocity feature is seen for only Na I D1 on all spectra with
approximately constant FWHM ~ 350+/-50 km/s and constant profile
despite increasing velocity. The last spectrum appears to show a very
broad emission component at +2000 to +3000 km/s. The velocity shifts
and profiles are consistent with a linear velocity law for some form
of continuous flow that is being occasionally loaded with mass by a source
that is pulsing, perhaps coincident with the events noted on the light curve
in ATel 3373. If so, the forcing cannot be radiative, there is no evidence of
a terminal velocity, and the velocity gradient appears to be very
steep near the temporary ``photosphere'' (see Shore et al. 1994,
AJ, 108, 671 for the symbiotic system MWC 560). The individual narrow
components appear to be emerging as the broad absorption features become
progressively more transparent but were already present. Similar changes
to Na I D are seen on the Fe II RMT 42 profiles and Ca II.
