The present work is based on two spectrograms, taken with the Coudé spectrograph of the 2 m RCC telescope of the National Astronomical Observatory Rozhen (NAO) on Sep. 8, 1995 (JD 2449969.38) and Sep. 13, 1995 (JD 2449974.38). The observations were performed in the region from 3600 Å to 5000 Å on ORWO ZU emulsion, with a resolution of 0.5 Å. (The reciprocal linear dispersion was 18 Åmm-1.) Both exposures were comparatively deep, each of 240 minutes, in order to bring out the wings of the bright emission lines and to detect the fainter features. The spectra were digitized with the Joyce Loebl microdensitometer of NAO and ReWiA package was used for wavelength and density calibration as well as for calculation of the radial velocities and the equivalent widths. Sections of the spectrum taken on JD 2449969.38 are displayed in Fig. 1 (click here) where the lines with measured radial velocities have been marked. As the strongest lines are not seen in this figure, the profile of one of them is displayed separately in Fig. 2 (click here). The profiles of the others are similar. The radial velocity of each group of lines is listed in Table 1 (click here).
Figure 1: Sections of the spectrum, taken on JD 2449969.38. The
ordinate scale is in arbitrary units
Figure 2: The profile of the HeII 4686 line, observed on
JD 2449969.38 and normalized with respect to the local
continuum. It consists of two components - a narrow and
a broad one
Elem. | JD 2449000![]() | \ | Elem. | JD 2449000![]() | ||||||
96938 | 97438 | 96938 | 97438 | |||||||
Abs. lines | ![]() | ![]() | HeII, NIII, CIII | ![]() | ![]() | |||||
HI | ![]() | ![]() | HeII 4686 (N) | -13.7 | -6.5 | |||||
He1I | ![]() | ![]() | [OIII] 4363 | -16.1 | -18.7 | |||||
He3I | ![]() | ![]() | FeII, TiII | ![]() | ![]() | |||||
|
We obtained the line fluxes using only the spectrogram of
JD 2449969.38 as it turned out that the sensitivity of the
other one was decreased in the long wavelengths region. Only
fluxes of comparatively stronger lines were measured such that
their equivalent width errors should be less than 30%.
We consider the intensities of the same emission lines
investigated in the work of Tomov (1993a) to have
possibility for comparison. Some of these lines are
the members of Pickering series of HeII having wavelengths
4200 and 4542 Å. They are unresolved blends. At the
phases of our observations the line HeII 4542 is blending
with the line FeII 4542, but the latter of them has
considerably lower intensity. The line HeII 4200 is blending
with the line NIII 4200 which has also lower intensity. In
our opinion the blending of these lines works unessentially
on the measurement of their equivalent widths.
The line fluxes have been obtained by means of our unpublished
and
photometric estimates, taken on
JD 2449974.34. The monochromatic continuum fluxes at the
positions of emission lines considered were calculated via
linear interpolation of the fluxes at the positions of the
sensitivity maxima of the B and V photometric systems. The
error of the monochromatic continuum fluxes, obtained in
this way, is due first of all to the presence of the bands
of titanium oxide. This error is approximately equal to the
error of the level of the local continuum (
10%), as
titanium oxide bands of the AG Peg system are shallow
because of an overwhelming by the hot continuum (Boyarchuk
1966; Tomov & Tomova 1992). The line fluxes were
corrected for interstellar reddening. There are several values for the
excess E(B-V), obtained by different methods and placed in
the range 0.08-0.15 (Penston & Allen 1985). We adopted
the value E(B-V)=0.12 and used the extinction law by Seaton
(1979). The line fluxes are listed in Table 2 (click here).
Line | 1986 | 1995 | Line | 1986 | 1995 | Line | 1986 | 1995 | ||
NIII 4097 | 0.43 | 0.19 | FeII 4296 | 0.06 | 0.03 | FeII 4584 | 0.14 | 0.14 | ||
H![]() | 4.95 | 1.52 | H![]() | 8.07 | 2.00 | FeII 4629 | 0.15 | 0.10 | ||
He3I 4121 | 0.32 | 0.16 | [OIII] 4363 | 0.34 | 0.07 | NIII 4634 | 0.19 | 0.15 | ||
He1I 4144 | 0.49 | 0.17 | He1I 4388 | 0.59 | 0.36 | NIII 4640 | 0.35 | 0.21 | ||
FeII 4173 | 0.11 | 0.07 | He3I 4471 | 0.71 | 0.38 | HeII 4686 (N) | 5.20 | 1.74 | ||
FeII 4179 | 0.12 | 0.09 | FeII 4508 | 0.09 | 0.04 | He3I 4713 | 0.53 | 0.29 | ||
HeII 4200 | 0.10 | 0.08 | FeII 4520 | 0.09 |
H![]() | 14.71 | 6.02 | |||
FeII 4233 | 0.23 | 0.11 | HeII 4542 | 0.12 | 0.12 | He1I 4922 | 1.18 | 0.65 | ||
|
JD![]() | Phase | Abs.lines | HeII 4686 | HI | He1I | HeII, NIII, | HeII 4686 | [OIII] 4363 |
2446000+ | (B) | OIII, CIII | (N) | |||||
221.50 | 0.300 | ![]() | -0.6 | ![]() | ![]() |
![]() | -6.8 | -21.1 |
244.55 | 0.329 | ![]() | ![]() | ![]() |
![]() | -22.3 | -31.4 | |
252.52 | 0.338 | ![]() | ![]() | ![]() |
![]() | -11.8 | -29.5 | |
252.57 | 0.339 | ![]() | -6.7 | ![]() | ![]() |
![]() | -21.7 | -29.9 |
273.52 | 0.364 | ![]() | 3.0 | ![]() | ![]() |
![]() | -25.3 | -36.6 |
277.40 | 0.369 | ![]() | ![]() | ![]() |
![]() | -19.5 | -33.7 | |
301.39 | 0.398 | ![]() | ![]() | ![]() |
![]() | -29.3 | -35.0 | |
330.23 | 0.434 | ![]() | -35.8 | ![]() | ![]() |
![]() | -34.6 | -40.2 |
370.30 | 0.483 | ![]() | -32.7 | ![]() | ![]() |
![]() | -43.1 | -42.3 |
452.21 | 0.583 | ![]() | ![]() |
![]() | -53.9 | -45.5 | ||
603.53 | 0.768 | ![]() | -36.8 | ![]() | ![]() |
![]() | -26.3 | -25.7 |
603.57 | 0.768 | ![]() | -47.4 | ![]() | -21.3 |
![]() | -22.6 | -30.1 |
605.49 | 0.771 | ![]() | ![]() | ![]() |
![]() | -27.8 | -20.2 | |
627.53 | 0.798 | ![]() | -41.7 | ![]() | ![]() |
![]() | -24.1 | -22.7 |
630.19 | 0.801 | ![]() | -50.4 | ![]() | ![]() |
![]() | -20.2 | -16.2 |
638.49 | 0.811 | ![]() | -43.3 | ![]() | ![]() |
![]() | -25.0 | -19.8 |
638.59 | 0.811 | ![]() | ![]() | ![]() |
![]() | -16.7 | -17.7 | |
660.53 | 0.838 | ![]() | ![]() | ![]() |
![]() | -21.0 | -14.1 | |
752.18 | 0.950 | ![]() | ![]() | ![]() |
![]() | 0.9 | 7.6 | |
755.27 | 0.954 | ![]() | -30.9 | ![]() | ![]() |
![]() | -2.8 | 2.1 |
775.15 | 0.979 | ![]() | -28.6 | ![]() | ![]() |
![]() | 5.8 | 14.8 |
928.50 | 0.166 | ![]() | 32.3 | ![]() | ![]() |
![]() | -3.1 | -4.0 |
990.52 | 0.242 | ![]() | 10.5 | ![]() | ![]() |
![]() | 2.8 | -37.6 |
991.51 | 0.244 | ![]() | ![]() | ![]() |
![]() | -9.4 | -31.7 | |
1023.53 | 0.283 | ![]() | ![]() | ![]() |
![]() | -14.0 | -33.3 | |
1025.48 | 0.285 | ![]() | ![]() | ![]() |
![]() | -22.3 | -33.2 | |
1047.26 | 0.312 | ![]() | 13.8 | ![]() | ![]() |
![]() | -16.7 | -34.9 |
1346.50 | 0.678 | ![]() | ![]() |
![]() | -40.7 | -31.8 | ||
|
For the aims of our consideration the ephemeris of Fernie
(1985)
will be used. The epoch of the photometric maximum when the
hot companion is before the giant is used as a start epoch.
In this case our observations are at phases 0.891 and 0.897.
The data obtained will be compared with the results of our previous
observations (Tomov & Tomova 1992) and that is why some of
these results are listed in Table 3 (click here) and displayed in
Fig. 3 (click here) as well. These are radial velocities data derived also on
the basis of photographic observations in the blue spectral region.
40% of these spectrograms were taken with the Coudé spectrograph
of the 6m telescope of the Special Astrophysical Observatory of
Russian Academy of Sciences and have dispersion of 9 Åmm-1
and the rest - with the Coudé spectrograph of the 2 m RCC telescope
of NAO, with dispersion of 18 Åmm-1. All these spectrograms
were processed with the oscilloscopic comparator of NAO, whose positioning
error is equal to 0.5 m.
Figure 3: The orbital radial velocity curves of the visual lines of AG Peg
from the work of Tomov & Tomova (1992).
The elements of each curve as well as the designation of the
M3 giant and the barycentric velocity have been marked
Group of lines | Phase | V0 | K | s |
shift | (kms-1) | (kms-1) | (kms-1) | |
Abs. lines | -18.37 | 5.22 | 1.60 | |
HeII 4686 (B) | 0.50 | -20.69 | 31.77 | 9.88 |
HI | 0.38 | -18.56 | 27.94 | 6.88 |
He1I | 0.38 | -16.96 | 9.01 | 3.91 |
HeII, NIII, OIII, CIII | 0.38 | -16.74 | 19.18 | 3.14 |
HeII 4686 (N) | 0.40 | -18.00 | 27.36 | 5.12 |
4363 | 0.34 | -22.81 | 24.08 | 6.83 |
|
The radial velocity curves of all groups of emission lines (Fig. 3 (click here)) were plotted by means of the same program, used for obtaining the orbital solution. The lines in this figure plot the best-fitting circular orbits for the data in Table 3 (click here). The phase shift of each curve with respect to the absorption lines velocity curve, determined by the orbital motion of the cool component, is presented in the second column of Table 4 (click here). The parameters corresponding to the baricentric velocity V0 and the semiamplitude K for each curve are presented in the third and fourth columns of this table. The standard deviation s is in the last column.