| Date | HJD 245... | file | SNR | WAL |
 |
He I |
 |
veil |
 |
V | B-V | U-B |
| 03/04 Dec 95 | 0055.521 | 06249 | 120 | +4.8 | 1.6 | +3 | 1.0 | 3.9 | 0.7 | -- | -- | -- |
| 05/06 Dec 95 | 0057.565 | 06424 | 120 | +8.8 | 2.8 | +7 | 2.0 | 3.1 | 0.5 | -- | -- | -- |
| 24/25 Oct 96 | 0381.586 | 07032 | 140 | +3.5 | 1.4 | +11 | 3.0 | 4.6 | 0.7 | 9.82 | 0.55 | -- |
| 24/25 Oct 96 | 0381.631 | 07036 | 130 | +0.8 | 1.4 | +15 | 2.0 | 3.4 | 0.4 | 9.94 | 0.52 | -- |
| 25/26 Oct 96 | 0382.570 | 07097 | 200 | -1.0 | 2.0 | 0 | 2.0 | 7.0 | 2.0 | 9.98 | 0.70 | -- |
| 25/26 Oct 96 | 0382.624 | 07103 | 150 | -2.6 | 2.0 | +3 | 2.0 | 10.0 | 2.0 | 10.04 | 0.68 | -- |
| 26/27 Oct 96 | 0383.536 | 07179 | 150 | -7.6 | 1.5 | +17 | 2.0 | 2.6 | 0.3 | 10.13 | 0.66 | -- |
| 26/27 Oct 96 | 0383.583 | 07183 | 180 | -9.4 | 1.5 | +17 | 1.0 | 2.8 | 0.3 | 10.11 | 0.65 | -- |
| 27/28 Oct 96 | 0384.568 | 07255 | 150 | +2.5 | 1.5 | -3 | 1.0 | 1.5 | 0.2 | 10.02 | 0.61 | -- |
| 27/28 Oct 96 | 0384.617 | 07259 | 150 | +3.6 | 1.5 | -5 | 1.0 | 1.7 | 0.2 | 10.16 | 0.62 | -- |
| 28/29 Oct 96 | 0385.580 | 07323 | 220 | +6.4 | 2.5 | -2 | 3.0 | 2.5 | 0.3 | 10.04 | 0.63 | -- |
| 28/29 Oct 96 | 0385.652 | 07329 | 180 | +6.0 | 2.5 | -4 | 4.0 | 3.5 | 0.6 | 10.16 | 0.61 | -- |
| 29/30 Oct 96 | 0386.576 | 07388 | 200 | +0.1 | 2.1 | +26 | 2.0 | 1.5 | 0.1 | 9.95 | 0.45 | -- |
| 29/30 Oct 96 | 0386.638 | 07392 | 170 | -1.2 | 2.1 | +28 | 2.0 | 1.2 | 0.2 | 9.96 | 0.46 | -- |
| 30/31 Oct 96 | 0387.721 | 07455 | 100 | +9.1 | 3.0 | +5 | 3.0 | 2.7 | 0.6 | 9.88 | 0.52 | -- |
| 31/01 Nov 96 | 0388.511 | 07491 | 230 | -3.9 | 3.0 | +8 | 4.0 | 1.3 | 0.2 | 10.04 | 0.73 | -- |
| 31/01 Nov 96 | 0388.573 | 07495 | 200 | -5.3 | 3.0 | +13 | 3.0 | 1.7 | 0.2 | 9.99 | 0.75 | -- |
| 17/18 Aug 97 | 0678.743 | 09972 | 52 | +9.0 | 3.0 | +1 | 1.0 | 5.2 | 0.8 | -- | -- | -- |
| 19/20 Aug 97 | 0680.719 | 10168 | 40 | 0.0 | 2.0 | - | - | 1.1 | 0.2 | -- | -- | -- |
| 19/21 Aug 97 | 0681.713 | 10258 | 50 | 0.0 | 3.0 | +14 | 1.0 | 2.3 | 0.4 | -- | -- | -- |
| 21/22 Aug 97 | 0682.719 | 10344 | 40 | -1.0 | 2.0 | - | - | 0.7 | 0.1 | -- | -- | -- |
| 04/05 Nov 98 | 1122.554 | 16418 | 60 | +7.0 | 2.0 | +6 | 3.0 | 2.6 | 0.4 | 10.69 | -- | -- |
| 04/05 Nov 98 | 1122.741 | 16448 | 80 | +5.0 | 2.0 | +10 | 3.0 | 2.6 | 0.5 | -- | -- | -- |
| 05/06 Nov 98 | 1123.545 | 16652 | 70 | -6.3 | 2.1 | +18 | 5.0 | 1.6 | 0.2 | 10.67 | 0.57 | -0.44 |
| 05/06 Nov 98 | 1123.622 | 16666 | 60 | -6.3 | 2.1 | +19 | 5.0 | 1.0 | 0.1 | -- | -- | -- |
| 06/07 Nov 98 | 1124.543 | 16756 | 100 | +3.5 | 2.6 | -13 | 3.0 | 1.0 | 0.1 | 10.58 | 0.60 | -0.48 |
| 06/07 Nov 98 | 1124.725 | 16784 | 100 | +8.2 | 2.6 | -12 | 2.0 | 1.6 | 0.1 | -- | -- | -- |
| 07/08 Nov 98 | 1125.545 | 16907 | 80 | +0.8 | 3.0 | +12 | 1.5 | 3.6 | 0.5 | 10.66 | 0.71 | -0.10 |
| 08/09 Nov 98 | 1126.657 | 17060 | 55 | -6.7 | 3.0 | +10 | 5.0 | 2.6 | 0.2 | 10.44 | 0.70 | -0.16 |
| 08/09 Nov 98 | 1126.712 | 17076 | 40 | -9.2 | 3.0 | +11 | 3.0 | 2.3 | 0.2 | -- | -- | -- |
| 09/10 Nov 98 | 1127.546 | 17161 | 50 | +2.0 | 2.0 | -3 | 3.0 | 1.4 | 0.2 | 10.17 | 0.76 | -- |
| 09/10 Nov 98 | 1127.718 | 17189 | 60 | +6.9 | 3.0 | -3 | 2.0 | 2.7 | 0.3 | -- | -- | -- |
| 19/20 Oct 99 | 1471.754 | 22344 | 80 | +6.4 | 1.4 | +8 | 1.0 | 3.9 | 0.8 | 10.29 | 0.76 | -- |
| 20/21 Oct 99 | 1472.758 | 22506 | 70 | -9.9 | 1.2 | +24 | 2.0 | 2.7 | 0.4 | 10.45 | 0.67 | -- |
| 21/22 Oct 99 | 1473.723 | 22649 | 60 | +2.9 | 2.2 | +5 | 2.0 | 8.0 | 2.0 | 10.63 | 0.67 | -- |
| 23/24 Oct 99 | 1475.753 | 22838 | 50 | -0.8 | 2.6 | +9 | 5.0 | 1.5 | 0.2 | 10.98 | 0.64 | -- |
| 25/27 Nov 99 | 1509.633 | 23018 | 60 | -5.5 | 1.6 | +20 | 2.0 | 1.1 | 0.2 | 10.50 | 0.62 | -- |
| 27/28 Nov 99 | 1510.709 | 23212 | 120 | +2.4 | 1.2 | +8 | 1.0 | 2.6 | 0.3 | 10.20 | 0.63 | -- |
 |
Figure 1: Colour-magnitude diagram. Open circles: data from the Herbst catalogue; filled circles: our observations |
 |
Figure 2: Light and colour curves for the seasons 1996, 1998, and 1999. Filled circles: CCD observations at NOT; open squares: photoelectric observations at the Swedish telescope |
High-resolution spectra were collected with the SOFIN échelle
spectrograph (Tuominen et al. 1999) at the 2.56 m Nordic
Optical Telescope (NOT) during several observing periods in 1995,
1996, 1997, 1998 and 1999 (Table 1). We used the 3rd camera, which
provides a spectral resolution of about 12kms-1 with the
entrance slit of
(
). The secondary components
(RW Aur B and C) were mostly outside of the entrance slit, but when
the seeing was not good enough, the secondary could contribute to the
observed spectrum. The flux ratio of the components A/BC is 18 at
5550Å and 12 at 6750Å (Ghez et al. 1997). From this,
we can estimate the contribution from the secondary stars as a few percent
(in the red continuum) in the worst case. In the night of best seeing
we took one spectrum of RW Aur BC separately. The only strong
emission line is H
,
and the lines of He I and Ca II
are weak
and narrow. All these lines are very much stronger in the spectrum of
RW Aur A. We conclude that the possible contribution from RW Aur BC in
the emission lines was less than 1 percent.
The 43 spectral orders registered in one CCD frame cover a region of 3500 to
11000Å with a length of 140Å per order near H.
Usually, we took
two exposures of 20 min which were added into one spectrum; this gave a
useful range of 3900 to 9000Å with some gaps in the red. In 1996,
we took spectra with a shift in the échelle position, so that the whole
spectral range was covered without gaps.
In some nights, two spectra were taken with an interval of a few
hours.
The CCD images of the échelle spectra were obtained and reduced with the 4A software package (Ilyin 2000). The standard procedure involves bias subtraction, estimation of the variances of the pixel intensities, correction for the master flat field, scattered light subtraction with the aid of 2D-smoothing splines, definition of the spectral orders, and weighted integration of the intensity together with elimination of cosmic spikes.
The wavelength calibration was done with a ThAr comparison spectrum; one was taken before and one after each individual object exposure to eliminate any temporal changes in the spectrograph during the exposure. The wavelength solution incorporates the Gaussian-centred positions, wavelengths, and times of all detected spectral lines from the two comparison images. The wavelength for every pixel in the stellar spectrum is calculated for the time of its mid-exposure. The wavelength solution also incorporates the positions of all detected telluric lines in the stellar spectrum which eliminates the wavelength shifts caused by the slit effect of the spectrograph. A typical error of the wavelength scale in the centre of the image is about 50-100ms-1. The correction of the spectra for the vignetting function and for the Earth orbital motion constitute the next steps of the data reduction. Finally, the continuum was determined by fitting a smooth curve to the ratio of each individual and the mean spectrum. The spectra are transformed into the stellar restframe, i.e. the average radial velocity of +16 kms-1 is subtracted; all velocities given in this paper are in the stellar restframe.
Photometric observations were carried out with the stand-by CCD camera at NOT in B and V. In 1996, CCD exposures were taken before and after each spectral exposures. In 1998 and 1999, the CCD photometry was done only before the spectral exposures. In addition, in 1998, UBV photoelectric photometry was carried out with the Swedish 0.6 m telescope on La Palma. A few spectra taken occasionally in 1995 and 1997 were not accompanied by photometry.
The log of the observations is given in Table 1 together with some parameters of the spectra discussed in the following sections.
The colour-magnitude diagram in Fig. 1, including the data published by Herbst et al. (1994), covers over 30 years of observations. It shows that during our observations RW Aur A varied in brightness within one magnitude in V. The light-curves are shown in Fig. 2.
Copyright ESO 2001
);
all velocities are in the stellar restframe,
i.e. the mean stellar radial velocity of +16kms-1 has been
subtracted. Columns 9 and 10 give the veiling factor and its standard
deviation. The last 3 columns give the simultaneous UBV photometry