In the following we describe the H
, Na I D1, D2,
and He I D3 spectra of the stars of this sample.
The line profiles of each
chromospherically active binary system
are displayed in Figs. 1 to 19
The name of the star, the orbital phase, and the expected
positions of the features for the hot (H) and cool (C)
components are given in each figure.
For each system we plot the observed spectrum (solid-line), the
synthesized spectrum (dashed-line), the subtracted spectrum, additively
offset for better display (dotted line)
and the Gaussian fit to the subtracted spectrum (dotted-dashed line).
Single-lined spectroscopic binary classified as K1III + F by
Bidelman & MacConnell (1973).
It presents strong Ca II H & K emission lines centered at the
absorption line (Montes et al. 1995c)
and the H line as moderate absorption (Fekel et al. 1986).
We have obtained one spectrum of this system
at the orbital phase 0.569 (see Fig. 1 (click here)).
The H subtracted spectrum shows a weak excess emission.
In the Na I line region no detectable filling-in of the
D1 and D2 lines is present.
A clear absorption in the He I D3 line
appears in the subtracted spectrum.
In both spectral regions the spectrum is matched
using a K2III as reference star.
AY Cet is a single-lined binary composed of a spotted G5III primary and a white
dwarf secondary. It presents strong Ca II H & K
emission lines (Montes et al. 1995c) and a filled in absorption H line
(Fekel et al. 1986;
Strassmeier et al. 1990).
We present here one observation of this system at the orbital phase 0.797
(see Fig. 2 (click here)).
In the H line region we have used a G8III reference star to perform
the spectral subtraction and the
subtracted spectrum obtained shows a weak excess emission.
No detectable filling-in of the Na I D1 and D2 lines
has been found, however, a weak absorption in the He I D3 line
appears in the subtracted spectrum.
This extremely active RS Cvn system is a
double-lined spectroscopic binary consisting of a K1IV primary and a G7V
secondary (Fekel 1996).
In our previous observations of this system we have found
strong Ca II H & K and 
emissions
from the cool component (FFMCC),
the H line of the active component in emission above
the continuum (FFMCC and Montes et al. 1995a, b) and an important filling-in
by chromospheric emission in the 
line (Montes et al. 1995d).
Now we have analysed
four spectra of this system in both spectral regions
at the orbital phases from 0.37 to 0.52 (see Fig. 3 (click here)).
The H line of the active component appears in emission above
the continuum, with a profile that changes with
the orbital phase owing to the different amounts of overlapping with
the absorption of the other component.
By subtracting the synthesized spectrum, constructed with G6IV and K0IV
reference stars and a relative contribution of 0.2/0.8
we have found a large excess H emission which is well matched
using a two-components Gaussian fit.
In the Na I D1 and D2 lines an important excess
emission is present in the subtracted spectra,
however, the He I D3 line does not appear in absorption.
Figure 3: H, Na I D1, D2, and He I D3
spectra of AR Psc
Figure 4: H, Na I D1, D2, and He I D3
spectra of XX Tri (HD 12545)
Figure 5: H, Na I D1, D2, and He I D3
spectra of V711 Tau
Figure 6: Subtracted H profiles of V711 Tau
at different epochs and orbital phases (line in histogram from).
We have superposed the two Gaussian components fit (solid-line).
The sort-dashed-line represents the broad component
and the large-dashed-line the narrow one
Figure 7: H, Na I D1, D2, and He I D3
spectra of V833 Tau
Figure 8: H, Na I D1, D2, and He I D3
spectra of V1149 Ori
Figure 9: H, Na I D1, D2, and He I D3
spectra of MM Her
Figure 10: H, Na I D1, D2, and He I D3
spectra of V815 Her
Figure 11: H, Na I D1, D2, and He I D3
spectra of BY Dra. In the subtracted H spectra we have superposed
the Gaussian fit used to deblend the contribution
of the hot and cool components
Figure 12: H, Na I D1, D2, and He I D3
spectra of V775 Her
Figure 13: H, Na I D1, D2, and He I D3
spectra of V478 Lyr
Figure 14: H, Na I D1, D2, and He I D3
spectra of HK Lac
This extremely active RS CVn binary
is a single-lined spectroscopic binary of spectral type K0III.
It has very strong Ca II H & K and H
emission lines
and the H line in emission above the continuum
(Strassmeier et al. 1990;
Bopp et al. 1993; Montes et al. 1995c).
This system shows the largest amplitude of light variation
from spots yet recorded (Hampton et al. 1996).
Our observed H spectrum at the orbital phase 0.401
(Fig. 4 (click here)) shows
a strong and very broad H emission above the continuum.
The synthesized spectrum has been constructed with a reference star of
spectral type K0III obtaining a satisfactory fit.
The subtracted spectrum exhibits an asymmetric profile
that is not well matched using a Gaussian fit, therefore
we fit the profile by means two Gaussian components.
In the Na I line region a clear excess emission in the
D1 and D2 lines is present, in agreement with the strong
activity of this system.
The behaviour of the He I D3 line is not clear in this spectrum,
but a weak absorption seems to appear.
The description of the simultaneous H, Na I D1, D2,
and He I D3 observations and the detection of a flare
on this system can be found in Montes et al. (1996b).
V711 Tau, one of the most active of the RS CVn binaries,
is a double-lined spectroscopic binary whose components have
spectral types G5IV and K1IV.
Our Ca II H & K analysis of this system (FFMCC)
showed that both components present
emissions. The cool component is the more active star
in the system, and also presents the H line in emission.
This system shows the H
line in emission above the continuum and the spectral subtraction
(Montes et al. 1995b)
reveals that the K1 star is responsible for most of
the excess H emission.
Recently UV observations obtained with the HST's GHRS
(Wood et al. 1996;
Dempsey et al. 1996b,c) indicate that the transition region
lines of V711 Tau are emitted almost entirely by the K1 star,
and the G star contributes 14% to the chromospheric Mg II h & k lines
flux.
We report here five new observations of this systems in
the H line region at the orbital phases 0.92, 0.26, 0.28, 0.61 and 0.64
(1995 September 13-15) (see Fig. 5 (click here))
that confirm the results obtained in our previous observations
taken in 1988, 1986 and 1992.
The H subtracted profiles presents at all the epochs broad wings and
are not well matched using a single-Gaussian fit.
These profiles have therefore been fitted using two Gaussian components.
The parameters of the broad and narrow components used in the two-Gaussian fit
are given in Table 4 (click here) and the corresponding profiles are
plotted in Fig. 6 (click here).
In contrast to the behaviour found in other systems in which
we have used a two-Gaussian fit, the broad component of V711 Tau dominates
the line profile (the average contribution of the broad component
to the total H EW is 77%, whereas in other stars the contribution
ranges between 35% and 63%).
Wood et al. (1996) and Dempsey et al. (1996c)
also found this behaviour in the broad component of the
chromospheric and transition region lines of V711 Tau in comparison with
the broad components found in the less active stars AU Mic and Capella.
In Fig. 6 (click here) we can also see that,
the contribution of the broad component is larger at orbital phases near 0.2
(
) than at larger orbital phases (
)
and this behaviour remains at different epochs
(see Fig. 6 (click here)).
These changes indicate not only that the broad component is the result
of microflaring in the chromosphere, as in other stars, but that
large and long-lived chromospheric flares,
that take place in this system (Dempsey et al. 1996c), could also produced
enhanced emission in the extended line wings.
Variable excess emission appears in the Na I D1 and D2 lines of the corresponding subtracted spectra, however, no detectable absorption is observed in the He I D3 line.
V833 Tau is a BY Dra system (dK5e) and one of the hottest known
flare stars.
In our previous observations of this system we have found
a moderate H emission above the continuum that
presents a variable little central self-reversal (Montes et al. 1995a,b)
and a strong H
excess emission (Montes et al. 1995d).
We analyse here three new observations of this systems in
the H line region at orbital phases 0.762, 0.319, and 0.851
(Fig. 7 (click here))
that confirm the behaviour previously noted.
The self-reversal feature changes its wavelength-position
across the emission H line profile, however, it appears always centered
with the corresponding H absorption line of the synthesized spectrum.
The Na I D1 and D2 lines exhibit very broad wings in the observed spectra, as correspond to a star of spectral type as later as K5. Although the observed and synthesized spectra are not well matches, due to problems in the normalization, a clear excess emission in the D1 and D2 lines can be seen in the subtracted spectra. The He I D3 line is not detected in this star.
A single-lined spectroscopic binary classified as K1III.
Our previous observations
reveal a clear excess H emission (Montes et al. 1995a,b),
strong Ca II H & K and H emission lines
(Montes et al. 1995c).
We present here one spectrum at the orbital phase 0.439
(see Fig. 8 (click here)).
The difference with respect to a K0III reference star reveals a
lower excess H emission than the obtained in our previous
observations in 1992 (Montes et al. 1995a).
The narrow absorption that appears in the red wing of the excess H
emission in the subtracted spectra could be attributed to a telluric line.
The spectral subtraction reveals that this star has no measurable filling-in of the Na I D1 and D2 lines. However, a clear absorption in the He I D3 line appears in the subtracted spectrum.
Double-lined spectroscopic binary (G2/K0IV) with partial eclipses.
This system has
Ca II H & K emission lines from both components and
excess H emission from the cool component
(FFMCC, Montes et al. 1995a).
We have obtained three new spectra (Fig. 9 (click here))
of this system
in the H and Na I D1 and D2 line regions
at orbital phases 0.498, 0.630, and 0.745.
At phase 0.498 the hot component hides a 0.30 fraction of the cool one,
(see the diagram of Fig. 9 (click here))
and the absorption lines from both
components appear overlapped in the observed spectrum.
However, at phases 0.630 and 0.745 there is not eclipse and
the lines are clearly wavelength-shifted.
The more intense H absorption observed in these spectra
corresponds to the hot component and the less intense and blue-shifted
absorption corresponds to the cool one.
The spectral subtraction,
using G2IV and K0IV as reference stars and a relative contribution
of 0.5/0.5, indicates that the excess H
emission arises only from the cool component.
The excess H emission line profiles obtained are
well matched using a two-component Gaussian fit.
In the subtracted spectra of the Na I D1 and D2 lines region we can also see an excess emission in these lines from the cool component. The narrow absorption that appears near the position of the hot component could be due to deficient sky correction in these spectra. The He I D3 line is not present.
Single-lined spectroscopic binary.
Our previous Ca II H & K and H observations
(FFMCC, Montes et al. 1995a) indicate that
the hot star is the active component.
Multiwavelength observations of this system have been
recently reported by Dempsey et al. (1996a).
We have taken three spectra of this system at orbital phases
0.978, 0.520, 0.099 (see Fig. 10 (click here)).
In the H line region the spectra show a filling-in absorption line
with noticeable night to night changes.
The excess H emission obtained with the spectral subtraction of a G5 V
reference star is larger at the orbital phases near to 0.0.
The subtracted H profile presents broad wings and is
well matched using a fit with two Gaussian components (narrow and broad).
The narrow component is more important when the excess H emission is
larger (see Table 4 (click here)).
A small filling-in is observed in the Na I D1 and D2 lines at the three orbital phases, and only at phase 0.523 absorption in detected in the He I D3 line.
The prototype of the BYDra stars.
Our previous Ca II H & K observations of this system (FFMCC)
clearly show that both components are
active with the hot component having the stronger Ca II emission.
The two components also show H in emission.
We present in this paper simultaneous
H and Na I D1 and D2
observations of this system at orbital phases 0.684 and 0.839
(see Fig. 11 (click here)).
These spectra show strong H emission above the continuum
and the Na I D1 and D2 lines with very broad
wings corresponding to the later spectral type of the components
of this system (K4V/K7.5V).
By applying the spectral subtraction technique
we have obtained an asymmetric
excess H emission line profile which has contributions from
both components.
A two-Gaussian fit has been used
to deblend the contribution of the hot and cool components
to the line profile.
This fit reveals that the hot component have the stronger excess
H emission EW in agreement with the behaviour observed by
us in the Ca II H & K lines.
The subtracted spectra in the Na I D1 and D2 line region reveal that the excess emission in these lines also arises from both components. The He I D3 line is not detected in these spectra.
Single-lined spectroscopic binary (
with strong Ca II H & K emission lines
from the hot component (FFMCC).
The H feature may change from a weak absorption feature to emission
above the continuum on times scales of hours (Xuefu & Huisong 1984).
In our H spectrum at the orbital phase 0.394
(Fig. 12 (click here)) we can see the H
line of the hot component totally filled-in by emission
and a small emission bump red-shifted
in relation to the absorption lines.
By subtracting the synthesized spectrum,
constructed with a K0IV reference star, we have obtained
a strong excess H emission coming from the hot component
and a small excess emission, red-shifted 1.9 Å with respect to the
emission of the hot component.
This small excess perhaps could be attributed to
the cooler star of the system, whose assumed spectral type is
and whose contribution to the observed spectra is negligible.
In the Na I lines region the spectral subtraction points out a filling-in of the D1 and D2 lines and not detectable absorption in the He I D3 line.
This BYDra system is a
single-lined spectroscopic binary with
strong Ca II H & K emissions from the hot component (FFMCC)
and a filled-in H absorption line (Fekel 1988).
The H spectrum of this system exhibits
a strong filling-in absorption line
(see Fig. 13 (click here)).
By subtracting the synthesized spectrum constructed with a
G8V star we have obtained strong excess H emission,
a small excess emission in the Na I D1 and D2 lines
and a clear absorption in the He I D3 line.
HK Lac is a single-lined spectroscopic binary (F1V/K0III) with very
strong Ca II H & K emissions, the H line in emission
and an important excess H emission (FFMCC; Montes et al. 1995a).
This system shows a very variable H profile (from filled-in absorption
to moderate emission) and flares (see Catalano & Frasca 1994).
However, in our six H spectra taken in three consecutive nights,
with orbital phases from 0.067 to 0.153, we always observe
filled-in absorption line with small night to night variations in the
excess H emission from the cool component.
In Fig. 14 (click here) a spectrum of each night is showed.
The observed spectra are well matched using a K0III as reference star. The subtracted spectra show an important excess emission in the Na I D1 and D2 lines and a clear absorption in the He I D3 line.
Figure 15: H, Na I D1, D2, and He I D3
spectra of AR Lac
Figure 16: H, Na I D1, D2, and He I D3
spectra of KZ And
Figure 17: H, Na I D1, D2, and He I D3
spectra of KT Peg
Figure 18: H, Na I D1, D2, and He I D3
spectra of II Peg
The total eclipsing binary AR Lac is one of the
best studied RSCVn systems.
Both components of the system (G2IV/K0IV) are active (CABS),
however, due to the orbital phase, in our previous
Ca II H & K and H observations (FFMCC)
it was not possible to separate the contribution from each component.
We analyse here H observations of this system at three orbital phases.
In Fig. 15 (click here) we have superimposed to each spectrum
the corresponding geometrical position of the cool and hot components.
At orbital phase 0.405 there is not eclipse and the subtracted spectrum
exhibits excess H emission from both components, being a slightly
larger that corresponding to the cool one.
At phase 0.425 the hot component hides a 4% of the cool one and
the excess emission obtained is now slightly larger in the hot component.
This change in the excess emission observed
in both components could be attributed
to the hot component hiding of prominence-like material or other active
regions responsible for the H emission of the cool component.
In the observation at the orbital phase 0.939, when a 33%
of the hot component is hidden by the cool component,
we detect an excess H absorption
located at the wavelength position corresponding to the hot component.
This excess absorption indicates the presence of prominence-like
extended material seen off the limb of the cool component that absorbs the
photospheric continuum radiation of the star behind.
Similar prominence-like structures have been found in other eclipsing RS CVn
systems (see Hall & Ramsey 1992) and recently,
Siarkowski et al. (1996)
have found geometrically extended structures in the corona of AR Lac.
At these three orbital phases the Na I D1 and D2 lines also present excess emissions from both components and the He I D3 shows absorption features in the subtracted spectra. At orbital phase 0.933 the He I D3 line presents a large excess absorption at the wavelength position corresponding to the hot component, which could also be attributed to the prominence-like material.
Figure 19: Subtracted H profiles of II Peg
at different orbital phases (dotted line).
We have superposed the two Gaussian components fit (solid-line).
The sort-dashed-line represents the broad component
and the large-dashed-line the narrow one
KZ And is the component B of the visual pair ADS 16557, and is a double-lined
spectroscopic binary with spectral types dK2/dK2.
This system presents Ca II H & K and H emissions
and excess H emission from both components
(FFMCC, Montes et al. 1995c,d).
By applying the spectral subtraction technique
we have found that also both components present
excess emission in the H line and in the
in the Na I D1 and D2 lines, with very similar intensities
(see Fig. 16 (click here)).
The He I D3 line is not present in the subtracted spectrum.
The synthesized spectrum has been constructed with two K2V stars
and with a contribution of each
component to the total continuum of 0.58/0.42.
This system is a double-lined spectroscopic binary (G5V/K6V) with small Ca II H & K emissions from both components (Montes et al. 1995c).
We analyse here two spectra at the orbital phases 0.693 and 0.024
(see Fig. 17 (click here)).
We have constructed the synthesized spectrum with two reference stars of
spectral types G2IV and K3V taking into account
that the hot component has the larger contribution to the
continuum.
In both subtracted spectra no detectable excess emission is observed in the
H line nor in the Na I D1 and D2 lines.
The He I D3 line appears in absorption.
Figure 20: Changes in the EW(H) and FWHM(H)
of II Peg from 12-15 September 1995. Note the different behaviour of the
broad and narrow components
This is a single-lined spectroscopic binary (
) with strong Ca II H & K
emission lines and variable H emission above the continuum.
We have reported a strong excess emission in the H line
(Montes et al. 1995d).
We present here eight spectra of this system taken in three consecutive nights
and with orbital phases ranging from 0.58 to 0.91.
The strong H emission present in the subtracted spectra
in all the phases shows remarkable night to night changes
(see Fig. 18 (click here)). In the second
night the spectrum at orbital phase 0.760
shows a remarkable excess H emission
enhancement with regard to the other phases,
which is much more noticeable in comparison with the spectra
of the first and third nights.
The excess H emission EW increases in a factor of 1.9
in an interval of 1 day.
This fact suggests that we have detected a flare since enhancements
of this amount during flares are typical of chromospheric emission lines
(Simon et al. 1980; Catalano & Frasca 1994) and has also been observed
by us in the flare detected in UX Ari (Montes et al. 1996b).
The He I D3 line appears in emission in the observed spectrum
only at orbital phase 0.760 (see Fig. 18 (click here))
corresponding to the increase of the emission observed in the H line.
This fact supports the detection of a flare-like event, since in the Sun
the He I D3 line appears as absorption in plage and weak flares
and as emission in strong flares (Zirin 1988).
At the other orbital phases of the first and second night an small emission
in He I D3 is also present in the subtracted spectrum.
However, in the third night where the H EW present the lower values
the He I D3 emission is not observed.
The subtracted spectra show that
the H profile presents broad wings, which are
much more remarkable in the flare spectrum.
In Fig. 19 (click here) we have represented
the subtracted spectrum at phases 0.587, 0.749, 0.760 and 0.890
and the corresponding narrow and broad components used to perform
the two-component Gaussian fit.
The changes in the EW(H) and FWHM(H) of the total subtracted
spectra and of the corresponding narrow and broad components
during the three nights can be seen in
Fig. 20 (click here). Note the strong change in the FWHM of the broad
component during the flare.
Figure 21: EW(H) (left-panel) and FWHM(H) (right-panel)
of the broad component versus the total EW(H).
We have used different symbols for each star
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