Topics addressed include: Cygnus Loop; P Cygni profiles in dwarf novae; YY Gem; nova shells; HZ Herculis; activity cycles in cluster giants; Alpha Ori; metal deficient giant stars; ultraviolet spectra of symbiotic stars detected by the Very Large Array; time variability in symbiotic stars; blue galaxies; and quasistellar objects with X-ray spectra

Baliunas, S. L.

Dupree, A. K.

Elvis, M.

Huchra, J. P.

Kenyon, S.

Raymond, J. C.

English

NASA Technical Reports Server

Combined U1 
, 
2 
ltraviolet Studim of Astronomical Sources 
The Smit hsonian Ast rop hysic a1 0 bservatory 
is a member of the 
Harvard-Smithsonian Center for Astrophysics 
NASA Grant NAG587 
Semiannual Progress Report No. 12 
For the Period 1 February 1986 through 31 July 1986 
Principal Investigators 
Drs. S. L. Baliunas; A. K. Dupree; M. Elvis; 
J. P. Huchra; S. Kenyon; J. C. Raymond; 
October 1986 
Prepared for 
National Aeronautics and Space Administration 
Greenbelt, MD 20771 
Smit hsonian Instit ut ion 
Astrophysical Observatory 
Cambridge, MA 02138 
The NASA Technical Officer for this Grant is Dr. Yoji Kondo 
Code 684, Laboratory for Astronomy and Solar Physics 
Goddard Space Flight Center, Greenbelt, MD 20771 
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Combined Ultraviolet Studies of Astronomical Sources 
NASA Grant NAG5-87 
Semiannual Progress Report No. 12 
For the Period 1 February 1986 through 31 July 1986 
Principal Investigators 
Drs. S. L. Baliunas; A. K. Dupree; M. Elvis; 
J. P. Huchra; S. Kenyon; J. C. Raymond; 
October 1986 
Prepared for 
National Aeronautics and Space Administration 
Greenbelt, MD 20771 
Smit hsonian Institution 
Astrophysical Observatory 
Cambridge, MA 02138 
The Smithsonian Astrophysical Observatory 
is a member of the 
Harvard-Smit hsonian Center for Astrophysics 
The NASA Technical Officer for this Grant is Dr. Yoji Kondo 
Code 684, Laboratory for Astronomy and Solar Physics 
Goddard Space Flight Center, Greenbelt, MD 20771 
c 
Cygnus Loop 
Three positions were observed; Miller’s position 3 in High Dispersion, and two 
positions along the Hester, Parker and Dufour “spur” at Low Resolution. We 
confirm the hypothesis that resonant scattering within S N R  filaments decreases the 
intensity of the C rV lines (Raymond e t  al., Ap. J., 246, 100). We find that the 
‘spur’ shows less complete cooling and recombination toward its tip as predicted by 
Hester, Parker and Dufour, but we also find that the shock velocity is higher near 
the tip, complicating the interpretation of an interstellar cloud struck by the 
supernova blast wave. Both high and low dispersion optical observations of the IUE 
positions have been reduced, and we have found the explanation for the ‘non- 
thermal’ velocity broadening observed in the Cygnus Loop and the old supernova 
remnants. We have obtained high dispersion spectra with the Kitt Peak 4.0-m 
telescope which provide the final observational data for papers on both radiative and 
non-radiative shocks. One paper is nearly complete. Results were presented at the 
University of Virginia. 
P Cygni Profiles in Dwarf Novae 
IUE observations of HL CMa were obtained December 28-30, 1985 with 
simultaneous optical coverage December 29-30. We now have good coverage through 
the orbital period and through outburst maximum and decline. C. Mauche has 
extended the profile model calculations reported at the Sixth Year IUE conference (J. 
Raymond, p. 301). We find that the wind must be very strongly clumped, perhaps 
by shocks like those believed to account for 0 star X-ray emission. The wind must 
originate in the disk or accelerate very slowly if i t  originates near the dwarf. Results 
were presented at the Ninth North American Workshop on Cataclysmic Variables 
2 
(Mauche and Raymond 1985, 1986; Raymond and Mauche 1985). We have 
computed the effect of the Ly a! absorption profile on the P Cygni emission of N V. 
J. Raymond presented an invited review of hot white dwarfs in cataclysmic variables 
at the AAS Meeting in Houston (Raymond 1986) describing the role of the white 
dwarf in ionizing the wind. 
Y Y  Gem 
Observations were carried out February 19-21, 1986. Variations in the C II/C 
IV intensity ratio with orbital phase were detected. Correlation of line ratios with 
activity level inferred from HP was presented at the International rcTE conference 
(Baliunas e t  al. 1986). 
Nova Shells 
Observations were carried out February 27 and 28, 1986. The C IV A1550 line 
was detected in the shell of DQ Her. We are presently examining the possibility that 
this is stellar line emission scattered by dust in the nebula. 
HZ Herculii 
The observations refute the Howarth and Wilson model for the origin of the 
N V emission line in HZ Her. The X-ray illuminated face of the companion star 
probably accounts for much of the radiation. 
Activity Cycles in Cluster Giants 
We have been monitoring the chromospheric and coronal fluxes present in the 
ultraviolet spectra of the Hyades and Praesepe KO III stars with 
Although ostensibly similar in other physical characteristics, the KO I11 stars in the 
since 1978. 
3 
Hyades and Praesepe clusters differ significantly in the ultraviolet for example, by a 
factor of 6 or more in the high-temperature C N line flux. One possible explanation 
for the spread in W emission strength among these stars is that they are at 
different phases of long-term activity cycles. We have been monitoring the 
ultraviolet spectra of these giants since, in order t o  search for long-term activity 
variations. Our measurements obtained in mid-March 1986, are being analyzed 
along with the earlier spectra in the time series. 
Alpha Ori 
Observations of Alpha Ori (M2 Iab) were acquired as planned twice per month 
during the times the star was accessible to I.U.E. All of the data taken has been 
received at the Center for Astrophysics, and reduced. Alpha Ori continues to show 
irregular fluctuations in brightness superposed upon a slowly varying brightness level 
consistent with the photometric period of 5.6 years. The measured continuum flux 
at 3000& the Mg I1 (X2800) total flux and that of the individual h and k lines are 
shown in the accompanying figure. In this figure, we note the good agreement 
between the W continuum flux and the B magnitude variations. The Mg I1 lines 
behave somewhat differently, by lagging the continuum variations by a few tenths of 
a year. Moreover the ratio of the k line to h line fluxes varies also. The detailed 
behavior of the Mg I1 h and k lines components is difficult t o  interpret, the blue 
wing of the k line being obscured by a circumstellar Mn I line. The Mg I1 flux 
minima (near 1985.0 and 1986.1), following local W and optical photometric minima 
near 1984.7 and 1985.9, suggest a periodic short-term variation in the photosphere 
and chromosphere. 
1 Alpha Ori W Continuum (AA 2950-3C60) 
Figure 1. - b magnitude ( a ) ,  u l t r a v i o l e t  continuum (3000t50 A) f l u x  ( b ) ,  t o t a l  
tlg XI h and k l ine f l u x  ( c ) ,  and tlg I1 h and k l i n e  f l u x e s  p lot ted  separate ly  
( d )  obtained during the  1984-1986 Alpha Or1 monitoring program. The 
u l t r a v i o l e t  continuum f l u x  &-sigma error bar i s  shown In ( b ) .  The error In 
the Mg I1 f l u x e s  is  est imated t o  be l e s s  than four percent.  
4 
We are gratified that this program of continuous optical and ultraviolet 
monitoring of Alpha Ori will be continued for the next two years by recommendation 
of the IUE Peer Review Panel. 
A brief communication describing these results to date was submitted for 
publication in the Proceedings of the Conference: New Insights in Astrophysics, an 
ESA/NASA/SERC sponsored conference held in London, England in July 1986. 
Metal Deficient Giant Stars 
I.U.E. observing time to measure the Mg I1 profiles at high dispersion in metal 
deficient giants, has been scheduled for August and October 1986. These exposures 
will be carried out jointly with ESA by using a shift preceding the NASA shift in 
order to obtain extended (14 hour) exposures. 
UV Spectra of Symbiotic Stars Detected by the VLA 
IUE observations have been acquired for CH Cygni (4 LWP and 4 SWP 
exposures), AG Pegasi (2 LWP and 2 S W  exposures), and RW Hydrae (1 LWP and 
1 SWP exposure). Contemporaneous infrard, optical, and radio data have been 
secured for each IUE exposure. 
Observations of RW Hya show that it is a fairly simple symbiotic star, 
Lo, R - 0.1 Ro). The system is surrounded by an H I1 region with a radius, R - 
7 10 AU and an electron density, ne - 3 x 10 ~ m - ~ .  The radio observations indicate 
that the giant component loses mass at a rate of 5 x lo-' % y f l .  The hot star 
accretes roughly 20% of this material, but requires only - 5% of the mass lost by 
the giant to maintain its present luminosity. Thus, hydrogen must accumulate on 
5 
the surface of the hot star, which will eventually lead to a symbiotic nova explosion. 
Results of this study are reported in a paper submitted to the Astrophysical Journal 
(Kenyon and Fernandez-Castro 1987). 
CH Cyg has evolved into a high excitation symbiotic star during the course of 
our program, and has developed into a triple radio source. We found that the radio 
brightening in this system was accompanied by an evolution of the hot source to 
higher effective temperature (T - 7,000 K to T - 150,000 K) at approximately 
constant luminosity. Thus, the eruption appears to  be the result of a nova-like 
explosion. The eruption is somewhat unusual, in that the maximum luminosity was 
apparently - 100-200 
very low mass white dwarfs (- 0.5 w, and we are currently attempting to 
determine the mass of the hot star from high resolution optical spectroscopy. 
Such low luminosities are predicted for nova eruptions on 
Time Variability in Symbiotic Stars 
Archival data for CI Cygni has been examined, and analysis of these data is 
nearly complete. Ultraviolet continuum magnitudes have been measured on over 60 
spectra, and a comparison with optical light curves has been finished. Emission line 
fluxes have been extracted from IUE spectra, as well, and have been combined with 
high quality optical data. We have found that the high ionization lines (He 11) are 
eclipsed when the giant in this binary eclipses its companion (a main sequence star 
surrounded by a massive accretion disk), while lower ionization lines (Mg I1 and 
C IV) are not. It appears that the high ionization lines are formed near the 
boundary layer of the disk, while the other lines are formed in a wind from the disk 
itself. 
6 
Blue Galaxies 
No observations were made during this period. We completed a related paper 
on the internal dynamics of NGC4214 and NGC 4449, and have drafted a paper on 
observations of redshifted blue galaxies. 
QSOs with IPC X-ray Spectra 
Observations were made on April 22, 1986. Data bank spectra has been reduced 
identically by Richard Green at NOAO and we now have a plan of action for the 
science analysis to be done with the derived numbers. 
7 
PUBLICATIONS 
Baliunas, S. L., Loeser, J. G., Raymond, J. C., Guinan, E. F. and Dorren, J. D. “The 
Surface and Atmospheric Structure of the Active G8III star FF Aquarii”, 
1986, in New Insights in Astrophysics: 8 Years of UVAstronomy with IUE, 
ed. E. Rolfe, ESA-SP, in press. 
Baliunas, S. L., Raymond, J. C. and Loeser, J. G. “Flares and Active Sectors on YY 
Geminorum”, 1986, in New Insights in Astrophysics: 8 Years of UV 
Astronomy with IUE, ed. E. Rolfe, ESA-SP, in press. . 
Guinan, E. F., Wacker, S. W., Baliunas, S. L. and Loeser, J. G. “Three-dimensional 
Mapping of the Atmosphere of an Active K-dwarf”, 1985, Bull. A.A.S., 17, 
565. 
Guinan, E. F., Wacker, S. W., Baliunas, S. L., Loeser, J. G. and Raymond, J. C. 
“Evidence of Large-scale Structures in the Atmospheres of the Active K-dwar 
Component of V471 Tauri,”, 1986, in New Insights in Astrophysics: 8 Years 
of UVAstronomy with IUE, ed. E. Rolfe, ESA-SP, in press. 
Hartmann, L. W., Geller, M. J. and Huchra, J. “Kinematics of HII Regions in the 
Blue Irregulars NGC4214 and NGC 4449”, 1986, A. J., in press. 
Hartmann, L. W., Huchra, J. and Geller, M. J. “IUE Observations of Ly Q! Emission 
in Redshifted Blue Galaxies”, in preparation. 
Hartmann, L., Jordan, C., Brown, A. and Dupree, A. K. “On the Outer Atmospheres 
of Hybrid Stars”, 1985, Ap. J., 296, 576. 
Mauche, C. W. and Raymond, J. C. “KJE 0hserva.tions of HL CMa a.nd the Winds 
of CVs”, in LAU Colloquium 93, Cataclysmic Variables. 
Sonneborn, G., Baliunas, S. L., Dupree, A. K., Guinan, E. F. and Hartmann, L. 
“Long-Term Spectroscopic Monitoring of Alpha Orionis”, 1986, in New 
Insights in Astrophysics: 8 Years of UVAstronomy with W E ,  ed. E. Rolfe, 
ESA-SP, in press. 


Combined ultraviolet studies of astronomical sources

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