scholarly journals IUE Observations of Z Andromedae

1980 ◽  
Vol 88 ◽  
pp. 543-546
Author(s):  
M. Friedjung
Keyword(s):  
Emission Lines ◽  
Close Binary ◽  
Line Of Sight ◽  
Symbiotic Star ◽  
High Excitation ◽  
Dilution Factor ◽  
Preliminary Results ◽  
Upper Limit ◽  
Resonance Emission ◽  
Joint Study

The preliminary results of a joint study of this symbiotic star with 6 Italian astronomers are reported. The relative intensities of the intercombination emission lines indicate electron densities of 1010 and an upper limit to the dilution factor between 10−4 and 10−6. The resonance emission lines give a maximum thickness in the line of sight. A hot (T between 19000° and 26000°) continuum is interpreted as coming from a hot subdwarf, but the high excitation emission lines appear to be formed near the cool giant component of what is probably a close binary.

scholarly journals Comparison of Planetary Nebulae and Symbiotic Star Emitting Regions

1983 ◽  
Vol 103 ◽  
pp. 321-322
Author(s):  
C. D. Keyes
Keyword(s):  
Spatial Distribution ◽  
Planetary Nebulae ◽  
Emission Lines ◽  
Symbiotic Star ◽  
Symbiotic Stars ◽  
High Excitation ◽  
Cool Star

The spectra of symbiotic stars generally display many emission lines seen in moderate to high-excitation planetary nebulae, but are superposed upon a strong continuum characteristic of a cool star, typically of type M. Furthermore, the spatial distribution of symbiotics has been noted to resemble that of planetaries. These similarities suggest that the symbiotic stars and planetary nebulae might have some relationship (causal or otherwise) or that they might arise from similar progenitors.

scholarly journals Simulation study for the Stratospheric Inferred Winds (SIW) sub-millimeter limb sounder

2018 ◽  
Author(s):  
Philippe Baron ◽  
Donal Murtagh ◽  
Patrick Eriksson ◽  
Jana Mendrok ◽  
Satoshi Ochiai ◽  
...  
Keyword(s):  
Simulation Study ◽  
Spectral Band ◽  
Chemical Species ◽  
Field Of View ◽  
Emission Lines ◽  
Horizontal Wind ◽  
Line Of Sight ◽  
Heterodyne Receiver ◽  
Vertical Field ◽  
Wind Measurements

Abstract. Stratospheric Inferred Winds (SIW) is a Swedish mini sub-millimeter limb sounder selected for the 2nd InnoSat platform launch planned near 2022. It is intended to fill the altitude gap between 30–70 km in atmospheric wind measurements and also aims at pursuing the limb observations of temperature and key atmospheric constituents between 10–90 km when current satellite missions are probably stopped. Line-of-sight winds are retrieved from the Doppler shift of the emission lines introduced by 5 the wind field. Observations will be performed with two antennas pointing toward the limb with perpendicular directions to reconstruct the 2-D horizontal wind vector. Each antenna has a vertical field of view of 5 km. The chosen spectral band near 655 GHz contains a dense group of strong O3 lines suitable for exploiting the small wind information in stratospheric spectra. Using both sidebands of the heterodyne receiver, a large number of chemical species will be measured including O3-isopotologues, H2O, HDO, HCl, ClO, N2O, HNO3, NO, NO2, HCN, CH3CN and HO2. This paper presents the simulation study for assessing the measurement performances. The line-of-sight winds are retrieved between 30–90 km with the best sensitivity between 35–70 km where the precision (1-sigma) is 5–10 m s−1 for a single scan. Similar performances can be obtained during day and night conditions except in the lower mesosphere where the photo-dissociation of O3 in day-time reduces the sensitivity by 50 % near 70 km. Profiles of O3, H2O and temperature are retrieved with a high precision up to 50 km (

scholarly journals Ultraviolet Variability of the Symbiotic Star AG PEG

1988 ◽  
Vol 103 ◽  
pp. 263-264
Author(s):  
D. Chochol ◽  
Z. Komárek ◽  
A. Vittone
Keyword(s):  
Optical Spectra ◽  
Radial Velocities ◽  
Roche Lobe ◽  
Emission Lines ◽  
High Dispersion ◽  
Symbiotic Star ◽  
Observational Material

Symbiotic star AG Peg consists of a hot subdwarf with a WN6 spectrum and a cool M3 giant, which is not filling its Roche lobe (Boyarchuk 1967, 1985). A detailed study of profiles, equivalent widths and radial velocities of emission lines in optical spectra allowed Hutchings et al. (1975) to conclude that a hot subluminous star approximately 1 M⊙ rotates rapidly and ejects material which streams towards the cool M giant with the mass 3-4 M⊙. UV observations seems to support this model.UV observations provided from the databank of the IUE satellite were obtained in 1978–81 by different observers. The observational material consists of 12 high dispersion SWP spectra and covers the region 1200 – 2100 A. The spectra were reduced at Trieste observatory using standard IUESIPS package. The radial velocities of emission lines were measured on tracings and corrected for the motion of Earth and satellite.

scholarly journals Chromatic Amplitudes and Line-of-Sight Velocity Variations for the Pulsating DB White Dwarf GD 358

2002 ◽  
Vol 185 ◽  
pp. 380-381
Author(s):  
R. Kotak
Keyword(s):  
Optical Spectroscopy ◽  
White Dwarf ◽  
Line Of Sight ◽  
Time Resolved ◽  
Preliminary Results ◽  
Velocity Variations

AbstractWe report on preliminary results from time-resolved optical spectroscopy of the He-rich variable white dwarf GD 358.

scholarly journals Interacting Binaries as Be Stars

1987 ◽  
Vol 92 ◽  
pp. 451-455
Author(s):  
Mirek J. Plavec
Keyword(s):  
Spectral Type ◽  
Binary Stars ◽  
Emission Lines ◽  
Close Binary ◽  
High Electron ◽  
Be Stars ◽  
Close Binary Stars ◽  
High Ionization ◽  
Mass Outflow ◽  
Balmer Lines

AbstractSemidetached close binary stars of the Algol type often have primary components of spectral type A0 or earlier and display emission at Hα (sometimes also at higher Balmer lines). They are therefore Be stars. Many binaries of this type are not eclipsing and must look like “ordinary” Be stars. We have discovered high-ionization emission lines of N V, C IV, Si IV, Fe III, etc. in the ultraviolet spectra of totally eclipsing Algols. They probably originate in circumstellar turbulent regions at fairly high electron temperatures, of the order of 100 000 K. They are not detectable in most non-eclipsing systems, but may be there and may play an important role in the dynamics of accretion and mass outflow from the systems.

scholarly journals Measurement of the 3 K Cosmic Background Noise in the Far Infrared

1983 ◽  
Vol 104 ◽  
pp. 135-138 ◽  
Author(s):  
G. Dall'oglio ◽  
P. de Bernardis ◽  
S. Masi ◽  
F. Melchiorri
Keyword(s):  
Background Noise ◽  
Quantum Fluctuations ◽  
Far Infrared ◽  
Preliminary Results ◽  
Upper Limit ◽  
Cosmic Background

Quantum fluctuations of the cosmic background have been measured in the 900 to 2000 micron range (H.P.B.W.) by means of a balloon-borne correlator operating between 5 and 150 Hz. Preliminary results indicate an upper limit √<dP2> ≤ 2.1 × 10−17 watt/(cm2 srad Hz)1/2, corresponding to the noise of a blackbody at a temperature T ≤ 3.1 K at 1σ.

scholarly journals Colliding Stellar Winds in O-type Close Binary Systems

1992 ◽  
Vol 135 ◽  
pp. 146-148
Author(s):  
D.R. Gies ◽  
M.S. Wiggs
Keyword(s):  
Binary Systems ◽  
Optical Emission ◽  
Emission Lines ◽  
Optical Observations ◽  
Close Binary ◽  
High Dispersion ◽  
Stellar Winds ◽  
Close Binary Systems ◽  
Circumstellar Gas ◽  
The Individual

In close binary systems of O-type stars, the individual stellar winds will collide between the stars to form shock fronts (Stevens et al. 1992). Binaries with equally luminous stars will have winds of comparable strength, and the shock will occur near the mid-plane between the stars, but in binaries of unequal luminosity, the interaction will occur along a bow shock wrapped around the star with the weaker wind. The presence of the shock region can be detected through excess X-ray emission (Chlebowski & Garmany 1990), and orbital phase-related variations in the UV P Cygni lines (Shore & Brown 1988) and optical emission lines (formed in high density regions of circumstellar gas).We have begun a search for colliding winds through a study of the optical emission lines and UV P Cygni lines in four massive binaries, AO Cas (Gies & Wiggs 1991), Plaskett’s star = HD 47129 (Wiggs & Gies 1992), 29 UW CMa and ι Ori. The optical observations consist of high S/N spectra of the Hα and He I λ6678 region obtained with the University of Texas McDonald Observatory 2.1-m telescope and coudé Reticon system. The UV observations were culled from archival IUE high dispersion spectra of several P Cygni features (N V λ1240, Si IV λ1400, C IV λ1550).

scholarly journals The IUE Ultraviolet Spectrum of PC 11

1993 ◽  
Vol 155 ◽  
pp. 398-398 ◽  
Author(s):  
M. Parthasarathy ◽  
S.R. Pottasch ◽  
J. Clavel
Keyword(s):  
Short Wavelength ◽  
Planetary Nebula ◽  
Significant Variation ◽  
Central Star ◽  
Ultraviolet Spectrum ◽  
Emission Lines ◽  
Symbiotic Star ◽  
Iras Source ◽  
Long Wavelength ◽  
Cold Dust

PC 11 (HD 149427, PK 331-5 1) is classified as a young planetary nebula with strong OIII 4363Å and a Zanstra temperature of TZ = 27000K. It is also classified as (D′ — type) yellow symbiotic star with A — F type companion. It is an IRAS source with detached cold dust with far intrared (IRAS) colours similar to planetary nebulae. The IUE short wavelength (SWP) spectra show emission lines due to OIII] (1661/1666Å). NIII] (1746/1754Å) CIII] (1907/1909Å). The OIII] and NIII] emission lines show significant variation. Variation in the strength of CIII] is not very significant. The strength of OIII] has decreased and NIII] has increased. The long wavelength (LWP) spectrum shows stellar continuum (A-F) and absorption lines due Mg II 2800Å feature. It also show emission lines at 2772Å (?) 3133Å −3140Å (very strong) (OIII, [FeV], 3209Å (He II?) ([FEII]). The variation in the strength of emission line due OIII] and NIII] and the presence of stellar continuum (A-F) suggests that the central star of PC 11 is a binary.

scholarly journals Quasars Disks and Cosmology

1987 ◽  
Vol 124 ◽  
pp. 695-696
Author(s):  
Hagai Netzer
Keyword(s):  
Black Hole ◽  
Ultraviolet Radiation ◽  
Equivalent Width ◽  
Selection Effect ◽  
Emission Lines ◽  
Line Of Sight ◽  
Apparent Brightness ◽  
Central Black Hole ◽  
New Ideas ◽  
Thin Disks

Much of the optical and ultraviolet radiation of bright quasars may originate in a massive accretion disk around a central black hole. Most searches for the signature of such disks gave ambiguous results but lately there are new ideas that may lead to their discovery. In particular, the apparent brightness of thin disks depend on their inclination to the observer's line of sight and this may be detected by the equivalent width of some emission lines (Netzer 1985, 1986). This idea may change our view on the inner structure of quasars and other AGN. In addition, it points to a potential selection effect that has not been taken into account so far. Magnitude limited optical quasar samples may contain, preferentially, face-on disks, thus cosmological evolution based on such samples may be biased. There are other implications, especially to the observed correlation of Lop with Lx in quasars.

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