scholarly journals High-resolution emission line profiles in blue luminous stars

1989 ◽  
Vol 113 ◽  
pp. 279-280
Author(s):  
Rino Bandiera ◽  
Paola Focardi ◽  
Aldo Altamore ◽  
Corinne Rossi ◽  
Otmar Stahl
Keyword(s):  
High Resolution ◽  
Emission Line ◽  
High Velocity ◽  
Large Scale ◽  
Velocity Fields ◽  
Emission Lines ◽  
Line Profiles ◽  
High Luminosity ◽  
Stellar Envelopes ◽  
Η Car

Emission lines are often observed in high luminosity stars and provide evidence of the presence of extended stellar envelopes. Ha is the most frequently observed across the H-R diagram, but lines of Hel or Fell are also found in emission in these stars. They could be used as diagnostics of the structure of their outer atmospheres and winds. High resolution (1/dl ~ 105) high S/N profiles of Ha and Hel 5876 in the galactic LBVs η Car, AG and HR Car, and in the LMC star S22 have been obtained with the ESO CAT-CES during 1984-87, and are described in Figs.1-5. We find that these stars show a large variety of profiles with narrow and broad emissions, wide or multiple blue-shifted absorptions. The profiles are largely variable. Once, a kind of inverse P Cyg profile was observed in HR Car (Fig.4). These results indicate the presence of large scale phenomena and high velocity fields which are dramatically variable in time. Continuous HIRES monitoring of these stars is urgently needed.

scholarly journals High-Resolution Emission-Line Spectroscopy of Be Stars: Comparison of Hα and Weak Emission Lines

1987 ◽  
Vol 92 ◽  
pp. 208-210
Author(s):  
Reinhard W. Hanuschik
Keyword(s):  
High Resolution ◽  
Emission Line ◽  
Rotational Velocity ◽  
Outer Radius ◽  
Emission Lines ◽  
Be Stars ◽  
Line Profiles ◽  
Component Structure ◽  
Double Peak Structure ◽  
Disk Component

AbstractFor a number of bright southern Be stars, high-resolution, high S/N spectroscopy has been performed for Hα, Si II λ6371 and four Fe II emission lines. With the exception of four stars, both Hα and weak emission line profiles exhibit resolved double-peak structure. Peak separation increases with stellar projected rotational velocity. In many cases, Hα profiles (but not Fe II lines) show resolved fine-structure (inflections in the flanks) indicating a two-component structure of the disk. Envelope models with arbitrary density and rotational velocity laws have been fitted to the Fe II line profiles with satisfactory results. It is found that the innermost Hα disk component also emits the Fe II lines and has an average outer radius of 5 r*; density falls off as r-l.5 or more rapidly. The outer disk component emits the faint and narrow secondary component of Hα lines with average outer radius 20 r*. The envelopes of the four stars with a strong, dominating single peak both in Hα and Fe II either are dominated by strong radial motions or, more likely, have elliptical disk-like structure.

scholarly journals Emission Line Profiles in the Planetary Nebulae IC 4593 and NGC 6153

1989 ◽  
Vol 131 ◽  
pp. 189-189
Author(s):  
D.P.K. Banerjee ◽  
B. G. Anandarao
Keyword(s):  
High Resolution ◽  
Emission Line ◽  
Planetary Nebulae ◽  
Central Star ◽  
Compact Objects ◽  
Emission Lines ◽  
Complex Structures ◽  
Line Profiles ◽  
Fabry Perot ◽  
Central Regions

The Planetary Nebulae IC 4593 and NGC 6153 are two rather compact objects not well studied. The nebula IC 4593 is about 12 arcsec in diameter and has a central star of Type 07 f; while the southern nebula NGC 6153 is about 22 arcsec in diameter and its central star is faint and of unknown spectral type. Using a high-resolution scanning Fabry-Pérot spectrometer we have made profile measurements of emission lines Hα λ6563 A, [O III] λ5007 A, and [N II] λ6584 A in the central regions of these two nebulae. We have found expansion velocities for IC 4593 of 40 km s−1 in [N II] and 16 km s−1 in [O III]. In the case of NGC 6153, we have obtained expansion velocities of 15 km s−1 in [N II] and 13 km s−1 in [O III] line. The profiles in Hα in both the nebulae dis not show a double peaked feature due to the larger thermal broadening. In the case of IC 4593, both [O III] and [N II] profiles showed complex structures. These results and their interpretation will be discussed.

scholarly journals Kinematics of Nuclei of Sc Galaxies

1980 ◽  
Vol 5 ◽  
pp. 191-191
Author(s):  
V. C. Rubin
Keyword(s):  
High Velocity ◽  
Stellar Population ◽  
Hii Regions ◽  
Emission Lines ◽  
High Luminosity ◽  
Rotation Curves ◽  
Velocity Gradients ◽  
Wide Range ◽  
Central Regions ◽  
Velocity Dispersions

For a sample of 21 Sc galaxies with a wide range of luminosities, of radii, and of masses, W. K. Ford and I have obtained spectra and determined rotation curves. By their kinematical behavior in their central regions, the Sc’s can be separated into two groups. Some galaxies, generally small and of low luminosity, have shallow central velocity gradients, reflecting their low central masses and densities. Other galaxies, most often large ones of high luminosity, have steep central velocity gradients. One reason this separation by central velocity gradients is of interest is because these galaxies exhibit other significant spectral differences which go hand-in-hand with the kinematical differences.The small, low luminosity galaxies show emission lines of Hα and [NII], with nuclear Ha sharp and stronger than [NII], and little or no stellar nuclear continuum, just as conventional HII regions. In contrast, the high luminosity galaxies show broad nuclear emission, with [NII] stronger than Ha. These galaxies have a strong red stellar continuum, arising from a red stellar population. The cause of the Hα[NII] intensity reversal in the nuclei of some galaxies remains unknown. However, the strong [NII] emission in generally high luminosity galaxies with massive nuclei, nuclei which show strong red continua, suggests that [Nil] intensity correlates with nuclear luminosity, and in turn with the density and velocity properties of the nuclear populations. We would expect high velocity dispersions and high bulge luminosities for galaxies with strong nuclear [NII] and steep central velocity gradients.

scholarly journals High resolution spectroscopy of RY Tauri: variability of the Na D line profiles

1990 ◽  
Vol 137 ◽  
pp. 219-220
Author(s):  
P.P. Petrov
Keyword(s):  
High Resolution ◽  
Large Scale ◽  
Young Stars ◽  
High Resolution Spectroscopy ◽  
Line Profiles

Ejection and accretion of gas clouds in the vicinity of RY Tau were discovered. The existense of large scale “stellar prominences” around young stars is suggested.

scholarly journals The Structure of the HH39 Region

1987 ◽  
Vol 115 ◽  
pp. 340-341
Author(s):  
J. R. Walsh
Keyword(s):  
High Resolution ◽  
Radial Velocity ◽  
Proper Motion ◽  
High Velocity ◽  
Velocity Structure ◽  
The Other ◽  
Emission Lines ◽  
High Resolution Spectroscopy ◽  
Bow Shocks ◽  
Hh Objects

HH39 is the group of Herbig-Haro (HH) objects associated with the young semi-stellar object R Monocerotis (R Mon) and the variable reflection nebula NGC 2261. An R CCD frame and a B prime focus plate of the region show a filament connecting NGC 2261 with HH39, confirming the association between R Mon and the HH objects. This filament is probably composed of emission material. The southern knot in HH39 has brightened over the last 20 years; its proper motion has been determined and is similar to that of the other knots. A total of 8 knots can be distinguished in HH39 surrounded by diffuse nebulosity. High resolution spectroscopy of the Hα and [N II] emission lines shows the spatial variation of the radial velocity structure over the largest knots (HH39 A and C). Distinct differences in excitation and velocity structure between the knots are apparent. The observations are compatible with the knots being high velocity ejecta from R Mon, decelerated by interaction with ambient material and with bow shocks on their front surfaces.

scholarly journals Spectroscopic Investigations of Luminous Emission-Line Objects

1975 ◽  
Vol 67 ◽  
pp. 297-298
Author(s):  
Angelo Cassatella ◽  
Roberto Nesci ◽  
Roberto Viotti
Keyword(s):  
Mass Loss ◽  
Emission Line ◽  
Physical Characteristics ◽  
Emission Lines ◽  
Expansion Velocity ◽  
Evolutionary Stage ◽  
High Luminosity ◽  
Spectroscopic Investigations ◽  
Differential Expansion ◽  
Parent Star

Emission lines are frequently observed in the spectra of the high luminosity stars, indicating the presence of extended atmospheric envelopes. We are investigating the physical characteristics (differential expansion velocity, density, extension, mass loss) and the origin of these envelopes in relation to the high luminosity of the parent star, and its evolutionary stage. Some results are presented concerning Eta Car, S Dor, HD 34664, P Cyg, AG and HR Car, and two WR stars.

scholarly journals High Luminosity F-K Stars Motions and Hα Emissions

1980 ◽  
Vol 51 ◽  
pp. 170-170
Author(s):  
J. Smolinski ◽  
J.L. Climenhaga ◽  
B.L. Harris
Keyword(s):  
Radial Velocity ◽  
Radial Velocities ◽  
Emission Lines ◽  
High Dispersion ◽  
Common Phenomenon ◽  
Line Profiles ◽  
High Luminosity ◽  
Regular Time ◽  
Time Variations

AbstractChanges and differences in radial velocities between neutral and ionized metals have been found for three F5-type supergiants: HD 231195, HD 10494, and HD 17971. Fifteen high dispersion coudé spectrograms (6 Å/mm) were used and 33 to 165 lines were measured on each. Semi-regular time variations up to about 8 km s-1 in radial velocity have been found. In addition, Hα line profiles for 8 high luminosity F-K stars have been analyzed. All of the stars show Ha emissions, variable in time, which is probably a common phenomenon in very luminous stars. Metallic emission lines with low excitation potentials, in particular the Ca I 6572.8 and the Fe I 6574.2 lines, are present in 5 of these stars.

scholarly journals A planetesimal orbiting within the debris disc around a white dwarf star

Science ◽  
2019 ◽  
Vol 364 (6435) ◽  
pp. 66-69 ◽  
Author(s):  
Christopher J. Manser ◽  
Boris T. Gänsicke ◽  
Siegfried Eggl ◽  
Mark Hollands ◽  
Paula Izquierdo ◽  
...  
Keyword(s):  
Emission Line ◽  
Solid Body ◽  
White Dwarf ◽  
Periodic Variation ◽  
Emission Lines ◽  
Line Profiles ◽  
Dwarf Star ◽  
Dwarf Stars ◽  
White Dwarf Stars ◽  
Short Period

Many white dwarf stars show signs of having accreted smaller bodies, implying that they may host planetary systems. A small number of these systems contain gaseous debris discs, visible through emission lines. We report a stable 123.4-minute periodic variation in the strength and shape of the Ca ii emission line profiles originating from the debris disc around the white dwarf SDSS J122859.93+104032.9. We interpret this short-period signal as the signature of a solid-body planetesimal held together by its internal strength.

scholarly journals The Structure of the Envelopes of Symbiotic Novae

1990 ◽  
Vol 122 ◽  
pp. 431-432
Author(s):  
G.B. Baratta ◽  
A. Damineli Neto ◽  
C. Rossi ◽  
R. Viotti
Keyword(s):  
High Resolution ◽  
Uv Spectra ◽  
Emission Lines ◽  
Broad Line ◽  
Line Profiles ◽  
Composite Spectrum ◽  
Multiple Structure ◽  
Broad Emission ◽  
Light History

Symbiotic novae are composite spectrum stars whose light history is characterized by one single major outburst. At high resolution their optical and UV spectra are very rich of emission lines belonging to a wide ionization range. Generally one can identify both narrow and broad line systems. The latter includes emission lines with multiple structure, broad emission wings, WR features, and P Cygnl lines. Frequently the broad line profiles are largely variable with time. They should be associated with the major stellar outburst. An overview of the problem with extensive references can be found in Viotti (1989).

scholarly journals Velocity-Resolved Line Response of the Emission Lines in the High-Luminosity (Mv ≈ −24) Seyfert 1 Galaxy Fairall 9

1997 ◽  
Vol 159 ◽  
pp. 151-154
Author(s):  
W. Wamsteker ◽  
M.C. Recondo-González ◽  
P.M. Rodríguez-Pascual ◽  
R. Vio ◽  
F. Makino
Keyword(s):  
Emission Line ◽  
Emission Lines ◽  
X Rays ◽  
High Luminosity ◽  
Spectral Variability ◽  
Model Calculations ◽  
Photoionization Model ◽  
Large Wavelength ◽  
The Continuum

AbstractA detailed emission-line decomposition has been made from 15 years of observations with the IUE satellite of the highly variable Seyfert 1 galaxy Fairall 9, allowing us to study the line variability as a function of velocity and continuum brightness. The variability over the different velocity domains of the broad lines has been related to the continuum variability over a large wavelength domain from the X-rays to the infrared. Clear delays were established between the redshifted and blueshifted parts of the lines in Lyα and C IV, with the red sides of the lines responding faster with no delay and the blue sides responding with a delay of some 230 days. The observed spectral variability behavior of the continuum has been used as input for photoionization model calculations and the combined constraints from the models and differences for gas at different velocities define the structure and motions in the BLR.

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