Doppler-shifted Emission Lines Research Articles

X-Ray Observations Of SS 433 With ASCA

AbstractSS 433 has been observed with ASCA for three years since the launch in 1993. The excellent energy resolution of ASCA revealed the Doppler-shifted emission lines from the both jets, though it had been generally accepted that the X-ray emitting region of the receding jet is hidden behind the accretion disk. Thus the estimation on the properties of the X-ray jet, such as length, temperature, and mass outflow rate, should be revised in accordance with the ASCA data. Modeling the jet as a radiating ballistic plasma, we determined these quantities. It is also tried to determine the mass of the system from a data covering an eclipse.

Validation of mesosphere and lower thermosphere winds from the high resolution Doppler imager on UARS

Horizontal wind fields in the mesosphere and lower thermosphere are obtained with the high resolution Doppler imager (HRDI) on the Upper Atmosphere Research Satellite (UARS) by observing the Doppler shifts of emission lines in the O2 atmospheric band. The validity of the derived winds depends on an accurate knowledge of the positions on the detector of the observed lines in the absence of a wind‐induced Doppler shift. Relative changes in these positions are readily identified in the routine measurements of onboard calibration lines. The determination of the absolute values relies on the comparison of HRDI observations with those obtained by MF radars and rockets. In addition, the degrees of horizontal and vertical smoothing of the recovered wind profiles have been optimized by examining the effects of these parameters both on the amplitude of the HRDI‐derived diurnal tidal amplitude and on the variance of the wind differences with correlative measurements. This paper describes these validation procedures and presents comparisons with correlative data. The main discrepancy appears to be in the relative magnitudes measured by HRDI and by the MF radar technique. Specifically, HRDI generally observes larger winds than the MF radars, but the size of the discrepancy varies significantly between different stations. HRDI wind magnitudes are found to be somewhat more consistent with measurements obtained by the rocket launched falling sphere technique and are in very good agreement with the wind imaging interferometer (WINDII), also flown on UARS.

Search for gamma-ray emission lines from SS 433: 2: 1980-1989

We have searched through the Solar Maximum Mission satellite gamma-ray spectrometer database for evidence of red and blue Doppler-shifted 1.37 MeV (24)Mg* nuclear lines. The data were obtained between 1980 and 1989 and span a total of 720 days when SS 433 was in the field of view. No evidence of Doppler-shifted line emission was found in any of our spectra. The range of 3 sigma upper limits for individual 9 day integration periods was (0.8-2.4) x 10(exp -3) photons/sq cm/s for the blue beam, encompassing the approximately 1.5 MeV feature reported by Lamb et al., and (0.2-2.1) x 10(exp -3) photons/sq cm/s for the red beam, encompassing the reported approximately 1.2 MeV feature. The average 3 sigma upper limit in each beam for shifted 1.37 MeV was 1.5 x 10(exp -3) photons/sq cm/s for single 9 day integration. The 3 sigma upper limits over 56 9 day integration intervals (504 days) for the red beam and 69 intervals (621 days) for the blue beam are 1.2 x 10(exp -4) photons/sq cm/s. The new limits can be reconciled with the HEAO 3 results only if SS 433 emits gamma rays at or above the SMM sensitivity limit on rare occasions due to variable physical conditions in the system.

Comparison of HRDI wind measurements with radar and rocket observations

Wind fields in the mesosphere and lower thermosphere are obtained with the High Resolution Doppler Imager (HRDI) on the Upper Atmosphere Research Satellite (UARS) by observing the Doppler shifts of emission lines in the O2 Atmospheric band. The validity of the measured winds depends on an accurate knowledge of the positions on the detector of the observed lines in the absence of a wind induced Doppler shift. These positions have been determined to an accuracy of approximately 5 ms−1 from the comparison of winds measured by HRDI with those obtained by MF radars. Excellent agreement is found between HRDI measured winds and winds observed with radars and rockets. In addition, the sensitivity of HRDI to migrating tides and other large scale waves is demonstrated.

Visible imaging of the diagnostic neutral beam on TFTR

An attempt was made to image the 2-D spatial patterns of the edge density turbulence of the Tokamak Fusion Test Reactor (TFTR) by using the visible light emission from an injected diagnostic neutral beam (DNB). A clear image of the 12 cm×20 cm DNB ‘‘sheet beam’’ was obtained using the Doppler-shifted line emission at 584.9±0.5 nm (2.7 nm blue shifted) from the neutral helium beam with a 2 ms exposure time. Although the signal level was too low to observe the edge density turbulence, potential improvements are described which could improve the sensitivity enough to obtain an image on the desired 10 μs timescale.

Ten years of SS 433 kinematics

Observations of the highly Doppler shifted emission lines in SS 433 have now been obtained over a period of 10 years, and some inferences available from this data base are discussed. The nature of the instability in the 164-day precession clock remains obscure; a conservative conclusion is that the instability amplitude is not increasing. The higher frequency nodding motions of the accretion disk is used to set an upper limit on any change in the orbital period of the binary system to absolute value of P-d at 13 less than 10 to the -6th (2 sigma). This limit, almost a full order of magnitude more stringent than the previously published one, in turn constrains the mass loss rate through the relativistic jets, and the jet kinetic energy. The nature of the substantial residuals remaining in the Doppler shift observations is discussed when the best-fit models for the precission, nodding, and clock noise are removed; no further periodic components are evident. 27 refs.

Search for Doppler-shifted gamma-ray emission from SS 433 using the SMM spectrometer

Data accumulated from 1980 to 1983 with the Gamma Ray Spectrometer aboard NASA's Solar Maximum Mission (SMM) satellite were searched for evidence of red and blue Doppler-shifted 1.37 MeV Mg-24 nuclear lines from SS 433. The SMM data base covers 270 days when SS 433 was in the field of view and includes periods of radio flaring and quiescence. No evidence was found for Doppler-shifted line emission in any of the spectra. The range of 3-sigma upper limits for individual 9 day integration periods was 0.0008-0.0023 photons/sq cm per sec for the blue beam, encompassing the reported about 1.5 MeV line, and 0.0008-0.002 photons/sq cm per sec for the red beam, encompassing the reported about 1.2 MeV line; the average 3-sigma upper limit in each beam for shifted about 1.37 MeV lines is 0.0015 photons/sq cm per sec for single 9 day integrations. The 3-sigma upper limit on 1.37 MeV gamma-ray emission over 23 9-day integration intervals for the red beam and 28 intervals for the blue beam is 0.0002 photons/sq cm per sec. These new limits from SMM can be reconciled with the HEAO 3 results only if SS 433 emits gamma radiation at or above the SMM sensitivity limit on rare occasions due to variable physical conditions in the system.

Optical emission spectroscopy for analysis of broad ion beams

In sputter etching and reactive ion beam etching (RIBE), contamination and disturbance free in situ methods are desired for control of etch relevant quantities like energy and angular distribution of particles. These requirements cannot be fulfilled by the conventional electrical methods. In this paper we show that optical emission spectroscopy is a valuable tool for in situ diagnostics of broad ion beams. We report on measurements in Argon ion beams of 300–1000 eV energy. Several emission lines of fast and slow atoms and ions are detected in the wavelength range 4000–7000 Å at a resolution of better than 0.1 Å. Impact of fast particles and electrons on neutral background gas atoms are specified as main excitation mechanisms. From the Doppler-shifted emission lines we obtain information on energy and angular distribution of the beam particles.

A small-scale energy release observed on the limb

The D3 emission lines observed on the emerging flux loops and mound prominences above the limb were locally found to consist of two components, i.e., the main and the broadened components. A number of Doppler shifted emission lines, separated distinctly from the main body of the emission lines were also detected, which we call the separated components. On the sequential spectrograms, the lifetimes of these broadened and separated components were obtained and their histograms were made. We present the results of fitting the observed emission lines with the sum of two gaussian profiles in two simple cases under two different assumptions. In each assumption, it is found that the line-of-sight velocities of the broadened components with lifetimes shorter than 10 min monotonously increase with time and we attribute this behaviour to a single ejection of mass from the parent structures. In the broadened components with lifetimes longer than 10 min, the acceleration turns on and off alternately, each with a duration of several minutes. We attribute this behaviour to multiple ejections of mass. Finally, it is shown that the corona over the active region is supplied with enough mass for the formation of a coronal condensation if the ejected mass diffuses out high into the corona and some heating mechanisms for the mass switch on.

The radiative acceleration of astrophysical jets - Line locking in SS 433

Convincing evidence exists that the Doppler-shifted line emission in SS 433 originates in a pair of oppositely directed, precessing jets in which the outflow velocity has remained remarkably constant to within a few percent of 0.26 c since the discovery of the moving lines. The constancy of this outflow speed over a number of cycles of the 164 day precession period, many 13 day binary orbit periods, and an extremely large number of flow transit times, together with the uniformity of the velocity in direction and magnitude across the jet (in the rest frame of the jet axis) at a given time, places a powerful constraint on models of the origin of the jets.

Radiative Acceleration of Astrophysical Jets: Line-Locking in SS 433

Observations of SS433 are consistent with the view that the Doppler-shifted line emission originates in a pair of oppositely-directed, precessing jets in which a gas outflow is maintained at the remarkably time- and space-invariant speed of 0.26c. A radiative acceleration mechanism is described for the jets and a detailed, numerical, relativistic flow calculation presented which explain this terminal velocity as the result of “line-locking”. The “line-locking” mechanism suggested here for SS433 may be important as well in extra-galactic radio sources in which the radio luminosity is similarly weak compared with the kinetic energy and optical luminosities.

Diffuse X-ray emission from the jets of SS433

The discovery of strong, variable emission lines1, which are Doppler-shifted2 from SS433, led to the development of a kinematic beam model3–5 which explains the principal features of the time varying optical spectrum. In this model two opposed jets of material moving outwards from the central star at 0.258c precess with a period of 164 days, about an axis inclined 80° (or 20°) to the line of sight of the observer. The locus of the two beams forms a cone with an opening half angle of 20° (or 80°) (in the model an ambiguity exists between the inclination and cone angles, as the optical data alone cannot distinguish between the two possibilities). A 13-day period observed in the velocity of the ‘stationary’ lines from this object6 shows that the system is binary. However, other models exist which also account for the time varying optical spectrum. For example, one model suggests that the Doppler-shifted emission lines originate in a ring of material orbiting a solitary massive black hole7. We now report the detection of large-scale X-ray ‘jets’ from SS433. The X-ray emission is diffuse, extending at least 30 arc min from SS433, and is exactly aligned with both SS433 and the bulges of the shell of the huge supernova remnant (SNR) W50. This detection now (1) directly confirms the existence of jets related to SS433, (2) shows the link between SS433 and W50, proving that SS433 is galactic, (3) establishes a minimum age of the jet phenomenon of ∼103 yr, and (4) offers an explanation of why W50 is so much larger than any other known SNR in at least one dimension. The morphology of the diffuse X-ray emission is strikingly similar to that of radio lobes of many extragalactic sources; either in situ heating or particle acceleration is required to explain the appearance of the diffuse X-ray emission.

The Bizarre Spectrum of SS 433

SS 433 is an emission-line star, a radio source, and an x-ray source centered in a supernova remnant, W50. Through observations and spectroscopic studies much has been learned of this object. The spectrum of SS 433 is characterized by Doppler-shifted emission lines of hydrogen and helium. This implies the presence of a gas. The wavelengths of these lines vary. Some of the moving lines of the spectrum are red-shifted and some are blue-shifted. Since the wavelengths of the Doppler-shifted features change rapidly with time, the velocity of both approaching gas and receding gas is changing. On any given night the average velocity is 12,000 km/sec. Also, the variations in velocity are periodic, with a 164-day period. These characteristics of the spectrum of SS 433 are explained by assuming the following hypothetical model. The object responsible for ejecting two jets in opposite directions is thought to be part of a binary system, consisting of a comparatively normal star bound in close orbit to a neutron star, which is in the process of pulling material away from the companion by virtue of its strong gravitational field. The gas streaming from the normal star forms a rotating accretion disk around the neutron star,more » and it is from the faces of this disk that the two jets are ejected in opposite directions. Precession of the plane of the disk is presumably what causes the axis of the jets to rotate, hence the 164-day period. (SC)« less

Infrared observations of SS433

SS433 has attracted much attention following the interpretation of its optical spectrum by Margon et al.1 and Liebert et al.2. A possible explanation of the Doppler-shifted Balmer emission lines has been proposed by Rees and Fabian3 and Abell and Margon4 in terms of two opposed jets that are ejected from the central source at speeds approaching 0.25c and may extend for ∼50 AU (∼7×1014 cm). Previous work has shown SS433 to be variable at radio wavelengths5, X rays6, IR7,8 and also in the visible9,10. We report here simultaneous observations at IR and visual wavelengths which show that SS433 has an IR excess. We attribute this to a region of gas that radiates by free–free and free–bound emission processes with a total emission measure of the order of 1061 cm−3.