Line Radial Velocity Research Articles

SS 433: How do the moving lines move?

A progress report is given on the analysis of our ever-increasing set of moving line radial velocity measurements of SS 433. Model fits to the “twin-beam” model are discussed, and an assessment of the quality of the fit is made. A preliminary investigation is conducted into the source of the “random” scatter of the data points around the best-fit model. Finally, a discussion of moving line bullets and light-travel-time effects is made with reference to a spectral montage of SS 433.

WZ Sge: Recent Observations Leading to a Model for Superhump Phenomena

AbstractThe short period eclipsing binary system and recurrent nova WZ Sge (1913, 1946, 1978) was observed spectroscopically during its renewed, December 1978 outburst. Absorption line radial velocities and Hα emission profiles suggest a clrcumblnary gaseous disk. A schematic model is presented to explain both the observed radial velocities and the photometric properties of WZ Sge during outburst. The model also accounts for ‘superhump’ phenomena in SU UMa type dwarf novae.

Radial Velocities of SS Cygni

SS Cygni was found by Joy (1956) to be a spectroscopic binary with an orbital period of about 6-1/2 hours. At minimum light it has mv=12 and is the brightest member of the dwarf nova class of variables. The minimum light spectrum reveals faint, narrow absorption lines of a G- or K-type star along with strong, broad emission lines of hydrogen, helium, and calcium which are produced by an accretion disk surrounding a white dwarf star. Joy’s radial velocities were not very accurate. Nevertheless, he was able to estimate the orbital elements, finding 115 km/s for the absorption line K-velocity and 122 km/s for the emission line K-velocity. In addition, he derived an orbital period of 0276244. Later minimum light observations by Walker and Chincarini (1968) were too few to be able to improve the orbital elements. Kiplinger (1979) refined the emission line radial velocities but was not able to remeasure the faint absorption line spectrum. This paper presents new radial velocity measurements of both the emission and absorption line spectra of SS Cygni at minimum light, and is the first thorough investigation of this star’s radial velocity variations in more than 20 years. The accuracy of the radial velocity curves has been greatly improved. We also find that Joy’s orbital period is in error by nearly two minutes.

The spectrum of 3C 58

Digital spectra of three faint knots in the SNR 3C 58 have been obtained in the wavelength range lambdalambda4700--7300 with the intensified Reticon spectrometer at the 1.3 m telescope of McGraw-Hill Observatory. Emission lines of (S II), (N II), H..cap alpha.., and (O III) were detected with radial velocities less than 100 km s/sup -1/. Although 3C 58 resembles the Crab Nebula in its radio properties and is thought to be the remnant of the supernova observed in A.D. 1181, the relative line intensities and radial velocities reported here more nearly resemble those of the Cygnus Loop and Kepler's SNR.

On the Inhomogeneity of Chemical Composition over the Surface of 21 Per

SummaryThe magnetic variable star 21 Per has been studied from 4 and 8 Å/mm spectra obtained with the 2.6 - meter reflector of the Crimean Astrophysical Observatory. Spectral line intensities (Wλ) and radial velocities (Vr) have been measured.

A STUDY OF RADIAL VELOCITIES AND MAGNITUDES IN R CYGNI

ABSTRACT Ten coude' spectra of R Cyg, obtained during four cycles in which the peak intensities differed by more than two magnitudes, are examined for a brightness-radial velocity relation. A more general relation is found in which the premaximum emission line radial velocities correlate strongly with magnitude, independent of both phase and the height of the maxima. Key words: Mira variables - S stars

THE SPECTRUM OF CH CYGNI FROM 1961 TO 1973

ABSTRACT Radial velocities of absorption lines from 30 spectrograms taken between 1964 and 1973 yield no evidence of orbital motion. Evidence is presented that a circumstellar envelope is always present and that an "outburst" occurs when the envelope is excited by a disturbed region on the surface of the star. Some comparisons are made of CH Cyg with the VV Cephei stars, symbiotic objects, and the symbiotic long-period variable H Aqr. Key words: radial velocities - spectrum variable - symbiotic star - circumstellar matter

Relevance of Variable Negative Radial Velocities to Models of Sco X-1

Westphal, Sandage and Kristian1 reported that the emission line radial velocities of Sco X-1 are variable on a time scale of days or even hours, with an amplitude of perhaps ±50 km s−1, or occasionally somewhat greater. I wish to point out that this has a bearing on possible models for Sco X-1. Naturally, this rapid velocity variation requires the source gas to be in close association with the central physical object and not simply a detached cloud outside its immediate gravitational influence. It must be, then, that the generally negative velocities (mean value ≃ −100 km s−1) are due either to (a) a true approach velocity for the central object, or (b) a preferential direction of motion in the observer's direction for the gas streams causing the lines. I shall now discuss the implication of points (a) and (b).

On a Correlation Between the Radial Velocities of Optical and Radio Interstellar Lines.

view Abstract Citations (28) References (22) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS On a Correlation Between the Radial Velocities of Optical and Radio Interstellar Lines. Howard, William E., III ; Wentzel, Donat G. ; McGee, Richard X. Abstract Optical and 21-cm data pertaining to interstellar clouds are analyzed. The radial velocity correlation coefficient pertaining to the directions toward 39 stars with b > 15 and single component Ca ii lines is +0.68 + 0.09 (m.e.). The dispersion of the histogram of the individual velocity differences is +3 km/sec at both high and low latitudes. A study of the radio and optical line intensities shows an agreement between the theoretical and observed ratios but a discrepancy between the theoretical and observed ,, ratios. Observation and theory can be reconciled by taking the sodium-tohydrogen abundance ratio equal to its value in the sun and by taking the free calcium-to-hydrogen abundance ratio to be of the order of 1/60 of its solar value The possibility of differential calciumhydrogen streaming is briefly discussed. Publication: The Astrophysical Journal Pub Date: November 1963 DOI: 10.1086/147700 Bibcode: 1963ApJ...138..988H full text sources ADS | data products SIMBAD (137)

On a Correlation between the Radial Velocities of Optical and Radio Interstellar Lines.

The radial velocities of the interstellar K line of Ca ii in a total of 39 high-latitude stars ( b ~ 150) having single interstellar line components have been analyzed in conjunction with the corresponding H I radial velocities of the 21-cm line profile. The correlation coefficient is found to be +0.65~*0.09 (m.e.). No radial velocity in the sample, either radio or optical, exceeds ~ 12 km/sec. When the H I radial velocity is subtracted from the corresponding optical value and a histogram of the points is plotted, the mean value of the difference (~ AV>) is +0.3t0.6 (m.e.) km/sec, showing that the large- scale motions of H I and Ca ii are statistically the same. The standard deviation of the AV histogram is 3.5*~0.4 (m.e.) km/sec. After this figure is corrected for instrumental effects, we find a cosmic dispersion of approximately 3 ~ 1 km/sec, which we attribute in varying degrees either to cloud rotation, to differential Ca-H streaming, or to turbulent motions on a scale that is smaller than the solid angle of the 20 radio beamwidth but large enough to include the optical solid angle through the interstellar cloud. The last alternative seems the most probable. From the area under the 21-cm line profile we can derive the number of H I atoms per cm 2in the line of sight (NH). Then, by adopting a hydrogen-tocalcium abundance ratio, we can estimate Nea (em-2). The optical lines are unsaturated with K/H ratio ~1.6. We can derive Ne ii (cm-2) from the usual curve-of-growth analysis given by Str6mgren (Stro~mgren, B., Astrophys. J. 108, 242,1948). The range of the ratio Nea/Nca ~~ over ten stars is 190/XY to 4500/XY, with a mean value of 1400/NY; the same ratio predicted theoretically is 83 Z/nu Pv, where N--the factor by which calcium is underabundant compared to the solar value (NH/NCa -6.5 X 10 N) Y the total H I optical depth/H I optical depth in front of the star; 7--the factor of overionization compared to Seaton's estimate, viz., flea iiifle =0.025Z cm-3 AT~a iii-Nea; flCa II ~V--the ratio of true-to-estimated electron density (n6-~3X10~4nu W cm-3). Most of the fluctuation in the observed ratio of N~a/N~a ii may be attributed to fluctuations in either the neutral hydrogen density 13~ or the ionization field 7 from star to star. However, on the average, the observed and predicted values disagree considerably in the sense that less Ca ii is observed than is predicted. An underabundance of calcium could account for this disagreement. A repetition of this analysis over five stars shows agreement between the observed and predicted NNa/NNa ratio. We note with interest that Spitzer and Routly (Spitzer, L., Jr., and Routly, P. M. Astrophys. I. 115, 227, 1952) have shown that calcium is underabundant relative to sodium in lowvelocity interstellar clouds.

A Coherence Analysis of Fraunhofer Line Radial Velocity Fine Structure and Continuum Brightness Fluctuations near the Center of the Solar Disk.

view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Coherence Analysis of Fraunhofer Line Radial Velocity Fine Structure and Continuum Brightness Fluctuations near the Center of the Solar Disk. Edmonds, Frank N., Jr. Abstract Cross correlation analyses between fluctuations in radial velocity V and continuum brightness I have been carried out for four sets of measurements made near the center of the solar disk; those obtained from a McMath-Hulbert spectrogram (w18), those of R. S. Richardson and M. Schwarzschild (Astrophys. J. 111, 351, 1950) (RS), those of H. H. Plaskett (Monthly Notices Roy. Astron. Soc. 114, 251, 1954) (P), and those of R. Servajean (Ann. Astrophys. 24, 1, 1961) (S). These analyses employed a coherence technique which gives the coherence or cross correlation between the Fourier components of the same wavelength for each set of fluctuations, and the phase difference (across the solar disk) between these Fourier components. The analyses also computed power spectra, RMS's and filtered and unfiltered cross correlations. A significant VI coherence with 180~ phase difference was found in the wavelength range 1200-5200 km (on the surface of the sun) for the RS measurements, no VI coherence was found for the w18 measurements, and the S and P measurements gave inconclusive results. These results cannot be explained in terms of differences in the solar atmosphere levels making an appreciable contribution to line formation and to continuum formation. The inconsistent picture presented by the four VI coherence analyses can be explained in terms of a negative VI cross correlation existing for wavelengths ~ 5000 km plus certain differences in instrumental and atmospheric resolution for the four sets of measurements. However, an explanation in terms of a heterogeneous convection pattern at the sun's surface seems more reasonable. Publication: The Astronomical Journal Pub Date: March 1962 DOI: 10.1086/108817 Bibcode: 1962AJ.....67Q.271E full text sources ADS |