Changes In Line Profiles Research Articles

Measuring black hole mass through variable line profiles from accretion disks

THE emission lines in the optical spectra of several active galactic nuclei (AGNs) show a broad double-horned profile which is likely to be produced by matter orbiting the central massive black hole in a disk-like geometry1–3. The unresolved and, sometimes, broad and redshifted Fe K α lines observed in the X-ray spectra of Seyfert galaxies4–6 and bright X-ray binaries7–10 might also be dominated by Doppler, transverse and gravitational shifts in a keplerian disk of tens to hundreds of Schwarzschild radii (rs = 2GM/c2) around the collapsed object11,12. Line emission from these disks is most likely to be driven by photoionization or Compton heating by radiation from closer to the central object; flux variations in this radiation will cause changes in the disk line emissivity. Here we present detailed calculations of the response of a line from a relativistic keplerian disk to flux variations in the central regions. Two characteristic features form on opposite sides of the line, which, owing to light travel-time effects, gradually drift from the line wings, corresponding to the innermost disk regions, to the blue and red horns. Observations of these line-profile changes could provide the first direct measurement of the mass of the central black hole in AGNs2,12,13.

Shock-Induced Behavior of Atomic Species in LPV Atmospheres

A dynamic model of the LPV atmosphere which calculates the time-dependent variations of density, temperature, velocity, and composition with radius has been used to predict changes in absorption line profiles with phase. General results based on density variations are shown in figure 1. Similar graphs, based on concentrations of individual species, are presented for six metals: Fe, Si, Mg, Ca, Cr, and Ti. Those species which remain essentially proportional to the density (e.g., most neutral metals) exhibit the same type of variation. Ionized metals show more individual variations, including some doubling at certain phases, caused by enhanced ionization in the regions traversed by the upper shock. The basic variation predicted by this model has been observed for CO lines in Chi Cygni. (Hinkle, Hall, and Ridgway 1982, Ap. J. 252, 697)

Broad Line Variations in NGC 5548

Since broad line variations can, in principle, constrain the structure and kinematics of the broad line region in active galaxies we have conducted a monitoring program of 20 Seyfert galaxies over a 5 year period in order to study broad line flux and profile changes. Included in our sample is the Seyfert 1.5 galaxy NGC 5548. Fifteen observations were taken from 1979 to 1984 mainly with the 60″ Palomar telescope and a SIT vidicon spectrograph. Measurements show (Fig. 1) that both the Hβ and Hγ line flux varied by 200% and the continuum varied by 300%. Furthermore, these changes were positively correlated as one would expect from photoionization by a central continuum source.

Influence of valence band states on the core hole screening in lanthanide perovskite compounds

Investigation on core level and valence band photoelectron spectra of lanthanide perovskite samples (Ag x La1−xCoO3;x<0,3) and reinvestigations of metallic lanthanum and La-oxide layers are reported. Differences in preparation method during perovskite formation are leading to different quality of sample purity and different electronic properties. This could be followed by changes in the density of states near the Fermi energy. On the other hand the screening mechanism after ionization of a La 3d core hole is affected by the relative energy position of occupied valence band states with respect to the empty La 4f* level in the core ionized state. Changes in La 3d line profile are discussed as changes in multi electron processes (e.g. “shake up” or “energy gain”) during photoionization. We attribute the two electron process during photoemission of La 3d electrons to the well screened energy gain transition in LaCoO3, whereas the two electron process results in a shake up transition in La2O3 and La(OH)3.

Shock Phenomena in β Cephei Stars

In this paper, we present new observations of β Cephei stars made with the CFHT coudé Reticon. Spectral sequences of the extreme star BW Vulpeculae show large velocity and line profile changes in Ha and in the C II doublet (λλ6578,6582) over 0.04 of a cycle, during three different cycles on three different nights. In fact, there are two such phases of line doubling where the velocities are nearly discontinuous before and after the so-called velocity “stillstand” (near maximum light). Also, the line doubling phases coincide with pronounced peaks in the Ha core residual intensity. The most straightforward interpretation of these observations is that there are two shock waves, separated by about 50 minutes, which generate double absorption components. For v Eridani and γ Pegasi, there are no discernible changes in the Ha profiles, despite rather regular velocity variations. This argues against the shock-wave interpretation for “classical” β Cephei stars.

SN 1987A: Ultraviolet Observations and Mass Loss

AbstractMass loss from the B3 Ia progenitor star for SN 1987A is revealed by the recent emergence of narrow ultraviolet emission lines. The emitting gas is nitrogen-rich, has low velocity, and may be located a light-year from the supernova. This gives every sign of having been ejected from the SK −69 202 progenitor when it was a red supergiant, prior to its brief and ultimately violent life as a blue supergiant. Changes in the hydrogen line profiles during the early evolution provide a way to estimate the density distribution in the supernova atmosphere, and the mass of hydrogen it contains. A preliminary estimate is that the power-law index of density in the envelope goes as V−11 and the mass that lies above a velocity of 6, 000 km s−1 is between 1 and 6 solar masses.

Variability of Some Be Stars on High-Resolution, High S/N Spectra

Rapid variability in Be stars could be understood by non radial pulsations or by rotation of an inhomogeous surface brightness distribution…The structure and the variability of the Hα and of the HeI λ6678 lines have been investigated with an optical fiber spectrograph and a CCD camera. The signal to noise ratio, measured in the continuum, is between 300 and 500.Weak changes in the Hα emission line profile of γ Cas have been detected on time-scale of hours and days. This line has an asymmetric profile exhibiting only one blue-shifted maximum while the HeI λ6678 has a double-peak emission, superimposed to the photospheric contribution, with a violet to red peak ratio V/R &gt;1.The Hα emission line of φ Per exhibits a complex structure with significant changes in its core, from night to night and on a short time scale &lt;lhr. The HeI λ6678 presents a blue-shifted asymmetric emission (red-winged) superimposed to the photospheric contribution.Furthermore the Hel photospheric line λ6678 of the B6 star o And has presented notable variations in its profile during the 2 observational campaigns, which do not seem correlated to the photometric period of 1.57 day.

Atlas of time-resolved spectrophotometry of cataclysmic variables

view Abstract Citations (61) References (50) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Atlas of Time-resolved Spectrophotometry of Cataclysmic Variables Honeycutt, R. Kent ; Kaitchuck, Ronald H. ; Schlegel, Eric M. Abstract Whole-orbit, time-resolved spectrophotometry of 18 cataclysmic variables is reduced and displayed in a homogeneous fashion. Each set of digital data is binned into a phase-dependent gray-scale image which resembles a single-trailed photographic spectrogram. This technique permits convient comparison of phase-dependent spectral changes among the different systems. The approximate wavelength interval 4250-4950 A was observed at 2.5 A resolution. This interval contains the accretion disk emission lines of H-beta, H-gamma, He I 4471 A, and He II 4686 A. A brief commentary on the phenomena that can be seen in the image of each star is given. These effects include orbital motion, line-profile changes during eclipse, and s-waves. Several epochs of data on UX UMa are presented, displaying yearly changes in the spectrum. A series of outburst spectra of RX And are included, showing how phase-dependent spectra evolve during outburst. EX Hya spectra are displayed folded on both the 98 minute and the 67 minute photometric periods. In all, 23 spectral data sets are displayed and discussed for the 18 systems. Publication: The Astrophysical Journal Supplement Series Pub Date: November 1987 DOI: 10.1086/191232 Bibcode: 1987ApJS...65..451H Keywords: Cataclysmic Variables; Dwarf Novae; Eclipsing Binary Stars; Stellar Mass Accretion; Stellar Spectrophotometry; Stellar Luminosity; White Dwarf Stars; Astronomy; STARS: ACCRETION; STARS: BINARIES; STARS: DWARF NOVAE full text sources ADS | data products SIMBAD (18)

High-pressure 57Fe Mössbauer study of Fe3O4 at 298 K

At 298 K, 57Fe Mössbauer spectra of Fe3O4 exhibit an increase in complexity with increasing pressure in the range 1×105 to 5×109 Pa. There is an incipient splitting of the B-site pattern into two components with relative intensities of 3 : 1. For the more intense pattern, Hn is 462 kOe and 470 kOe at 1×105 and 5×109 Pa, respectively; the corresponding values for the less intense patterns are 454 and 448 kOe. The B-site electric quadrupole interactions also exhibit appreciable changes. The A-site pattern exhibits no qualitative changes in line profiles and only modest changes in the hyperfine interaction parameters are observed. For example, at 1×105 and 5×109 Pa, Hn is 492 and 490 kOe, respectively; the corresponding isomer-shift values are 0.258 and 0.233 mm s−1. These results are consistent with the broadening of the lines of the B-site patterns at ambient temperature and pressure arising from the different relative orientations of the direction of magnetization and of the axes of the electric field gradient tensor.

Hot wind in the double degenerate system Am CVn

The close binary system Am CVn consists of two helium white dwarf stars in close orbit. Strong flickering in the optical light curve and the observed spin-up in the rotation period indicate that mass transfer takes place (Solheim et al., 1984). The optical spectrum shows broad helium absorption lines (Robinson and Faulkner, 1975) sometimes partly filled in by emission (Voikhanskaya, 1982). The optical spectrum shows no sign of hydrogen, and the line profiles are interpreted as due to an accretion disk of intermediate angle of inclination with a temperature of the order of 20.000 K (Robinson and Faulkner, 1975). Another possibility is direct accretion onto a magnetized BD white dwarf (Voikhanskaya, 1982). In the latter case a magnetic field B≃106 to 109 gauss is needed. Voikhanskaya also reports significant changes in the absorption line profiles from 1978 to 1980.

Hot Wind in the Double Degenerate System AM CVn

AbstractThe close binary system Am CVn consists of two helium white dwarf stars in close orbit. Strong flickering in the optical light curve and the observed spin-up in the rotation period indicate that mass transfer takes place (Solheim et al., 1984). The optical spectrum shows broad helium absorption lines (Robinson and Faulkner, 1975) sometimes partly filled in by emission (Voikhanskaya, 1982). The optical spectrum shows no sign of hydrogen, and the line profiles are interpreted as due to an accretion disk of intermediate angle of inclination with a temperature of the order of 20.000 K (Robinson and Faulkner, 1975). Another possibility is direct accretion onto a magnetized BD white dwarf (Voikhanskaya, 1982). In the latter case a magnetic field B ≃ 106to 109gauss is needed. Voikhanskaya also reports significant changes in the absorption line profiles from 1978 to 1980.

CONTINUOUS TIME-RESOLVED SPECTROSCOPY OF THE AM HERCULIS BINARY 0139-68.

ABSTRACT Results of single-trailed spectrograms of the magnetic accreting white-dwarf binary 0139 - 68 are presented. The spectral resolution is approximately 2.5 A and the time resolution is 45 seconds. Line-profile changes and radial velocities are derived and described. A discussion of possible orbital velocities indicates probable masses of 0.2-0.6 solar mass for the white-dwarf primary and 0.3 solar mass for the M-star secondary. The position of the active pole is suggested. The origin of the high-velocity line components is not clear, but their behavior is similar to those in the system VV Pup.

IUE observations of proto-planetary and variable planetary nebulae. I - V1016 Cygni, HM Sagittae, and HBV 475. II - A search for variability in IC 4997 and NGC 6905

view Abstract Citations (47) References (47) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS IUE observations of proto-planetary nebulae. I. V1016 Cyg, HM SGE andHBV 475. Feibelman, W. A. Abstract The IUE satellite has undertaken UV observations of the proto-planetary nebulae V1016 Cyg, HM Sge, and HBV 475, yielding emission line fluxes, line ratios, line profiles, electron densities, and distances from these objects. While levels of increasing excitation and ionization as a function of time are shown by the data for the first two nebulae, the trend for HBV 475 is found to lead in the opposite direction. The formation of a shell is suggested by dramatic changes in the HM Sge UV line profiles over the last four years, including the disappearance of W-R features and the incipient splitting of the semi-forbidden C III 1909 A line. An additional IUE search for UV variability in the planetary nebulae IC 4997 and NGC 6905 has yielded emission line fluxes, line ratios and profiles, and central star temperatures, as well as stratification effects data for several ions in NGC 6905 Publication: The Astrophysical Journal Pub Date: July 1982 DOI: 10.1086/160105 Bibcode: 1982ApJ...258..548F Keywords: Emission Spectra; Iue; Line Spectra; Planetary Nebulae; Protoplanets; Ultraviolet Spectra; Electron Density (Concentration); Ionization; Molecular Excitation; Stellar Temperature; Astronomy full text sources ADS | data products SIMBAD (6) MAST (1) INES (1) Related Materials (1) Part 2: 1982ApJ...258..562F

The light variations of nonradial pulsators - Theory and application to the line profile variable 53 Persei

view Abstract Citations (113) References (23) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The light variations of nonradial pulsators: theory and application to the line profile variable 53 Persei. Buta, R. J. ; Smith, M. A. Abstract The nonradial pulsator 53 Persei (B4.5 V) has been observed during 13 nights in late 1977 to determine whether its photometric variations are reminiscent of its spectral line profile changes. Inspection of the resulting light curve shows a variable amplitude with an estimated time scale of 1.9 days. Simultaneous photographic spectroscopy confirms this behavior. The light variations can be modeled successfully with a pair of sinusoidal oscillations having closely spaced periods near 1.7 and 2.1 days and amplitudes of 0.03-0.04 mag. The theory of linear, adiabatic nonradial oscillations is developed for low-order modes and applied to 53 Per. In general, sinusoidal light variations are produced by two geometric distortions of the star (the projected surface area and distorted surface normal effects) and a local compression of the gas. For the long periods observed in 53 Per, compression caused by horizontal motions in traveling waves is predicted to be the primary source of light variations. However, our predicted light amplitudes are about an order of magnitude larger than those observed. The source of the disagreement can be traced to our assumption of adiabaticity. Moreover, our observed color curve is half a cycle out of phase with the predicted light curve arising from this compression (temperature) effect. This suggests again substantial departures from adiabaticity in this long- period object. Nonradial theory also predicts that a star's rotation will split a nonradial mode into several closely spaced frequencies. An analysis of the two close frequencies in our photometric data leads to a rotational velocity which agrees to within 17% of the spectroscopic value. Our solution precludes stellar models with rapidly rotating cores. It also places a condition on the two rn-mode indices: Am = 1. We are able to place firm constraints on the physical identifications of the observed rn-mode pair, namely, m = - I, - I + 1, where 1 = 2 or 3, only. There is some difficulty in interpreting the great length of the 1.9 day period. In linear theory a single overtone of very high order (k 20) would be required. However, if one drops linearity it becomes possible to understand the long periods in terms of nonlinear coupling with a subharmonic or "stray" high-overtone mode. 53 Persei has now become the first star to show both photometric and spectroscopic variations that can best be explained in the framework of nonradial pulsation. Subject headings: stars: individual - stars: pulsation Publication: The Astrophysical Journal Pub Date: August 1979 DOI: 10.1086/157281 Bibcode: 1979ApJ...232..213B Keywords: B Stars; Light Curve; Stellar Spectrophotometry; Variable Stars; Adiabatic Conditions; Least Squares Method; Line Spectra; Sine Waves; Stellar Rotation; Astrophysics; Light Curves:Pulsating Stars; Line Profiles:Pulsating Stars; Photometry:Pulsating Stars; Pulsating Stars:Models; Pulsating Stars:Spectroscopy full text sources ADS | data products SIMBAD (4)

Spectroscopy of WZ Sagittae

WZ Sge was observed spectroscopically during quiescence in August 1978 and July 1979, before and after the December 1978 outburst. The same instrumental set up was used, namely the Image Photon Counting System on the Anglo-Australian Telescope. Time resolved spectra were obtained in phase over several orbital periods, in wavelength ranges covering Hβ and Hγ and also separately Hα. These data are being used to study the “before and after” changes in the emission line profiles, in the radial velocities of the S-wave and of the emission lines, and in the broad absorption line profiles. Additionally these features are being studied as a function of orbital phase in order to improve the determination of system parameters. When completed, the results will be published elsewhere.

Rapid Spectral Variations in Be Stars — New Techniques and Results

AbstractHigh resolution spectral scans of some Be stars, taken with an Isocon television camera, show changes in the Ha line profile in times of the order of a minute or less.

An X-Ray Study on the Relation between Hydrogen Embrittlement and Sulphounic Stress Corrosion in High Tension Steel

It is the object of the present study to clarify the relations in respect of behaviors between the hydrogen detected by the X-ray line profiles in high tension steels, in the class of 80kg/mm2 charged by cathodic hydrogen, and the hydrogen in the steel immersed in hydrogen sulfide solution.As the result of the two tests the following facts have been made clear.(1) In the test made by charging annealed material with cathodic hydrogen, the crystals were deformed plastically, and the lattice of the crystals expanded. In the case of quenched and tempered material, and in the case also of the so-called“received”material, the behaviors of hydrogen detected by the X-ray line profiles are mostly static.(2) In the test made of annealed material in hydrogen sulfide solution, (immersed in the solution non-stressed or restricted by bending stress), there were little change in the X-ray line profiles though the test was continued until crackings by the stress corrosion began to be observed. This was also the case with the so-called“received”material.The following conclusion can be made from the two tests mentioned above: that the hydrogen in the test (1) behaves differently from that in the test (2), and so it is considered that hydrogen is not allowed to invade the lattice of the crystals through hydrogen sulfide solution.

An Atlas of Extreme-Ultraviolet Spectroheliograms from OSO-IV

view Abstract Citations (70) References (9) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS An Atlas of Extreme-Ultraviolet Spectroheliograms from OSO-IV Reeves, E. M. ; Parkinson, W. H. Abstract The atlas contains a collection of far-ultraviolet solar spectroheliograms obtained by the Harvard College Observatory spectrometer on the fourth Orbiting Solar Observatory launched in 1967 October. An extended series of plates depicts composite spectroheliograms as a numerical matrix suitable for quantitative studies and is accompanied by pictorial representation in quasi-photographic form and in the form of contour maps. The necessary photometric conversion factors are contained on each plate to convert the numerical data into emergent solar flux and also flux received at the top of the Earth's atmosphere. Each spectroheliogram is a composite of the best data within the daylight portion of the orbits, and the series includes most of the stronger solar emission lines and continua in the wavelength region 3( A covering stages of ionixation from neutral species to species ionized fifteen times. The spectroheliograms have a spatial resolution of 1 minute of arc. The operational characteristics of the instrument are discussed, together with the wavelength sensitivity, telescope slit function, spectrometer line profile, photometric calibration, and calibration changes on the ground and in orbit. Publication: The Astrophysical Journal Supplement Series Pub Date: August 1970 DOI: 10.1086/190217 Bibcode: 1970ApJS...21....1R full text sources ADS |

Magnetograph measurements with temperature-sensitive lines

Certain discrepancies between theoretical and empirical calibrations of magnetograph response are resolved by recognizing the existence of line profile changes in magnetic regions. Many of the photospheric lines commonly used for magnetic field measurements weaken greatly in magnetic regions outside of sunspots. Unless due account is made of the line profile change, the magnetograph measurements underestimate magnetic flux and field strengths.

The Solar Magnetograph of the High Altitude Observatory

We describe the novel features of a magnetograph which has been designed especially to utilize the Hα emission line for measurement of field intensities in solar prominences. 2-G sensitivity and continuous calibration even during rapid changes in line intensity and profile are achieved.