Radial Velocities Of Absorption Lines Research Articles

The binary millisecond pulsar PSR J1023+0038 – II. Optical spectroscopy

ABSTRACT We present time-resolved optical spectroscopy of the ‘redback’ binary millisecond pulsar system PSR J1023+0038 during both its radio pulsar (2009) and accretion disc states (2014 and 2016). We provide observational evidence for the companion star being heated during the disc state. We observe a spectral type change along the orbit, from ∼G5 to ∼F6 at the secondary star’s superior and inferior conjunction, respectively, and find that the corresponding irradiating luminosity can be powered by the high-energy accretion luminosity or the spin-down luminosity of the neutron star. We determine the secondary star’s radial velocity semi-amplitude from the metallic (primarily Fe and Ca) and Hα absorption lines during these different states. The metallic and Hα radial velocity semi-amplitude determined from the 2009 pulsar-state observations allows us to constrain the secondary star’s true radial velocity K2 = 276.3 ± 5.6 km s−1 and the binary mass ratio q = 0.137 ± 0.003. By comparing the observed metallic and Hα absorption-line radial velocity semi-amplitudes with model predictions, we can explain the observed semi-amplitude changes during the pulsar state and during the pulsar/disc-state transition as being due to different amounts of heating and the presence of an accretion disc, respectively.

Properties of the redback millisecond pulsar binary 3FGL J0212.1+5320

Linares et al. (2016) obtained quasi-simultaneous g', r' and i-band light curves and an absorption line radial velocity curve of the secondary star in the redback system 3FGL J0212.1+5320. The light curves showed two maxima and minima primarily due to the secondary star's ellipsoidal modulation, but with unequal maxima and minima. We fit these light curves and radial velocities with our X-ray binary model including either a dark solar-type star spot or a hot spot due to off-centre heating from an intrabinary shock, to account for the unequal maxima. Both models give a radial velocity semi-amplitude and rotational broadening that agree with the observations. The observed secondary star's effective temperature is best matched with the value obtained using the hot spot model, which gives a neutron star and secondary star mass of $M_{\rm 1}$=1.85$^{+0.32}_{-0.26}$ $M_{\odot}$and $M_{\rm 2}$=0.50$^{+0.22}_{-0.19}$ $M_{\odot}$, respectively.

Dynamical masses of a nova-like variable on the edge of the period gap

We present the first dynamical determination of the binary parameters of an eclipsing SW Sextantis star in the 3–4 h orbital period range during a low state. We obtained time-resolved optical spectroscopy and photometry of HS 0220+0603 during its 2004–2005 low-brightness state, as revealed in the combined Small & Moderate Aperture Research Telescope System, IAC80 and M1 Group long-term optical light curve. The optical spectra taken during primary eclipse reveal a secondary star spectral type of M5.5 ± 0.5 as derived from molecular band-head indices. The spectra also provide the first detection of a DAB white dwarf in a cataclysmic variable. By modelling its optical spectrum we estimate a white dwarf temperature of 30 000 ± 5000 K. By combining the results of modelling the white dwarf eclipse from ULTRACAM light curves with those obtained by simultaneously fitting the emission- and absorption-line radial velocity curves and I-band ellipsoidal light curves, we measure the stellar masses to be M1 = 0.87 ± 0.09 M⊙ and M2 = 0.47 ± 0.05 M⊙ for the white dwarf and the M dwarf, respectively, and an inclination of the orbital plane of i ≈ 79°. A radius of 0.0103 ± 0.0007 R⊙ is obtained for the white dwarf. The secondary star in HS 0220+0603 is likely too cool and undersized for its mass.

High ions towards white dwarfs: circumstellar line shifts and stellar temperature

Based on a compilation of OVI, CIV, SiIV and NV data from IUE, FUSE, GHRS, STIS, and COS, we derive an anti- correlation between the stellar temperature and the high ion velocity shift w.r.t. to the photosphere, with positive (resp. negative) velocity shifts for the cooler (resp. hotter) white dwarfs. This trend probably reflects more than a single process, however such a dependence on the WD's temperature again favors a CS origin for a very large fraction of those ion absorptions, previously observed with IUE, HST-STIS, HST-GHRS, FUSE, and now COS, selecting objects for which absorption line radial velocities, stellar effective temperature and photospheric velocity can be found in the literature. Interestingly, and gas in near-equilibrium in the star vicinity. It is also probably significant that the temperature that corresponds to a null radial velocity, i.e. \simeq 50,000K, also corresponds to the threshold below which there is a dichotomy between pure or heavy elements atmospheres as well as some temperature estimates for and a form of balance between radiation pressure and gravitation. This is consistent with ubiquitous evaporation of orbiting dusty material. Together with the fact that the fraction of stars with (red-or blue-) shifted lines and the fraction of stars known to possess heavy species in their atmosphere are of the same order, such a velocity-temperature relationship is consistent with quasi-continuous evaporation of orbiting CS dusty material, followed by accretion and settling down in the photosphere. In view of these results, ion measurements close to the photospheric or the IS velocity should be interpreted with caution, especially for stars at intermediate temperatures. While tracing CS gas, they may be erroneously attributed to photospheric material or to the ISM, explaining the difficulty of finding a coherent pattern of the high ions in the local IS 3D distribution.

The spectral variations of MWC 314

AbstractNew spectra of MWC314 are presented; they indicate that the V/R emission line flux ratios show signs of varying in an opposite way to the absorption line radial velocities. The latter appear to be due to apparently non-periodic pulsations, perhaps in strange modes.

Analysis of the variability of the luminous emission line star MWC 314

Context. We investigated the surroundings of MWC 314 in the framework of the study of hot emission line star environments using the SAC method. This star is either a B[e] supergiant or a luminous blue variable and appears to be extremely luminous and massive. Aims. We determine the structure and physical conditions of the emitting region and study the possible variations. Methods. We measured the absorption and emission line radial velocities and the emission line fluxes on high-resolution spectra obtained with Aurelie at the 1.52 m OHP telescope in July 1998, with Elodie at the 1.93 m OHP telescope at various epochs, and with echelle spectrographs of the Asiago and Loiano observatories (Italy) in 2006. We used the statistical approach of the self-absorption curve method (SAC) to derive physical parameters of the line-emitting region. Results. We detected drastic variations of the photospheric absorption line radial velocities with time, while the emission line velocities appear to be stable. The Cr II, Ti II, and Fe II emission lines have a complex structure. They are double-peaked, and each of these two 60 km s -1 separated components, is composed of a narrow and a broad component, while the [Fe II] line components are narrower. The fit of the various components of the Fe II lines to a SAC curve indicates that their intensities are affected by some self absorption. We obtained a Boltzmann-type population law whose mean excitation temperature is 6500 +1500 -1000 K for the narrow component lower and upper levels. We obtained a higher Boltzmann-type population law of 10 500 +3000 -2000 K for the forbidden transition upper levels. Conclusions. From the absorption lines we confirm the binarity for MWC 314. The periodicity has nevertheless to be improved with a higher sampling frequency. Our results from the emission lines are consistent with line formation in a rotating disk around a star. The typical minimum radius of the line emitting region obtained from the SAC study is 3.5 x 10 13 cm (2.0 x 10 13 cm < R < 6.3 x 10 13 cm). We argue, in the framework of a very simplified geometrical model, that the [Fe II] lines are emitted farther out than the permitted Cr II, Ti II, and Fell lines, in a disk inclined 25 ± 5 degrees to the plane of sky. If the rotation of the disk is Keplerian, the Fell lines are emitted in a zone defined by 4 x 10 12 cm < R < 7 x 10 13 cm, while for a rotation with conservation of angular momentum, they are emitted from 4 x 10 12 cm < R < 2 x 10 13 cm.

The eccentric accretion disc of the black hole A0620−00★

We present spectroscopic observations of the quiescent black hole binary A0620-00 with the 6.5-m Magellan Clay telescope at Las Campanas Observatory. We measure absorption-line radial velocities of the secondary and make the most precise determination to date (K-2 = 435.4 +/- 0.5 km s(-1)). By fitting the rotational broadening of the secondary, we refine the mass ratio to q = 0.060 +/- 0.004; these results, combined with the orbital period, imply a minimum mass for the compact object of 3.10 +/- 0.04 M-circle dot. Although quiescence implies little accretion activity, we find that the disc contributes 56 +/- 7 per cent of the light in B and V, and is subject to significant flickering. Doppler maps of the Balmer lines reveal bright emission from the gas stream-disc impact point and unusual crescent-shaped features. We also find that the disc centre of symmetry does not coincide with the predicted black hole velocity. By comparison with smoothed particle hydrodynamics (SPH) simulations, we identify this source with an eccentric disc. With high signal-to-noise ratio (S/N), we pursue modulation tomography of H alpha and find that the aforementioned bright regions are strongly modulated at the orbital period. We interpret this modulation in the context of disc precession, and discuss cases for the accretion disc evolution.

Is FIRST J102347.6+003841 Really a Cataclysmic Binary?

The radio source FIRST J102347.6+003841 was presented as the first radio-selected cataclysmic. In the discovery paper, Bond et al. (2002) show a spectrum consistent with a magnetic AM Her-type system and a light curve with rapid, irregular flickering. In contrast, Woudt, Warner, and Pretorius (2004) found a smoothly-varying light curve with a period near 4.75 h and one minimum per orbit, indicating a dramatic change. We present time-resolved spectra showing a superficially normal, mid-G type photosphere, with no detectable emission lines. The absorption-line radial velocity varies sinusoidally, with semi-amplitude 268 +- 4 km/s, on the orbital period, which is refined to 0.198094(2) d. At this orbital period the secondary's spectral type is atypically early, suggesting an unusual evolutionary history. We also obtained BVI photometry around the orbit. The light curve resembles that given by Woudt et al., and the color modulation is consistent with a heating effect. A simple illumination model matches the observations strikingly well with a Roche-lobe filling secondary near 5650 kelvin being illuminated by a primary giving out around 2 solar luminosities. The modest amplitude of the observed modulation constrains the orbital inclination to be less than about 55 deg, unless the gravity darkening is artificially reduced. The resulting primary star mass is above the Chandrasekhar limit (assuming conventional gravity darkening). We examine the possibility that the compact object in this system is not a white dwarf, in which case this is not actually a cataclysmic variable. On close examination, FIRST J102347.6+003841 defies easy classification.

The Massive Neutron Star or Low-Mass Black Hole in 2S 0921-630

We report on the optical spectroscopy of the eclipsing halo low-mass X-ray binary 2S 0921-630, which reveals the absorption-line radial velocity curve of the K0 III secondary star with a semiamplitude K2 = 92.89 ± 3.84 km s-1, a systemic velocity γ = 34.9 ± 3.3 km s-1, and an orbital period Porb of 9.0035 ± 0.0029 days (1 σ). Given the quality of the data, we find no evidence for the effects of X-ray irradiation. Using the previously determined rotational broadening of the mass donor and applying conservative limits on the orbital inclination, we constrain the compact object mass to be 2.0-4.3 M☉ (1 σ), ruling out a canonical neutron star at the 99% level. Since the nature of the compact object is unclear, this mass range implies that the compact object is either a low-mass black hole with a mass slightly higher than the maximum possible neutron star mass (2.9 M☉) or a massive neutron star. If the compact object is a black hole, it confirms the prediction of the existence of low-mass black holes, while if the object is a massive neutron star, its high mass severely constrains the equation of state of nuclear matter.

Multi-frequency variations of the Wolf-Rayet system HD 193793 (WC7pd+O4-5)

The colliding-wind binary system WR140 (HD193793, WC7pd+O4-5, P=7.94 yr) was monitored in the ultraviolet by IUE from 1979 to 1994 in 35 short-wavelength high-resolution spectra. An absorption-line radial-velocity solution is obtained from the photospheric lines of the O component, by comparison with a single O star. The resulting orbital parameters, e=0.87 +/- 0.05, w=31 degrees +/- 9 degrees and Ko star=25 +/- 15 km s(-1), confirm the large eccentricity of the orbit, within the uncertainties of previous optical studies. This brings the weighted mean UV-optical eccentricity to e=0.85 +/- 0.04. Occultation of the O-star light by the WC wind and the WC+O colliding-wind region results into orbital modulation of the P-Cygni profiles of the C II, CIV and Si IV resonance lines. Near periastron passage, the absorption troughs of those resonance-line profiles increase abruptly in strength and width, followed by a gradual decrease. In particular, near periastron the blue black-edges of the P-Cygni absorption troughs shift to larger out ow velocities. We discuss that the apparently larger wind velocity and velocity dispersion observed at periastron could be explained by four phenomena: (i) geometrical resonance-line eclipse effects being the main cause of the observed UV spectral variability, enhanced by sightline crossing of the turbulent wind-wind collision zone; (ii) the possibility of an orbital-plane enhanced WC7 stellar wind; (iii) possible common-envelope acceleration by the combined WC and O stellar radiation fields; and (iv) possible enhanced radiatively driven mass loss due to tidal stresses, focused along the orbiting line of centers.

Dynamics of Ringed Barred Spiral Galaxies. I. Surface Photometry and Kinematics of NGC 1433 and NGC 6300

This paper presents new near-infrared images and surface photometry and Hα Fabry-Perot radial velocities for NGC 1433 and NGC 6300, two large and previously well-studied nearby ringed barred spiral galaxies. Stellar absorption-line radial velocities and new optical surface photometry are also presented for NGC 1433. The data are intended to set the stage for dynamical modeling of the two galaxies, with the principal goals being to derive mass distributions, bar mass-to-light ratios, bar pattern speeds, and resonance locations, parameters which have been derived for very few ringed disk galaxies. The presence of strong rings and pseudorings in the two galaxies allows the possibility to link specific orbital resonances with the observed rings. The new data allow us to derive a fairly complete composite rotation curve of NGC 1433, leading us to make some interesting preliminary judgments about the structure of the galaxy. The new data also verify the previous finding that the radial velocity of the Seyfert nucleus in NGC 6300 differs from the actual systemic velocity of the galaxy by nearly 100 km s-1. We demonstrate in this paper that the offset is not an artifact of significant extinction in the inner regions of the galaxy.

The system parameters of the polars MR Ser and ST LMi

We obtain the Na I λλ8183, 8195 absorption-line radial velocity curves for the polars ST LMi and MR Ser, from which we find the semi-amplitudes to be Kabs = 329 ± 6 and 289 ± 9 km s−1 respectively. We find that for both systems the effects on the Na I absorption lines due to X-rays heating the inner face of the secondary are negligible, and so the values obtained for Kabs can be taken as the true semi-amplitude of the secondary star. We then determine the projected rotational velocities, Vrot sini, to be 104 ± 9 and 66 ± 13 km s−1 for ST LMi and MR Ser respectively, and this enables their mass ratios to be calculated. For ST LMi and MR Ser we find the mass ratios to be 0.22 ± 0.04 and 0.10 ± 0.05 respectively, values which are significantly different only at the 94 per cent level. Using the value for the orbital inclination derived from polarimetric measurements, we determine the mass, and the orbital and rotational velocities of the secondary stars. These are significantly different at less than the 90 per cent level. However, if the limb darkening is the same in both objects, these quantities are significantly different at the 96 per cent level. We present Doppler maps of the Na I absorption and Ca II emission in ST LMi and MR Ser. In both systems the Na i absorption covers the secondary star. In ST LMi the Doppler image of the Ca II emission shows that it originates at the inner face of the secondary star. In MR Ser, however, the emission lies close to but not on the secondary star. We show that the ‘spike’ in the orbital period distribution of polars is a significant feature, although the discovery of only one more system with a period outside the ‘spike’ would decrease its significance below a 99 per cent confidence level. We conclude that, even if the limb-darkening coefficients for the secondary stars in ST LMi and MR Ser are the same, we cannot rule out the possibility of the two systems having identical parameters. Our observations are therefore compatible with the theory explaining the ‘spike’ in the period distribution of the AM Hers.

The discovery of a brake on the white dwarf in AE Aquarii

We report the discovery of a rapid spindown of the 33-s rotation period of the white dwarf in AE Aqr at a steady rate of 5.64×10 −14 s s −1 over a baseline of at least 14.5 yr. The newly derived orbital period by Welsh, Horne & Gomer is confirmed, and it is shown that the secondary star's absorption-line radial velocities provide the correct phasing for the 33-s oscillations if they originate at the white dwarf. The amplitude of the pulse-timing delays, a wd sin i=2.04 s, yields a white dwarf mass of between 0.9 and 1.0 M ○. . The spindown power of the white dwarf is −IΩΩ˙=6×10 33 I 50 erg s −1 , which exceeds the accretion luminosity of AE Aqr by a factor of ∼120

EC 19314 - 5915: a bright, eclipsing cataclysmic variable from the Edinburgh-Cape Blue Object Survey

A deeply eclipsing cataclysmic variable, with an orbital period of 4.75 hr, has been discovered in the southern Edinburgh–Cape Blue Object Survey. The star, EC 19314 – 5915, lies close to the positional constraints of a previously unidentified HEAO-1 hard X-ray source, 1H1930 – 589. Its optical spectrum is unusual in that it shows, apart from the emission lines characteristic of a nova-like, or dwarf nova cataclysmic variable (Balmer, He I and He II), metallic absorption lines typical of a late-G star. These lines come from a probable third stellar component in the system: a G8 dwarf, which contributes ∼ 23 per cent of the light at B. The individual time-resolved spectra, with the tertiary absorption lines removed, show absorption reversals in the Balmer emission lines, increasing in strength for the higher series. The Balmer emission radial velocities are therefore severely distorted in comparison to the He IIλ4686-Å emission and He Iλ4471-Å absorption radial velocity curves. While dynamical solutions based on the emission lines are problematic, as in most CVs, a consistent result for this system is derived using the He Iλ4471-Å absorption-line radial velocity amplitude. An independent distance estimate of ∼ 600 pc is derived for EC19314 – 5915, from the spectroscopic parallax of the third star.

Optical spectroscopy of SN 1987A

AbstractMt John Observatory photographic spectra of SN 1987A have been obtained on 111 nights during the first year at resolutions of 1.1 Å (blue) and 1.6 Å (red). The early spectra are dominated by broad P Cygni profiles from neutral or singly ionised species. Ba absorption lines may be present. After six months nebular emission features emerged, including [OI] 630, 636 nm and two unidentified UV lines (367, 375 nm) in the previously dark region below 380 nm. Absorption line radial velocities show steep declines in the first month, but are almost constant or only slowly decline after 100 days. For the Hα absorption minimum the initial decline rate was 690 ± 70 km s−1d−1 and the initial velocity was −20.2±0.5 Mm s−1 (LMC frame). By 1988 Feb the slowest material in absorption was at −2.2 Mm s−1.The emission maxima of Hα and NaID show anomalous redshifts of about 1.0 Mm s−1. The [OI] lines show no such redshift. Recent [OI] and Hα spectra at higher resolution show ‘fine structure’ in the profiles, indicating inhomogeneity in the ejecta. Hβ, Hγ and Hδ (but not Hα) were all weaker or absent from 1987 late March to early May, but strong thereafter. From about 1987 Mar 18 to Apr 17 Hα showed a bump on the blue side of the emission at 647 nm and a double peak (658 and 668 nm). Absorption bumps in the Hα profile in early spectra (1987 Feb) may be due to circumstellar water vapour.

WZ Sagittae - Recent observations leading to a model for superhump phenomena

view Abstract Citations (22) References (20) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS WZ Sagittae : recent observations leading to a model for superhump phenomena. Gilliland, R. L. ; Kemper, E. Abstract The short-period eclipsing binary system and recurrent nova WZ Sge (1913, 1946, 1978) was observed spectroscopically during its renewed 1978 December outburst. Absorption-line radial velocities and H-alpha emission profiles suggest a circumbinary 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. Publication: The Astrophysical Journal Pub Date: March 1980 DOI: 10.1086/157810 Bibcode: 1980ApJ...236..854G Keywords: Dwarf Stars; Eclipsing Binary Stars; Novae; Radial Velocity; Stellar Models; Stellar Spectra; Emission Spectra; H Alpha Line; Stellar Mass Accretion; Stellar Spectrophotometry; Astrophysics full text sources ADS | data products SIMBAD (2)

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.

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

Raies n�bulaires et coronales dans le spectre infrarouge de la Nova Delphini

Nova Delphini 1967 has been observed in the red and photographic infrared at the Haute-Provence Observatory from September 7 to November 12, 1968. Dispersions range from 230 A/mm to 4 A/mm. The slope of the continuous spectrum in the region 1.3–1.7 μ−1 leads to a gradient of 3.06, which did not appear to vary during the observing period. This gradient is, however, very different from the value 1.71 measured on plates secured in August 1968. Lines ofHi, Hei, Heii, Feii,Oi,Cii and forbidden transitions due toOi,Oii, Fevii, Fex, Fexi,Siii,Aiii,Av,Axi and Nixv have been identified. Their intensities at various dates are given in Table II. Line profiles could be measured for a few lines taken on a 39 A/mm spectrogram on October 3. Hei λ 6678 and λ 7065 are displayed on Figures 2 and 3. Figure 4 gives the [Oii] doublet at λ 7319–7330, while the Hα profile, obtained on October 4 can be seen on Figure 5. The line extends over more than 45 A and narrow absorptions are seen at λλ 6551.05; 6555.75; 6563.15; 6571.49; 6574.45. Due to the absence of published data on radial velocities of absorption lines in the visible spectrum at that time, it is not possible to give a clear identification for these features. Some of them may belong to Hα, while others are probably due to metals.