An Emission Line Model for AM Herculis Systems: Application to E1405-451

1987 ◽  
Vol 7 (2) ◽  
pp. 119-122 ◽  
Author(s):  
Lilia Ferrario ◽  
D. T. Wickramasinghe ◽  
I. R. Tuohy
Keyword(s):  
Emission Line ◽  
White Dwarf ◽  
Velocity Dispersion ◽  
Orbital Plane ◽  
Emission Lines ◽  
Lagrange Point ◽  
Broad Emission ◽  
Straight Line ◽  
Dispersion Data ◽  
The Magnetic Field

AbstractThe optical spectra of the AM Herculis binaries are characterized by extremely complex emission lines whose profiles can be resolved into at least three components which are formed in different regions of the accretion stream leading from the companion star towards the magnetic white dwarf. We present a theoretical model which localizes the formation region of the broad emission line component and provides information regarding the structure of this emitting region. In our model the particle trajectories are integrated in a Roche potential and the volume between the white dwarf and the companion has been divided into two different regimes of motion. In one region the gas escapes from the secondary near the inner Lagrange point and is accelerated along a straight line towards the white dwarf. In the other region the magnetic field is strong enought to divert the gas out of the orbital plane and to channel it towards the white dwarfs surface. The model has been used to interpret radial velocity and velocity dispersion data from the AM Herculis system E1405-451.

scholarly journals Modeling Line Emission from Disk Winds

2009 ◽  
Vol 5 (S267) ◽  
pp. 398-398
Author(s):  
Patrick B. Hall ◽  
Laura S. Chajet
Keyword(s):  
Emission Line ◽  
Accretion Disk ◽  
Line Emission ◽  
Emission Lines ◽  
Broad Emission

Murray & Chiang (1997) developed a model wherein broad emission lines come from the optically thick base of a rotating, outwardly accelerating wind at the surface of an accretion disk. Photons preferentially escape radially in such a wind, explaining why broad emission lines are usually single-peaked. Less well understood are the observed shifts of emission-line peaks (from 1000 km s−1 redshifted to 2500 km s−1 blueshifted in C iv, with an average 800 km s−1 blueshift).

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 Observations of Southern Dwarf Novae

1979 ◽  
Vol 53 ◽  
pp. 497-497
Author(s):  
N. Vogt
Keyword(s):  
Orbital Period ◽  
White Dwarf ◽  
Photometric Data ◽  
Emission Lines ◽  
List Type ◽  
Type Number ◽  
Dwarf Novae ◽  
Broad Emission ◽  
Cataclysmic Binaries ◽  
Short Period

Preliminary results of spectroscopic and photometric data for five dwarf novae are presented : 1) V 436 Cen. The orbital period of 0.0669 days was determined from radial velocity variations. The RV half amplitude of the primary, K1. = 159 km/s, implies very small masses of M1 ≲ 0.20 M⊙ and M2 = 0.18 M⊙ for the binary components.2) Z Cha. Broad emission (Hβ, Hγ, Hδ) and superimposed narrow absorption lines of Hβ-HII, HeI 4471, Cal 4427 and Call K characterize the spectrum during quiescence. Apparently, the cool, optically thin outer disc is seen on the background of a hot continuum, originating from the white dwarf or the inner disc. The RV half amplitude K1 = 87 km/s results in masses of M1 = 1.10 M⊙ and M⊙ = 0.21 M⊙.3) EX Hya. The RV half amplitude K1 = 68 km/s reveals masses of M1 = 1.4 M⊙ and M2 = 0.19 M⊙ The equivalent widths of the emission lines of H, HeI 4471 and HeII 4686 vary with the phase of the recently detected 67 minute cycle (maximal EW coincides nearly with maximal continuum intensity).4) 0Y Car is an eclipsing binary with an orbital period of 0.0631 days. The eclipses show strong variations in shape and amplitude in the course of an outburst, similar as those of Z Cha. The observations seem to confirm that the location of the eruption is the central part of the disc which increases in size and luminosity.5) EK TrA shows periodic superhumps (P = 0.0645 days) during supermaximum, and therefore belongs to the SU UMa sub-group of dwarf novae which are also characterized by a quasi-periodic occurence of super-maxima. The SU UMa sub-group comprises 70% of the ultra-short period cataclysmic binaries, and at least 18% of all dwarf novae.

scholarly journals Stellar velocity dispersions and emission line properties of SDSS-III/BOSS galaxies

2012 ◽  
Vol 8 (S295) ◽  
pp. 129-132
Author(s):  
D. Thomas ◽  
O. Steele ◽  
C. Maraston ◽  
J. Johansson ◽  
A. Beifiori ◽  
...  
Keyword(s):  
Emission Line ◽  
Velocity Dispersion ◽  
Target Selection ◽  
Emission Lines ◽  
Clear Correlation ◽  
Data Set ◽  
Star Forming ◽  
Public Data ◽  
Data Release ◽  
Stellar Velocity

AbstractWe perform a spectroscopic analysis of 492,450 galaxy spectra from the first two years of observations of the Sloan Digital Sky Survey-III/Baryonic Oscillation Spectroscopic Survey (BOSS) collaboration. This data set has been released in the ninth SDSS data release, the first public data release of BOSS spectra. We show that the typical signal-to-noise ratio of BOSS spectra is sufficient to measure stellar velocity dispersion and emission line fluxes for individual objects. The typical velocity dispersion of a BOSS galaxy is 240 km/s, with an accuracy of better than 30 per cent for 93 per cent of BOSS galaxies. The distribution in velocity dispersion is redshift independent between redshifts 0.15 and 0.7, which reflects the survey design targeting massive galaxies with an approximately uniform mass distribution in this redshift interval. The majority of BOSS galaxies lack detectable emission lines. We analyse the emission line properties and present diagnostic diagrams using the emission lines [OII], Hβ, [OIII], Halpha, and [NII] (detected in about 4 per cent of the galaxies). We show that the emission line properties are strongly redshift dependent and that there is a clear correlation between observed frame colours and emission line properties. Within in the low-z sample around 0.15 < z < 0.3, half of the emission-line galaxies have LINER-like emission line ratios, followed by Seyfert-AGN dominated spectra, and only a small fraction of a few per cent are purely star forming galaxies. AGN and LINER-like objects, instead, are less prevalent in the high-z sample around 0.4 < z < 0.7, where more than half of the emission line objects are star forming. This is a pure selection effect caused by the non-detection of weak Hβ emission lines in the BOSS spectra. Finally, we show that star forming, AGN and emission line free galaxies are well separated in the g - r vs r - i target selection diagram.

scholarly journals The WISSH quasars project

2020 ◽  
Vol 635 ◽  
pp. A157 ◽  
Author(s):  
A. Travascio ◽  
L. Zappacosta ◽  
S. Cantalupo ◽  
E. Piconcelli ◽  
F. Arrigoni Battaia ◽  
...  
Keyword(s):  
Average Velocity ◽  
Rest Frame ◽  
Velocity Dispersion ◽  
High Redshift ◽  
Emission Lines ◽  
Host Galaxy ◽  
Uv Emission ◽  
Broad Emission ◽  
Highly Sensitive ◽  
Integral Field

Context. In recent years, Lyα nebulae have been routinely detected around high redshift, radio-quiet quasars thanks to the advent of the highly sensitive integral field spectrographs. Constraining the physical properties of the Lyα nebulae is crucial for a full understanding of the circum-galactic medium (CGM). The CGM acts both as a repository for intergalactic and galactic baryons as well as a venue of feeding and feedback processes. The most luminous quasars are privileged test-beds to study these processes, given their large ionising fluxes and dense CGM environments in which they are expected to be embedded. Aims. We aim to characterise the rest-frame ultraviolet (UV) emission lines in the CGM around a hyper-luminous, broad emission line, radio-quiet quasar at z ∼ 3.6, which exhibits powerful outflows at both nuclear and host galaxy scales. Methods. We analyse VLT/MUSE observations of the quasar J1538+08 (Lbol = 6 × 1047 erg s−1), and we performed a search for extended UV emission lines to characterise its morphology, emissivity, kinematics, and metal content. Results. We report the discovery of a very luminous (∼2 × 1044 erg s−1), giant Lyα nebula and a likely associated extended (75 kpc) CIV nebula. The Lyα nebula emission exhibits moderate blueshift (∼440 km s−1) compared to the quasar systemic redshift and a large average velocity dispersion (σ¯v ∼ 700 km s−1) across the nebula, while the CIV nebula shows average velocity dispersion of σ¯v ∼ 350 km s−1. The Lyα line profile exhibits a significant asymmetry towards negative velocity values at 20−30 kpc south of the quasar and is well parametrised by the following two Gaussian components: a narrow (σ ∼ 470 km s−1) systemic one plus a broad (σ ∼ 1200 km s−1), blueshifted (∼1500 km s−1) one. Conclusions. Our analysis of the MUSE observation of J1538+08 reveals metal-enriched CGM around this hyper-luminous quasar. Furthermore, our detection of blueshifted emission in the emission profile of the Lyα nebula suggests that powerful nuclear outflows can propagate through the CGM over tens of kiloparsecs.

scholarly journals Preliminary Analysis of the Broad He I Emission Lines in R CrB

1985 ◽  
Vol 87 ◽  
pp. 199-202
Author(s):  
R. Surendiranath ◽  
K.E. Rangarajan ◽  
N. Kameswara Rao
Keyword(s):  
Emission Line ◽  
Preliminary Analysis ◽  
Emission Lines ◽  
Minimum Phase ◽  
Physical Conditions ◽  
Light Minimum ◽  
Broad Emission ◽  
Emission Line Spectrum ◽  
Intensity Ratios ◽  
Broad Emission Line

Abstract:During light minimum phase, R CrB shows a broad emission line spectrum of He I including λ10830, λ7065, λ7281, λ3889, λ6678 and λ3188. But λ5876 is very weak. The observed intensity ratios of I(λ3889)/I(λ5876) and I(λ7065)/I(λ5876) were greater than 1. The anomalous intensities of these lines appear to be due to optical depth efects. Peliminary analysis is presented to derive the physical conditions of the emitting gas.

scholarly journals Microlensing Induced Spectral Variability In Q2237+0305

1996 ◽  
Vol 173 ◽  
pp. 241-246
Author(s):  
Geraint F. Lewis ◽  
Mike J. Irwin ◽  
Paul C. Hewett
Keyword(s):  
Emission Line ◽  
Line Emission ◽  
Emission Lines ◽  
Broad Line ◽  
Spectral Variability ◽  
Broad Emission ◽  
Quasar Spectra ◽  
Line Region ◽  
Broad Emission Line ◽  
The Continuum

The degree of microlensing induced amplification is dependent upon the size of a source. As quasar spectra consist of the sum of emission from different regions this scale dependent amplification can produce spectral differences between the images of a macrolensed quasar. This paper presents the first direct spectroscopic evidence for this effect, providing a limit on the scale of the continuum and the broad line emission regions at the center of a source quasar (2237+0305). Lack of centroid and profile differences in the emission lines indicate that substructure in the broad emission line region is > 0.05 parsecs.

scholarly journals Dichotomy of radio loud and radio quiet quasars in four dimensional eigenvector one (4DE1) parameter space

2019 ◽  
Vol 15 (S356) ◽  
pp. 351-354
Author(s):  
Shimeles Terefe ◽  
Ascensión del Olmo ◽  
Paola Marziani ◽  
Mirjana Pović
Keyword(s):  
Emission Line ◽  
Parameter Space ◽  
Signal To Noise Ratio ◽  
High Redshift ◽  
Emission Lines ◽  
Signal To Noise ◽  
Broad Emission ◽  
Broad Emission Line ◽  
Two Populations ◽  
Calar Alto

AbstractRecent work has shown that it is possible to systematize quasars (QSOs) spectral diversity in 4DE1 parameter space. The spectra contained in most of the surveys have low signal to noise ratio which fed the impression that all QSO’s are spectroscopically similar. Exploration of 4DE1 parameter space gave rise to the concept of two populations of QSOs that present important spectroscopic differences. We aim to quantify broad emission line differences between radio quiet and radio loud sources by exploiting more complete samples of QSO with spectral coverage in Hβ, MgII and CIV emission lines. We used a high redshift sample (0.35 < z < 1) of strong radio emitter QSOs observations from Calar Alto Observatory in Spain.

scholarly journals The Remarkable Spin-down and Ultrafast Outflows of the Highly Pulsed Supersoft Source of Nova Herculis 2021

2021 ◽  
Vol 922 (2) ◽  
pp. L42
Author(s):  
Jeremy J. Drake ◽  
Jan-Uwe Ness ◽  
Kim L. Page ◽  
G. J. M. Luna ◽  
Andrew P. Beardmore ◽  
...  
Keyword(s):  
White Dwarf ◽  
Emission Lines ◽  
Optical Observations ◽  
High Mass ◽  
X Rays ◽  
Pulse Profile ◽  
X Ray ◽  
Classical Nova ◽  
First Time ◽  
The Magnetic Field

Abstract Nova Her 2021 (V1674 Her), which erupted on 2021 June 12, reached naked-eye brightness and has been detected from radio to γ-rays. An extremely fast optical decline of 2 magnitudes in 1.2 days and strong Ne lines imply a high-mass white dwarf. The optical pre-outburst detection of a 501.42 s oscillation suggests a magnetic white dwarf. This is the first time that an oscillation of this magnitude has been detected in a classical nova prior to outburst. We report X-ray outburst observations from Swift and Chandra that uniquely show (1) a very strong modulation of supersoft X-rays at a different period from reported optical periods, (2) strong pulse profile variations and the possible presence of period variations of the order of 0.1–0.3 s, and (3) rich grating spectra that vary with modulation phase and show P Cygni–type emission lines with two dominant blueshifted absorption components at ∼3000 and 9000 km s−1 indicating expansion velocities up to 11,000 km s−1. X-ray oscillations most likely arise from inhomogeneous photospheric emission related to the magnetic field. Period differences between reported pre- and post-outburst optical observations, if not due to other period drift mechanisms, suggest a large ejected mass for such a fast nova, in the range 2 × 10−5–2 × 10−4 M ⊙. A difference between the period found in the Chandra data and a reported contemporaneous post-outburst optical period, as well as the presence of period drifts, could be due to weakly nonrigid photospheric rotation.

scholarly journals Bardeen-Petterson Effect and Broad HI Profiles of Seyferts

1999 ◽  
Vol 194 ◽  
pp. 313-316
Author(s):  
Rumen Bachev
Keyword(s):  
Black Hole ◽  
Accretion Disk ◽  
Rotation Axis ◽  
Kerr Black Hole ◽  
Orbital Plane ◽  
Emission Lines ◽  
Planar Structure ◽  
X Ray ◽  
Broad Emission ◽  
Schwarzschild Radius

A thin accretion disk could be not only the energy source of AGN but also the matter producing broad emission lines of Seyfert 1 type nuclei (Dumont & Collin-Souffrin, 1990 B). A possible mechanism for this is reprocessing of central hard X-ray radiation by the outer (at 102–5 RG, RG is the Schwarzschild radius), low-temperature regions of the disk. This mechanism is effective enough especially if the disk is a non-planar structure (a warped or twisted disk), when the outer parts could be directly seen from the centre. An accretion disk around a Kerr black hole could be twisted if the angular momentum of the accreting gas is initially not aligned with the rotation axis of the hole. Due to the differential Lense-Thirring precession of orbits around a Kerr black hole, a viscous disk is a steady but non-planar structure. This is the well-known Bardeen-Petterson effect (Bardeen & Petterson, 1975). Near the hole, at distances R>RBP, where RBP is the Bardeen-Petterson radius, the flow is aligned with the equatorial plane of the black hole, while at larger distances it is tilted to its initial orbital plane (Fig. 1).

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