Doppler imaging of the dwarf nova U Geminorum

Marsh, T. R.; Horne, K.; Schlegel, Eric M.; Honeycutt, R. K.; Kaitchuck, R. H.

doi:10.1086/169446

Cited by 112 publications

(87 citation statements)

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“…The O vi emission probably arises from irradiated turbulent gas around the hot spot, which, after the shock, shares the velocity of the gas stream and the accretion disk. This is identical to the Doppler maps of He ii 4686 and He i 4471 computed for the cataclysmic variable U Gem (Marsh et al 1990). …”

Section: No 2 2003 Bowen Fluorescence In X1822à371supporting

confidence: 82%

Bowen Fluorescence from the Companion Star in X1822−371

Casares

Steeghs

Hynes

et al. 2003

ApJ

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We present clear evidence for the motion of the companion star in the low-mass X-ray binary (LMXB) X1822À371. We detect N iii 4640 emission moving in antiphase with the radial velocity curve of the neutron star and produced on the X-ray-heated hemisphere of the donor star. From the motion of this feature we derive a lower limit to the radial velocity semiamplitude of the companion star, K 2 ! 300 AE 8 km s À1 , which, combined with a previous determination of the inclination angle and the pulsar's radial velocity curve, yields M 2 ! 0:36 2 ð Þ M and M 1 ! 1:14 6 ð Þ M . The He i 4471 absorption line moves at lower velocities ('225 km s À1 ) and with a À0.05 phase shift, suggesting a likely origin on the gas stream near the L1 point. In addition, we detect an S-wave emission of O vi 3811 produced by illumination of the hot spot bulge by the central source. The Balmer lines are dominated by broad absorptions probably due to obscuration of the accretion disk by vertically extended cool material from the splash region and overflowing stream. We also derive a more accurate, and significantly different (compared to earlier work), systemic velocity of ¼ À44 AE 5 km s À1 , based on the motion of the He ii 4686 wings and Doppler tomography. This work confirms the power of imaging the companion stars in LMXBs and outbursting transients using the Bowen fluorescence transitions.

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Section: No 2 2003 Bowen Fluorescence In X1822à371supporting

confidence: 82%

Bowen Fluorescence from the Companion Star in X1822−371

Casares

Steeghs

Hynes

et al. 2003

ApJ

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“…Both of the Balmer tomograms (H and H ) in Marsh et al (1990) show much more prominent stream emission (and comparatively much weaker disk emission) than do our Balmer tomograms. It is possible that we observed U Gem when its disk was especially bright (in H ) or the stream emission especially faint.…”

Section: Optical Tomogramsmentioning

confidence: 44%

“…Even though photon pileup of 30%-50% affects the count rate, a light curve (Fig. 2) constructed by phasing on the 4.25 hr binary period (using the ephemeris of Marsh et al 1990) reveals the usual dip at phase 0.8 that is evident in both outburst (L96) and quiescence (S96), as well as a second dip near phase 0.3 that is apparent in one of the past quiescent data sets (S96). Compensating for the pileup (which reduces the count rate difference between bright and faint features) yields a dip amplitude of $50%, close to that seen in the ASCA Solid-State Imaging Spectrometer (SIS) data (S96).…”

Section: Observationsmentioning

confidence: 99%

“…Past tomograms have shown a relatively featureless disk ring in H (during 1986 and1987;Kaitchuck et al 1994) or a disk ring with a prominent stream emission component superimposed on it (during 1983;Marsh et al 1990), and sometimes a component from the secondary star (Marsh 2000). The accompanying He i 4471 and He ii 4686 tomograms in Marsh et al (1990) show a single locus of emission situated in the ðÀV x ; þV y Þ quadrant, along/ between the stream trajectories (similar to the He i tomogram in Marsh 2000). Emission in this part of the tomogram might originate from matter in the post-stream-impact region of the disk that has not yet fully integrated into the local velocity field of the disk.…”

Section: Optical Tomogramsmentioning

confidence: 99%

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ChandraSpectra of the Prototype Dwarf Nova U Geminorum at Quiescence

Szkody¹,

Nishikida

Raymond

et al. 2002

ApJ

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We have observed the prototypical dwarf nova U Gem at quiescence with the Chandra medium-and highresolution gratings to accomplish the first study of resolved X-ray emission lines in a disk-accreting cataclysmic variable. Doppler tomograms constructed from optical spectra obtained close in time to the X-ray observation show a typical quiescent disk structure with an irradiated secondary but no prominent disk hot spot. The unprecedented spectral resolution of Chandra over past X-ray telescopes reveals prominent narrow emission lines of O, Ne, Mg, Si, S, and Fe. The line fluxes, ratios, and widths indicate that X-ray emission arises from a range of temperatures in a high-density (greater than 10 14 cm À3 ) gas, moving at low (less than 300 km s À1 ) velocity, with a small (less than 10 7 cm) scale height compared to the white dwarf radius. Simple models with cooling flows, cooling flows plus isothermal zones, and thermal conduction give reasonable agreement with the low-temperature emission lines, but a good fit to the entire range of lines will require a better understanding of all the parameters that affect the boundary layer.

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“…The list is worryingly short: only 10 systems (including SDSS J1006) satisfy our criteria, of which one is magnetic (DQ Her). The weighted mean and standard deviation of Gänsicke et al (2000); (4) Thorstensen (2000); (5) Feline et al (2005); (6) Marsh et al (1990); (7) Long & Gilliland (1999); (8) Naylor et al (2005); (9) Echevarría et al (2007); (10) Horne et al (1993); (11) Wood et al (2005); (12) Fiedler et al (1997); (13) Baptista et al (2000); (14) Baptista & Catalán (2001); (15) Thoroughgood et al (2005); (16) Thoroughgood et al (2004). the WD masses is 0.78 ± 0.19 M .…”

Section: Summary and Discussionmentioning

confidence: 99%

Orbital periods of cataclysmic variables identified by the SDSS

Southworth¹,

Hickman²,

Marsh³

et al. 2009

A&A

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We present time-resolved spectroscopy and photometry of SDSS J100658.40+233724.4, which we have discovered to be an eclipsing cataclysmic variable with an orbital period of 0.18591324 days (267.71507 min). The observed velocity amplitude of the secondary star is 276 ± 7 km s −1 , which an irradiation correction reduces to 258 ± 12 km s −1 . Doppler tomography of emission lines from the infrared calcium triplet supports this measurement. We have modelled the light curve using the lcurve code and Markov Chain Monte Carlo simulations, finding a mass ratio of 0.51 ± 0.08. From the velocity amplitude and the light curve analysis we find the mass of the white dwarf to be 0.78 ± 0.12 M and the masses and radii of the secondary star to be 0.40 ± 0.10 M and 0.466 ± 0.036 R , respectively. The secondary component is less dense than a normal main sequence star but its properties are in good agreement with the expected values for a CV of this orbital period. By modelling the spectral energy distribution of the system we find a distance of 676 ± 40 pc and estimate a white dwarf effective temperature of 16 500 ± 2000 K.

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Doppler imaging of the dwarf nova U Geminorum

Cited by 112 publications

References 0 publications

Bowen Fluorescence from the Companion Star in X1822−371

Bowen Fluorescence from the Companion Star in X1822−371

ChandraSpectra of the Prototype Dwarf Nova U Geminorum at Quiescence

Orbital periods of cataclysmic variables identified by the SDSS

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