Recent Photometric and Spectroscopic Observations of Southern Dwarf Novae

1979 ◽  
Vol 46 ◽  
pp. 24-28
Author(s):  
N. Vogt
Keyword(s):  
Orbital Period ◽  
Special Interest ◽  
Dwarf Novae ◽  
Spectroscopic Observations ◽  
Photometric And Spectroscopic Observations ◽  
Cataclysmic Binaries

This contribution concerns three dwarf novae of special interest: one of them has the longest known orbital period of all dwarf novae (BV Cen); the remaining two variables (Z Cha and EX Hya) belong to the group of the ultra-short periodic cataclysmic binaries. Here only short summaries are given. The detailed results will be published elsewhere, in the case of BV Cen together with J. Breysacher, and in the case of EX Hya together with D. Comte, C. Sterken and W. Krzeminski.

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 Simultaneous Multiwavelength Observations of Dwarf Novae Systems at Quiescence and in Outburst

1996 ◽  
Vol 158 ◽  
pp. 79-80
Author(s):  
G. Tovmassian ◽  
J. Echevarria ◽  
E. Perez ◽  
D. H. P. Jones ◽  
M. Shara ◽  
...  
Keyword(s):  
Dwarf Novae ◽  
Preliminary Results ◽  
International Program ◽  
Spectroscopic Observations ◽  
Photometric And Spectroscopic Observations ◽  
Photometric Observations ◽  
Northern And Southern Hemispheres ◽  
Multiwavelength Observations

The results of photometric and spectroscopic observations of dwarf novae are presented. The data were obtained during an international program of multiwavelength observations, held in 1986 February at several observatories, of dwarf novae during the first and subsequent days of outburst. During the campaign numerous dwarf novae were monitored in order to catch them in outburst. Preliminary results and analysis of some objects are reported elsewhere. A total of 30 dwarf novae were observed in the northern and southern hemispheres. Among them 37% were caught in outburst, including 10% on the rise to outburst and 17% in decline. Photometric observations were carried out in the UBVRI system and colour indexes were calculated.

scholarly journals ASASSN-18aan: An eclipsing SU UMa-type cataclysmic variable with a 3.6-hr orbital period and a late G-type secondary star

2021 ◽  
Author(s):  
Yasuyuki Wakamatsu ◽  
John R Thorstensen ◽  
Naoto Kojiguchi ◽  
Keisuke Isogai ◽  
Mariko Kimura ◽  
...  
Keyword(s):  
Spectral Type ◽  
Orbital Period ◽  
Mass Ratio ◽  
Dwarf Novae ◽  
Tidal Dissipation ◽  
High Q ◽  
Secondary Star ◽  
Long Period ◽  
Photometric And Spectroscopic Observations ◽  
Sodium Abundance

Abstract We report photometric and spectroscopic observations of the eclipsing SU UMa-type dwarf nova ASASSN-18aan. We observed the 2018 superoutburst with 2.3 mag brightening and found the orbital period (Porb) to be 0.149454(3) d, or 3.59 hr. This is longward of the period gap, establishing ASASSN-18aan as one of a small number of long-Porb SU UMa-type dwarf novae. The estimated mass ratio, [q = M2/M1 = 0.278(1)], is almost identical to the upper limit of tidal instability by the 3 : 1 resonance. From eclipses, we found that the accretion disk at the onset of the superoutburst may reach the 3 : 1 resonance radius, suggesting that the superoutburst of ASASSN-18aan results from the tidal instability. Considering the case of long-Porb WZ Sge-type dwarf novae, we suggest that the tidal dissipation at the tidal truncation radius is enough to induce SU UMa-like behavior in relatively high-q systems such as SU UMa-type dwarf novae, but that this is no longer effective in low-q systems such as WZ Sge-type dwarf novae. The unusual nature of the system extends to the secondary star, for which we find a spectral type of G9, much earlier than typical for the orbital period, and a secondary mass M2 of around 0.18 M⊙, smaller than expected for the orbital period and the secondary’s spectral type. We also see indications of enhanced sodium abundance in the secondary’s spectrum. Anomalously hot secondaries are seen in a modest number of other CVs and related objects. These systems evidently underwent significant nuclear evolution before the onset of mass transfer. In the case of ASASSN-18aan, this apparently resulted in a mass ratio lower than typically found at the system’s Porb, which may account for the occurrence of a superoutburst at this relatively long period.

scholarly journals First detection of two superoutbursts during the rebrightening phase of a WZ Sge-type dwarf nova: TCP J21040470+4631129

2020 ◽  
Vol 72 (3) ◽  
Author(s):  
Yusuke Tampo ◽  
Kojiguchi Naoto ◽  
Keisuke Isogai ◽  
Taichi Kato ◽  
Mariko Kimura ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Accretion Disk ◽  
Late Stage ◽  
Large Radius ◽  
Mass Ratio ◽  
Dwarf Novae ◽  
Dwarf Nova ◽  
Spectroscopic Observations ◽  
The Third ◽  
Photometric And Spectroscopic Observations

Abstract We report on photometric and spectroscopic observations and analysis of the 2019 superoutburst of TCP J21040470+4631129. This object showed a 9 mag superoutburst with early superhumps and ordinary superhumps, which are the features of WZ Sge-type dwarf novae. Five rebrightenings were observed after the main superoutburst. The spectra during the post-superoutburst stage showed Balmer, He i, and possible sodium doublet features. The mass ratio is derived as 0.0880(9) from the period of the superhump. During the third and fifth rebrightenings, growing superhumps and superoutbursts were observed, which have never been detected during a rebrightening phase among WZ Sge-type dwarf novae with multiple rebrightenings. To induce a superoutburst during the brightening phase, the accretion disk needs to have expanded beyond the 3 : 1 resonance radius of the system again after the main superoutburst. These peculiar phenomena can be explained by the enhanced viscosity and large radius of the accretion disk suggested by the higher luminosity and the presence of late-stage superhumps during the post-superoutburst stage, plus by more mass supply from the cool mass reservoir and/or from the secondary because of the enhanced mass transfer than those of other WZ Sge-type dwarf novae.

Models of Cataclysmic Variables from Photometric and Spectroscopic Data

1979 ◽  
Vol 46 ◽  
pp. 65-74 ◽  
Author(s):  
A.C. Fabian ◽  
J.E. Pringle ◽  
J.A.J. Whelan ◽  
J.A. Bailey
Keyword(s):  
Spectroscopic Data ◽  
Cataclysmic Variables ◽  
System Parameters ◽  
Dwarf Nova ◽  
Spectroscopic Observations ◽  
Photometric And Spectroscopic Observations

Abstract.Recent photometric and spectroscopic observations of the dwarf nova system Z Cha are discussed. Methods for constraining the system parameters are applied and the disc emissivity is deduced as a function of radius. Indications are found that the disc shrinks in size with increasing time after outburst.

scholarly journals An attempt of seismic modelling of β Cephei stars in NGC 6910

2014 ◽  
Vol 9 (S307) ◽  
pp. 222-223
Author(s):  
D. Moździerski ◽  
Z. Kołaczkowski ◽  
E. Zahajkiewicz
Keyword(s):  
Seismic Modeling ◽  
Preliminary Results ◽  
Spectroscopic Observations ◽  
Seismic Modelling ◽  
Photometric And Spectroscopic Observations

AbstractWe present preliminary results of seismic modeling of β Cephei-type stars in NGC 6910 based on simultaneous photometric and spectroscopic observations carried out in 2013 in Białków (photometry) and Apache Point (spectroscopy) observatories.

scholarly journals V 3903 Sagitarii: A Main-Sequence (07V+09V) Detached Eclipsing Binary

1993 ◽  
Vol 137 ◽  
pp. 371-373
Author(s):  
L.P.R. Vaz ◽  
N.C.S. Cunha ◽  
E.F. Vieira ◽  
M.L.M. Myrrha
Keyword(s):  
Main Sequence ◽  
Eclipsing Binary ◽  
Spectroscopic Observations ◽  
Photometric And Spectroscopic Observations ◽  
Absolute Dimensions

AbstractPhotometric and spectroscopic observations of V3903 Sgr are analyzed, and absolute dimensions (masses and radii) are determined to a precision better then 3%.

scholarly journals New photometric and spectroscopic observations of the Seyfert galaxy Mrk 315

2005 ◽  
Vol 360 (1) ◽  
pp. 253-271 ◽  
Author(s):  
S. Ciroi ◽  
V. L. Afanasiev ◽  
A. V. Moiseev ◽  
V. Botte ◽  
F. Di Mille ◽  
...  
Keyword(s):  
Seyfert Galaxy ◽  
Spectroscopic Observations ◽  
Photometric And Spectroscopic Observations
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