scholarly journals Long-Term Photometric and Spectroscopic Behaviour of Symbiotic System AG Dra

2004 ◽  
Vol 194 ◽  
pp. 242-242
Author(s):  
R. Gális ◽  
L. Hric ◽  
K. Petrík
Keyword(s):  
Orbital Period ◽  
White Dwarf ◽  
Velocity Analysis ◽  
Symbiotic System ◽  
General Behaviour ◽  
Cool Component ◽  
Spectroscopic Behaviour ◽  
Thermonuclear Burning ◽  
Second Period

The general behaviour of AG DRA was studied in the context of the long-term photometry and radial velocity analysis.AG DRA is a symbiotic binary with quiescent and active stages; the latter may be explainable by increased thermonuclear burning of a white dwarf accreting from the wind of the cool component.In our previous studies a second period in addition to the orbital period of 549.7 days has been found for AG DRA. Such a period of about 350 days was indicated in our study using photometry (Friedjung et al. 1998, Petrík et al. 1998)as well as radial velocities (Gális et al. 1999 Friedjung et al. 2003).

scholarly journals The Effective Temperature Distribution Function of Cataclysmic Variable White Dwarfs

1987 ◽  
Vol 93 ◽  
pp. 47-51
Author(s):  
E.M. Sion
Keyword(s):  
Distribution Function ◽  
Temperature Distribution ◽  
Orbital Period ◽  
White Dwarf ◽  
White Dwarfs ◽  
Cataclysmic Variables ◽  
Cataclysmic Variable ◽  
Term Evolution ◽  
Effective Temperatures

AbstractWith the recent detection of direct white dwarf photospheric radiation from certain cataclysmic variables in quiescent (low accretion) states, important implications and clues about the nature and long-term evolution of cataclysmic variables can emerge from an analysis of their physical properties. Detection of the underlying white dwarfs has led to a preliminary empirical CV white dwarf temperature distribution function and, in a few cases, the first detailed look at a freshly accreted while dwarf photosphere. The effective temperatures of CV white dwarfs plotted versus orbital period for each type of CV appears to reveal a tendency for the cooler white dwarf primaries to reside in the shorter period systems. Possible implications are briefly discussed.

scholarly journals Multiwavelength Variability in the Symbiotic Nova V1016 CYG

2004 ◽  
Vol 194 ◽  
pp. 224-224
Author(s):  
Š. Parimucha ◽  
M. Vańko
Keyword(s):  
Binary System ◽  
Light Curve ◽  
Orbital Period ◽  
Uv Spectroscopy ◽  
Infrared Photometry ◽  
Symbiotic System ◽  
Photoelectric Photometry ◽  
Mira Variable ◽  
Multiwavelength Variability

Analysis of the optical and infrared photometry together with UV spectroscopy led to discovery of the 15-years periodicity in the symbiotic system V1016 Cyg. This period could be interpreted as a orbital period in the binary system consisting of the Mira variable and the hot white dwarf.We have analyzed long-term optical photographic and UBV photoelectric photometry of V1016 Cyg. Collected observations cover pre- and post-outburst stages of the system. The light, curve suggests four stages of activity: the pre-out burst flare in 1949, the main nova-like outburst in 1904, and two post-outbursts, decreasing-amplitude flares in 1980 and 1994, respectively. Activity episodes affecting the system repeat with an interval of ~ 15 years. The ephemeris for the activity maxima is (see Parimucha et al., 2000).

scholarly journals A comparative two-cohort study of pediatric patients with long term stay in ICUs

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Julia García Mancebo ◽  
Sara de la Mata Navazo ◽  
Estíbaliz López-Herce Arteta ◽  
Rosario Montero Mateo ◽  
Isabel María López Esteban ◽  
...  
Keyword(s):  
Healthcare Resources ◽  
Non Invasive ◽  
Non Invasive Ventilation ◽  
Number Of Patients ◽  
Single Center Study ◽  
High Flow Oxygen ◽  
Hospital Acquired ◽  
Complications And Mortality ◽  
Second Period

AbstractDuring the last decades, the number of patients with long stay admissions (LSA) in PICU has increased. The purpose of this study was to identify factors associated with PICU LSA, assessing healthcare resources use and changes in the profile of these patients. A retrospective, observational, single-center study was carried out. Characteristics of LSA were compared between two periods (2006–2010 and 2011–2015). During the earlier period there were 2,118 admissions (3.9% of them LSA), whereas during the second period, there were 1,763 (5.4% of them LSA) (p = 0.025). LSA accounted for 33.7% PICU stay days during the first period and 46.7% during the second (p < 0.001). Higher use of non-invasive ventilation (80.2% vs. 37.8%, p = 0.001) and high-flow oxygen therapy (68.8% vs. 37.8%, p = 0.005) was observed in the 2011–2015 cohort, whereas the use of arterial catheter (77.1% vs. 92.6%, p = 0.005), continuous infusion of adrenaline (55.2% vs. 75.9%, p = 0.004), and hemoderivative transfusion (74% vs. 89.2%, p = 0.010) was less frequent. In the 2006–2010 cohort, hospital-acquired infections were more common (95.2% vs. 68.8%, p < 0.001) and mortality was higher (26.8% vs. 13.8%, p = 0.026). The number of long-stay PICU admissions have increased entailing an intensive use of healthcare resources. These patients have a high risk for complications and mortality.

scholarly journals The relation between white dwarf mass and orbital period in wide binary radio pulsars

1995 ◽  
Vol 273 (3) ◽  
pp. 731-741 ◽  
Author(s):  
S. Rappaport ◽  
Ph. Podsiadlowski ◽  
P. C. Joss ◽  
R. Di Stefano ◽  
Z. Han
Keyword(s):  
Orbital Period ◽  
White Dwarf ◽  
Radio Pulsars ◽  
Wide Binary

scholarly journals RAPID DECREASING IN THE ORBITAL PERIOD OF THE DETACHED WHITE DWARF–MAIN SEQUENCE BINARY SDSS J143547.87+373338.5

2016 ◽  
Vol 817 (2) ◽  
pp. 151 ◽  
Author(s):  
S.-B. Qian ◽  
Z.-T. Han ◽  
B. Soonthornthum ◽  
L.-Y. Zhu ◽  
J.-J. He ◽  
...  
Keyword(s):  
Orbital Period ◽  
White Dwarf ◽  
Main Sequence

scholarly journals Fluorescence and Chromospheric Activity of V471 Tau

2002 ◽  
Vol 187 ◽  
pp. 167-172
Author(s):  
T.R. Vaccaro ◽  
R.E. Wilson
Keyword(s):  
Light Curve ◽  
Radial Velocity ◽  
Orbital Period ◽  
White Dwarf ◽  
Binary Star ◽  
Star Model ◽  
Orbital Inclination ◽  
Orbital Parameters ◽  
Maximum Emission ◽  
Chromospheric Activity

AbstractThe red dwarf + white dwarf eclipsing binary V471 Tau shows a variable Hα feature that varies from absorption during eclipse to maximum emission during white dwarf transit. In 1998 we obtained simultaneous BVRI photometry and Hα spectroscopy, with thorough phase coverage of the 12.5 hour orbital period. A binary star model was used with our light curve, radial velocity, and Hα data to refine stellar and orbital parameters. Combined absorption-emission profiles were generated by the model and fit to the observations, yielding a red star radius of 0.94R⊙. Orbital inclination 78° is required with this size and other known parameters. The model includes three spots 1,000 K cooler than the surrounding photosphere. The variable Hα profile was modeled as a chromospheric fluorescing region (essentially on the surface of the red star) centered at the substellar point. Additional emission seen outside our modeled profiles may be large co-rotating prominences that complicate the picture.

scholarly journals Superoutbursts and Superhumps of SU UMa Stars

1988 ◽  
Vol 108 ◽  
pp. 238-239
Author(s):  
Yoji Osaki ◽  
Masahito Hirose
Keyword(s):  
Accretion Disk ◽  
Orbital Period ◽  
White Dwarf ◽  
Binary Systems ◽  
Roche Lobe ◽  
Light Curves ◽  
Close Binary ◽  
Dwarf Novae ◽  
Dwarf Nova ◽  
Close Binary Systems

SU UMa stars are one of subclasses of dwarf novae. Dwarf novae are semi-detached close binary systems in which a Roche-lobe filling red dwarf secondary loses matter and the white dwarf primary accretes it through the accretion disk. The main characteristics of SU UMa subclass is that they show two kinds of outbursts: normal outbursts and superoutbursts. In addition to the more frequent narrow outbursts of normal dwarf nova, SU UMa stars exhibit “superoutbursts”, in which stars reach about 1 magnitude brighter and stay longer than in normal outburst. Careful photometric studies during superoutburst have almost always revealed the “superhumps”: periodic humps in light curves with a period very close to the orbital period of the system. However, the most curious of all is that this superhump period is not exactly equal to the orbital period, but it is always longer by a few percent than the orbital period.

scholarly journals Photometry of AM Her Stars – Line and Continuum Emission

1979 ◽  
Vol 53 ◽  
pp. 324-328
Author(s):  
Paula Szkody
Keyword(s):  
Emission Line ◽  
White Dwarf ◽  
Main Sequence ◽  
Close Binary ◽  
Line Spectrum ◽  
Continuum Emission ◽  
Late Type ◽  
Emission Line Spectrum ◽  
Orbital Periods

The 4 known AM Her stars or polars (AM Her, ANUMa, W Pup, and 2A0311-227) are characterized by large circular polarizations of 10-35%, (Tapia 1977a, b, Krzeminski and Serkowski 1977), an emission line spectrum with strong H and He lines (Crampton and Cowley 1977, Greenstein et al. 1977), complex photometric variations (Szkody 1978, Priedhorsky and Krzeminski 1978, Warner & Nather 1972), long term high and low states and short orbital periods (80-180 min.). Models of these systems envision a close binary containing a magnetic white dwarf primary (B ~ 108G) and late type main sequence secondary transferring material into an accretion funnel over one or both poles of the white dwarf (Stockman et al. 1977, Lamb & Masters 1979, Liebert et al. 1978).

scholarly journals CH Cygni and Other Symbiotic Stars with Low Luminosity Hot Components

2004 ◽  
Vol 194 ◽  
pp. 223-223
Author(s):  
L. Leedjärv ◽  
T. Tomov ◽  
M. Mikołajewski ◽  
M. Burmeister
Keyword(s):  
White Dwarf ◽  
Time Scale ◽  
High Velocity ◽  
Activity Period ◽  
Symbiotic Stars ◽  
High Luminosity ◽  
Thermonuclear Burning ◽  
Recent Activity ◽  
Symbiotic Binaries ◽  
Lower Luminosity

Some aspects of the recent activity period of the peculiar symbiotic binary CH Cyg, which has ejected both bipolar jets and discrete centrifugal outflows, are discussed.In symbiotic binaries, the red giant's wind is accreted onto the white dwarf. High luminosity of the hot components (Lhot ~103L⊙, reaching ~104L⊙ in the outbursts) (Mikołajewska 2003; Sokoloski 2003) indicates that the accreted matter undergoes thermonuclear burning. There are about 10 symbiotic stars which have ejected high-velocity, collimated, bipolar jets. Some of them show flickering of the optical light on the time scale of minutes. Both jet ejection and flickering indicate that an accretion disk should be present in those systems. Jet emitting symbiotic stars seem to have lower luminosity of the hot component ( ~1 – 100 L⊙) than in most other symbiotics.

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