scholarly journals Time-Resolved Spectroscopy of Accretion Disks in Algols

1989 ◽  
Vol 107 ◽  
pp. 51-61 ◽  
Author(s):  
Ronald H. Kaitchuck
Keyword(s):  
Emission Line ◽  
Accretion Disks ◽  
Velocity Fields ◽  
Continuum Emission ◽  
Turbulent Structures ◽  
Time Resolved ◽  
Time Resolved Spectroscopy ◽  
Long Period ◽  
Short Period ◽  
The Impact

AbstractTime-resolved spectroscopy during the eclipse of short-period Algol systems, has shown their accretion disks to be small, turbulent structures with non-Keplerian velocity fields and asymmetries between the leading and trailing sides of the disk. These transient disks are produced by the impact of the gas stream on the mass-gaining star, and occur in systems where the star is just large enough to ensure the stream collision is complete. These emission line disks and the excess continuum emission do not always occur together. The permanent accretion disks in at least a few of the long-period Algol systems have features in common with the transient disks including non-Keplerian velocity fields.

scholarly journals Characterizing Quasar C iv Emission-line Measurements from Time-resolved Spectroscopy

2020 ◽  
Vol 899 (2) ◽  
pp. 96
Author(s):  
Angelica B. Rivera ◽  
Gordon T. Richards ◽  
Paul C. Hewett ◽  
Amy L. Rankine
Keyword(s):  
Emission Line ◽  
Time Resolved ◽  
Time Resolved Spectroscopy

scholarly journals Time-Resolved Spectroscopy and Doppler Tomography of UX UMa

2004 ◽  
Vol 194 ◽  
pp. 270-270 ◽  
Author(s):  
V. F. Suleimanov ◽  
V. V. Neustroev ◽  
N. V. Borisov ◽  
I. S. Fioktistova
Keyword(s):  
Radial Velocity ◽  
Emission Line ◽  
Orbital Period ◽  
Velocity Curve ◽  
Cataclysmic Variable ◽  
Radial Velocity Curve ◽  
Doppler Tomography ◽  
Time Resolved ◽  
Time Resolved Spectroscopy ◽  
Medium Resolution

Medium resolution spectroscopy of nova-like cataclysmic variable UX UMA was performed using the 6-m telescope SAO RAS in April 1999. Obtained spectra cover the total orbital period including eclipse phases and allow us to reproduce the radial velocity curve. The radial-velocity variations of the Hβ emission line are found to have semi-amplitude of about 100 km/s.

scholarly journals Freezing: how do water mites (Acari: Hydrachnidia) survive exposure to sub-zero temperatures?

2021 ◽  
Author(s):  
Andrzej Zawal ◽  
Tomasz Czernicki ◽  
Grzegorz Michoński ◽  
Aleksandra Bańkowska ◽  
Robert Stryjecki ◽  
...  
Keyword(s):  
Survival Rate ◽  
Survival Rates ◽  
Living Environment ◽  
Individual Species ◽  
Water Mites ◽  
Climatic Zones ◽  
Long Period ◽  
Short Period ◽  
The Moment ◽  
The Impact

AbstractUntil now, very little is known about the ability of adult and deutonymph water mites (Acari, Hydrachnidia) to survive in sub-zero temperatures. Information concerns mainly water mites from vernal astatic waters, and the knowledge has never been experimentally verified. To determine the sensitivity of water mites to freezing, experiments were conducted on (1) the impact of acclimatization, (2) temperature, and (3) duration of freezing on survival, (4) the survival rate of water mites from various types of water bodies, and (5) the survival rate of water mites from different climatic zones. The experiments were carried out in a phytotron chamber, and water mites were placed in containers (10 × 10 × 5 cm) filled with 4/5 of water for 10 specimens each. Water mites were identified to the species level after finishing the experiments. The temperature was lowered 1 °C every hour until the target temperature was reached. After a certain period of freezing (depending on the treatment) the temperature was raised by 1 °C every hour until it reached 4 °C. The time of the experiment was measured from the moment the desired temperature was reached (below 0 °C) until the ice thawed and the temperature of 4 °C was reached again. The highest survival rates had Limnochares aquatica, Piona nodata, Sperchon clupeifer and Lebertia porosa, followed by L. insignis, Hygrobates longipalpis, H. setosus, Limnesia undulatoides, Piona pusilla, Arrenurus globator, Hydrodroma despiciens, Piona longipalpis, Sperchonopsis verrucosa, Unionicola crassipes and Mideopsis crassipes; no specimens of Torrenticola amplexa survived. The following conclusions were drawn: (1) water mites can survive freezing to −2 °C, lower temperatures are lethal for them; (2) they survived better the short period of freezing (24–48 h) than the long period (168 h); (3) resistance to freezing seems to be an evolutionary trait of individual species, only partly related to the living environment; and (4) freezing survival rates are linked to the region of Europe and are much lower in Southern than in Central Europe.

scholarly journals STATISTICAL TIME-RESOLVED SPECTROSCOPY: A HIGHER FRACTION OF SHORT-PERIOD BINARIES FOR METAL-RICH F-TYPE DWARFS IN SDSS

2015 ◽  
Vol 806 (1) ◽  
pp. L2 ◽  
Author(s):  
T. Hettinger ◽  
C. Badenes ◽  
J. Strader ◽  
S. J. Bickerton ◽  
T. C. Beers
Keyword(s):  
Time Resolved ◽  
Time Resolved Spectroscopy ◽  
Short Period ◽  
Statistical Time

scholarly journals Quantifying the impact of variable BLR diffuse continuum contributions on measured continuum interband delays

2019 ◽  
Vol 489 (4) ◽  
pp. 5284-5300 ◽  
Author(s):  
K T Korista ◽  
M R Goad
Keyword(s):  
Emission Line ◽  
Power Laws ◽  
Continuum Emission ◽  
Reverberation Mapping ◽  
Density Distributions ◽  
Line Region ◽  
Total Light ◽  
Approximate Power ◽  
Dc Component ◽  
The Impact

ABSTRACT We investigate the contribution of reprocessed continuum emission (1000–10 000 Å) originating in broad-line region (BLR) gas, the diffuse continuum (DC), to the wavelength-dependent continuum delays measured in AGN disc reverberation mapping experiments. Assuming a spherical BLR geometry, we adopt a Local Optimally emitting Cloud (LOC) model for the BLR that approximately reproduces the broad emission-line strengths of the strongest UV lines (Ly α and C iv) in NGC 5548. Within this LOC framework, we explore how assumptions about the gas hydrogen density and column density distributions influence flux and delay spectra of the DC. We find that: (i) models which match well measured emission-line luminosities and time delays also produce a significant DC component, (ii) increased $\rm {\mathit{ n}_H}$ and/or $\rm {\mathit{ N}_H}$, particularly at smaller BLR radii, result in larger DC luminosities and reduced DC delays, (iii) in a given continuum band the relative importance of the DC component to the measured interband delays is proportional (though not 1:1) to its fractional contribution to the total light in that band, (iv) the measured DC delays and DC variability amplitude depend also on the variability amplitude and characteristic variability time-scale of the driving continuum, (v) the DC radial surface emissivity distributions F(r) approximate power laws in radius with indices close to −2 (≈1:1 response to variations in the driving continuum flux), thus their physics is relatively simple and less sensitive to the unknown geometry and uncertainties in radiative transfer. Finally, we provide a simple recipe for estimating the DC contribution in disc reverberation mapping experiments.

scholarly journals Libration-induced Orbit Period Variations Following the DART Impact

2021 ◽  
Vol 2 (6) ◽  
pp. 242
Author(s):  
Alex J. Meyer ◽  
Ioannis Gkolias ◽  
Michalis Gaitanas ◽  
Harrison F. Agrusa ◽  
Daniel J. Scheeres ◽  
...  
Keyword(s):  
Momentum Transfer ◽  
Binary Asteroid ◽  
Long Period ◽  
Short Period ◽  
Planetary Defense ◽  
Period Variations ◽  
Post Impact ◽  
Binary Asteroid System ◽  
Orbit Period ◽  
The Impact

Abstract The Double Asteroid Redirection Test (DART) mission will be the first test of a kinetic impactor as a means of planetary defense. In late 2022, DART will collide with Dimorphos, the secondary in the Didymos binary asteroid system. The impact will cause a momentum transfer from the spacecraft to the binary asteroid, changing the orbit period of Dimorphos and forcing it to librate in its orbit. Owing to the coupled dynamics in binary asteroid systems, the orbit and libration state of Dimorphos are intertwined. Thus, as the secondary librates, it also experiences fluctuations in its orbit period. These variations in the orbit period are dependent on the magnitude of the impact perturbation, as well as the system’s state at impact and the moments of inertia of the secondary. In general, any binary asteroid system whose secondary is librating will have a nonconstant orbit period on account of the secondary’s fluctuating spin rate. The orbit period variations are typically driven by two modes: a long period and a short period, each with significant amplitudes on the order of tens of seconds to several minutes. The fluctuating orbit period offers both a challenge and an opportunity in the context of the DART mission. Orbit period oscillations will make determining the post-impact orbit period more difficult but can also provide information about the system’s libration state and the DART impact.

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