scholarly journals The Polarization of the Crab Pulsar with HST

1996 ◽  
Vol 160 ◽  
pp. 301-302
Author(s):  
Joseph F. Dolan ◽  
Patricia T. Boyd ◽  
Robert J. Hill ◽  
F. Graham-Smith ◽  
A. G. Lyne ◽  
...  
Keyword(s):  
Time Resolution ◽  
Linear Polarization ◽  
High Speed ◽  
Hubble Space Telescope ◽  
Position Angle ◽  
Crab Pulsar ◽  
Pulse Profile ◽  
Space Telescope ◽  
Pulse Phase ◽  
Sample Time

The linear polarization of the Crab pulsar as a function of pulse phase was observed by the High Speed Photometer on the Hubble Space Telescope in March, 1993. Observations were obtained in a bandpass centered on 2770 A using a 0.25 ms sample time, corresponding to a time resolution of 0.0075 in pulse phase. The UV polarization of the pulsar [Fig. 1] is strikingly similar to that observed in the visible (cf. Smith et al. 1988). The same values of polarization and the same swing of position angle occur through the main and secondary pulses. The polarization pulse profile must be essentially wavelength independent at frequencies above the infrared.

scholarly journals High Speed UV Photometry of the AM Her Systems AM Her, VV Pup And V834 Cen, with the Hubble Space Telescope

1996 ◽  
Vol 158 ◽  
pp. 223-224
Author(s):  
K. Schaefer ◽  
H. Bond ◽  
G. Chanmugam
Keyword(s):  
Preliminary Analysis ◽  
High Speed ◽  
Hubble Space Telescope ◽  
Cataclysmic Variables ◽  
Low Frequency ◽  
Gabor Transform ◽  
Periodic Oscillations ◽  
Space Telescope ◽  
Uv Photometry ◽  
Magnetic Cataclysmic Variables

We have used the High Speed Photometer (HSP) aboard the Hubble Space Telescope to observe the magnetic cataclysmic variables VV Pup, AM Her, and V834 Cen in the UV (1400…3300 Å) with 0.01 s time resolution. We detected low frequency flickering in all three systems, and compare the time-scales with the predictions of King (1989). At higher frequencies we searched for shock oscillations from the accretion column(s) in these systems. The data were analyzed using the Gabor transform wavelet-like technique (Heil & Walnut 1989) to search for frequency evolution throughout each observation. Preliminary analysis suggests the detection of rapid UV quasi-periodic oscillations (QPOs) in VV Pup at 0.74 Hz, and at 4.4 Hz in V834 Cen. As in ground based observations, our observations failed to yield any rapid QPOs in AM Her itself.

Elliptically Polarized Natural Modes in Pulsar Magnetospheres

1982 ◽  
Vol 4 (4) ◽  
pp. 365-370 ◽  
Author(s):  
Michelle C. Allen ◽  
D.B. Melrose
Keyword(s):  
Circular Polarization ◽  
Linear Polarization ◽  
Strong Support ◽  
Position Angle ◽  
Average Degree ◽  
Pole Model ◽  
Magnetic Pole ◽  
Pulse Profile ◽  
Linearly Polarized ◽  
High Degree

The most obvious feature of the polarization of the radio emission from most pulsars is the rotation of the plane of linear polarization across pulses. The original interpretation of this in terms of the magnetic pole model (Radhakrishnan 1969, Radhakrishnan et al. 1969, Radhakrishnan and Cooke 1969) accounts for the variation of position angle extremely well for some pulsars (e.g. Manchester and Taylor 1977, Manchester 1978). Conversely, this provides strong support for the magnetic pole model for pulsar emission. It also suggests that the emission is basically linearly polarized as implied by virtually all proposed emission mechanisms, e.g. the reviews by Ginzburg and Zheleznyakov (1975) and Arons (1979). However, there are two features of the polarization which require a separate explanation. First, some pulsars have a moderately high degree of circular polarization, even in the integrated pulse profile (Manchester 1971, Lyne, Smith and Graham 1971). In some pulsars the average degree of circular polarization can exceed the average degree of linear polarization, e.g. in PSR 0835-41 and 0959-54 (McCulloch et al. 1978). Second, some pulsars exhibit the phenomenon of transitions between orthogonal elliptical polarizations (Manchester, Taylor and Huguenin 1975, Backer, Rankin and Campbell 1976, Cordes and Hankins 1977, Cordes, Rankin and Backer 1978). In many pulsars the orthogonal polarizations have substantial circular components, e.g. in PSR 1133 + 16 (Manchester et al. 1975) and PSR 2020 + 28 (Cordes et al. 1978).

High-Speed Hubble Space Telescope Ultraviolet photometry of two DB white dwarfs: Nonradial and radial pulsations

1994 ◽  
Vol 107 ◽  
pp. 298 ◽  
Author(s):  
Steven D. Kawaler ◽  
Howard E. Bond ◽  
Lisa E. Sherbert ◽  
Todd K. Watson
Keyword(s):  
High Speed ◽  
White Dwarfs ◽  
Hubble Space Telescope ◽  
Space Telescope ◽  
Radial Pulsations

A Search for a Pulsar in the Remnant of SN 1987A with the Hubble Space Telescope High-Speed Photometer

1995 ◽  
Vol 446 ◽  
pp. 832 ◽  
Author(s):  
J. W. Percival ◽  
P. T. Boyd ◽  
J. D. Biggs ◽  
J. F. Dolan ◽  
R. C. Bless ◽  
...  
Keyword(s):  
High Speed ◽  
Hubble Space Telescope ◽  
Space Telescope ◽  
Sn 1987A

scholarly journals Pulsar Optical Emission as Amplified Synchrotron Emission

1981 ◽  
Vol 95 ◽  
pp. 235-238
Author(s):  
R. J. Stoneham
Keyword(s):  
Optical Emission ◽  
Position Angle ◽  
Main Pulse ◽  
Synchrotron Emission ◽  
Crab Pulsar ◽  
Pulse Profile ◽  
Inverse Compton Scattering ◽  
Inverse Compton ◽  
Linearly Polarized ◽  
Long Time

Pulsed optical emission has been observed from the Crab and Vela pulsars (Manchester and Taylor 1977). The pulse profile of the Crab pulsar has a main pulse and a strong interpulse separated by about 40% of the pulsar period; the peak of the main pulse is just resolved at 20 μs resolution; the spectrum is peaked at about 1014.8 Hz; the pulse profile is constant over long time intervals; both the main pulse and the interpulse are strongly linearly polarized with position angle varying smoothly through each profile and with a minimum of polarization near each peak; the pulses are not significantly circularly polarized. A number of models have been proposed to explain the optical emission from the Crab pulsar but none is completely satisfactory. The spectral peak is too low for incoherent synchrotron emission, the pulse profile is too constant for inverse Compton scattering of radio emission and the similarity with the low-energy X-ray emission argues against coherent curvature emission.

scholarly journals Prospects for space Telescope in the search for other Planetary Systems

1985 ◽  
Vol 112 ◽  
pp. 75-84
Author(s):  
J. L. Russell
Keyword(s):  
High Speed ◽  
Hubble Space Telescope ◽  
Planetary Systems ◽  
Wide Field ◽  
Minor Planets ◽  
Scientific Instruments ◽  
The Moon ◽  
Space Telescope ◽  
Faint Object

The Hubble Space Telescope (ST) will be launched with five dedicated scientific instruments and a capability to do astrometric measurements with the fine guidance sensors. Four of these – the Faint Object Camera, the Wide Field Camera, the Fine Guidance Sensors and the High Speed Photometer – can be used in the search for extrasolar planetary systems. The Faint Object Camera will be able to directly detect planets around a few of the nearby bright stars. The Wide Field Camera and the Fine Guidance Sensors can be used astrometrically, both with an accuracy of about 2 mas per observation. The High Speed Photometer possibly can detect planets during occultation of stars by the moon and minor planets. The ST is expected to be launched in mid-1986 and these observations are the among the first planned with the instruments.

scholarly journals Unseen companions of V Hya inferred from periodic ejections

2019 ◽  
Vol 487 (3) ◽  
pp. 3029-3036 ◽  
Author(s):  
Jesus M Salas ◽  
Smadar Naoz ◽  
Mark R Morris ◽  
Alexander P Stephan
Keyword(s):  
Orbital Period ◽  
Triple System ◽  
High Speed ◽  
Hubble Space Telescope ◽  
Eccentric Orbit ◽  
Brown Dwarf ◽  
High Eccentricity ◽  
Distant Object ◽  
Space Telescope ◽  
Ejection Mechanism

ABSTRACT A recent study using Hubble Space Telescope observations found periodic, high-speed, collimated ejections (or ‘bullets’) from the star V Hya. The authors of that study proposed a model associating these bullets with the periastron passage of an unseen, substellar companion in an eccentric orbit and with an orbital period of ∼8 yr. Here we propose that V Hya is part of a triple system, with a substellar companion having an orbital period of ∼8 yr, and a tertiary object on a much wider orbit. In this model, the more distant object causes high-eccentricity excitations on the substellar companion’s orbit via the Eccentric Kozai–Lidov mechanism. These eccentricities can reach such high values that they lead to Roche-lobe crossing, producing the observed bullet ejections via a strongly enhanced accretion episode. For example, we find that a ballistic bullet ejection mechanism can be produced by a brown-dwarf-mass companion, while magnetically driven outflows are consistent with a Jovian-mass companion. Finally, we suggest that the distant companion may reside at few a hundred astronomical units on an eccentric orbit.

scholarly journals HST/FGS High-Speed Photometric Observations of Transits of HD 209458b

2004 ◽  
Vol 213 ◽  
pp. 89-92
Author(s):  
William F. Welsh ◽  
A. B. Schultz ◽  
W. Kinzel ◽  
M. Kochte ◽  
I. Jordan ◽  
...  
Keyword(s):  
Time Resolution ◽  
Preliminary Analysis ◽  
High Speed ◽  
Hubble Space Telescope ◽  
Extrasolar Planet ◽  
High Time Resolution ◽  
Orbital Parameters ◽  
Preliminary Results ◽  
Photometric Observations ◽  
Limb Darkening

We present preliminary analysis of new HST observations of the transiting extrasolar planet HD 209458b. Photometric observations were obtained with the Fine Guidance Sensor (FGS) on the Hubble Space Telescope (HST), providing milli-mag precision and high time resolution (40 Hz). The FGS photometry allows us to derive precise stellar/orbital parameters (ephemeris, inclination, limb darkening) and planetary radius, and also allows a search for the presence of planetary rings and satellites. We discuss preliminary results and two approaches to modelling the observations.

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