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Various types of objects and phenomena and their significance in high energy astrophysics are discussed. The current concepts of the nature of the objects and the mechanisms generating high energy electromagnetic radiation are also discussed. Current observational data is presented. Objects of special interest include black holes, supernova remnants, neutron stars, and pulsars.
VLBI observations of SS 433 at 2.3 GHz made on 12 days between 1979 May and 1980 August yield the following results: (a) the position angle of the radio 'jet' of angular size of about 0.1 arcsec varies approximately sinusoidally about a mean value of 100.2 + or - 1.7 deg with an amplitude of 19.3 + or - 3.4 deg for a period fixed at 163.6 days. This resolves the ambiguity in the two angles of the optical model of Abell and Margon and assigns the inclination of the axis of the precession cone to the 79 deg value; (b) the position angle of the radio structure on this scale lags that of the optical model by 17.4 + or - 1.6 days; and (c) at least some of the radio emitting material appears to propagate away from the core in blobs. Using the rate of change of angular separation of the blobs from the core obtained from measurements on four different days, and assuming that the radio emission is traveling at the speed derived for the optical jets from the kinematic model, a distance to SS 433 of 5.1 + or - 0.5 kpc is obtained.
Five pairs of isolated pairs of galaxies with radio sources from the sample of Stocke et al. (1978) were observed with a three-element VLBI array operating at 4996 MHz. Parsec-scale components were detected in NGC 3894, Arp 102, and NGC 6500. Arp 102B was found to be a strong X-ray source with a luminosity in the 0.5-4.5 keV band of about 10 to the 43rd ergs/sec. Arp 102B was also found to be an elliptical galaxy for which no emission lines have been reported, and was the only source in the sample which appeared unresolved on the milli-arcsec scale, indicating that it may be related to BL Lac type objects.
The first detection of a quasar between 10 and 1000 microns is reported. The observation permits (1) the determination of the intersection of the optical/infrared and millimeter continua; (2) more precise determination of the total luminosity; (3) the placing of limits on the contribution of any thermal dust emission to the total luminosity. The quasar is the first object ever to have been observed whose energy distribution peaks at wavelength of about 100 microns without a large contribution to the total luminosity from thermal dust emission. The observed flux density of 2.2 + or - 0.5 Jy at 100 microns and an upper limit of 0.5 + or - 0.6 Jy at 50 microns clearly define the overall energy distribution and show the quasar to be a powerful far-infrared source.
(Previously announced in STAR as N80-33332)
The optical, X-ray, and ultraviolet emissions of the X-ray system 2A1822-371 are modulated with a period of 5.57 hr. The 5.57 hr modulation is believed to reflect orbital motion about a mass donating companion star. The modulation at high energies is caused by the combined effects of an occultation by the companion and by a bulge on the accretion disk. The present investigation is concerned with an extension of the study of 2A1822-371, taking into account medium resolution optical spectroscopy of the system covering the 5.57 hr cycle. Broad shallow absorption lines are observed in the optical spectrum of 2A1822-371. These lines are similar to the rotationally broadened lines which are found in the spectra of disk accreting cataclysmic variables. Their presence in 2A1822-371 is, therefore, strong confirmation that it is a disk accreting star. The He II 4686 A and H-alpha emission lines have a breadth comparable to the absorption lines at all phases in the 5.57 hr cycle.
Each cell in array has own concentrator. A Cassegrain Reflector combination of paraboloidal and hyperboloidar mirrors-used with conical reflector at each element of array. Three components direct light to small solar cell. No cooling fins, fans, pumps, or heat pipes needed, not even in vacuum.
Sixteen Einstein X-ray sources in the field of the Large Magellanic Cloud (LMC) that appear non-extended in the IPC detector have recently been accurately positioned with the HRI to make optical follow-up studies feasible. At least twelve of these are not associated with the LMC, including one Seyfert galaxy at a redshift of 0.076 and eleven late type galactic foreground stars, some showing photometric behavior typical for RS CVn and BY Dra variables. Two sources are identified with faint blue variable objects, one of them has been observed to exhibit He II 4686 and variable Balmer emission lines being reminiscent of the low mass X-ray binary LMC X-2. The IPC source 1E0501438-7037.6 is probably associated with the LMC OB star Sk-70 36 which has been found to show ellipsoidal light variations with a period of 6.94 d. The results strongly suggest that a gap in the X-ray binary luminosity function of the LMC exists between 10 to the 36th and 10 to the 38th ergls.
A three axis controlled magnetic bearing and its application to a momentum wheel are described. The four divided stators provide a momentum wheel with high reliability, low weight, large angular momentum storage capacity, and gimbal control. Those characteristics are desirable for spacecraft attitude control.
Reactor system technologies suitable for a variety of aerospace and terrestrial applications are considered. Technologies, safety and regulatory considerations, potential applications, and research and development opportunities are covered.
Broad-band 1 mm continuum observations of 3C 273, 3C 279, BL Lac, 3C 84, OJ 287, and 3C 345 made between 1977 March and 1981 January are reported. With the possible exception of 3C 279, all of the objects exhibited evidence for variability in the 1 mm flux density on the time scale of a few months. Flux variations at wavelengths of 1 mm and 2 cm are well correlated for the 'blazars' (BL Lac objects and optically violent variable quasars) observed; emission outbursts occur simultaneously and have similar amplitude at the two wavelengths. In contrast, an outburst in the flux from the Seyfert galaxy 3C 84 was observed at a wavelength of 1 mm in early 1980 but has not appeared at 2 cm as of 1 yr later. The observed relationship between 'blazar' emission variability at 1 mm and 2 cm is inconsistent with the canonical expanding-source model of radio variability or any of its modifications. Instead, models in which the number of synchrotron-radiating electrons is time variable (due to particle injection or acceleration behind a relativistic shock) are required.
Hudson and Ohki (1972) pointed out that the increase of the soft X-ray emission measure during flares might be accounted for in two different ways, either by 'coronal condensation', or by what they termed 'chromospheric rarefaction', now more commonly called 'chromospheric evaporation'. They ruled out coronal condensation on the basis of cornal mass content arguments. Moore et al. (1980) found it highly probable that the bulk of the mass of the soft X-ray emitting plasma is supplied during the rise phase by chromospheric evaporation from the feet of the soft X-ray loops. On the other hand, Cheng et al. (1981) argued that chromospheric evaporation is not important as a source of soft X-ray plasma. The present investigation is concerned with an event in which direct chromospheric observations contradict the conclusions reached by Cheng et al. Up to now chromospheric evaporation has always been an inference, without compelling positive evidence. In the current investigation, observations are considered which constitute such evidence.
Observations of the solar flare of May 7, 1980 using several Solar Maximum Mission instruments are presented as an investigation of the phenomenon of chromospheric evaporation. The total amount of plasma at temperatures greater than 2 x 10 to the 6th K were determined from the X-ray data, and the amount of plasma that was evaporated from the chromosphere was determined from the H-alpha data. The H-alpha profiles indicate that for the flare as a whole, at the time of peak soft X-ray emission measure, the number of atoms evaporated from the chromosphere was 7 x 10 to the 37th. The soft X-ray emission measure of 1 x 10 to the 49th/cu cm, coupled with the flare volume estimate of 10 to the 26th cu cm, indicates that there were 3 x 10 to the 37th electrons in the soft X-ray plasma with temperatures greater than 2 x 10 to the 6th K. These results indicate that enough material had been evaporated from the chromosphere to account for the X-ray plasma. Taken together, the H-alpha, soft X-ray, and hard X-ray images indicate that chromospheric evaporation is driven both by flare-accelerated electrons during the impulsive phase and by conduction during the thermal phase.
Radio, near IR, optical, and UV observations of I Zw 36 = Mrk 209 = Haro 29 are reported. The H I distribution shows a core-halo structure, the core containing half of the mass and showing systematic motions; the halo is diffuse and contains several H I clumps. The visible star formation region is associated with the core but is shifted slightly with respect to the H I peak column density; and the virial mass is 5 to 7 times the H I mass. Star formation models with an initial mass function of slope 1.5 (the Salpeter value being 1.35) and a burst age or duration of a few million years fit well the optical spectrophotometric measurements. The data also suggest that the column density of molecular hydrogen in I Zw 36 is 6 + or - 3 times that of the neutral hydrogen, about the right amount to account for the virial mass.
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Costs and complexity of parachute system greatly reduced. Rigidtowline parachute system operates in three steps: (1) When aircraft begins to spin, parachute compartment opened up, and parachute unfolds; (2) Parachute deployed and spin terminated; and (3) Parachute released. Advantage of towline system allows use of much smaller parachute, reducing design loads on structural reinforcement. Also, complex pyrotechnic-deployment or jettison systems no longer necessary.
Observations of the binary X-ray source Circinus X-1 provide samples of a range of spectral and temporal behavior whose variety is thought to reflect a broad continuum of accretion conditions in an eccentric binary system. The data support an identification of three or more X-ray spectral components, probably associated with distinct emission regions.