Engineering topics

Mcclintock, J.

Publications and source records attributed to Mcclintock, J..

10 records

NASA NTRS1988

4U 1626-67 - The binary with the smallest known mass function

The pulsing X-ray source 4U 1626-67 is an accreting neutron star in a binary system with a very low mass companion. The source was observed by Exosat continuously for 23 hr on March 30-31, 1986 UT. It is found that, if the orbital inclination angle equals 90 deg, the optical companion star has a mass of less than about 0.002 solar mass; however, it is found that a companion star mass of greater than about 0.06 solar mass is required if gravitational radiation is responsible for driving the mass transfer in this system. Also presented are results on flaring activity in the system on time scales of about 1000 s, the energy-dependent pulse profiles, and the pulse period history over the past decade.

Levine, A.↗

NASA NTRS1986

H 0323 + 022 - A new BL Lacertae object with extremely rapid variability

Results of a multiband, multiepoch series of observations are reported, demonstrating beyond reasonable doubt that H 0323 + 022 is a remarkably variable BL Lac object. The optical nebulosity around the stellar object is confirmed, the stellar optical radiation is polarized, the radio characteristics and the overall electromagnetic spectrum resemble those of other BL Lac objects. Variability is seen in all bands, including radio and broad-band optical variations in days, optical polarization changes on time scales of tens of minutes, and X-ray changes on time scales of about 30 s. H 0323 + 022 is an active galactic nucleus with much of the observed emission emerging from a region less than about 10 to the 12th to 10 to the 14th cm in size.

Feigelson, E. D.↗

NASA NTRS1983

H0323 + 022 - A puzzling high-latitude X-ray/optical/radio source

HEAO 1 has located a flaring X-ray source, H0323 + 022, at high galactic latitude. This source is identified with a V = 16.5 UV-excess object. While the counterpart has been observed on two occasions to have zero redshift absorption lines, these features have been absent on at least five other occasions. The high IR flux of the object indicates a multicomponent source. Einstein Observatory observations indicate that the X-ray source has two components, a steady soft component and a variable hard one which exhibits a pronounced 60-sec dip, as well as flaring activity, on time scales as small as six hours. A 5 GHz detection of the source, with a flux density of 41 + or - 1 mJy, has also been made by Feigelson et al (1982).

Doxsey, R.↗

NASA NTRS1977

On the optical identifications of five X-ray sources

The data from a recently completed survey of the galactic plane with the SAS-3 modulation collimators provide precise (20 to 60 arcsec) celestial positions of galactic X-ray sources. Preliminary positions of 60-arcsec precision are reported for five sources. One of these led to the identification of the star, Gamma Cas, as an X-ray source, and the others lend substantial confidence to previously proposed optical identifications: 3U 0352+30 = X Per, 3U 1145-61 = HEN 715, GX301-2 = WRA977, and GX304-1 = MMV star. These identifications seem to establish the existence of a previously suggested class of Be-star X-ray emitters.

Bradt, H. V.↗

NASA NTRS1976

The transient X-ray source A0620-00 - Intensity variations and evidence for an 8 day periodicity

The X-ray intensity of the transient source A0620-00 has been measured frequently with the SAS-3 X-ray Observatory from August 8, 1975 to February 13, 1976. This brightest of all known X-ray transients shows intensity variations on a time scale of days superposed on a general decline. Intensity data for the period from January 7 to February 13, 1976, show evidence of an approximate 7.8-day periodicity that may be the result of binary motion.

Matilsky, T.↗

NASA NTRS1976

Orbital elements and masses for the SMC X-1/Sanduleak 160 binary system

The binary X-ray source SMC X-1 was observed with the SAS-3 satellite for approximately four days (February 26-29, 1976). Sufficient timing data were obtained on the 0.71 s X-ray pulsations to measure the Doppler velocity curve of the X-ray source and thereby derive orbital and stellar parameters for the system. The projected velocity of the X-ray star is 301.5 plus or minus 2.0 (1 sigma) km/s, and the corresponding mass function is 11.05 plus or minus 0.22 (1 sigma) solar masses. Combining the X-ray timing data with constraints imposed by the X-ray eclipse duration and the available optical data on Sk 160, a range of allowable values of not less than 1.1 and not greater than 4.0 solar masses for the mass of the X-ray star is obtained.

Primini, F.↗

NASA NTRS1976

Recurrent brief X-ray bursts from the globular cluster NGC 6624

Observational data are presented on ten brief X-ray bursts, recurrent at nearly equal time intervals, recorded during a two-day observation of 3U 1820-30 in the globular cluster NGC 6624 with the wide-field modulation collimator detectors on the SAS-3 X-ray observatory. The occurrence times were fitted by least squares to a linear sequence with an rms deviation of 621 sec, corresponding to a phase jitter of 3.9%. The bursts were observed in two energy channels. For a sequence of five of the most clearly observed bursts, the 2-6 keV rate rose to its peak value in about 1 sec and then decayed to preburst level in about 10 sec. The 6-11 keV rate rose more slowly and decayed similarly. The smooth decay of their averaged light curve suggests the temporal evolution may have a geometrical origin, where Compton scattering in a surrounding cloud of hot plasma stretches the pulse out and causes a progressive hardening of the spectrum.

Clark, G. W.↗

NASA NTRS1976

A fast transient source of hard X-rays at high galactic latitude

An extremely short-lived transient X-ray source has been detected with the SAS-3 satellite at a high galactic latitude (about -51 deg). The source, designated MX 2346-65, had a duration of between 45 s and 2200 s as well as a very hard spectrum. This source had not been detected in previous sky surveys and was not seen again by SAS-3 in 7 days of further periodic observations. Possible explanations of this type of event are discussed.

Rappaport, S.↗

NASA NTRS1976

An X-ray determination of the orbital elements of 3U 0900-40

The orbital elements of the 3U 0900-40 binary system were determined by measuring the variations in the arrival times of the 283-second X-ray pulses. The best-fit values of the system parameters and their 95% confidence limits are listed.

Mcclintock, J.↗

NASA NTRS1974

Possible detection of very soft X-rays from SS Cygni

An ultrasoft X-ray source is described which is less than 30 min in diameter and is possibly identified with the well-known variable star SS Cygni. Previous soft X-ray observations of this region of the sky have failed to detect the soft source reported. There is a possibility that Cyg X-6 is the same source, but the spectrum reported by Coleman et al. (1971) is inconsistent with the observations. The spectrum of the soft source cannot be uniquely determined since it was detected only in the lowest energy channel.

Rappaport, S.↗