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Preliminary determinations of the masses of the neutron star and mass donor in the high mass X-ray binary system EXO 1722-363
Aims: We intended to measure the radial velocity curve of thesupergiant companion to the eclipsing high mass X-ray binary pulsar EXO1722-363 and hence determine the stellar masses of the components. Methods: We used a set of archival K_s-band infrared spectra of thecounterpart to EXO 1722-363 obtained using ISAAC on the VLT, andcross-correlated them in order to measure the radial velocity of thestar. Results: The resulting radial velocity curve has asemi-amplitude of 24.5 ± 5.0 km s-1. When combinedwith other measured parameters of the system, this yields masses in therange 1.5 ± 0.4 - 1.6 ± 0.4 ~Mȯ for theneutron star and 13.6 ± 1.6 - 15.2 ± 1.9~Mȯ for the B0-1 Ia supergiant companion. These lowerand upper limits were obtained under the assumption that the system isviewed edge-on (i = 90°) for the lower limit and the supergiantfills its Roche lobe (β = 1) for the upper limit respectively. Thesystem inclination is constrained to i>75° and the Rochelobe-filling factor of the supergiant is β>0.9. Additionally wewere able to further constrain our distance determination to be 7.1 ≤d ≤ 7.9 kpc for EXO 1722-363. The X-ray luminosity for this distancerange is 4.7 × 1035 ≤ L_X≤ 9.2 ×1036 erg s-1. Conclusions: EXO 1722-363therefore becomes the seventh of the ten known eclipsing X-ray binarypulsars for which a dynamical neutron star mass solution has beendetermined. Additionally EXO 1722-363 is the first such system to have aneutron star mass measurement made utilising near-infrared spectroscopy.Based on observations carried out at the European Southern Observatoryunder programme ID 077.B-0872(A).
| The Tokyo PMC catalog 90-93: Catalog of positions of 6649 stars observed in 1990 through 1993 with Tokyo photoelectric meridian circle
The sixth annual catalog of the Tokyo Photoelectric Meridian Circle(PMC) is presented for 6649 stars which were observed at least two timesin January 1990 through March 1993. The mean positions of the starsobserved are given in the catalog at the corresponding mean epochs ofobservations of individual stars. The coordinates of the catalog arebased on the FK5 system, and referred to the equinox and equator ofJ2000.0. The mean local deviations of the observed positions from theFK5 catalog positions are constructed for the basic FK5 stars to comparewith those of the Tokyo PMC Catalog 89 and preliminary Hipparcos resultsof H30.
| Cloudcroft occultation summary. I - December 1978-March 1980
Results are presented from the first 16 months of a program undertakento record lunar occultations at Cloudcroft Observatory. The 85 eventssummarized include 38 observations of stars brighter than seventhmagnitude, 26 reappearances, nine angular diameter measurements, and 11observations of binary stars or stars which may be double.
| Discoveries on southern, red-sensitive objective-prism plates. IV Extension to higher latitudes
This fourth in a series of papers (MacConnel, (1978, 1979, 1981) listingnewly-found objects detected on Curtis Schmidt objective-prism platesextends the previous, 4500-sq deg coverage, confined to within 15 deg ofthe southern galactic plane, to higher galactic latitudes and to anadditional 3100 sq deg. The lists presented cover 107 non-banded H-alphaemission stars, 12 M-type H-alpha emission stars, five suspectedplanetary nebulae, 10 carbon stars, 121 S/MS stars, three M dwarfs, anda peculiar and previously unreported star.
| Photoelectric observations of lunar occultations. XII
Occultation observations of 414 events observed between 6 July 1979 and4 September 1980 with the 0.76-m telescope of McDonald Observatory arereported. Timings and data on double stars are given. Angular diameterinformation in six cases is included. The stars concerned with their runnumbers are: SAO 161754 (5270); 94027 (Alpha Tau) (5319, 5381, 5454);159370 (Gamma Lib) (5325, 5571); 162413 (43 Sgr) (5332); 97472 (3 Cnc)(5414); and 93955 (Theta Tau) (5445).
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Observation and Astrometry data
| Constellation: | Sagittarius |
| Right ascension: | 19h18m10.94s |
| Declination: | -18°51'49.7" |
| Apparent magnitude: | 6.97 |
| Distance: | 1052.632 parsecs |
| Proper motion RA: | 0 |
| Proper motion Dec: | -14.7 |
| B-T magnitude: | 6.944 |
| V-T magnitude: | 6.968 |
Catalogs and designations:
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