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| last change Sat, 12 Mar 2011 11:52:50 GMT, U. Hanschur |
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Stars: Neutron Stars |
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The Chandra X-ray observatory discovers
5 sec pulsations in an isolated neutron star
RBS1223 was discovered as a bright X-ray source in the ROSAT All-Sky Survey. Even when imaged with the giant 10m Keck telescope on Hawaii the X-ray source remained without optical counterpart, suggesting an isolated neutron star as source of the X-ray radiation. The image shows X-ray contours overlaid over the Keck optical image). These bizarre objects have about 1 solar mass concentrated in a radius of only about 10 kilometer. The surface temperature of 1 Million degree makes this star bright at X-ray wavelengths despite its negligible size (for comparison, our sun has a radius of 700000 kilometers).
See next figure
credits: V. Hambaryan, G. Hasinger, A. Schwope (AIP), Schulz (MIT)
more at http://www.aip.de/groups/xray/ (image added 2002-12-05) |
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The Chandra X-ray observatory discovers
5 sec pulsations in an isolated neutron star
RBS1223 was re-observed with the Chandra X-ray observatory on June 24, 2000, for a total of 9000 seconds. The Chandra X-ray image is shown here. Due to the larger collecting area compared with ROSAT much more X-ray photons were collected per unit time interval, thus allowing the study of the time variable X-ray emission. (See also previous picture)
credits: V. Hambaryan, G. Hasinger, A. Schwope (AIP), Schulz (MIT)
more at http://www.aip.de/groups/xray/ (image added 2002-12-05) |
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The Chandra X-ray observatory discovers
5 sec pulsations in an isolated neutron star
A 5.157 second periodicity was found, the phase-averaged X-ray light curve is shown in the lower figure. The period found in the recent Chandra-observations is significantly longer than that found with ROSAT in the past. Some breaking mechanism is acting making the neutron star"s period spinning down. The most likely physical mechanism is the decay of a superstrong magnetic field of the order of 100 TeraGauss (10^14 Gauss), i.e. more than 10^14 times stronger than the mean terrestrial magnetic field. Only a handful of these strange stars are known today. They are under intensive investigation with the NASA Chandra and the ESA XMM-Newton X-ray observatories. (See also previous picture.)
credits: V. Hambaryan, G. Hasinger, A. Schwope (AIP), Schulz (MIT)
more at http://www.aip.de/groups/xray/ (image added 2002-12-05) |
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