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J/AN/321/81 Orion Trapezium area ROSAT PSPC obs. II. (Lohmann+, 2000)
The following files can be converted to FITS (extension .fit .fgz or .fiZ)
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Query from: http://vizier.cds.unistra.fr/viz-bin/VizieR?-source=J/AN/321/81
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Beginning of ReadMe :J/AN/321/81 Orion Trapezium area ROSAT PSPC obs. II. (Lohother/mann+, 2000)
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ROSAT PSPC observations of the Orion Trapezium area.
II. Source variability and revised source list.
Lohmann P., Wendker H.J.
<Astron. Nachrichten, 321, 81 (2000)>
=2000AN....321...81L
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ADC_Keywords: Clusters, open ; X-ray sources ; Stars, pre-main sequence
Mission_Name: ROSAT
Keywords: open clusters and associations: general -
open clusters and associations: individual (Orion OB1) -
stars: activity - stars: pre-main sequence - X-rays
Abstract:
A deep ROSAT PSPC image centred on the Orion Trapezium has been
reduced a second time using an improved version of the PSF to fit the
data. The outer rim of the field of view was also included. The new
catalogue contains 316 X-ray sources which are easily identified with
pre-main sequence stars of the Ori OB1 Ic and Id association. All 316
sources were tested for variability. No variations were found inside
the single exposures of about 45 minutes length each. Between the 4
exposures spaced over 5 days about 1/3 of the sources show signs of
activities of various forms. As above 25% of these have somewhat
regular lights curves (monotonically rising or falling or hill-
shaped) we infer that at least some outbursts with time scales longer
than a day are present and that past searches for X-ray flares of
pre-main sequence stars were biased towards shorter time scales.