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Astron. Astrophys. 349, L1-L4 (1999)

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Letter to the Editor

The discovery of 321 s pulsations in the ROSAT HRI light curves of 1BMW J080622.8+152732 = RX J0806.3+1527

Gian Luca Israel *  1, Maria Rosa Panzera 2, Sergio Campana[FORMULA]  2, Davide Lazzati 2,3, Stefano Covino 2, Gianpiero Tagliaferri 2 and Luigi Stella[FORMULA]  1

1 Osservatorio Astronomico di Roma, Via Frascati 33, I-00040 Monteporzio Catone (Roma), Italy
2 Osservatorio Astronomico di Brera, Via E. Bianchi 46, I-23807 Merate (Lc), Italy
3 Dipartimento di Fisica, Università degli Studi, via Celoria 13, I-20133 Milano, Italy

Received 12 July 1999 / Accepted 1 August 1999


During a systematic search for periodic signals in a sample of [FORMULA] 3000 ROSAT HRI (0.1-2.4 keV) light curves, we discovered [FORMULA] 321 s pulsations in the X-ray flux of RX J0806.3+1527. Two different HRI observations of RX J0806.3+1527 were obtained with the source at flux level of 3 and 5 [FORMULA] 10-12 erg cm-2 s-1, respectively. Only a faint B [FORMULA] 20.5 object is possibly present within the error circle, while no optical counterpart is present in the R plate down to a limiting magnitude of [FORMULA] 20. This indicates that the object is intrinsically blue. The X-ray and optical findings imply that RX J0806.3+1527 is a relatively distant ([FORMULA] 500 pc) intermediate polar (IP) or, more unlikely, a nearby ([FORMULA] 10 pc) isolated neutron star accreting from the interstellar medium .

Key words: stars: individual: RX J0806.3+1527 – stars: novae, cataclysmic variables – stars: pulsars: general – stars: rotation – X-rays: stars

* Affiliated to I.C.R.A.

Send offprint requests to: Gianluca.Israel@oar.mporzio.astro.it

© European Southern Observatory (ESO) 1999

Online publication: August 25, 1999