EDP Sciences
Free access
Volume 389, Number 1, July I 2002
Page(s) L1 - L5
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:20020651

A&A 389, L1-L5 (2002)
DOI: 10.1051/0004-6361:20020651


Discovery of an optical bow-shock around pulsar B0740-28

D. H. Jones1, 2, B. W. Stappers3, 4 and B. M. Gaensler5

1  European Southern Observatory, Casilla 19001, Santiago 19, Chile,
    e-mail: hjones@eso.org
2  Observatorio Cerro Calán, Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile
3  Stichting ASTRON, 7990 Dwingeloo, The Netherlands
    e-mail: stappers@astron.nl
4  Sterrenkundig Instituut "Anton Pannekoek", 1098 SJ Amsterdam, The Netherlands
5  Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge MA 02138, USA

(Received 6 February 2002 / Accepted 24 April 2002)

We report the discovery of a faint H $\alpha$ pulsar wind nebula (PWN) powered by the radio pulsar B0740-28. The characteristic bow-shock morphology of the PWN implies a direction of motion consistent with the previously measured velocity vector for the pulsar. The PWN has a flux density more than an order of magnitude lower than for the PWNe seen around other pulsars, but, for a distance 2 kpc, it is consistent with propagation through a medium of atomic density $n_{\rm H} \sim 0.25$ cm -3, and neutral fraction of 1%. The morphology of the PWN in the area close to the pulsar is distinct from that in downstream regions, as is also seen for the PWN powered by PSR B2224+65. In particular, the PWN associated with PSR B0740-28 appears to close at its rear, suggesting that the pulsar has recently passed through a transition from low density to high density ambient gas. The faintness of this source underscores that deep searches are needed to find further examples of optical pulsar nebulae.

Key words: ISM: general -- pulsars: individual: B0740-28

Offprint request: D. H. Jones, hjones@eso.org

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