Letter to the Editor

The distance of the SNR Kes 75 and PWN PSR J1846-0258 system

¹ Department of Physics & Astronomy, University of Calgary, Calgary, Alberta T2N 1N4, Canada e-mail: tww@iras.ucalgary.ca
² National Astronomical Observatories, CAS, Beijing 100012, PR China

Received: 26 November 2007
Accepted: 24 January 2007

Abstract

The supernova remnant (SNR) Kes 75/PSR J1846-0258 association can be regarded as a certainty due to the accurate location of young PSR J1846-0258 at the center of Kes 75 and the detected bright radio/X-ray synchrotron nebula surrounding the pulsar. We provide a new distance estimate to the SNR/pulsar system by analyzing the HI and ¹³CO maps, the HI emission and absorption spectra, and the ¹³CO emission spectrum of Kes 75. That there are no absorption features at negative velocities strongly argues against the widely-used large distance of 19 to 21 kpc for Kes 75, and shows that Kes 75 is within the Solar circle, i.e. a distance d < 13.2 kpc. Kes 75 is likely at a distance of 5.1 to 7.5 kpc because the highest HI absorption velocity is at 95 km s^-1, and no absorption is associated with a nearby HI emission peak at 102 km s^-1 in the direction of Kes 75. This distance to Kes 75 gives a reasonable luminosity of PSR J1846-0258 and its PWN and also leads to a much smaller radius for Kes 75, so the age of the SNR is consistent with the spin-down age of PSR J1846-0258, confirming this pulsar as the second-youngest in the Galaxy.