The expansion rate, age, and distance of the supernova remnant G266.2-1.2

• Main Authors: Allen, Glenn E., DeLaney, Tracey A., Filipovic, Miroslav (R7673), Houck, John C., Pannuti, Thomas G., Stage, Michael D.
• Other Authors: School of Computing, Engineering and Mathematics (Host institution), American Astronomical Society. High Energy Astrophysics Division Meeting (Event place)
• Format: Conference Object
• Language: English
• Published: U.S., American Astronomical Society 2014
• Subjects: 020104 - Galactic Astronomy; 970102 - Expanding Knowledge in the Physical Sciences; South Pole; ice core; South pole
• Online Access: http://handle.uws.edu.au:8081/1959.7/uws:28672; https://aas.org/meetings/head14

We reprocessed and analyzed the 2003 and 2008 Chandra ACIS data for the supernova remnant G266.2-1.2. The data for two adjacent annular wedges along a relatively bright and narrow portion of the northwestern rim indicate that it has moved by about 2.39 ± 0.57 arcsec over a period of 5.652 yr. The corresponding expansion rate (0.42 ± 0.10 arcsec/yr or 13.6 ± 5.7 %/kyr) is about half of the rate reported for an analysis of XMM data from a similar region of the remnant over a similar time interval (Katsuda, Tsunemi & Mori, 2008). A hydrodynamic analysis was performed using the models of Truelove & McKee (1999). Many scenarios were considered using broad ranges of initial kinetic energies, ejecta masses, ejecta mass density distributions, ambient densities, and evolutionary states. The results were constrained by the Chandra expansion rate (assuming it is representative of the remnant as a whole), an inferred lower limit on the forward shock speed, an upper limit on the inferred thermal X-ray emission, and energy considerations. The results of this analysis suggest that G266.2-1.2 is most likely between 2.4 and 5.1 kyr old, whether or not it was produced by a type Ia or type II event. If the remnant is expanding into the material shed by a steady stellar wind instead of a uniform ambient medium, then it could be older by a factor of up to 1.5. In no case is the remnant expected to be younger than 2.2 kyr. Therefore, it is too old to be associated with emission from the decay of Ti-44 or with features in the abundance of nitrate in South Pole ice core samples. The hydrodynamic results provide only a weak constraint on the distance of G266.2-1.2. An analysis of previously-published distance estimates and constraints suggests that the remnant is between about 0.5 and 1.0 kpc. This limitation does not significantly affect the estimate of the age. We adopt the distance of thecloser of two groups of material in the Vela Molecular Ridge (i.e. 0.7 ± 0.2 kpc, Liseau et al. 1992). This distance is consistent with the progenitor having been a member of the Vel OB1 association (Eggen 1982).