The Expansion Center and Dynamical Age of the Galactic Supernova Remnant Cassiopeia A

By J. Thorstensen, R. Fesen, S. van den Bergh. 2001

170 citations recorded by the source corpus.

We present proper motions for 21 bright main shell and 17 faint, higher velocity, outer ejecta knots in the Cas A supernova remnant and use them to derive new estimates for the remnant's expansion center and age. Our study included 1951–1976 Palomar 5 m prime focus plates, 1988–1999 CCD images from the KPNO 4 m and MDM 2.4 m telescopes, and 1999 HST WFPC2 images. Measurable positions covered a 23 to 41 yr time span for most knots, with a few outer knots followed for almost 48 yr. We derive an expansion center of α(J2000) = 23h23m27.ˢ77 ± 0.ˢ05, δ(J2000) = 58°48′49.″4 ± 0.″4 (ICRS), with little difference between centers derived using outer or main shell knots. This position is 3.″0 due north of that estimated by van den Bergh & Kamper. It also lies 6.″6 ± 1.″5 almost due north (P.A. = 354°) of the remnant's recently detected central X-ray point source, implying a transverse velocity for the X-ray point source ≃330 km s-1 at a distance of 3.4 kpc. Using the knots which lie out ahead of the remnant's forward blast wave, we estimate a knot convergent date of A.D. 1671.3 ± 0.9 assuming no deceleration. However, a deceleration of just ∼1.6 km s-1 yr-1 over a 300 yr time span would produce an explosion date ≃A.D. 1680, consistent with the suspected sighting of the Cas A supernova by J. Flamsteed.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/09b2012d9fe7aff7d73143d1268481e8faec56a6

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Nuclear and High Energy Physics

Citations in the corpus

Non-spherical core collapse supernovae. I. Neutrino-driven convection, Rayleigh-Taylor instabilities, and the formation and propagation of metal clumps (2003, background): “Clumps moving with up to∼6000 km s−1 were, however, observed in Cas A (van den Bergh 1971; Thorstensen et al. 2001), which is probably the remnant of a type Ib explosion (Fesen & Becker 1991), and clump velocities of up to∼6000km s−1 and ∼4000 km s−1 were measured shortly after the explosion in the…”
OBSERVING THE NEXT GALACTIC SUPERNOVA (2013, background): “While the supernova that produced Cas A might have been observed in 1680 as a 6th magnitude event (see, e.g., Thorstensen et al. 2001), we do not consider it in our analysis since the historical record is clearly incomplete for such faint SNe.”
A Million Second Chandra View of Cassiopeia A (2004, background): “Furthermore, the kick direction for the compact object that is inferred from the motions of optical knots (Thorstensen et al. 2001) is notalong the jet axis, as would be expected, but is instead perpendicular to it.”