Archive for MIRI

SN1987A, Past and Present

Posted in Biographical, The Universe and Stuff with tags , , , , , , on February 23, 2024 by telescoper

There’s a new paper in Science featuring observations using the MIRI and NIRSpec instruments on JWST of Supernova SN1987A in the Large Magellanic Cloud. I couldn’t resist doing a short post about this result, partly because the paper features Maynooth colleague Paddy Kavanagh, and partly because I’m old enough to remember when this supernova was detected, in 1987. In fact I was doing my PhD at the time. When I started lecturing a few years later I used to use it as an example of a Type II (core-collapse) supernova. At first I would say “you will remember SN1987A” then, as the years passed, I realized that students would have been quite young in 1987 so I changed this to “some of you will remember SN1987A”. Still later, I realized that none of my students had even been born in 1987 so I forgot about the remembering bit and just talked about SN1987A. As of 2024, nobody under the age of 37 was born in 1987. Tempus has a distinct tendency to Fugit.

In 1987 I was in Sussex and I remember Roger Tayler getting very excited about the detection of anti-neutrinos from SN1987A at the Kamioka Observatory in Japan. There weren’t many – 12 altogether – but he wanted to do a statistical analysis of the arrival times to see if there was any evidence that might indicate the neutrinos had mass. Being rather “old-school”, he did a Monte Carlo experiment involving drawing numbers written on bits of paper out of a cardboard box. After a brief chat I suggested I could do a much better job using a random-number generator on a computer so I wrote a bit of code and did the computation. The results showed no evidence for neutrino mass.

Anyway, this type of supernova should produce a neutron star or black hole sitting inside a ring-shaped remnant. The ring has been well studied, but in 37 years of observation the central object has not been detected. The results in the latest paper (by Fransson et al.) involve a spectroscopic study of the emission lines of ionized argon from the SN1987a remnant at sufficiently high spectral resolution to map the velocity structure. The results suggest that ionizing radiation from a neutron star is illuminating gas from the inner parts of the remnant.

https://doi.org/10.1126/science.adj5796

For more details, see the paper.

Two Views of the Ring Nebula

Posted in Cardiff, Maynooth, The Universe and Stuff with tags , , , , , , , , , on August 22, 2023 by telescoper

It’s very nice to have an opportunity, courtesy of JWST, to congratulate astronomers from my current institution (Maynooth, Ireland) and my previous one (Cardiff, UK) – as well as many others – or their involvement in stunning new observations of the Ring Nebula (aka M57 and NGC 6720), a planetary nebula. There is a full story on the Maynooth University website here detailing the involvement of Dr Patrick Kavanagh in the processing of the images and another on the Cardiff University website here about Dr Roger Wesson, who led the programme. Not surprisingly there has been a lot of news coverage about these wonderful images obtained with the NIRCam and MIRI instruments on JWST here in Ireland and in Wales and elsewhere.

A particular excuse for reproducing the pictures here is to try out the fancy “image comparison” tool on WordPress, which allows the reader – that’s you – to slide one picture over the other. Have a go!

This groovy visual shows two images side by side of the Ring Nebula. The image on the left shows the NIRCam view and the image on the right shows the MIRI image. The left image shows the planetary nebula as a distorted doughnut with a rainbow of colours with a blue/green inner cavity and clear filamentary structure in the inner region. The right image shows the nebula with a red/orange central cavity with a ring structure that transitions from colours of yellow to purple/blue. Picture credits ESA/Webb, NASA, CSA, M. Barlow, N. Cox, R. Wesson

The full paper describing these observations can be found on the arXiv here.