Archive for March 10, 2019

The Gaia Sausage

Posted in The Universe and Stuff with tags , , , , , on March 10, 2019 by telescoper

I had to undertake a top secret mission on Friday, which turned out to be much less exciting than I’d hoped, but at least it gave me an excuse to catch some of the Royal Astronomical Society Open Meeting followed by dinner at the RAS Club. I actually sat next to the Club Guest Michael Duff, the eminent theoretical physicist Michael Duff who gave a nice after-dinner speech.

An artist’s impression of the Gaia Sausage. The Gaia fork has not yet been proved to exist.

The last talk at the RAS Meeting was by Neil Wyn Evans of Cambridge University in the Midlands on the subject of the `Gaia Sausage‘ (which, as you can see, has its own Wikipedia page). The Gaia Sausage is so named because it is consists of a marked anisotropy of the velocity distribution of stars in Milk Way, which is elongated in the radial direction (like a sausage) indicating that many stars are on near-radial (i.e. low angular momentum orbits). This feature has been revealed by studying the second data release from Gaia.

The work Wyn described in his talk is covered by a nice press release from Cambridge University which links to no fewer than five articles on it and related topics, which can all be found on the arXiv here, here, here, here and here.

The most plausible explanation of the Gaia Sausage is that it is a consequence of a major collision between the Milky Way with a smaller galaxy containing about 109 stars about 8-10 billion years ago, as illustrated in this simulation.

I vote that this explanation of the velocity structure of the Milky Way should henceforth be called the Big Banger Theory.


I’ll get my coat.


Technical Problems

Posted in Biographical, Cardiff with tags , , , , on March 10, 2019 by telescoper

This morning I got up early to travel to Cardiff Airport to get a flight back to Dublin.

We boarded the plane on time, left the gate on time and arrived at the end of the runway, apparently about to take off. We then sat there for 20 minutes before the pilot explained that there was a problem with the instruments on the flight deck. The plane then taxied back to the terminal, and an engineer got on, but he was unable to fix the problem so we all got off the plane which is clearly going nowhere soon.

A FlyBe Embraer 175 actually flying.

I’m currently sitting in the departure lounge drinking a coffee and wondering when (if) I’ll get to Dublin.

We’re told a plane will arrive from Edinburgh in half an hour and that will take us to Dublin. I’m not convinced. I think there’s a significant probability that my flight will be cancelled, but you never know..

The service with FlyBe has deteriorated in recent weeks almost as quickly as its fares have gone up. The airline has only recently been rescued from collapse and I suspect a major reorganisation is coming up.

Anyway, I know it’s safety first and all that, but my main concern is that we got all the way to the runway before anyone noticed there was a problem. Don’t they check before leaving the gate?

Update: we arrived in Dublin on Plane Number Two at 12.30, two hours and twenty minutes late but all in one piece.