The Hyper-Velocity Stars Project: Serendipity at its Best
Hello everyone and thank you for reading this blog post. You will read how a group of people, non-professional astronomers, from around the world got together to seek a common goal.
My name is Aida Bergés and my Galaxy Zoo name is Lovethetropics. I’m Dominican by birth but live in Puerto Rico, and I hunt Irregular Galaxies, asteroids, Voorwerpjes and now Hyper-Velocity Stars.
The Hyper-Velocity Star Project was due to one of those many accidental discoveries that happen at Galaxy Zoo. I was looking for irregular galaxies for Waveney’s Irregular Project. I saw an intensely blue star and checked it out to see if it was a white dwarf (it amuses me to no end that white dwarfs are all blue). It wasn’t. SIMBAD said it was a Hyper-velocity star. I kept looking for more irregulars, five minutes later saw another very blue star and checked it too – expecting it to be a white dwarf; but it was another HVS. At that point I looked the name up because I had never heard of that type of star. It is a star moving at a vast speed relative to the rest of the galaxy. Possible explanations for this are being flung away from a black hole; being part of a galaxy merger; a binary system being disrupted either by a black hole, the proximity of another star, or one of the pair going supernova . . . and so on. They can travel at about 4000 kilometres per second, and seem to be heading out of our galaxy! All the ones discovered are massive and blue.
I posted the two stars and a brief explanation on the newbies thread. The newbies thread was started by Thomas Jennings, Thomas J or “Tommy” on the forum, on my “zoobirthday” – the day I came to the Galaxy Zoo Forum. A week or two later, Alice Sheppard, Galaxy Zoo moderator and close friend, asked me to post an Object of the Day. I said yes but had no idea what to write. Thomas J reminded me of the hyper-velocity stars I had posted on his thread.
Tommy and I started to look for papers about hyper-velocity stars and he found a powerpoint presentation made by one of the Zookeepers, Jordan Raddick. At the time Jordan created it (2003), there were only three confirmed hyper-velocity stars. All of this dialog was written on the Object of the Day thread, which meant we started to get the attention of and much help help from other zooites. Mark Redgwell – BlackProjects on the Zoo, from the UK – found more papers. When I wrote the Object of the Day we had found 10 hyper-velocity stars, but they didn’t have an SDSS number and I had no idea on how to get them. Tommy again came to the rescue and found their SDSS ObjIDs, and I posted these onto Object of the Day.
It was a hit! We started getting help and more papers, especially from Stellar, 14, child genius from the UK who should be in college already. We found out there were 16 confirmed hyper-velocity stars, most of which had been found by Dr. Warren Brown from the Smithsonian Astrophysical Observatory and Harvard University. He is the outmost authority on HVSs, and you’ll be hearing more about him in a minute . . .
The question came up on the Object of the Day: How can we find more of these mysterious stars? Many Zooites joined the discussion, especially Mukund Vedapudi from India, Jules Wilkinson from the UK, and Dave, Curtis Garrett and Gargleblaster, all from the USA.
We decided we needed our own place to talk, for one thing because we were burying newer Objects of the Day, and for another this was the time of the forum merger which caused a few technical problems. Waveney (Richard Proctor, UK), our “fairy godfather”, offered his test forum, where a handful of zooites play. It’s more private than this one, but nevertheless we kept getting links to papers and articles from Jamartins from Portugal. By now nine or so of us had decided we were a team.
I have an interview for our “She’s an Astronomer” blog project on October 1st, and as it loomed closer and closer I wanted us to have a first post back on the Galaxy Zoo Forum so as to have a link from my interview, and to invite all zooites to join us. Stellar and I worked for 16 hours with some help from Alice and Half65 from IT – both of whom became part of the team, too – we posted our own thread, started a blog and a twitter account, and got ourselves a gmail account so we could spread the word that we are looking for Hyper-Velocity Stars and help from anyone who would like to work with us or advise us.
Jules, Dave, and Mukund Vedapudi have between them found 40 possible hyper-velocity stars, about half of which have a known radial velocity, and which you can examine here. Our new thread has grown to six pages due to the interest of our fellow Zooites; and yesterday I received a lovely personal message from Oswgeo9050 presenting another possible candidate, just from examining the spectra! She’s just joined us, too.
Help is flooding in, some from astronomically unexpected quarters. Karen Masters , who works at Portsmouth University, runs the “She’s an Astronomer and Galaxy Zoo” project, and has been part of Galaxy Zoo’s work on dust in galaxies, red spirals, and outreach generally, just happens to be a former colleague of the very Warren Brown mentioned earlier! It is due to her kindness that we have just got in touch with him – he has heard about our work from Karen and has graciously sent us pointers on how to find more Hyper-Velocity Stars. It looks like it’s going to be tricky: there is only one of these for every 100 million “normal” stars, and there is in any case an error range of 220 kilometres per second (plus or minus) due to our own Solar System’s rotation round our spiral galaxy!
Just to add to this, on Wednesday 9th September, we heard from ZookeeperKevin that he was about to meet Warren Brown and hoped to set up a collaboration. We had a few hours to decide exactly what sort of help from the experts we wanted, and to send him our first e-mail! This was no easy task, not knowing the ins and outs of academic life. We waited on tenterhooks, our hearts pounding . . .
On Thursday evening Kevin got back to Alice. He and Warren Brown had taken a look at some of the candidates. He believed that none of them were hyper-velocity stars for many reasons, one being that the SDSS people have already combed the data. But, apparently, “one object looks interesting”. We don’t yet know what that is, and just have to wait for him to – and this is the good new – join the forum and talk to us more, which apparently he will be doing!
What will happen next? There are probably more stones to unturn. Even if we fail, we still set up an exciting project and discovered many things – as amateurs who decided to work together. In the meantime, please join us to put forward any questions, suggestions, and ideas.
Very special thanks to Zookeepers Jordan, Karen and Kevin for taking such an interest in our work and kindly providing so much information and hope. We also thank Geza Gyuk from Adler planetarium http://www.adlerplanetarium.org for his enthusiastic help.And thanks to our fellow zooites for being serendipities with all of us!