Date: May 27, 2011
Title: Pan-STARRS1
Podcaster: Niall Deacon
Links: http://www.ps1sc.org/
http://www.ps1sc.org/blog
Description: Pan-STARRS1 is the first of a new generation of astronomical surveys. With the world’s largest digital camera and a survey area 32 times the size of the full moon Pan-STARRS1 will repeatedly survey the sky many times per year. This has allowed it to discover new killer asteroid that could threaten the Earth and a new population of massive supernova explosions in the furthest reaches of the universe.
The PS1 Surveys have been made possible through contributions of the Institute for Astronomy at the University of Hawaii at Manoa; the Pan-STARRS Project Of?ce; the Max Planck Society and its participating institutes, the Max Planck Institute for Astronomy, Heidelberg and the Max Planck Institute for Extraterrestrial Physics, Garching; the Johns Hopkins University; the University of Durham; the University of Edinburgh; the Queen’s University Belfast; the Harvard-Smithsonian Center for Astrophysics; the Las Cumbres Observatory Global Telescope Network, Incorporated; and National Central University of Taiwan.
Bio: Niall Deacon from the University of Hawai`i focusses on identifying brown dwarfs in Pan-STARRS1 data.
Sponsor: This episode of “365 Days of Astronomy” is
sponsored by David Rossetter on behalf of the Lifetime Learning Institute of New Paltz, New York.
Transcript:
Niall Deacon: Last week, astronomers from the Pan-STARRS1 Science Consortium got together in Boston for their annual meeting. I’m Niall Deacon from the University of Hawai`i and in this edition of 365 Days of Astronomy we’ll be finding out what Pan-STARRS1 is and what interesting science it’s been doing. In addition to a few chats with Pan-STARRS1 astronomers, you’ll be hearing from scientists from across the consortium giving you a flavour of the sort of science they’ve been doing with the data. And those scientists, they’ll sound a wee bit like this,
Massimo Viola: Hi, my name is Massimo Viola and I’m a postdoc at the University of Edinburgh. I’m using Pan-STARRS to study properties of dark matter and dark energy in the Universe using weak gravitational lensing.
ND: To get the ball rolling and to find out a bit more about Pan-STARRS1, I sat down with the head of the science consortium, Ken Chambers
ND: Ken, what is Pan-STARRS1?
Ken Chambers: Pan-STARRS1 is a wide-field telescope and that means it has a wide field of view. Its field of view is 3.2 degrees across and so if you imagine holding your fist at arms length that’s about the size of the field of view. And so if you march your fist across the sky, you can imagine the rate at which we survey the sky. So we do a picture every thirty seconds so we will cover the sky quite quickly. It’s built on the summit of Haleakelā in Maui at 10,000ft level and has the world’s largest digital camera, and the combination of the wide field of view and the world’s largest digital camera make it in effect the most powerful telescope on Earth for surveying the sky.
Thomas Henning: So my name is Thomas Henning, I’m from the Max Planck Institute for Astronomy and I’m very much interested to use Pan-STARRS to search for planets using the transit method.
ND: So Ken, what kind of science is Pan-STARRS1 going to be doing?
KC: Well the incredible thing about the science from Pan-STARRS is the diversity of it. We’re doing everything from moving objects in the Solar System to stars in our Galaxy to the distribution of galaxies and the large scale structure of the Universe. The important thing is that we’re studying the time domain that is we actually take a movie of the sky so we see how things change over time. That not only includes those moving objects in the Solar System but explosive events like supernovae or material accreting onto a black hole. At the same time we can stack all the images so we make a very deep map of the universe and that gives us a census of all the objects in the solar system, the objects in the Galaxy and the objects in the universe and these give us clues to the formation of these structures.
ND: And does it actually work?
KC: It works. It’s an very complicated experiment with the highest technology in the telescope and the camera and we certainly had our problems getting up and running in the beginning. But it’s under appreciated that we’ve been on the sky now for a year taking high quality data and we’ve taken, in this last year we’ve taken as much data on the sky as the total history of humanity has taken on the sky to date. And as we get that data reduced and turned into products for scientists to do their science, I think the world will be very impressed with the science coming out of PS1 right now.
Michael Liu: Hi, I’m Michael Liu at the University of Hawai`i and I’ve been using Pan-STARRS to find the nearest low mass stars and failed stars close to Earth.
ND: One of the key goals of Pan-STARRS1 is identifying killer asteroids that may threaten the Earth. To find out more, I sat down with one of the software engineers charged with finding these potentially hazardous objects objects, Larry Denneau.
ND: So Larry, what exactly are killer asteroids?
Larry Denneau: Well Niall, killer asteroids are objects that Pan-STARRS1 telescope discovers in its data that have orbital paths that can bring them hazardously close to Earth. The way we find these is that PS1 with its wide field of view can take a picture of a large of the sky relatively to other telescopes. And we do this many times per night by repeating the pictures we take at the same part of the sky. So if you imagine a picture containing many points of light that are stars, some of those points of light will be moving because they are asteroids in our own Solar System that appear like stars but have moved from one position to another over a short amount of time say 15 or 20 minutes. When the solar system processing software sees that it recognises that as potential asteroid and if we have enough of those positions, then we are able to compute an orbit. And once we have an orbit, then we can say that this is an asteroid that might be hazardous to Earth.
Stephanie Phleps: Hi, I’m Stephanie Phleps from MPE in Garching and I’m interested in using Pan-STARRS data to study the large-scale structure of the Universe.
ND: Larry, are you actually finding these things?
LD: We are Niall, in late 2010 we made some changes to the way we find these hazardous asteroids and our software is much better at discovering these. And starting around early 2011, we have really started to discover them. And to date we’ve discovered about 70 Near Earth Asteroids of which eight of those are called potentially hazardous asteroids which have orbital paths which bring them within five million miles of the Earth’s orbit. So that’s pretty close by astronomical standards.
ND: So if one of these things was going to hit the Earth, what would you do about it?
LD: Well the easiest answer is to get on the red phone with Bruce Willis and have his Hollywood team of experts fly out to the asteroid and dispatch it. But in the real world the answer is, it depends. And the reason it depends is we don’t know what these things are made of, exactly how big the next dangerous asteroid we find will be. And so we want to make sure know what it is, what it’s composed of before we think of any ideas to either blow it up or move it. And the best answer we have is that after all our searching, we’ll find that there is not one in the next few hundred years that is hazardous to us and we don’t have to do anything.
Roger Lin: I’m Roger Lin of National Central University in Taiwan. I’m using PS1 data to search for new star clusters in the Milky Way.
ND: Pan-STARRS1 is also searching for massive explosions in the furthest reaches of the universe. I skyped Stephen Smartt of Queen’s University Belfast to discuss supernovae and Pan-STARRS1.
ND: So Stephen, why are you so interested in finding supernovae with Pan-STARRS1?
Stephen Smartt: So supernovae have become extremely interesting over the last decade for several reasons. First of all, they were the objects that were used to first discover the existence of dark energy. And there is a particular type of supernovae called thermonuclear supernovae or type Ia supernovae that come from white dwarfs and these seem to be very good standard candles in that we know how bright they are, so when we observe them at very large distances we can estimate how far away they are and we can probe the geometry of the Universe. And that technique has shown that the universe is expanding and accelerating, surprisingly we see this evidence of dark energy. So that was first discovered with supernovae and large samples of type Ia supernovae are needed to really pin down the cosmological parameters very well. And Pan-STARRS will do this extremely well because it’s such a well calibrated survey and produces such large numbers of supernovae. The other reason that we want to study them is that pretty much all the chemical elements that we see in our Solar System and our Galaxy so the iron and silicon in the rocks in the Earth, the oxygen that we breath, those were all created in supernovae explosions. So if we want to understand the origins of the Solar System, the origins of life, we really want to understand the origins of the chemical elements that we see and those chemical elements that can give rise to rocky planets and planets with life on them. So we are really probing how elements are formed, how they are formed in very massive stars that produce supernovae and then how those elements are dispersed throughout galaxies. And that’s a fundamental input to understanding how galaxies form and how stars and solar systems within galaxies form.
ND: And why is Pan-STARRS1 so good for finding supernovae?
SS: The simple answer to that is that it searches a very large volume of the Universe, much larger than previous surveys. A typical telescope, the way we measure it is that the volume surveyed is the area of the sky we see times the depth that you can go to. And Pan-STARRS is a reasonably big telescope with a huge camera so we can see a very large volume of the Universe. The extra thing of course that Pan-STARRS gives us is because it sees such a wide field we can revisit areas of the sky quickly that allows us to pick up things which change on the sky, either things that move or things that flash. So we we can do is we can survey a large volume of the Universe multiple times and that gives us the opportunity to find supernovae or anything that changes in that area of the Universe.
ND: So have you found anything yet?
SS: Pan-STARRS has started to make extremely interesting discoveries and because it searches such a large volume it can find extremely rare events. And we’ve found a population of supernovae that are nearly 100 times brighter than the previously known population. And we’re finding these at redshifts out to 0.5 and out to more than 1 and that’s unprecedented really for supernovae. We’ve discovered them, we’ve followed them up with other big telesopes, we know there distances and now know they’re extremely luminous. So the challenge is now understanding what physical mechanism drives these huge luminosities and really this is a new area in supernova reseach.
ND: And redshift 1, that’s when the Universe was about half its current age.
SS: That’s right yes. So we’re seeing, bizzarrely we’re seeing these huge supernovae, these very bright supernovae in small galaxies. They’re almost all in what we call dwarf galaxies which are low mass and tend to have very low amounts of the heavy chemical elements like oxygen and iron and we know that that can influence how very massive stars evolve. And presumably it influences how they die in these extremely bright supernovae events.
Tim Heckman: Tim Heckman from Johns Hopkins’ University and I’m using Pan-STARRS to study galaxies.
ND: So that’s just about it from the Pan-STARRS1 Science Consortium meeting, we’ve just got time for one more of these,
Matt Hollman: I’m Matt Holmann of the Harvard Smithsonian Center for Astrophysics. I’m using Pan-STARRS1 data to develop a complete census of moving objects in the outer Solar System.
ND: And it’s just left to me to say, thank you for listening.
End of podcast:
365 Days of Astronomy
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