Gould: Now that you mention this alleged conspiracy in my activities, it seems very coherent, but I think I got involved in each of these things from a completely different perspective. I don’t know, maybe there’s an inner drive that leads me to search for low-luminosity things. Honestly, I’m not sure.
I got involved in searching for faint stars when I was at the Institute for Advanced Study [(IAS) in Princeton, New Jersey]. John Bahcall [IAS] and Dani Maoz [Tel Aviv University] had early Hubble Space Telescope [HST] images of quasars, and I came up with this idea that we could find and extract M dwarfs from the images.
Actually, this is often how I get involved in things. I see it’s possible to do something even though I wasn’t particularly interested in doing it before. I thought it was technically neat to try [to] do it. This was before the HST mirror was corrected, so the images were pretty [bad]. Still, you could see fainter stars than you could from the ground.
G: For celestial objects, the only fundamental way to measure mass is from gravity. Astronomers can employ the impact of a star’s orbit on another nearby body to measure mass. That pretty much limits you to the Sun, which obviously has planets orbiting it, or stars that are in binary systems.
Another effect astronomers can use is the bending of light, or gravitational lensing. Gravitational lensing, up until our measurement of the lens in MACHO-LMC-5, had been used only to measure the mass of one star — the Sun. The Eddington experiment [studying the 1919 total solar eclipse] was a kind of reverse example of this. They knew the mass of the Sun and used the gravitational lensing effect — predicted by Einstein — to test the theory of general relativity.
Measuring the mass of a star this way isn’t easy because light travels extremely fast and doesn’t get bent that much. So, you need just the right conditions to have enough bending so there is some effect you can later measure.
G: Bohdan Paczynski [Princeton University] first proposed microlensing experiments in 1986. When I heard about it, I thought it was a really cool idea, but as I recall, it was pretty much ridiculed in the astronomical community as hopeless. I guess I’m just iconoclastic and began thinking about what you could do with microlensing. Avi Loeb [Harvard University] and I showed that finding planets with microlensing was more practical to do than most people thought. [So, we] did detailed calculations of what you could actually detect. At the time, I really had no observational experience, so it was hopeless for me to think about doing it myself.
As I became more involved with planet finding and microlensing, I was called upon to analyze what people were doing in other types of planet searches. I became convinced from reading what other people were doing with transits there must be a better way to go about [planet finding]. That’s how I got involved with super-small telescopes.
G: KELT stands for Kilodegree Extremely Little Telescope.
One of my students, Josh Pepper, and I began considering the general problem of what would be the best instrument to find transits. So, we worked out general formulae that anyone could have worked out any time during the last century — but apparently no one ever did — and they led us to some very interesting conclusions. We found the most interesting transits would be very bright, and these bright transits would be easier to find with smaller telescopes. It’s not simply that these events are brighter and supply more photons. They’re more rare, so you have to survey more of the sky, which means you need smaller telescopes.
Originally, we were just interested in it abstractly and what the scalings of the problem were, and we weren’t really intending to go out and find planetary transits ourselves. We wrote a paper about it. Paczynski wrote us a letter saying if we were serious about this, we should do it and build a camera. He said he was willing to give us help if we did it. Paczynski is iconoclastic himself and has a track record for recognizing great ideas — not just his own. So we took it seriously. I had some money set aside from being a “distinguished” scholar here at Ohio State. Now that the camera is built, it’s got a home in Arizona at a telescope farm, and it’s finishing up taking some test data. We’re going to go over to trial data for our project.
G: I’m always rolling things over in my mind and looking for the edges that don’t fit. Usually, I’m looking for things that make an explanation wrong, [things] people have taken for granted. Figuring out how things fit together in a different way makes them add up better, like in the case of the microlensing parallax for MACHO-LMC-5. I was not satisfied with having found two solutions, and I really wanted to figure out why they were both there.
So that’s pretty much how my life goes on the good days. It’s just a great time in astronomy to be asking these sorts of questions because there are a lot of new missions and data. But you know I should point out that I do a lot of calculations that don’t lead anywhere, and I’m not being interviewed about them. I guess all I can say is that if you keep at it, sometimes you hit on something that works.
G: I’m a principal investigator on one of the SIM key projects. And one of the things we’re doing is nearby star microlensing — this MACHO-LMC-5 event is kind of an example of that. It doesn’t seem that nearby, but compared to the LMC, it’s 1/100th the distance. We’re trying to find pairs of stars where one is going to pass in front of the other sometime during the SIM mission.
To find these nearby star candidates takes a lot of time. It really is like looking for a needle in a haystack. In fact, if I weren’t doing this interview, that’s what I’d be doing this very minute. And we’re still a few years away from launch.
Gould: Now that you mention this alleged conspiracy in my activities, it seems very coherent, but I think I got involved in each of these things from a completely different perspective. I don’t know, maybe there’s an inner drive that leads me to search for low-luminosity things. Honestly, I’m not sure.
I got involved in searching for faint stars when I was at the Institute for Advanced Study [(IAS) in Princeton, New Jersey]. John Bahcall [IAS] and Dani Maoz [Tel Aviv University] had early Hubble Space Telescope [HST] images of quasars, and I came up with this idea that we could find and extract M dwarfs from the images.
Actually, this is often how I get involved in things. I see it’s possible to do something even though I wasn’t particularly interested in doing it before. I thought it was technically neat to try [to] do it. This was before the HST mirror was corrected, so the images were pretty [bad]. Still, you could see fainter stars than you could from the ground.
G: For celestial objects, the only fundamental way to measure mass is from gravity. Astronomers can employ the impact of a star’s orbit on another nearby body to measure mass. That pretty much limits you to the Sun, which obviously has planets orbiting it, or stars that are in binary systems.
Another effect astronomers can use is the bending of light, or gravitational lensing. Gravitational lensing, up until our measurement of the lens in MACHO-LMC-5, had been used only to measure the mass of one star — the Sun. The Eddington experiment [studying the 1919 total solar eclipse] was a kind of reverse example of this. They knew the mass of the Sun and used the gravitational lensing effect — predicted by Einstein — to test the theory of general relativity.
Measuring the mass of a star this way isn’t easy because light travels extremely fast and doesn’t get bent that much. So, you need just the right conditions to have enough bending so there is some effect you can later measure.
G: Bohdan Paczynski [Princeton University] first proposed microlensing experiments in 1986. When I heard about it, I thought it was a really cool idea, but as I recall, it was pretty much ridiculed in the astronomical community as hopeless. I guess I’m just iconoclastic and began thinking about what you could do with microlensing. Avi Loeb [Harvard University] and I showed that finding planets with microlensing was more practical to do than most people thought. [So, we] did detailed calculations of what you could actually detect. At the time, I really had no observational experience, so it was hopeless for me to think about doing it myself.
As I became more involved with planet finding and microlensing, I was called upon to analyze what people were doing in other types of planet searches. I became convinced from reading what other people were doing with transits there must be a better way to go about [planet finding]. That’s how I got involved with super-small telescopes.
G: KELT stands for Kilodegree Extremely Little Telescope.
One of my students, Josh Pepper, and I began considering the general problem of what would be the best instrument to find transits. So, we worked out general formulae that anyone could have worked out any time during the last century — but apparently no one ever did — and they led us to some very interesting conclusions. We found the most interesting transits would be very bright, and these bright transits would be easier to find with smaller telescopes. It’s not simply that these events are brighter and supply more photons. They’re more rare, so you have to survey more of the sky, which means you need smaller telescopes.
Originally, we were just interested in it abstractly and what the scalings of the problem were, and we weren’t really intending to go out and find planetary transits ourselves. We wrote a paper about it. Paczynski wrote us a letter saying if we were serious about this, we should do it and build a camera. He said he was willing to give us help if we did it. Paczynski is iconoclastic himself and has a track record for recognizing great ideas — not just his own. So we took it seriously. I had some money set aside from being a “distinguished” scholar here at Ohio State. Now that the camera is built, it’s got a home in Arizona at a telescope farm, and it’s finishing up taking some test data. We’re going to go over to trial data for our project.
G: I’m always rolling things over in my mind and looking for the edges that don’t fit. Usually, I’m looking for things that make an explanation wrong, [things] people have taken for granted. Figuring out how things fit together in a different way makes them add up better, like in the case of the microlensing parallax for MACHO-LMC-5. I was not satisfied with having found two solutions, and I really wanted to figure out why they were both there.
So that’s pretty much how my life goes on the good days. It’s just a great time in astronomy to be asking these sorts of questions because there are a lot of new missions and data. But you know I should point out that I do a lot of calculations that don’t lead anywhere, and I’m not being interviewed about them. I guess all I can say is that if you keep at it, sometimes you hit on something that works.
G: I’m a principal investigator on one of the SIM key projects. And one of the things we’re doing is nearby star microlensing — this MACHO-LMC-5 event is kind of an example of that. It doesn’t seem that nearby, but compared to the LMC, it’s 1/100th the distance. We’re trying to find pairs of stars where one is going to pass in front of the other sometime during the SIM mission.
To find these nearby star candidates takes a lot of time. It really is like looking for a needle in a haystack. In fact, if I weren’t doing this interview, that’s what I’d be doing this very minute. And we’re still a few years away from launch.
