Exoplanets, spectroscopy and the amateur?

[JB80]

Firstly let me say I don't have much of an idea about spectroscopy beyond the basic concept of it so I apologise if the questions are a bit silly but I am curious to know at any rate.

Basically I want to know if there is a role that can be played in the search for exoplanets by the amateur in spectroscopy.

Now I suspect I already know the answer to this first one but here goes anyway.

So as I recently learned it turns out that if you have a star that has a known exoplanet that transits the star you can combine the spectra readings of the star at the time of the transit and subtract the readings of the star while no transit is occurring and it is possible to read what the atmosphere of the exoplanet would be with what data is left.

Now this seems to be something that is best left to the big space telescopes like KEPLER and others as they are big enough and have what I would assume is far more sophisticated hardware to carry out these studies but I still wonder if there is a role for the amateur to play with this type of method?

Like I said I suspect the answer to this is really it's a matter of aperture and equipment restraints but what would it take for someone to be able to gather some usable data?

Would the star have to be really close or even then would it not be possible?

Is it worth taking data at times of transit anyway?

The second question may have the same answer too but I have been thinking of this one a bit longer. I'm not even certain this is spectroscopy to be honest.

Again it's to do with transits of exoplanets and their parent stars and again it's something the space telescopes are good at but I figure there is slightly more of a chance that the amateur can do this, maybe.

As you may or may not know that one of the more successful methods of exoplanet detection is when a planet transits it's star and there is a dip in the light emitted that may suggest a planet is there.

Can an amateur detect the dip in the light as well?

And again would it help things if it was a closer star or brighter star?

If any of the above is possible what sort of equipment would be needed to carry out the tasks and I guess if it's not possible to do then what would it take?

Are there any other methods or areas that I didn't mention which could be useful in exoplanet detection or study by the amateur?

Hopefully my questions made enough sense, I'm sorry if they didn't.

[gkec]

I think the main issue is the atmosphere. The way variable star measurements are taken is to compare them with one or more nearby "stable" stars as the opacity of the atmosphere varies greatly. I think the variations in brightness would be lost in the noise. Also it is very hard to detect small changes when you have incomplete data sets due to cloud. You need several orbits of the planet to be sure and then this can be confusing if there is more than one planet.

For spectroscopy I imagine that you look for Doppler shift in the emission spectra and the presence of absorption spectra during a transit. The absorption spectra would be probably be messed up by the atmosphere for terrestrial like planets. You could always practice on Venus! (Insert looking at the sun warning here!)

Although possible I think the tiny changes you have to measure is what the main issue is. I would expect the sensors would be liquid nitrogen cooled to remove thermal noise which would be a real problem as is any other noise source.

But don't let that stop you! For variable stars observing techniques I would reccomend "Getting the Measure of the Stars". (Cooper and Walker) It's a bit old (1980's) but you can pick copies up very cheaply and it is aimed at amateurs wanting to do real science.

[JB80]

Thanks for the reply.

I think the main issue is the atmosphere. The way variable star measurements are taken is to compare them with one or more nearby "stable" stars as the opacity of the atmosphere varies greatly. I think the variations in brightness would be lost in the noise.

Does the atmosphere create that much noise so a relatively stable star appears variable and couldn't the same principle apply then to a star with a suspected planet?

I honestly don't know as I said I no next to nothing on the subject. I guess that's why we build big scopes in Chile.

Also it is very hard to detect small changes when you have incomplete data sets due to cloud. You need several orbits of the planet to be sure and then this can be confusing if there is more than one planet.

I was thinking though what if you already knew the planet was there?

Many have already be found so if you were to pick one and already know the exact timings of transits and conditions of the parent star like Kepler 22 couldn't this then be used to separate the data from the noise?

I suppose it's not so much discovery in this respect but a form of independent analysis and was curious if anybody is doing this although I am willing to believe it is out of the reach for the backyarder and given what you have said there would be numerous obstacles to overcome.

For spectroscopy I imagine that you look for Doppler shift in the emission spectra and the presence of absorption spectra during a transit. The absorption spectra would be probably be messed up by the atmosphere for terrestrial like planets. You could always practice on Venus! (Insert looking at the sun warning here!)

Although possible I think the tiny changes you have to measure is what the main issue is. I would expect the sensors would be liquid nitrogen cooled to remove thermal noise which would be a real problem as is any other noise source.

But don't let that stop you! For variable stars observing techniques I would reccomend "Getting the Measure of the Stars". (Cooper and Walker) It's a bit old (1980's) but you can pick copies up very cheaply and it is aimed at amateurs wanting to do real science.

Yes it was absorption spectra that was talked about but only gave a brief description of it which didn't sink in at the time.

So again it would be the terrestrial atmosphere that would be the big problem, what about the limitations of equipment?

[JB80]

Should of googled some.

It seems some of what I was thinking is possible.

http://astronomyonline.org/Exoplanets/AmateurDetection.asp

[badgerchap]

I have seen a couple of chaps online who have been doing exoplanetary detection, but it don't look easy. The change in flux for most transits is <1/1000 so you need very sensitive equipment to pick it up. If I may be a bit forward though, I reckon if you give it give or ten years, this should be fairly easy for most amateurs with money to spend, as the tech catches up. I actually imagine that the pro's depend on this prospect. Amateur Astronomy has proven itself in the field of research over the last few decades and as technology improves I see no reason why dedicated amateurs shouldn't make excellent contributions to the exoplanetary database.

[badgerchap]

Five* or ten sorry

[robin_astro]

Hi Guys

Several interesting questions here.

Transits

Firstly it is possible to measure transits of planets if you pick a known one with a relatively large dip eg here with a webcam

http://www.threehillsobservatory.co.uk/astro/TrES_1.htm

It has also been done with DSLR though a setup with an astro-camera can detect much smaller dips

Finding transiting planets though is much tougher as it takes means measuring thousands of stars repeatedly as often as possible. There is at least on amateur who is doing this though. He has found hundreds of new variable stars but no planet yet

There are other areas where amateurs can potentially contribute by measuring transits eg by monitoring known transiting planets looking for changes in timing of the transit which might signal the existence of other undetected planets or by checking for transits of planets which have been discovered spectroscopically but where it is not known if they transit.

There is also a related area of detection by gravitational lensing where a foreground star passing in front of a star with a planetary system produced spikes on the light curve due to the planet. There is a network of amateur observers who get alerts of graviational lensing events from professional survey systems and then monitor the lensing looking for any spikes due to planets.

And of course there is the data mining work going on by amateurs on the Kepler data by Galxyzoo which has found many new planets

Detecting atmospheres at ingress and egress by measuring the timing at different wavelengths is being done by professionals but not amateurs yet AFAIK. That would be very tough but perhaps not imposisble

Spectroscopy

Detecting exoplanets spectroscopy is possible (but tough) for amateurs eg these four measured here

http://www.astrosurf.com/buil/extrasolar/obs.htm#Observation of HD189733 b

which also shows a transit measured with a DSLR

Discovering one would be even tougher but there may be some candidate stars worth looking at which the professionals are not currently considering. (The team who did the observations above believe so)

Cheers

Robin

[JB80]

Thanks for the replies all.

I guess my question could of been a bit broader to include all the methods, if the mods feel like moving the thread elsewhere then that's fine. "Exoplanets and the amateur"

. If I may be a bit forward though, I reckon if you give it give or ten years, this should be fairly easy for most amateurs with money to spend, as the tech catches up. I actually imagine that the pro's depend on this prospect. Amateur Astronomy has proven itself in the field of research over the last few decades and as technology improves I see no reason why dedicated amateurs shouldn't make excellent contributions to the exoplanetary database.

I tend to agree with you, it's the money to spend part where it gets tricky.

Transits

Firstly it is possible to measure transits of planets if you pick a known one with a relatively large dip eg here with a webcam

http://www.threehill...stro/TrES_1.htm

It has also been done with DSLR though a setup with an astro-camera can detect much smaller dips

Having a quick search and yeah there are a few doing this, which was exactly my line of thinking when I asked the question but I wasn't sure if it was possible with a relatively simple setup. Turns out it is, if you know what you are doing and are patient.

Actually my thinking was more to chase up potential candidates but more on that later.

Finding transiting planets though is much tougher as it takes means measuring thousands of stars repeatedly as often as possible. There is at least on amateur who is doing this though. He has found hundreds of new variable stars but no planet yet

Yes, I imagine it would be extremely difficult to gather the amount of data that say Kepler does, in fact impossible really but again it seems some people are doing it to the best of their abilities.

Not sure if this is the same group but they are gathering data too, not sure how amateur of a set up is a 32" RC though but they do have William Shatner as a sponsor.

http://www.spectrashift.com/transit.shtml

They are also doing spectra work.

There are other areas where amateurs can potentially contribute by measuring transits eg by monitoring known transiting planets looking for changes in timing of the transit which might signal the existence of other undetected planets or by checking for transits of planets which have been discovered spectroscopically but where it is not known if they transit.

There is also a related area of detection by gravitational lensing where a foreground star passing in front of a star with a planetary system produced spikes on the light curve due to the planet. There is a network of amateur observers who get alerts of graviational lensing events from professional survey systems and then monitor the lensing looking for any spikes due to planets.

Definitely going to look more into these, the gravitational lensing one I would of thought out of reach of amateurs.

And of course there is the data mining work going on by amateurs on the Kepler data by Galxyzoo which has found many new planets

I have been a member of planethunters for a while and this is what has urged me to ask about the transit part. In the latest paper they released which confirmed a new planet it also mentioned a host of potential new candidate planets, one of which I was the first to stumble across in the data so if Kepler or the science team go back and study the star in question and confirm a planet then that would be pretty cool. But I was also wondering if the amateur can follow up themselves at home, and well that has been mostly answered.

There is also a lot you can do in planethunters outside of the general user interface of flagging dips.

Detecting atmospheres at ingress and egress by measuring the timing at different wavelengths is being done by professionals but not amateurs yet AFAIK. That would be very tough but perhaps not imposisble

Spectroscopy

Detecting exoplanets spectroscopy is possible (but tough) for amateurs eg these four measured here

http://www.astrosurf...htm#Observation of HD189733 b

which also shows a transit measured with a DSLR

Discovering one would be even tougher but there may be some candidate stars worth looking at which the professionals are not currently considering. (The team who did the observations above believe so)

I think that is the same group as mentioned above.

http://www.spectrashift.com/basics.shtml

The reason I asked about spectroscopy and atmospheres was it was part of an astrobiology course and thought I'd ask before that info falls out my head.

[gkec]

Should of googled some.

It seems some of what I was thinking is possible.

http://astronomyonli...urDetection.asp

I'm surprised at how big the dip is, more than 1%, although I suppose that could be a large planet orbiting a smallish star.

Which seems to be the case.

http://en.wikipedia.org/wiki/HD_209458_b

And at 3.5 days not long to wait between transits. You could also test general relativity as well. Fascinating.

[robin_astro]

the gravitational lensing one I would of thought out of reach of amateurs.

It is a group called "micro-FUN" doing this. The requirements are similar to transit detection plus input from a pro survey system looking for the initial gravitational lensing of the parent star.

http://en.wikipedia.org/wiki/MicroFUN

Actually gravitational lensing events can be very large. This one was caught by an amateur by chance and first confirmed spectroscopically by me to be a probable lensing event. No sign of any planets in the curve though for this one

http://www.threehill.../spectra_30.htm

I think that is the same group as mentioned above.

http://www.spectrash...om/basics.shtml

No. Tom Kaye and the well resourced spectrashift team were the first "amateurs" to detect Tau Boo b but Christian Buil used a commercial off the shelf spectrograph (The eShel spectrograph which he designed) They measured 4 exoplanets and even made some of the observations from Christian's apartment balcony. Neither team have gone further yet though.

Here is the link to Christian Buil's work again, hopefully not mangled

http://www.astrosurf...rasolar/obs.htm

The amateur surveying for exoplanet transits is a member of the BAA variable star section whose name escapes me for the moment. The Kepler project uses the same technique as he is using (He started long before the Kepler satellite), An automated system taking wide field images continuously every clear night (as it happens near the Kepler field) and using software he developed himself to track the brightnesses of all the stars and analyse the light curves. A fantastic long term project.

Cheers

Robin

[robin_astro]

The amateur surveying for exoplanet transits is a member of the BAA variable star section whose name escapes me for the moment. The Kepler project uses the same technique as he is using (He started long before the Kepler satellite), An automated system taking wide field images continuously every clear night (as it happens near the Kepler field) and using software he developed himself to track the brightnesses of all the stars and analyse the light curves. A fantastic long term project.

I remember now. Stan Waterman is the chap. The Kepler mission is nothing new. Here is one of his presentations covering his results from 2003-2009

http://rr-lyr.ast.obs-mip.fr/capas2012/presentations/S_Waterman-1-CAPAS_en.pdf

Cheers

Robin

[the rev]

Hello Robin,

How much of this can be achieved with a star analyser? I know it is limited being low res, but could it pick up changes in spectra when a planet passes in front of a star, or even a star in front of a star?

Kate

[robin_astro]

Hello Robin,

How much of this can be achieved with a star analyser? I know it is limited being low res, but could it pick up changes in spectra when a planet passes in front of a star, or even a star in front of a star?

Kate

I am pretty sure the effect of a planet atmoshpere would be much to small to detect directly using the Star Analyser, even if we launched one into space which is where the future exoplanet atmosphere work will be done.

Changes in the spectra of eclipsing binararies where the two star have different spectral classes should potentially be detectable though. I am currently monitoring AZ Cas for example which is just coming out of eclipse over the next week.

http://www.threehillsobservatory.co.uk/astro/spectra_43.htm

This is a B and an M star and shows significant changes in high resolution spectra as the B star is eclipsed which might also be detectable using a Star Analyser

Cheers