Amateur astronomer glimpses an alien solar system

By Phil Plait | November 26, 2011 9:58 am

This is truly astonishing: an “amateur” astronomer in New Zealand, Rolf Olsen, has for the first time actually been able to get a direct photograph of the disk of swirling material forming a planet around a nearby star!

Holy wow!

OK, first, the picture:

This may not look like much at first glance, but that’s often true of amazing pictures. When you realize what you’re actually seeing…

This is a picture of Beta Pictoris (or just β Pic to those in the know), a young star just over 60 light years away. The light from the star itself has been subtracted away (more on that in a sec), and the two big crosshair streaks of light are called diffraction spikes — they’re caused by light inside the telescope and aren’t real. But the fuzz you see above and below the star is real, part of the disk of material forming planets right before our eyes! The dashed line was added by Rolf to show the orientation of the disk.

In the 1980s, infrared images of β Pic revealed that it’s surrounded by a flat dust disk almost exactly edge-on to us. We see that disk as a broad line crossing the star itself, like in the false-color image here from the Las Campanas observatory.

β Pic became a very popular object, with many telescopes pointed at it to try to determine the nature of this material. This was the first time we had ever directly seen the disk of protoplanetary material. We now know that not only is that disk actively forming planets, there is a planet orbiting the star inside that disk, and we’ve even seen it move!

At the bottom of this post is a gallery of exoplanet images, several of which show the best pictures of β Pic and its planet ever taken.

The disk wasn’t discovered until the 1980s because the star is so bright its light swamps the much fainter material around it. The disk is huge, bigger than our solar system, but so far away — 600 trillion kilometers! — that it appears small in telescopes, and very close to the star. What Rolf did was to get rid of all that unwanted light. He first took a bunch of pictures of β Pic, and then took a second bunch of pictures of another star, Alpha Pictoris, which is very similar in brightness and color. He subtracted the image of the second star, removing the glare from β Pic itself. Adjusting for brightness is easy — that’s just a bit of algebra — but color was critical. Cameras respond differently to different colors, so making sure the two stars had the same hue was very important.

And it worked! He says the raw subtracted image was messy, so he cleaned it up a bit to make the disk easier to see. I’ll note that the method he used is very close to what I myself did years ago when I was working on a project to use Hubble to observe planet-forming disks! It’s also used to see exoplanets themselves as they orbit their stars. The method is tried and true, and worked well for Rolf.

The disk of material stretches just long enough to be seen in the image. But is it real?

I decided to check. In the Las Campanas observatory picture above, you can three stars near β Pic (the black dots with bright halos; remember, it’s false color), and I saw three stars in Rolf’s image that looked to be the same ones. I rotated the Las Campanas image and resized it; it’s inset in the image here. Note the three stars; I marked those same stars in Rolf’s image with arrows (one is right on β Pic’s diffraction spike, but you can still see it). As you can see, it’s a good match, and it also gets the size and the orientation of the disk right as well.

Looks like he nailed it!

Which is amazing. I wouldn’t have thought it was possible, especially with only a 25 cm (10 inch) telescope! β Pic is a bright star, so it’s easy to spot from the southern hemisphere, but the disk is so faint and so overwhelmed by the star light I would’ve thought it couldn’t be seen. But there you go: a bold experiment has paid off.

I wonder how many others of these are out there, too. Telescopes and cameras are getting better all the time. I still think getting a direct picture of a planet orbiting another star is beyond the current capability of small ‘scopes… but it is not only possible but relatively easy to detect them if they pass directly in front of (” transit”) their host star, blocking its light a little bit. So not only can we detect their presence using backyard telescopes, as Rolf has shown it’s possible to see the material from which they formed!

My sincere and hearty congratulations to Rolf Olsen for achieving this (and you should look through his gallery of astrophotographs; they’re beautiful and some are astonishing). I think it’s a milestone in “amateur” astronomy, and it goes to show you that sometimes, the sky is not the limit.

Tip o’ the dew shield to antcaesar on Twitter. I’ll note that while writing this I found Universe Today has written about it as well. Image credits: Rolf Olsen (used by permission); Las Campanas Observatory.


Below is a gallery of exoplanets that have been directly imaged using telescopes on ground and in space. Click the thumbnail picture to get a bigger picture and more information, and scroll through the gallery using the left and right arrows.

exoplanet_betapic3
exoplanet_1rxs1609b
exoplanet_2m1207b
exoplanet_betapicb1
exoplanet_betapicb2
exoplanet_fomalhautb
exoplanet_fomalhautb2
exoplanet_gliese581c_art
exoplanet_hr8799
exoplanet_hr8799b_art
exoplanet_hr8799cspec
hr8799e
hst_hr8799_1998
lkca-15-b_andstar
vlt_betapicb_2011


 

Comments (47)

  1. Superluminously marvellous accomplishment! Congratulations Rolf Olsen. :-)

  2. abadidea

    I love how astronomy is a field where amateurs regularly make contributions. Clever bit with the image subtraction, very clever.

  3. That word “amateur” gets abused by people like this, and I for one am glad for it! :D

  4. Chris

    That is amazing. Would it be possible to do this using an occulting disk in front of the star?

  5. – “Would it be possible to do this using an occulting disk in front of the star?”

    I really don’t think so, mainly because, even if you had a disc small enough the tracking mount is not accurate enough to keep it over the star. (At least with Rolf’s equipment).

    Phil, To make the results even a little bit more amazing, It looks like Rolf is not using some fancy multi-megapixel camera to do is imaging. He is using only using an older 640×480 webcam that was modified to do long exposure imaging (http://www.philchris.co.uk/tcp2_mods.htm).

    The method looks easy enough that nearly any amateur with a decent sized telescope could replicate this . Would be interesting to see what others with a more powerful scope and smaller pixel camera could do.

    Congrats Rolf for thinking out of the box!

  6. andy

    This is pretty cool actually.

    Incidentally it may be time for a couple of updates to your exoplanets gallery: for starters the 1RXS J160929.1-210524 is not a cold planet, it has a temperature of 1800 K – heat from its star is not the main driver of the temperature!

    Secondly Fomalhaut b seems to have various peculiarities which have called its nature into question: the orbit now appears to cross the dust ring. The nature of what is imaged is now unclear: it might be a debris cloud produced by collisions in an irregular satellite swarm around a low-mass planet, or something else entirely.

    Furthermore calling 2M1207b as “definitely a planet” is pretty shaky, there’s a good case to be made that the 2M1207 system is a binary brown dwarf (with one of the brown dwarfs being below the deuterium-burning threshold) rather than a true planetary system.

  7. John O'Meara

    One should note that there is a bit of controversy over one of the planets in the gallery, namely Fomalhaut b. Link here from Nature: http://www.nature.com/news/2011/110923/full/news.2011.555.html

  8. Chris

    @7 John
    Interesting info on Fomalhaut B. Although I found it a little frustrating they never went into details of how much it deviated or even showed an updated picture. Probably waiting for peer review to get all the data analyzed.

  9. Jess Tauber

    It would really help similar efforts out there (citizen science, you listening?) if there were a growing online catalogue of subtractor starlight sorted for type and color, etc. Then one could simply zero in on what you need based on the star you want to zero out. Heck with a little AI the process could be automated- let the amateur astronomer plug in his info, and the system could do the rest.

  10. John

    Drop the quotes around ‘amateur’ please. Unless Rolf is a professional astronomer, they he’s not getting paid for his work, in which case amateur is the correct adjective to use.

  11. Gekko

    Why is the word amateur in “quotes” in the article?

    He is either an amateur astronomer ( not paid ), or he is a professional astronomer ( paid ).

    I’m sincerely hoping you don’t mean amateur as in inexperienced/unskilled.

  12. Geert Jalink

    What will be next?

  13. Jim

    Great achievement, except… I don’t see any disk. Seriously. I’ve searched the image above, loaded it in a photo program, increased the contrast,…. and I still don’t see any disk. I feel like the little child who cried “But the emperor has no clothes!” I’m not being malicious, just being honest here.

  14. Wayne Robinson

    Aha, diffraction spikes. I was wondering if it had a name.

    Another thing I’ve been wondering about is that occasionally in videos in which one of the characters is holding a torch in a dark room (a Doctor Who episode from Series 6 springs to mind) you get a similar effect, with a long horizontal bright line extending from the light and sometimes a shorter vertical one too. Obviously that’s not due to struts in a reflecting telescope.

    Do any of the readers know the optical explanation?

  15. Crux Australis

    Yaaaaaay Kiwi! Hooray for us!

  16. Chris

    @15 Wayne
    Without reviewing all the Doctor Who episodes, I believe you are thinking of “lens flare”. Some is due to the bright light bouncing off the optics and some is due to the iris. Those hexagons you see is from the iris being partially closed.

  17. Jerry

    Do you seriously think an amateur with a 10 inch telescope and a webcam, (a webcam !), no matter how good his skillset, can image a protoplanetary disk around another star?

    Seriously?

    He says the raw image was “messy” (I’ll bet!) and he “cleaned it up a bit” to make the disk easier to see?

    I will wait to see if this feat can be duplicated by someone else, but I am skeptical and I am surprised you are not a bit more skeptical about this also, Phil.

    Jerry

  18. Wow!!! Congrats, Rolf Olsen! Way to blur the heck out of that Amateur/Pro boundary :)

  19. @12 Gekko: Why is the word amateur in “quotes” in the article?

    He is either an amateur astronomer ( not paid ), or he is a professional astronomer ( paid ).

    I’m sincerely hoping you don’t mean amateur as in inexperienced/unskilled.

    Well, yes, that’s just it. Often, the word “amateur” connotes someone who isn’t terribly skilled, the assumption being that if they were, they’d be a professional. The “doubt quotes” in this case imply that, while he may not be getting paid for his work, Mr. Olsen is displaying quite a lot of skill.

  20. @14 Jim: I could be wrong, but I believe that those “lobes” on either side of the star ARE the disk. That the disk itself isn’t visible that far out in the image.

  21. John Doe

    @15 Wayne:
    Bright lines that extend exactly horizontally and vertically are probably an effect of the CCD sensor getting saturated. If that happens, the parts of the sensor that have been exposed to too much light leak current into the entire adjacent column or row of pixels.

  22. Rob

    I don’t mean to nitpick but I have a question. In the Las Campanas image, the three stars seem significantly brighter than the disk. In Mr. Olsen’s image they seem dimmer than the disk. Is this a difference between the infrared Las Campanas image and Olsen’s visible image? Are there any large observatory visible images of the Beta Pic disk?

  23. Chris

    I wonder if the difference between amateur and professional astronomer is the difference between getting or not getting paid. If a professional astronomer retires but still looks through his telescope, does he become an amateur? Perhaps the difference should be whether or not the astronomer has a PhD.

  24. Jim

    @20 Joseph G: Thank you, that could be it. (BA, can you confirm?) I guess I was expecting a flatter, wider disk from looking at the IR picture.

  25. Ken

    It occurs to me that Beta Pic is the best possible match for Beta Pic, so couldn’t you just rotate the original image 90 degrees, then align them at the star and subtract, setting any pixels that go negative to black. Is there some reason this wouldn’t work?

  26. Jerry (18): I was skeptical at first – of course – but when I saw the orientation and extent matched known observations, i was fairly well convinced. Note the PSFs of the other stars don’t really match what we’re seeing (though a log scale image would show that better).

    It’s a fair point though: he should do this with a star we know doesn’t have a disk, and see what happens. But given what he’s presented on his page, yes, I do in fact think he got it.

    Rob (23): The Las Campanas image was in a different wavelength, so the stars would appear to be different brightnesses.

    Ken (26): That might work, though it’s tricky in practice. The disk rotates too, so you’d be subtracting it from the original image, leaving a black line through it. We did some self-subtracted images with Hubble observing similar objects, and it was a pain. :) You have to iterate a few times and adjust it to make sure you’re not removing real stuff!

  27. Wow.

    There really aught to be a different word for what guys like this do and my hobby. Perhaps they get quotes around the word and I get the word underlined?

    Really, a lot of these guys sell pictures or even write books, so in making money at it perhaps they can be called professional despite the lack of academic credentials or affiliations.

  28. Jerry@18 & Rob@23 –
    I am pretty sure I know what he did when he “cleaned up his images”. Because all of the background stars would be different between the two exposures, when he subtracted the two images, it would cause holes in his final image. I am pretty sure that those holes would look pretty nasty when he did his curves adjustments and the final images would just look like a total mess.

    What he did is to only take a small portion of the subtracted, curves adjusted image (I would estimate a ~100pixel circle from the center), and then blended it in with the ORIGINAL β Pictoris image stack (without curves adjustment). Because of this the planetary disc may look brighter than some of the stars since they have been processed differently.

    Ken@26,
    I’m not sure if rotating the star 90 degrees would work too well…mainly because of the diffraction spikes that the telescope produces. The diffraction spikes are caused mainly by the spider vanes and secondary mirror on the front of the scope. The spider vanes cause the big cross in the stars, but there are many smaller diffraction spikes that are caused by diffraction off of the secondary mirror. ***These spikes are orientation specific!!!*** (look at this pic to see what I am talking about: http://www.pbase.com/rolfolsen/image/123609046)

    To completely get rid of all of the diffraction spikes, he would have needed to keep the images at the same orientation when subtracting (would also need to not touch focus, or change the camera orientation either to make sure). Otherwise he may have introduced some artifacts due not subtracting out all of the diffraction spikes.

  29. Kethinov

    Star system. Not solar system. There is only one solar system.

  30. Wayne Robinson

    @John Doe (comment 22),

    Yep, that sounds correct. I was wondering whether it had something to do with the pixels. Thanks.

  31. Jerry

    Take a look at the paper Olsen cites by Lecavelier des Etangs where Olsen got the idea for this technique :

    http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?db_key=AST&bibcode=1993A%26A…274..877L&letter=.&classic=YES&defaultprint=YES&whole_paper=YES&page=877&epage=877&send=Send+PDF&filetype=.pdf

    The images in this paper were taken with a 2.2 meter scope.

    Compare the quality of these images to Olsen’s images taken with a 10 inch scope.

  32. Takeru K

    Wayne (#15) said:

    Another thing I’ve been wondering about is that occasionally in videos in which one of the characters is holding a torch in a dark room (a Doctor Who episode from Series 6 springs to mind) you get a similar effect, with a long horizontal bright line extending from the light and sometimes a shorter vertical one too. Obviously that’s not due to struts in a reflecting telescope.

    After I posted this, I realised it had already been answered! Oh well, here is a more in-depth explanation: pixels in CCD (i.e. digital) cameras can be thought of as “bins” for storing electrons. Basically, when light hits the CCD camera, the photons get converted to electrons and then stored in pixels. Eventually, the camera is “read” and the electrons are counted and we can recreate the image. However, when there is a very bright light source, a LOT of electrons gets put into the same pixel/bin. The bins are not infinitely deep, eventually they “overflow” and the electrons spill into neighbouring pixels/bins. Usually, the CCD pixels/bins are designed so that the “walls” between bins are taller in one direction than another, so these overflow electrons generally form a bright line either horizontally or vertically in the final image!

  33. Takeru K @ 36

    – Most likely what people see in Movies/TV is NOT due to CCD Blooming, but it is most likely due to special effect filters on the cameras.

    Camera shops have a variety of different filters available to give different star patterns for bright sources of light. See here: http://www.bhphotovideo.com/c/buy/Star-Spectral-Effects/ci/119/N/4256189583

    There are even filters that will give only two points in any direction that is wanted (depends on how the filter is oriented on the camera). See here: http://www.bhphotovideo.com/c/product/13952-REG/Cokin_CA058_A058_Star_Effect_2.html

    TV and Movie studios pay lots of bucks for cameras, CCD blooming would be something that they would want to *avoid*. it is much better to control the effects with filters that can be applied at will.

  34. #24 Chris:
    When the word “amateur” is used correctly – whether in relation to astronomy or anything else – it simply means someone who isn’t being paid for what they do, irrespective of qualifications or the lack thereof.
    The word is derived from the Latin amat, to love. Its original and correct meaning is someone who does something for the love of it, rather than for a living.
    In the case of astronomy, there is no reason why the same person can’t be both a professional and an amateur! i.e. a professional researcher with a Ph.D., who also observes with a backyard telescope in his/her spare time. I personally know a couple of such people.

  35. Justin

    @ Wayne #15

    Whenever you see a blue horizontal stripe in front of a light source it’s what’s known as an anamorphic lens flare. With real anamorphic lenses on movies that have an aspect ratio of 2.39:1, it’s caused by a cylindrical lens element that squeezes the image horizontally onto a 1.18:1 film frame for later 2x “un-squeezing” during projection at the theater.

    In a show like Doctor Who which is shot using normal spherical lenses, the effect is either done with a filter during shooting (as stated by the poster above)… or, more likely, simulated during post-production with computer software that adds flares wherever the filmmakers want. See also: Fringe.

  36. Robert Sutton

    Living in Auckland as I do it’s particulary impressive considering what the seeing (or not seeing) conditions are often like in Auckland.
    Would be interesting to know what dates, times and lat/long the observations were made from

    Will a great flurry go forth with webcams Dobsonians and all?

  37. Super. Such a fantastic discovery. Perhaps, ametures are unknowingly much fine than professionals.

  38. MattTheTubaGuy

    Yay New Zealand!
    New Zealand is a great place to do astronomy. not much light pollution and very clear air. perfect conditions when it is not cloudy (which it is a lot!)
    I grew up in Twizel, a little town in the middle of the South Island, and really close to the Mount John Observatory. This is probably what got me interested in astronomy.

    I am planning on getting a telescope myself, I can’t wait!

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