No longer "blinded by the light"

[docm]

PhysOrg....

Planet hunters no longer blinded by the light

(PhysOrg.com) -- University of Arizona astronomers have developed a way to see faint planets previously hidden in their star's glare. The new mode enables scientists to search for planets closer to the star than has been previously possible.

Using new optics technology developed at the University of Arizona's Steward Observatory, an international team of astronomers has obtained images of a planet on a much closer orbit around its parent star than any other extrasolar planet previously found.

The discovery, published online in Astrophysical Journal Letters, is a result of an international collaboration among the Steward Observatory, the Swiss Federal Institute of Technology Zurich, the European Southern Observatory, Leiden University in the Netherlands and Germany's Max-Planck-Institute for Astronomy.

Installed on the European Southern Observatory's Very Large Telescope, or VLT, atop Paranal Mountain in Chile, the new technology enabled an international team of astronomers to confirm the existence and orbital movement of Beta Pictoris b, a planet about seven to 10 times the mass of Jupiter, around its parent star, Beta Pictoris, 63 light years away.
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[emperor_of_localgroup]

I hope I don't have to tell you the picture in the article is fake, or is so called artist's rendering.
Take a close look at the pic, the planet is exactly at the center of the star. What is the odd to
capture a planet's image when it is exactly at the center, when it could be anywhere on the
larger disk (star).

Also, one may not need a special optical device, such as phase imaging as used by this scientists,
to detect any dark object in front of a bright object. Some ingenious image processing techniques
(read the thread in Free Space that eliminates objects in real time to see how far image processing has gone)
can also do the same job. But in either case, a planet's edges will never be as sharp as the picture in the article.

My another thought is does Mercury or Venus ever come between earth and the sun? If they do, we can test this technique(s)
using pictures of mercury-eclipse or venus-eclipse, lunar eclipse will not do the job.

 

[centsworth_II]

...Take a close look at the pic, the planet is exactly at the center of the star. ...a planet's edges will never be as sharp as the picture in the article.

It seems you think the small white circle in the center of the large black circle is the planet. In fact the planet is the small white blob to the left of the large dark circle which is blocking out the star.

 

[emperor_of_localgroup]

...Take a close look at the pic, the planet is exactly at the center of the star. ...a planet's edges will never be as sharp as the picture in the article.

It seems you think the small white circle in the center of the large black circle is the planet. In fact the planet is the small white blob to the left of the large dark circle which is blocking out the star.

Ok, my mistake, somewhat.
First, it does not explain what those other 'white spots' are on the other side of the disk.
Why are not they planets?

Second, according to the labels on the picture, any one can assume the center smaller disk is also a planet.

 

[centsworth_II]

...according to the labels on the picture, any one can assume the center smaller disk is also a planet.

It would be best to read the picture's caption rather than making up your own interpretation.

"The planet Beta Pictoris b imaged using the Apodizing Phase Plate coronagraph. The “bad” (bright) side of the image is visible to the right while the central bright regions of the central star (Beta Pictoris) have been masked out to enable the viewer to clearly see the planet to the left of the star."

 

[silylene]

Here is a further explanation of the technicque using an apodizing phase plate (APP): http://sarahaskew.net/2010/09/07/exoplanets-at-a-discount/

Fig. 2: Image of a single star with the APP (without exoplanet). Diffraction rings on one side, a dark hole on the other. Credit: ESO

Fig. 1: An image of Beta Pic's companion taken with the apodising phase plate on VLT/NaCo, after processing. The light from the central star was blocked out (in processing). Credit: ESO

And here is a picture of the APP being used in the VLT:
http://www.flickr.com/photos/djulik/4194993490/
Stellar PSF through an APP (Apodizing Phase Plate) coronograph
Preliminary tests with the NaCo instrument at the VLT at 4.05 µm. The left part of the PSF is obscured to allow an eventual (faint) planet detection closer to the parent star. The APP isn't offered at the moment as more tests need to be performed.

 

[TheAnt]

@emperor_of_localgroup

I see what you thinking. Edited images claimed to be false are floating around at the moment.
In fact Space.com got a story on the front page right now
http://www.space.com/scienceastronomy/n ... 01015.html

What do I say about it, well all have have to know was that it was edited by Emily Lakdawalla. And all fears was put to rest, I known about her work for years. And actually been on the same discussion forum discussing image editing with pro and semi pro's. The kind of image work that NASA does is generally acceptable.
But we agreed that some ESA images made for public use are so heavily edited that they sometimes are nothing more but one interpretation of the original images taken by the spacecraft.

Image processing is here to stay like it or not, and it doesnt matter if it is in your newspaper, advertising, images of your the local politician, or even on contact ads. :lol:

So back to the archs at the right are caused by diffraction. I posted in another thread about this find before this thread was started. But I repeat it here and If you read up on the following text which describes the method of obtaining the image you might understand it better. http://www.sciencedaily.com/releases/2010/10/101015105935.htm

And yes, these news are of interest since we might now have a method of confirming the planet hunting that so many teams are doing. And this also done from Earth, it was long thought that this only would be possible to do by space based telescopes.
Lastly by getting actual images of the larger planets further out. We gain better confidence in other planet claims even if they're not not possible to get images of them yet.

 

[3488]

Thank You very much docm,

Fantastic article. At least we know this planet physically exists in real life unlike the 'hundreds' supposedly found by the radial method alone (not including those we have follow up heat detections & spectra), i.e the Gliese 581 system being a great case in point.

The next step now, as for Fomalhaut b is to try & get spectra. This is such a young system only about 200 million years old, or about the age of our solar system.

Andrew Brown.

 

[UFmbutler]

Sorry, what exactly are you implying when you say "supposedly" found by the radial velocity method? I agree that having spectra of exoplanets is useful, but just because we don't have them doesn't make the detection wrong (though in some cases it can be, but it's usually a "it's a brown dwarf/M star companion, not a planet" type of mistake.). The more interesting planets are being found with the transit method (i.e. Kepler telescope) anyway, but radial velocity is always needed as a followup to make sure it's really a planet, not the other way around.

The bottom line is, while direct imaging is great and exciting to see, it will not be a viable method of planet hunting for a long time. I think there may be a mission going up in 2015-2020 to make a coronagraph equipped space telescope dedicated to finding planets this way, but that is quite a ways off.

As a side note, the Swedes (http://exoplanet.eu/star.php?st=Gl+581) are not recognizing the discovery of the "habitable" planet around Gliese 581 (if that was covered in the main thread for it, my apologies). It is looking like that announcement was very premature and I'd expect a lot of rebuttal papers in the near future.

 

[emperor_of_localgroup]

@emperor_of_localgroup

Image processing is here to stay like it or not, and it doesnt matter if it is in your newspaper, advertising, images of your the local politician, or even on contact ads. :lol:

So back to the archs at the right are caused by diffraction. I posted in another thread about this find before this thread was started. But I repeat it here and If you read up on the following text which describes the method of obtaining the image you might understand it better. http://www.sciencedaily.com/releases/20 ... 105935.htm

And yes, these news are of interest since we might now have a method of confirming the planet hunting that so many teams are doing. And this also done from Earth, it was long thought that this only would be possible to do by space based telescopes.
Lastly by getting actual images of the larger planets further out. We gain better confidence in other planet claims even if they're not not possible to get images of them yet.

The link doesn't take me to any article, but I read the article again posted by OP, which does not explain the technical details of the new instrument. Yes, the patterns on the right side of the center disk look like a diffraction pattern, but the scientists may call them ripples, because they introduced an artificial ripples in their instrument, according to the article.


The reasons which curb my enthusiasm about extra-solar planets is this. We all know by observing our own solar system that almost all other stars must have planets around them. So, to find this planets we rely on the simplest of symptoms on and around the star. I may be wrong, but I think we are forcing ourselves to believe all this symptomsare definitive indications of existence of exoplanets. If you are in a completely dark room with a few gadgets and you definitely know there is black cat in the room, you would make several claims of locating the cat.

If the new technique and instrument is this good, the instrument should also be able to locate Venus, Mercury, Mars or other planets from a picture of the sun taken during the day time, when the planets are near the sun as seen from the earth. Why don't they demonstrate the merits of the instrument using a simpler experiment?

 

[TheAnt]

@emperor_of_localgroup It takes a full 3 seconds of you life to go to the frontpage of astronomy section and find it.
I have corrected the link now though.

 

[silylene]

If the new technique and instrument is this good, the instrument should also be able to locate Venus, Mercury, Mars or other planets from a picture of the sun taken during the day time, when the planets are near the sun as seen from the earth. Why don't they demonstrate the merits of the instrument using a simpler experiment?

The Apodizing Phase Plate (APP) requires the star to be a point source. The sun is not a point source, but rather a disc 30' in diameter. I thought the need for a point source of light (star) in order for APP to work was clear in the links I had cited earlier.

....Which by the way is why I attached photos of a star without a planet and with a planet - so you can see the difference (since a star with a planet is not a pure point source). The photo comparison was not in the links others had cited.

 

[centsworth_II]

...The Apodizing Phase Plate (APP) requires the star to be a point source...

An actual point source or a disc of a certain maximum size? If the star is a point source then the planet is also a point source and the blob hinting at an orb is just an illusion.

 

[silylene]

...The Apodizing Phase Plate (APP) requires the star to be a point source...

An actual point source or a disc of a certain maximum size? If the star is a point source then the planet is also a point source and the blob hinting at an orb is just an illusion.

A star with a big enough planet isn't a perfect point source, which is why the planet shows up with APP. And a star with a large enough disc (Betelgeuse or Vega for example) may also not qualify as a point source. I don't know what the upper limit on 'point source' is in terms if disc angular diameter.

 

[emperor_of_localgroup]

@emperor_of_localgroup It takes a full 3 seconds of you life to go to the frontpage of astronomy section and find it.
I have corrected the link now though.

No, it takes more than 3 sec of my life, I bookmarked the forum not SDC to come to this page directly. ha ha ha.
Thanks for the link again.

The Apodizing Phase Plate (APP) requires the star to be a point source. The sun is not a point source, but rather a disc 30' in diameter. I thought the need for a point source of light (star) in order for APP to work was clear in the links I had cited earlier.
....Which by the way is why I attached photos of a star without a planet and with a planet - so you can see the difference (since a star with a planet is not a pure point source). The photo comparison was not in the links others had cited. silylene

What I understand from this links is the scientists are trying to create an artificial solar eclipse. They may have got the idea from sightings of day-time stars during our own solar eclipse (our sun). Instead of blocking the star with a solid opaque disk (in our case it's the moon) they are using some type of interference.

But the problem is they are creating this artificial solar eclipse inside the telescope!!!. Unless they have an extraordinary, mind blowing technique, the length of the telescope in no way can replace the distance between moon and the earth (which plays an important part in what we see during a solar eclipse in our solar system).

Btw, I think it's time to give our solar system a name, to separate it from all other solar systems we are "discovering".

 

[silylene]

emporer, what they are doing is using the APP method. Please read the links I attached, and you can see what the APP plate looks like (the Flickr link has an APP plate in it). It isn't a 'solar eclipse' inside a telescope, that is way too simplified a description, and comes from bad science journalism trying to make a difficult optical physics design concept readable by a 2cnd grader. The plate is central obstruction with a set of small concentric etched rings or ring-arcs which may also include pixellated regions.

Unfortunately, most of the good links are in journals which require a fee to read (I hate that). There are several patents with good descriptions of APP plate designs you can read for free however.

Here is one plate design: The Astrophysical Journal, 660:762-769, 2007 May 1

Phase map of the APP design and its resultant theoretical PSF. The left-hand image shows the phase plate design cut into the zinc selenide plate, with the scale bar on the right showing height in microns. The secondary obscuration is deliberately over sized to allow for rapid in situ alignment. Shown in the right-hand panel is the calculated PSF logarithmically scaled over six decades normalized to the peak intensity. The pixel scale on the right hand panel is for 5 m imaging at the MMTO 6.5 m telescope.

 

[silylene]

Here is another APP plate design from this SPIE paper "Photon sieve telescope: imaging with 10 million pinholes
by Geoff Andersen" 4 September 2006, SPIE Newsroom. DOI: 10.1117/2.1200608.0358 :

Figure 1. The central 20% of a photon sieve is shown (left), along with a photograph of the actual sieve lit with red, green, and blue lasers (right). The colorful rings are a Moir pattern from the underlying circular symmetry.