6
$\begingroup$

I am currently looking into light spectrometers, and I noticed that the ones I found had a similar problem; when the light reaches the spectrometer, it mixes giving a broad range of light wavelengths.

Are there astronomical spectrometers in observatories on Earth or in space telescopes that can measure the spectrum *from a single, specific star separately, i.e. without getting light from other stars contaminating the target star's spectrum?

If so, how do they do it?

$\endgroup$
6
  • 1
    $\begingroup$ I don't understand the last sentence of your question. Do you know how spectrometers work? Which did you find and look at to reach your premise of the question, what are the sources of your observations? $\endgroup$ Commented Nov 11, 2022 at 3:30
  • 1
    $\begingroup$ I just made a general assumption as I have used many spectroscopy programs but this is just a general question. I am just wondering if spectrometers can focus on a small beam of light like a far away star. $\endgroup$ Commented Nov 11, 2022 at 5:24
  • 3
    $\begingroup$ Would you like to ask "How do astronomical spectrometers measure spectra from single stars separately, without contamination from all of the nearby starts?" $\endgroup$
    – uhoh
    Commented Nov 11, 2022 at 8:20
  • 2
    $\begingroup$ Yes, that is my question. $\endgroup$ Commented Nov 11, 2022 at 15:39
  • 3
    $\begingroup$ @AakarshTathachar thanks for your reply! This is a great question! I've adjusted title and text of body a bit to make it a better fit for this site. I dropped the last bit because it wasn't about Astronomy. As you know, you can ask as many (good) questions as you like here or in any of the other SE sites so based on what you learn from answers here you can always ask a follow-up question. $\endgroup$
    – uhoh
    Commented Nov 11, 2022 at 23:56

1 Answer 1

5
$\begingroup$

SDSS Plug Plate

I imagine it's done differently based on the goals. Anything wanting to study just one object could simply mask out everything else. But the Sloan Digital Sky Survey studies numerous objects at once. The method they use is to create a "plug plate" corresponding to each object to be studied. A fiber optic cable was attached to each hole and ran to a separate spectrograph to study that object.

The article SDSS Plates has more information, including a video on the making of the plates, and another showing the fiber optic hookups.

The image above is the bare plate, and the image below is the plate with the cables hooked up.

SDSS Plug Plate with cables

$\endgroup$
9
  • 2
    $\begingroup$ This is very helpful but on a satellite I don't think a plug plate is used because the satellite keeps moving and the orientation of the objects changes. Are there any other ways to find the spectra? $\endgroup$ Commented Nov 12, 2022 at 2:58
  • $\begingroup$ Telescopes on the ground are also moving, even more so than those in Earth orbit. A satellite's motion around the Earth will be negligible as long as it maintains its orientation. But they won't have people there to switch out the plates. So, as I said above, they're more likely to just mask off everything but one object using an adjustable mask. $\endgroup$ Commented Nov 12, 2022 at 17:54
  • 1
  • 1
    $\begingroup$ @uhoh As mentioned in the first link ProfRob provided, the individual fibers have diameters of 3 arc seconds in the case of the original spectrograph and 2 arc seconds for the newer (“BOSS”) spectrograph. $\endgroup$ Commented Nov 12, 2022 at 23:11
  • 1
    $\begingroup$ @uhoh I’m sorry, I meant Greg Miller’s answer! $\endgroup$ Commented Nov 12, 2022 at 23:20

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .