Questions tagged [spectroscopy]

Questions about the measurement of light waves whereby the wavelength is classified by its position in the electromagnetic spectrum.

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5
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0answers
159 views

Does the current “fainting” of Betelgeuse show any spectral trends that differ from it's normal variability?

update: With all the newest news about including what the Dr. Becky video discusses as linked in How do magnetic fields mess with astronomers' observations? I'll bet this question can now be ...
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3answers
689 views

Why does Gaia use only calcium NIR lines for stellar radial velocity measurements?

I was reading this overview article about the Gaia spacecraft and I saw the following statement: These spectra provide radial velocity information that are used to study the kinematic and dynamic ...
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72 views

Stellar electromagnetic signatures

By using only the electromagnetic signature of a star, could a star be distinguished with reliable accuracy from any other star? To elaborate a little, say we have a collection of about 200,000 stars. ...
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1answer
64 views

Nebula and its colors

A Nebula has bright awesome colors that include red, blue, green, orange, white, etc? They're result of excitation of electrons. Is there a clear explanation as to which color is attributed to an ...
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2answers
5k views

How does one determine the effective temperature of a star from its spectrum?

Determining effective temperature of a star is in general a non-trivial task. Simple reason for this is that we can only study the electromagnetic radiation from a star, but not the temperature ...
3
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1answer
692 views

Why do linear velocity redshifts correspond to linear pixel shifts when the spectra are binned in constant log wavelength?

In Tonry & Davis (1979), they describe spectroscopic redshift measurement via correlating with templates at known redshift. In Section IIIa, they say "Because the spectra are binned linearly with ...
3
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1answer
227 views

What is a pupil slicer, and how does it work with anamorphic optics in VLT's ESPRESSO Echelle spectrograph?

This excellent answer points to ESPRESSO, - Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations. From there I looked at the Instrument Description and Performance page. ...
3
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1answer
113 views

What is the dimensions of the smallest object detectable by an optical fiber from a specific distance?

Optical fibers are well-known to observe astronomical objects, say, galaxies, to generate massive spectroscopic surveys. The galaxies are often very far from the optical fibers of a telescope. However,...
7
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1answer
122 views

Is it conceivable that the presence of chlorophyll (or similar) could be distinguishable from other chemicals on an exoplanet?

If an Earth-like exoplanet had a sufficiently extensive plant biosphere (i.e large forests, aquatic algal mats etc), is it at all conceivable that scientists could spectroscopically detect the ...
3
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1answer
2k views

How deep is the “A” Fraunhofer line in the solar spectrum? Is it from the Sun's or Earth's atmosphere?

Question: Where can I see - or even download - a fairly high resolution (~0.1 nm) solar spectrum at zero air mass - in other words from space without absorption and other features from the Earth's ...
3
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1answer
468 views

How to specify SM libraries for MOOG

I am running MOOG on OS X Yosemite and with $MOOG running the abfind driver I can force fit elemental abundances with an appropriate input line list and model ...
2
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1answer
90 views

How will microshutter arrays be used in the James Webb and future space telescopes?

Question: How will microshutter arrays be used in the James Webb and future space telescopes? Are they acting as a sort of moving pinhole or slit, or is the pattern more complicated, like a coded ...
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2answers
72 views

First spectroscopic detection of Uranus' rotation?

As an undergraduate exercise quite a while ago, we placed the equator of Jupiter's disk across the slit of a high resolution grating spectrometer and then measured the tilt of the resulting line in ...
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1answer
975 views

How do I apply a velocity shift to a wavelength array with uniform logarithmic spacing?

Suppose I have a wavelength array for a spectrum in units of Angstroms. Suppose further that the wavelength has "uniform logarithmic spacing" such that if I just take the difference in Angstroms ...
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9 views

How were “microshutters” or other multiplexed or multi-object techniques first used in Astronomical spectroscopy?

This answer to How will microshutter arrays be used in the James Webb and future space telescopes? explains how multiple objects can be selected so that the throughput of a spectrometer can be ...
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1answer
65 views

How does an Echelle spectrograph put such a long, high resolution spectrum into a square-ish format?

In order to obtain a very high resolution spectrum to resolve closely spaced lines, or to measure doppler shits, spectrographs are operated with very high dispersion. But photographic plates and CCDs ...
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1answer
839 views

Converting ångström spectral dimension to galaxy speed (km/s)

I have a spectral cube (in FITS format) whose spectral dimension is in ångströms. The sampling along the spectral dimension is 0.28A (CDELT=0.28). The observation in the cube is Ha emission of a ...
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238 views

How does the ESPRESSO Echelle spectrograph fold the spectrum so nicely?

The CBC News Technology and Science Q&A This ESPRESSO machine doesn't make coffee but scans the skies for habitable planets includes a nice description of ESPRESSO (Echelle SPectrograph for Rocky ...
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136 views

How is IR spectroscopy used to determine the composition of asteroids?

I am trying to understand how spectrometers or spectroscopy can be used to calculate the surface composition of asteroids for the purposes of asteroid mining.
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1answer
68 views

What might a CN filter be in the context of comet watching? Is it showing dust, or gas, or something else?

In this post on the website for the Comet Wirtanen Observing Campaign at wirtanen.astro.umd.edu, there's mention of a CN filter being used to observe the comet, and this cool GIF. What exactly is a ...