Questions tagged [spectrometry]

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Why does Hubble's F850LP filter have a different shape than all the others shown in Dr. Becky's video "ALL THE DETAILS on Earendel..."?

It will take some time to read through @Pela's excellent answer to Is there a better explanation of this picture showing the very distant star "Earendel"? and to slowly ease myself into it I'...
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balmer alpha , beta line intensity [closed]

In different temperature environments, the intensity of the Balmer lines is determined by the Saha equation and the Boltzmann equation. What I'm curious about is as follows. How can we measure the ...
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1 vote
1 answer
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Where do Astronomers usually get their wavelengths? Where do they turn to look up standard, accepted values for spectral features?

When identifying isolated observed spectral features or fitting complex observed spectra or even running complex numerical simulations, one needs a reliable, standard table of known wavelengths and ...
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2 votes
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How to calculate rest-frame luminosity in a specific wavelength band?

For instance, I have a set of templates whose y is in Jy and x is in Angstroms. I have both of their rest-frame and obs-frame wavelength (i.e. redshift). I want to know their luminosity in one ...
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Line Flux Ratios in Active galaxies

Good day to everyone. I wanted to know what is the importance of estimation of line flux ratios in active galaxies? What does it help in characterizing? As in Lyman $\alpha /$Carbon IV, or Mg II$/$...
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Optical emission line data archives

I am trying to do exhaustive optical emission line analysis of some active galaxies using archival data. What are some of the publically available data archives from where one could obtain optical ...
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What is the O[III]/H$\alpha$ line ratio for Active Galactic Nuclei?

I have the H$\alpha$ line flux of an AGN and I am trying to calculate the Bolometric luminosity using it. Bolometric luminosity can be calculated from O[III] fluxes by $L_{\rm Bol} = 3500 L_{\rm O[III]...
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2 votes
1 answer
517 views

Are binary stars with only one visible sibling common enough to contribute noticeable to dark matter?

Single-lined spectroscopic binaries is a binary system where only one star can be detected. Are they common enough to contribute noticeable to dark matter?
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1 answer
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What does "the depth of the 13.0 Å feature differs by 7 sigma from zero" mean?

In a paper I've read, I have seen the following: In view of the noise levels, it is difficult to perform such a search effectively using statistical significance criteria only. We will therefore ...
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1 vote
1 answer
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Specutils Gaussian1D fitter and estimators

I am running the "simple example" from specutils to do some line-fitting. The demo code is here: https://specutils.readthedocs.io/en/stable/fitting.html This runs and does what it says. ...
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5 votes
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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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What is the difference between spectroscopy, spectrography and spectrometry?

Spectroscopy is the study of spectra, spectrography is the writing of the spectra, and spectrometry is the measure of spectra. So from an etymological perspective, there is no real difference between ...
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mm-wavelengths Moon map, scientific case

I would like to test a telescope with a Moon observation. It is a low spectrometer-imager at 110-300 GHz with a resolution of 4 arcmin@150 GHz. Is there any scientific target that concerns the Moon ...
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1 answer
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Help understanding the false MRO observations of hydrated minerals on Mars

The Science News article An orbiter glitch may mean some signs of liquid water on Mars aren’t real begins: Some signs of water on Mars may have just dried up. Thanks to the way data from NASA’s Mars ...
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Where can I find a database of elemental spectra? [closed]

I know that spectroscopy can be used to analyze the light of stars to determine the elements causing their emissions in the visible spectrum, but this requires knowing the emission spectra of the ...
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5 votes
0 answers
107 views

Need help understanding stellar spectroscopy data from ESO

The European Southern Observatory webpage has a web page that has tabular spectrogram data from A. J. Pickles, University of Hawaii. There are over 130 .dat files there. Each one represents a ...
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Can all astronomical signals be considered Gaussian noise?

While studying the techniques astronomers use to mitigate radio frequency interference (RFI) I found it's often assumed that astronomical signals are (band-limited) Gaussian noise. Is this a ...
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10 votes
1 answer
3k views

How do scientists determine if a star's color is due to Doppler shift vs the star's composition vs temperature?

When looking at visible light coming from, say a star, scientists can determine by the shifting of the light towards the red or the blue end of the spectrum to determine if it is moving towards or ...
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1 vote
2 answers
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Photodetector Question: Does converting an RGB image to grayscale produce the same result as using a grayscale image detector?

FYI my application is not astronomy related, but I know astronomy folks have a lot of knowledge of photodetection and spectrometry instrumentation, so I am seeking this community's help. I'm ...
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4 votes
1 answer
242 views

If the Sun were bigger but colder, Earth would be hotter or colder?

That is the question. I know the concepts of luminosity $(L=4\pi R^2F)$ and the flow $F=\sigma· T^4$, with $T$ the temperature in its surface. But how I use that to know if the Earth would get warmer ...
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4 votes
0 answers
127 views

Spectral analysis of AGN (velocity dispersion of galaxy absorption, doppler shifts)

I was wondering what parameters I need to know/measure to calculate the velocity dispersion of a galaxy, specifically an AGN. Also, I have spectra where there are blueshifted and redshifted ...
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10 votes
1 answer
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How much oxygen did the Warwick/Cambridge study find in the rocky debris around white dwarf GD 61?

There are several articles out saying that a Warwick/Cambridge study of ultraviolet spectroscopy data from the Cosmic Origins Spectrograph on the Hubble Space Telescope found a large amount of oxygen ...
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9 votes
1 answer
116 views

Current limitations in radio-astronomical spectrometry analysis of local interstellar cloud's hyperfine structures

I've been trying to wrap my head around capabilities of current radio-astronomical spectrometry technology to isolate not too distant tenuous sources, say, chemical composition and density of the the ...
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