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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Velocity dispersion of stars in galaxies
Velocity dispersion of stars in a galaxy could be useful for example in calculating the galaxy's mass, using the viral theorem.
I am wondering how this velocity dispersion (standard deviation in ...
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ML astrophysics for PhD project (This is a cry for help!) [closed]
I have been studying astrophysics for six years (recently obtaining my bachelor's and master's degrees), and now I've decided to focus on machine learning applications in astrophysics after receiving ...
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What is DESI's spatial resolution?
I'm using data from the Dark Energy Spectroscopic Instrument (DESI), and I need to check if its beam coincides with coordinates I've collected for objects in GALEX.
From the Fermilab conference ...
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Degrade resolution of theoretical spectrum before fitting
I want to fit a theoretical spectrum on a finely spaced wavelength
grid to an observed stellar spectrum at coarser resolution. I understand
that I have to apply convolution to the theoretical spectrum ...
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Why does infrared pass through clouds of gas and dust with minimal extinction?
Why do we use Infrared to view through clouds of gas and dust in space? I understand that it is because it can pass through without being absorbed, but why is this? My thinking is that it is because ...
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Why MIT's Benjamin Rackham says "nearby ultracool dwarf SPECULOOS-3" would look "purplish-red, spotted, and flaring" from an airless orbiting planet?
May 15, 2024 MIT News article Newly discovered Earth-sized planet may lack an atmosphere includes the following:
“We can say from our spectra and other observations that the star has a temperature of ...
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Rectification of M-type spectra
I would appreciate references and/or tips on estimating the continuum
in the spectra of M dwarf stars. The ultimate aim is to obtain radial
velocities from sequences of spectra by comparing to a ...
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How to identify Hydrogen lines of slitless spectrograph of Type A9 star
Hi I am analysing slitless spectrograph of type A9 star Canopus. Here is as sample of the spectrograph.
I basically did a simple summing up of the columns and added the data (as a simple spectrum co- ...
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Where in a star are the spectral absorption lines formed?
This question was inspired by a recent Cool Worlds video "The Star That Shouldn't Exist", in which one of the speculative solutions to Przybylski’s Star's strange spectrum is aliens "...
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Why is the filter needed for low resolution GMOS spectroscopy?
I am considering writing a proposal for using the GMOS with the R150 grating. I want to measure the redshift of multiple systems from the strong lensing effect of some clusters, so the redshift range ...
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Does the expansion and contraction of a variable star affect the measured radial velocity?
I've measured the heliocentric radial velocity of Beta Cephei using the doppler shift of the helium lines, I corrected for earth's motion using the doppler shift of the oxygen in the atmosphere. I ...
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How to convert flux to flux density for a synthetic spectrum?
I have several model SEDs generated by the CLOUDY spectral synthesis code. The data is formatted with one wavelength column and one flux column. I wish to perform Hubble synthetic photometry on these ...
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Calculate change in spectral line intensity for a change in temperature
I am trying to do some simple modelling of spectral line emission. I am starting with some ALMA observations of a protoplanetary disk, where the emission from a particular molecule at frequency 344GHz ...
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Why is the H-alpha line slightly shorter in wavelength (656.28 nm) in air than in vacuum (656.46 nm)? Shouldn't it be longer?
Perhaps this is a question better suited for Physics SE, but since the H-alpha line is so important in astronomy, I'm posting this here....
I would, naively, assume that wavelengths would be longer, ...
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What is a good resource for finding accurate apparent magnitudes stars in different filters?
I am unable to find this information online, does anyone know of a database, book, or website that contains all of the B-band, V-band, I-band etc.... apparent magnitudes for each star?
Thanks for any ...
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Determining Stellar Activity
I've been into exoplanets and the search for life for a few years now, but I'm still very much an amateur. The basics are fairly easy: habitable zone adjusted for planet/moon mass, no brown dwarves (...
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Formation of spacecraft instrumentation [closed]
List of spacecraft instruments are selected to meet a mission's science goals.
Let's take New Horizons as an example and study the composition of Pluto's atmosphere, the shape and geological ...
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Calculating intensity of moonlight per unit area
I have a photodiode that can measure intensity in picowatt to milliwatt range.
I have a telescope of 5 inch diameter. I want to calculate the intensity of moonlight received by this area? This will ...
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What spectroscopic methods are there? [closed]
It was said in a comment on this site that there are different ways spectroscopy can be achieved. I am therefore asking: What methods are available when doing spectroscopy on the composition of ...
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How accurate is astronomical spectroscopy?
We all now that green is a mixture of blue and yellow, and that purple is a mixture of red and blue. In astronomical spectroscopy the chemical composition of a planet’s atmosphere is determined, by ...
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What instruments do amateur astronomers use in their ground based telescopes in order to avoid atmospheric absorption/telluric contamination?
What instruments do amateur astronomers use in their ground based telescopes in order to avoid atmospheric absorption/telluric contamination? For example, when an astronomer observes a celestial body ...
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Obtaining Transit Spectrum for Celestial Bodies Using JWST NIRSPEC
I've recently been tasked with obtaining transit spectrum data for some fascinating celestial bodies, including Ceres, Enceladus, Ganymede, Io, and Titan. The goal is to compare their transit spectra ...
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How can I compute reasonable errors on my Gaussian fits to the observed strong optical lines of interest?
I'm fitting Gaussians to optical lines spanning from H-beta to Sulfur using Astropy's Gaussian (https://docs.astropy.org/en/latest/api/astropy.modeling.functional_models.Gaussian1D.html) model with a ...
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Star surface temperature?
I'm already familiar with using the difference in B and V magnitudes to calculate temperature, but Wikipedia (trustworthy source, I know) mentions that U-B, V-R, and R-I are also used depending on ...
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Using Gaia Passbands with L_nu coordinates
I am trying to find the coordinates of my bundles of gas on the gaia ($G, G_{bp}-G_{rp}$) hr diagram. I have its spectrum in $\nu L_\nu$ coordinates. Thus far, my attempts have mainly been to ...
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Space telescope spectroscopic data for stellar classification using Wien's law
My goal is to make a simple project which consists of classifying stars by applying Wien's displacement law.
I need public spectroscopic data about different stars from a space telescope, so that I ...
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How do nuJ(nu) units work?
I'm working with (Nublado) Cloudy, which is essentially a spectral modelling tool for stellar matter. Using the software, I model my own stellar object and obtain its continuum.
According to Hazy, ...
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How do you use Gaia Passbands to find Gbp-Grp Coordinates?
I've never used Gaia passbands, or any type of passbands before for that matter. I have a theoretical model of a stellar object, and its corresponding emissions as a function of wavelength. I'd like ...
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How do they see BOTH "anomalously cool with a significant mid-IR excess" rather than one or the other? (SN 2023ixf progenitor)
The abstract of the arXiv preprint SN 2023ixf in Messier 101: A Variable Red Supergiant as the Progenitor Candidate to a Type II Supernova (itself recently "discovered" in the observatory) ...
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Determining the rotation curve of a galaxy via given spectroscopic data
Here is the data analysis question from IOAA-2011,
1. Weighing a galaxy: The image 8.2 shows a photograph of the spiral
galaxy NGC 7083, which lies at a distance of 40 Mpc, and image 8.3 a
fragment of ...
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How does one estimate the mass of a galaxy using the Balmer break region?
I am currently reading the recent astrophysical paper "A population of red massive galaxies ~600Myr after the Big Bang'.
In the first paragraph/abstract it mentions, "It has been difficult ...
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How has the resolution of astronomical spectrographs improved over time?
Is there something like a Moore's law for spectral resolution? Maybe a chart from which one could extrapolate?
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How do amateur astronomers do stellar spectroscopy?
This question consists of 2 parts:
How can amateur astronomers measure the spectrum of stars?
In addition to diffraction gratings, what equipment do they use (like telescopes, and the focal length ...
user47732
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Is there any open data base for raw spectroscopy data?
I'm msc. student in physics and will start my thesis in a month. We are in search of a topic with my thesis professor and we talked about many ideas. After all, "what will this give us ...
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What is meant by " elliptical galaxies stabilize due to the chaotic motion of stars"?
I read that elliptical galaxies stabilize due to the chaotic motion of stars. As I understand that means that the stellar motions are more nearly random in direction. So they perform independent ...
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What accounts for a Lyman-break for all wavelengths shorter than 91.2nm if the Lyman limit is the highest energy photon that neutral hydrogen absorbs?
From this description of Lyman-break galaxies, I don't understand how:
...radiation at higher energies than the Lyman limit at 912 Å is almost completely absorbed by neutral gas around star-forming ...
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You find yourself on a random planet in the milky way 2000 years in the future. Can you figure out where/when you are? [duplicate]
Imagine you're on a planet in a distant part of the milky way, 2000 years from now. You don't know where you are or how much time has passed. You have access to modern astronomical data and technology ...
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What data has JWST obtained of the Trappist-1 exoplanets and where is it? [duplicate]
I have been long waiting spectral data regarding the exoplanets around Trappist-1 and their atmospheres, and I was also long awaiting JWST's launch to get to know more about the system. However, now ...
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How would a person know if a planet is orbiting a binary star?
I read in Neil deGrasse Tyson's book Astrophysics for People in a Hurry that scientists can tell if a star has a planet orbiting it because the light appears to shake.
So if in the case of a binary ...
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Natural line width from absorption lines
Emission lines have a certain natural width. Due to the uncertainty principle systems that spontaneously decay or produce radiation have a fundamental energy blur, and their radiation has a ...
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How do astronomical spectrometers measure spectra from single stars separately, without contamination from all of the nearby stars?
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.
...
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Where can I find datasets for all confirmed exoplanets, terrestrial exoplanets, and Super-Earth exoplanets?
The NASA Exoplanet Archive has a Planetary Systems dataset offers celestial mechanical data for 5,197 confirmed exoplanets. The Exoplanets Catalog classifies these exoplanets as terrestrial, super-...
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Different types of line broadening in stellar and galactic spectra
When analyzing stellar and galactic spectra with spectrographs, the spectral lines get broadened from the instrument. Why do the spectral lines get broadened after the light moves through the ...
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Does the luminosity of a star have the form of a Planck curve?
Figure shows the intensity of the radiant energy emitted from stars A and B over a unit time according to the wavelength. The area between the graph and the horizontal axis is S and 4S, respectively.
...
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How do astronomers calibrate the intensity scale of their spectrometers?
Discussion on Strange bump in solar spectrum taken with home-made spectrograph made me wonder: How do astronomers calibrate the intensity scale of their spectrometers? I mean, how to take in ...
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Strange bump in solar spectrum taken with home-made spectrograph
I am an astronomy teacher, and made some kind of spectrograph with a difraction grating, a 3D printed slit, water pipes and a reflex camera. With a group of students we got this picture of the solar ...
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Is it possible for us to have mistaken a few brown dwarfs and a few white dwarfs for a burning ethane-octane-oxygen planet?
Is it possible that we humans may have missclassified a handful few but not all brown dwarf stars or white dwarfs, when there really could be possibly a burning planet? Assuming a large enough planet ...
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Calculate the uncertainty in measured flux density from an integrated intensity map
I have some ALMA data, in the form of a spectral cube, which I have integrated along the velocity axis to create an integrated intensity ('moment 0') map.
The integrated intensity map shows emission ...
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Have we detected spectra of exotic atoms in stars?
I was reading this wikipedia article on positronium (a type of exotic atom) and noticed it mentioned that positronium has a spectra (of course).
So naturally this makes me wonder, have we looked at ...
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General questions about SDSS
I'm considering doing research on SDSS spectral classification (STAR, GALAXY, QSO) with machine learning for my school dissertation. Not sure if this is an appropriate place for these kinds of ...
