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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Spectroscopy of Exoplanets [closed]
How is accurate spectral analysis of a planets atmosphere achieved, bearing in mind that its host star's resultant light emission is not a full spectrum?
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Source for Identification of Balmer Hydrogen Absorption Lines
I'm working on an assignment, where I have to classify stars using the raw data of the telescope. I'm now trying to calibrate the pixel to armstrong ratio, and for that I need to identify the ...
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Solar visible light spectrum
So the visible light from stars can be used to identify the elements in that star by looking at the spectral emission lines and comparing those lines to emission lines of various elements (and their ...
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How long would it take to collect a certain amount of photons? [closed]
So, I've received this question to solve, it's not a very advanced one, though advanced enough to cause headaches.
The situation is as follows:
Say, you are observing with a telescope with an ...
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Integral Field Spectroscopy vs Fabry-Perot Interferometry
Why are Fabry-Perot Interferometers (FPIs) and Fourier Transform Spectrographs (FTSs less common than Integral Field Spectrographs (IFS) nowadays? My understanding is that:
With FPIs and FTSs you ...
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What forces expelled these huge clouds, then blocked further progress, yet allowed it to maintain its threads?
From Wikipedia and NASA:
Caption: NASA: S74-15583
(July 1973) --- A huge solar eruption can be seen in this Spectroheliogram obtained during the Skylab 3 mission by the Extreme Ultraviolet ...
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How do elements with only one shell emit light? [closed]
Electrons move to higher energy levels and drop back (electron migration). When they drop levels, photons are emitted and the wavelength/frequency emitted is based on how many levels are dropped. My ...
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How to convert theoretical template spectrum from luminosity density to flux density units?
I'm working with galaxy spectral templates (e.g., Bruzual & Charlot 2003) which seem to always come with y-axis units of $L_{\odot}$/A and x-axis units of Angstroms. Thus the y-axis is a ...
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Can some stars not emit any energy in the visible spectrum?
Stars convert mass into energy. Even converting the slightest mass into energy is immense because the speed of light is so great and $E = mc^2$. This means that stars have to emit large amounts of ...
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Was the discovery of six exoplanets around one star as "easy" as counting six peaks in the FT?
The phys.org article Scientists make huge dataset of nearby stars available to public describes the release of a publicly accessible database of Echelle radial velocity measurements; The LCES HIRES/...
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Why do different instrumental filters use different magnitude systems (Vega vs AB)?
Suppose I wanted to construct the spectral energy distribution (SED) of an object. Further suppose I observe this object through the 9 broad-band filters using the Subaru Suprimecam (just for an ...
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How does glass affect taking solar spectra?
In this case I'm using a CCD camera mounted telescope pointed at the clouds to take solar spectra and was wondering how the telescope being pointed at the clouds through a double gazing (two layer) ...
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Are blue and red shift visible?
When looking into the sky at night using my bare eyes, I see that stars appear in different colors. From my understanding this is caused by different chemical compositions of those stars which show up ...
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wavelength-based IFU data cubes VS velocity-based IFU data cubes
I have 2 simulated IFU data cubes of the same observation, let's say A and B. The 3rd dimension of cube A is in wavelengths. In order to create cube B I just rebinned cube A in log-wavelengths and ...
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Have we Observed Continuum Emission from Neutron Stars?
Have we detected continuum optical emission from any rotating neutron stars that do not have an accretion disk dominating the light? I ask because I know we have observed Doppler broadening of ...
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What's the differences between one-dimensional spectrum and two-dimensional spectrum?
mostly, we use the one-dimensional spectrum. But sometimes we use two-dimensional spectrum, what's the differences between them?
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What's the slit and slot on EIS(EUV Imaging Spectrometer) instrument of Hinode?
There are two slits and two slots on EIS, are they just four types of grating?
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How to calculate the S/N of IFU or long-slit galaxy observations
I would like to calculate the Signal-to-Noise ratio (SNR) of long-slit or integral field unit (IFU) observations of H$\alpha$ emission. I can calculate the SNR or each individual spectrum, just fine. ...
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What (actually) does "peculiar periodic spectral modulations" refer to in this preprint?
I saw this ArXiv preprint after reading about it in the popular media.
I can not even understand the beginning of the introduction (much less the whole paper):
INTRODUCTION
A Fourier transform ...
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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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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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Signal-to-noise in inverse angstrom for spectroscopy?
In a paper I came across the description of the signal-to-noise ratio (SNR) for observations with a spectograph. This was reported as $10\:1/\mathring{A}$. I am rather new to spectroscopy, so could ...
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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 ...
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What is the temperature of the solar atmosphere (the corona) and how is it measured?
The temperature of the Sun's atmosphere, also referred to as the solar corona, is known to be hot even hotter than the Sun's surface. What is its temperature and how is it measured? How does it ...
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Is remote measurement of isotope ratios possible, or must a sample be aquired
Is it possible to measure to measure isotopic abundance of remote astronomical objects - ie measurement without having a sample to feed into a mass spectrometer? Do different isotopes show any ...
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Extraction of error spectrum in Sloan Digital Sky Survey
I need to know does SDSS spectrum contains error spectrum as well?
http://www.sdss.org/dr12/spectro/spectro_basics/#AbouttheSpectra
The above link says, further HDU's contain error spectrum and than ...
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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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How do astronomers distinguish the spectral lines?
As a black body a star emits a continuous spectrum of light and other radiation. I've learned they are capable of knowing of what elements the stars are made of because of the spectral lines. But how ...
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How can I convolve a template spectrum with a photometric filter response spectrum?
Suppose I have a template stellar population spectrum (say, from Bruzual & Charlot 2003) which runs from like 1000 Angstroms to 160,000 Angstroms and which has x-axis wavelength units of Angstroms ...
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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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Which elements are an indication of habitable exoplanets?
Using spectroscopy the chemical composition of exoplanets atmosphere is determined. As a scientist, what spectral lines would you look for?
Which elements are relevant in pursue of a second earth?
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What is meant by ionization states?
I am going through the theory of Saha equation but I am not able to understand the concept of ionisation state? What are ionization states actually?
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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 ...
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How can ionized emission line flux decrease as a function of increasing metallicity or abundance?
The chemical evolution of galaxies is an important way to learn about their formation and stellar/gaseous constituents. Many galaxies show narrow emission lines at optical wavelengths (3500-9000 ...
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Infrared Astronomy for non transiting objects?
I understand how infrared spectroscopy works for determining molecules in the atmosphere of a transiting object (like Venus from Earth). But how does this work for objects that don't pass between us ...
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Can visible wavelength spectroscopy study an exoplanet's chemical composition directly?
I know spectroscopy of light in visible wavelengths is very effective for studying and determining the chemical composition of bodies within the solar system and bright objects outside of it. However, ...
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Bright lines in a continuum spectrum
Dark lines in a continuum spectrum is common. But are there bright lines too?
By the stimulated emission process, the light can also be amplified, right?
In this case, we should get bright lines ...
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How do you estimate the error on the height/width of a Gaussian?
I'm trying to fit Gaussians to several lines in a spectrum that I have. Some of them overlap with one another, causing the fitting program that I'm using to not be able to give reasonable estimates ...
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What is an "arc" spectrum ?
I sometimes hear about astronomers using an arc spectrum to calibrate observations. For example a "He-Ar arc spectrum". What is an "arc" in this context? I assume it's nothing got to do with angles (...
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Why do spectroscopic binaries have approximate circular orbits?
So for an assignment I have to answer the question what I can conclude concerning the shape of the orbit, knowing that it is both an eclipsing and spectroscopic binary.
Now, I think the answer I ...
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How can I determine line luminosities from equivalent width measurements?
I have a set of equivalent width measurements for different emission lines. How can I use them in order to determine the corresponding line luminosities?
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How to use spectral profiles to determine luminosity class?
I know the luminosity classes are: Ia-0 ( Hypergiants ), Ia ( bright supergiants ), ... , VII ( white dwarf ).
I also have learned that you can use the presence of absorption lines ( ie. use spectral ...
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How to determine atomic number density of an element in a star based on equivalent width measurements
Given an equivalent width measurement $W$ of a spectral line of element $X$ and the effective temperature $T_{eff}$ of a star, how can you determine the atomic number density of $X$ in that star?
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user5341
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Gaia: What is the difference between CCDs used for astrometry, photometry, and spectroscopy?
My knowledge of CCDs is that these are sensors which collect photoelectrons. That's about it.
What is a difference between CCDs used for astrometry, spectroscopy, and photometry? As an example, each ...
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Is any consensus forming on the solution to the "Lithium Problem"?
The "Lithium Problem" relates to the fact very-low-metallicity stars appear to have a Li/H ratio approximately one third of what would be expected. The ratio should be the same as the prediction from ...
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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 ...
user5341
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Why do we observe spectral lines of specific energy?
The basis of my confusion is that atomic orbitals, even when described accurately by quantum numbers, have definite energies, meaning they represent energy eigenstates of the wave function. They're ...
user5341
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Why is $g$ tied to the oscillator strength $f$ in $\log{gf}_{\odot}$
The $\log{gf}$ value of an element in a star, where $f$ is the oscillator strength, or probability of transition in an atom, is a scientifically pursued quantity with relation to the model atmosphere ...
user5341
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How to run MOOG on OS X Yosemite
By what process can a user running the latest version of OS X Yosemite execute MOOG with $MOOG in bash?
Due to the removal of 32bit libraries in OS X 10.7+, the ...
user5341
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H-alpha velocity fields of spirals falling into a cluster
What kind of impact would you expect ram pressure stripping / tidal interactions / harassment / interactions with the cluster potential (etc!) to have on the h-alpha velocity fields of infalling ...
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