Questions tagged [spectra]

Questions about the observed frequency range of the electromagnetic radiation of a celestial object.

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What is the meaning or information given by the solar image at 4500Å?

On the latest solar images from NASA, there is one picture lablled "continuum 4500 Å". There are bands diagonally in the picture as well. What is the ...
not2qubit's user avatar
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6 votes
3 answers
469 views

Is it practical to build a DIY spectroscope that can clearly show absorption lines in a spectra of the Sun?

Is it practical to build a DIY spectroscope that can clearly show absorption lines from the Sun? "Practical" means that the kit can be made at home or relatively cheaply bought (less than £...
Slarty's user avatar
  • 349
0 votes
0 answers
49 views

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 ...
Ankit Biswas's user avatar
0 votes
0 answers
24 views

Solar system datasets for exoplanet analogs?

Are there data from the solar system available, that are about quantities we regularly investigate in exoplanet searches? The only collection I know of comes from this paper: "A Catalog of ...
Helen's user avatar
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24 votes
3 answers
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Did the Sun's light always peak in the green wavelengths?

So, I know the sun is getting brighter over it's lifespan and I'm wondering how that affects its emission spectrum. The reason I'm asking this is because I find it weird that plants reflect green ...
Elhammo's user avatar
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1 vote
0 answers
23 views

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 ...
starry_explorer's user avatar
1 vote
2 answers
167 views

How to get the flux from a synthetic spectrum in a bandpass, when only given specific luminosity times frequency?

I have some synthetic spectra of stars (M and K giants) with columns wavelength [Angstroms], continuum normalised flux and specific luminosity $\times$ frequency [ergs/s]; I also have some Euclid ...
Rumi's user avatar
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4 votes
1 answer
509 views

Has the new type II supernova SN 2023ixf's subtype been determined yet, and is a tentative light curve possible? Is it still getting brighter?

Wikipedia's article on SN 2023ixf begins: SN 2023ixf is a type II (core collapse) supernova located in the Pinwheel Galaxy (M101). It was first observed on May 19, 2023 by Koichi Itagaki and ...
uhoh's user avatar
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0 votes
1 answer
38 views

What is the unit of the correlation function between logarithmically rebinned galaxy spectrum and stellar template spectrum?

Assume I have a logarithmically rebinned galactic spectrum $G(x)$ and a stellar template spectrum $S(x)$, where $x = \ln{\lambda}$. When $[\lambda] = 1 Å$, then $[x] = 1 Np/Å$. The fourier transformed ...
trynerror's user avatar
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3 votes
2 answers
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How to construct optimal Wiener Filter?

I am trying to construct a Wiener Filter, to filter the ratio of the peak from the cross-correlation function, between a galaxy spectra and a template spectra, with the peak of the auto-correlation ...
trynerror's user avatar
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0 votes
1 answer
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What am I doing wrong in this ppxf application?

I am trying to derive the kinematics of a galaxy spectra. To test my results I want to implement the Penalized Pixel Fitting method. For the galaxy spectrum I use a central line with sufficient S/N. I ...
trynerror's user avatar
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2 votes
1 answer
244 views

How can someone take narrowband data from an OSC narrowband filter

To those who aren’t aware, an OSC narrowband filter is a filter with multiple band passes, for different emission lines. These can include a combination of Hα, Hβ, OIII, SII, and other emission lines. ...
Topcode's user avatar
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2 votes
1 answer
37 views

Are we searching for supercriticality of exoplanet water via passive spectral analysis?

Much spectrum analysis on many chemical compounds are mapped and categorized at Earth atmosphere (1000 millibar) or thereabouts. But many celestial objects are of greater ranges of surface pressure. ...
John Greene's user avatar
2 votes
2 answers
98 views

Supernova remnant spectral lines

I have some trouble to find which spectral lines are the ones in this SNR N49 fitted spectrum. They are at 1.3 keV, 1.9keV, 2.5keV, 3.2keV, 3.95keV and maybe at 0.65keV and 6.8keV (approximately). ...
martín canullán's user avatar
3 votes
1 answer
117 views

Stellar classification spectral lines: chemical abundance vs temperature

I'm an amateur who watched the Cosmos episode on Cecilia Payne's contributions to stellar classification, which I liked. I've been going down a rabbit hole on this and and I have a question for ...
Stephen's user avatar
  • 131
4 votes
2 answers
712 views

What causes the Balmer Jump?

To quote Wikipedia: Balmer Jump is caused by electrons being completely ionized directly from the second energy level of a hydrogen atom (bound-free absorption), which creates a continuum absorption ...
Hika's user avatar
  • 43
1 vote
0 answers
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Which stars are elliptical galaxies constituted by?

I know that elliptical galaxies are old galaxies, with almost no star formation and an old stellar population. This can be seen by their dominantly red spectra in the optical. I am trying to get a ...
trynerror's user avatar
  • 839
7 votes
1 answer
326 views

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 ...
user avatar
2 votes
2 answers
230 views

Reduced chi square value

I am currently plotting a continuum of observed data. I need to check the effectiveness of the fitted continuum with the reduced chi-square method. Ideally, should the reduced chi-square value ...
summer's user avatar
  • 31
2 votes
0 answers
43 views

Provided a relative flux v/s wavelength plot, how can I calculate the radial velocity of an exoplanet? [closed]

I imagine the relativistic version of the Doppler effect would be appropriate but I'm not entirely sure since flux is a measure of intensity. Alternatively, where could I find redshift data for ...
chuffyduffy's user avatar
6 votes
1 answer
374 views

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 ...
trynerror's user avatar
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2 votes
0 answers
87 views

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 ...
trynerror's user avatar
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3 votes
1 answer
98 views

What objects in the night sky have the narrowest range of visible light

What objects visible to the naked eye at night have the narrowest spectrum of visible light reaching the earth. Put another way, Which objects are most visible as a specific color or colors rather ...
Schquestoning's user avatar
7 votes
1 answer
138 views

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 ...
Sidharth Ghoshal's user avatar
2 votes
0 answers
47 views

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 ...
Robert Mifsud's user avatar
1 vote
0 answers
45 views

How can I estimate a stars surface temperature, luminosity, radius, and lifetime only knowing it's solar mass and peak wavelength? [duplicate]

For example: if a 10 solar mass star emits light at a peak wavelength of λ = 300nm. How can I calculate a stars surface temperature, luminosity, radius, and lifetime with this infomation?
R-802's user avatar
  • 57
3 votes
1 answer
111 views

How does instrumental dispersion work?

I am trying to understand the mathematical formulation of instrumental dispersion in galaxy and star spectra. Let $x=ln(\lambda)$. Assuming that the galaxy spectra G(x) is composed of many identical ...
trynerror's user avatar
  • 839
3 votes
0 answers
71 views

How to obtain exoplanets transmission spectra from JWST's NIRISS data of WASP96?

I was having a look at JWST's NIRISS data of WASP96 (specifically at the x1dints fits file which should be already calibrated). From this, I would like to obtain a result in a fashion similar to the ...
gangio's user avatar
  • 31
5 votes
2 answers
657 views

How to find the resolution of a spectrum?

I have been tasked to find the spectral resolution of some synthetic spectra (wavelength in Angstroms vs. flux) of different stars and degrade them to the resolution of observed spectra. But I am not ...
SaptarshiS's user avatar
4 votes
0 answers
59 views

How are plage regions related to the density of medium and velocity FeII ions?

During a literature review (abstract), I found that the intensity of FeII (298.5 nm) ions in the last solar minimum was higher than the two previous solar minima 21 & 22. The velocity of FeII ions ...
Autodidact's user avatar
2 votes
1 answer
104 views

How to fit LOSVD of a galaxy with gauss hermite parametrization

I have recovered the following LOSVD from an elliptical galaxy, that I now want to fit a gauss-hermite-parametrization to and derive the kinematical parameters rotational velocity, velocity dispersion ...
trynerror's user avatar
  • 839
3 votes
1 answer
50 views

When measuring the spectrum of an object at the zenith, is it better to orient the spectroscopic slit N-S of E-W?

If you were to measure the spectrum of an object while it's exactly at the zenith, how should you orient the slit of the spectrograph to minimise atmospheric dispersion? Is North-South or East-West ...
Soph's user avatar
  • 33
2 votes
1 answer
154 views

How to convert spectra to log-wavelength and interpolate them into linear spacing in log-wavelength

I want to write a function that cross correlates a spectrum with a quasar template I’d like to ask you how can I convert my flux density vs wavelength spectrum to log-wavelength. It’s not clear to me ...
Q Wolf's user avatar
  • 23
3 votes
0 answers
67 views

S/N binning of 2D spectral galactic data

I have the 2D spectrum of the ellipical galaxy NGC 4697 taken by a long slit spectrograph. The x-direction (horizontal) corresponds to wavelength and the y-direction (vertical) corresponds to distance ...
trynerror's user avatar
  • 839
14 votes
1 answer
899 views

What happened to the reemitted photons during recombination?

To my understanding, the Cosmic Microwave Background Radiation (CMBR) is light released during the recombination epoch where the formation of neutral hydrogen atoms allowed for a sudden drop in the ...
YiFan's user avatar
  • 558
1 vote
0 answers
30 views

what is the difference between Composite Stellar Population and Galaxy Spectral Energy Distribution?

I am reading Conroy et al. (2013), an extensive review on Stellar Population Synthesis technique, and I really can't get the difference between Composite Stellar Population and Spectral Energy ...
fslack's user avatar
  • 51
1 vote
1 answer
142 views

How to handle empty tables returned by astroquery Nist.query() in Python?

I'm writing a code to extract wavelengths of certain species of atoms/ions in a given wavelength range using the Nist.query() command of the Python package ...
ShaunakP's user avatar
1 vote
1 answer
258 views

How to calculate S/N in galaxy absorption spectra?

I want to calculate the S/N of an galaxy absorption spectrum. I therefore chose a part of the spectrum which contains very little to none absorption features and should be only made up of noise and ...
trynerror's user avatar
  • 839
3 votes
1 answer
172 views

Meaning of "blue continuum spectrum"?

The textbook Astrophysics in a Nutshell, talks about the "blue continuum spectrum" in relation to the spectrum of an AGN: I know that a continuum spectrum is caused by the interaction of a ...
Jim421616's user avatar
  • 2,498
3 votes
0 answers
30 views

How to find x-values of fourier-transformed correlation functions in velocity space?

I am trying to extract the kinematic parameters (rotation velocity, velocity dispersion, ...) of an elliptical galaxy by extracting the kinematical broadening function using the FCQ-Algortihm first ...
trynerror's user avatar
  • 839
1 vote
1 answer
46 views

Are there any SuperCam spectra available?

A lot of pictures from the SuperCam, the NavCam or the Mastcam onboard the Perseverance rover are available online (for instance on the NASA and JPL websites). Have any SuperCam spectra been made ...
usernumber's user avatar
  • 17.5k
5 votes
1 answer
338 views

How to remove redshift from galaxy spectra in Python?

Hello I extracted a spectrum from the central region of the 2D spectrum of the major axis from NGC 4697 (I just took a central row in the 2D data set, see this question for more information: How to ...
trynerror's user avatar
  • 839
1 vote
0 answers
163 views

How far can a star's visual colour deviate from black body radiation?

The primary driver of a star's colour is its temperature, by way of black-body radiation. Black body radiation restricts stellar colour to a narrow slice of the full RGB spectrum. However, all stars ...
Ingolifs's user avatar
  • 4,157
2 votes
0 answers
67 views

starting from SSP spectra to evaluate galaxy spectrum and observed mag

I know that the galaxy spectrum, namely the flux per unit wavelength versus the wavelength, is the sum of the Simple Stellar Population (SSP) spectra at a fixed redshift (e.g. similar to eq. 1 in ...
fslack's user avatar
  • 51
2 votes
1 answer
107 views

Spectra of different stellar classes?

I'm beyond an amateur, but I've been failing to find this information and it makes me think I'm missing something. Anyway: I am trying to write a procedurally generated simulation that includes ...
Edward Peters's user avatar
2 votes
1 answer
170 views

Spectral lines of the Sun?

If I remember correctly, the pp chain and (partially) the CNO cycle are the dominating set of reactions in our Sun. On the other hand, the composition of the Sun has many more elements/isotopes than ...
B--rian's user avatar
  • 5,616
5 votes
1 answer
314 views

How to extract galaxy spectra for different radii in Python for spectra taken by long slit spectrograph?

I am trying to extract the kinematics from the elliptical galaxy NGC 4697 using the Fourier Correlation Quotient (FCQ) algorithm described by Bender (http://adsabs.harvard.edu/full/1990A%26A...229.....
trynerror's user avatar
  • 839
2 votes
1 answer
159 views

What type of spectrum does the Wolf-Rayet star WR137 have?

Is it an Emission Spectra or an Absorption Spectra? I think that it's an absorption spectrum, but then why is the light intensity curve focused on elements that should not be in the star in this case, ...
evgeni fotia's user avatar
2 votes
1 answer
157 views

Question regards to Kirchhoff’s Laws (of spectroscopy)

In the book "Horizons: exploring the universe-Cengage learning (2018)", page 210, it states that: Observational evidence can tell you how nova explosions occur. As the explosion begins, ...
Jack the Ranger's user avatar
1 vote
1 answer
117 views

Derive LOSVD from galaxy spectrum, using fourier method

I am trying to implement a programm, that derives the kinematics (specifically the kinematic parameters: mean rotation velocity, velocity, dispersion, hermite coefficients h3 and h4) from an ...
trynerror's user avatar
  • 839