# Questions tagged [luminosity]

Questions regarding the amount of energy produced by an object per unit of time.

21 questions with no upvoted or accepted answers
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### What is the average and the median mass and luminosity of a star?

I've heard in many places that the Sun is an average star, but in Wikipedia it says that about 75% of stars are M-type stars that are way less massive and fainter that the Sun. So how massive and ...
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### DIY Sky Quality Meter: Conversion between Illuminance and Luminance

I am trying to create a homemade Sky Quality Meter (SQM) using a TSL2591 light sensor. This sensor measures Illumination (lux), but SQMs measure Luminance (mpsas). I have seen that there are many ...
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### What is the spectral power output of a typical galaxy?

I'm looking for a function which gives the typical isotropic spectral power of light emitted by an entire galaxy on the whole electromagnetic spectrum (in watts per frequency unit), as a function of ...
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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 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 ...
• 21
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### What is the spectral energy distribution (SED)?

I see the SED being referred to as several different things and now I am confused about what it actually is and what are its units. In particular, I find the SED Wikipedia page not understandable. ...
438 views

### Q: Calculating the luminosity of a galaxy

I am currently working on a project on which I am calculating the luminosity of galaxies by using the SDSS data. They use a system of asinh magnitudes, and according to their website they use a system ...
335 views

### Stars that don't fit $L=4\pi R^{2}\sigma T^{4}$?

When calculating luminosity/radius/temperature for several stars, I've noticed that while the majority of stars conform to the luminosity relationship $L=4\pi R^{2}\sigma T^{4}$, there are a few that ...
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### Luminosity of the Milky Way compared to Seyfert galaxies

This page lists the total luminosity of the Milky Way (MW) Galaxy to be $4\times10^{10}$ $L_{\rm sol}$, and $L_{\rm sol}=3.86 \cdot 10^{33} {\rm ergs.sec}^{-1}$; this gives a total luminosity for the ...
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1 vote
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### Calculate Luminosity of a star from the Hipparcos catalogue

Is it possible to calculate the star's luminosity based on the data in the Hipparcos catalogue? Currently I'm using this algorithm, I have even fitted the bolometric correction to the Johnson V band (...
1 vote
50 views

### Calculating the absolute magnitude of a solar system body

I am trying to calculate the absolute magnitude of a solar system object, given its albedo, and assuming all of its luminosity comes from reflecting light from the sun. Using $L_{sun}$ = solar ...
1 vote
19 views

### 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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1 vote
41 views

### Magnitude cuts in different bands/surveys

I have data on around 142,000 galaxies. Some of these galaxies have apparent magnitude data in different bands. For example, many of my galaxies have SDSS PSF data in ugriz bands,GALEX FUV, GALEX NUV, ...
1 vote
848 views

### Schechter Luminosity Function fitting plot of galaxies

I would like to plot the Schechter Luminosity function of galaxies. Here is my data(I have the Luminosity L[Ha] in erg/s). I would like to plot like this figure from this paper. In this paper, they ...
1 vote
24 views

### Equilibrium Temperature for Extremely Cold Planets: Incorporating the CMB and Intrinsic Radiation

I want to check if I'm doing this right. I'm computing the equilibrium temperature for planets where the CMB and/or the planet's intrinsic radiation (as in weakly radiating jovians) matters. I start ...
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1 vote
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### Units confusion while calculating flux of a star using distance and luminosity, Python

I am trying to calculate the flux of various stars in Python. I am using the information from a database containing all stars in Hipparcos, Yale Bright Star, and Gliese catalogs (almost 120,000 stars)....
1 vote
463 views

### Conversion factors for flux

I have a flux value in the infrared band of 8 mJy at a wavelength of 80 microns that I want to translate into X-ray conventional ...
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1 vote
67 views

### Change in angular diameter of Cepheid variables

I'm a highschool student and in the process of writing a research paper of deriving period-lumniosity relation of Cepheid variable independently of the pre-existing PL relation. Thus, I need to derive ...
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### How luminous does a brown dwarf have to be to illuminate an Earth-sized planet with 0.5 lux at 2,000,000 kilometers away?

A brown dwarf is a deuterium-fusing substellar object, and, in the cases of the larger ones, a lithium-fusing one. They often emit electromagnetic radiation in frequencies that humans cannot see. ...
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### Samples from the double Schechter luminosity funcion

I want to produce samples from a double Schechter luminosity function. Ideally, I am looking for a python implementation of this problem but am open to other tools if necessary. Do you know of any ...
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