Questions tagged [luminosity]
Questions regarding the amount of energy produced by an object per unit of time.
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Confusion over habitable zone
I am confused over the habitable zone, as I calculated the expected temperature of Earth (minus greenhouse effects), and it would be -17 C. Which is below the freezing point of water.
I also made a ...
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Is there a way to calculate a star's luminosity from its apparent magnitude?
I was wondering if there's a way to calculate a star's luminosity from apparent magnitude data.
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Period-Luminosity Relation of Cepheids via Gaia Data
I was trying to verify Leavitt's Law of Period Luminosity Relationships of Cepheid Variables using Gaia data. To do this I calculated the period using the Lomb Scargle Periodogram for 1450 stars and ...
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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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What's the relation between the parallax distance and the luminosity distance?
I have read that Riess and his team are able to measure $H_0$ from supernovae calibrated using Cepheid in a model independent way.
from what I have gathered they find the absolute luminosity of ...
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Help converting Jansky/beam to erg s^-1
I have some radio observation data in jansky/beam from NVSS at 1.4GHZ, and I want to convert these values into luminosity values (erg/sec).
I have the distance data and I made a formula to convert it:
...
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How to convert Flux Density to Flux?
I have a radio catalogue with flux density values. (Jy/bm) I'm confused converting this value to flux. Because I want to calculate luminosity, I need flux values. The unit made me confused. Since I ...
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Protoplanetary disk luminosity - looking for a sanity check please
I've been told to "consider an Earth-mass of interplanetary grains (roughly spherical with a radius of a few microns) in a protoplanetary disk. Let the particles be in a torus with a cross-...
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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, ...
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What's the issue with Olbers' paradox?
I'm not quite grasping the reasoning behind Olbers' Paradox, or why an eternal, non-expanding and spatially infinite universe would be incompatible with a dark sky. For simplicity, let's suppose that ...
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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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How do I determine the Luminosity with a half-life decay?
I know there is a proportionality between the luminosity and $\frac{dN}{dt}$, but I am not sure why they are proportional and why there is a need for an initial mass to compute the luminosity if the ...
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What is the infrared self-luminosity value of Jupiter and Saturn?
I'm looking for these data to apply them to the Kelvin-Helmholtz mechanism but I can't find the values. Or at least if there is an order of magnitude compared to the solar luminosity.
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How bright will Alpha Centauri A be from Earth when it becomes a red giant?
As of right now, both stars from Alpha Centauri are in their main sequence stages, but eventually Alpha Centauri A is going to quickly expand in a matter of time, and I’m pretty sure its luminosity is ...
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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?
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How can I calculate the luminosity and mass of a star only knowing it's peak wavelength and it's subtended angle?
For example if a certain star subtends an angle of 32 arcminutes at the Earth’s orbit and it's light has a peak wavelength of 500 nm, how can I find the luminosity and mass of that star?
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Change in Luminosity of a planet
When viewed from the sun, the brightness of the planet with a given
size and albedo changes according to the fourth power of inverse
distance.
I found the statement in one encyclopedia but I can't ...
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Is luminosity distance related to both heliocentric redshift and CMB restframe redshift？
The luminosity distance
$$d_l=(1+z)r(z)\ ,$$
where $r(z)$ is given by $$r(z)=cH^{-1}_0\int_{0}^{z}\frac{dz'}{E(z')}\ .$$
When I use the SNe dataset "Pantheon", I find there are two redshifts:...
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On finding the magnitude of Stars
I am wondering how I would be able to predict the Magnitude of fictional stars, given we know enough about them. As the formulae I can find online are mostly getting overly high values that don't seem ...
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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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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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Calculating the luminosity of a comet
Assuming a 9-km comet is heading towards the Earth and it is at distance 5.2 AU away from the Sun, what is its luminosity? Assume that it has an albedo of 0.5?
For now, I have calculated the Sun's ...
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Finding stellar radii
Is apparent magnitude of star, distance(in pc) and effective temperature enough to calculate its stellar radii or we need some extra information?
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Measuring the mass of the luminous matter in a galaxy
The mass of total matter in a galaxy can be measured using the rotation curve of the galaxy. However, how do people determine the mass of luminous matter in the galaxy, as a function of the distance ...
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Brightness and flux density
The alpha star in a constellation has the highest brightness, but does that mean it has the highest flux density among the other stars in the constellation?
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How to find luminosity from a light curve? [closed]
I am currently trying to find the luminosity from the light curve. I have the data about the distance, counts/sec and the energy range in which it is measured for an object. What equation can be used ...
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Could a black hole's accretion disk be bright through natural means?
This question is based on this description of the Cormoran Supermassive Black Hole in the Orion Arm's website:
Surrounding this event horizon is an (apparently artificial) accretion
disk about 4AU in ...
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What does a + (plus) mean in stellar classification?
I've noticed some stellar classifications might look like this:
A0IV+G: (HD 70003)
F3IV+F0IV (HD 82434)
...
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Spectral class and luminosity of hydrogen bomb explosions?
Since hydrogen bombs detonating are like tiny little stars, I wonder what luminosity and spectral classification they would get if one were to categorize them like this. E.g. Starfish Prime and the ...
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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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Is it dangerous to look at an L-type brown dwarf from too close?
Are some L-type brown dwarves bright enough so that it would be dangerous to the eyes if one looked at them from habitable distance or closer? If not, are the weakest M-type stars undangerous to look ...
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How is the difference of bolometric magnitudes not dependent on the stars' radii?
The difference of 2 bolometric magnitudes is given by:
$$M_{bol, ★} - M_{bol, ☉} = -2.5 \cdot \log \left( \frac{L_★}{L_☉} \right)$$
But Pogson's equation is:
$$M_{bol, ★} - M_{bol, ☉} = -2.5 \cdot \...
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HR diagram x-axis (color) and redshift?
I've read several articles and watched some videos on the HR diagram, but no-one seems to mention the effect of redshift on the color of a star. Is there some calibration step that needs to be applied ...
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Is something wrong with my luminosity calculation?
A few million years after a white dwarf forms, its surface temperature reaches $100000\text{K}$, while its radius is $0.01R_\odot$. Would this mean that its luminosity is $\Big(\dfrac{100000}{5778}\...
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How to calculate galaxy bolometric luminosity?
I am a bit confused by bolometric corrections. If I have an x-ray luminosity in the 2-10 keV band, how does one convert that to $L_{bol}$?
From Netzer's book The Physics and Evolution of Active ...
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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 ...
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Estimating Sun luminosity from first principles
In a lecture, it was claimed that luminosity can be estimated by dividing how much energy there is in the Sun with the typical time it takes for a photon to get out from the centre of the Sun to its ...
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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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Does photon capture in a black hole (or any other "very compact" object) reduce the luminosity/photon flux from its self isotropic emission?
I don't know if this is even a feasible question or if I have a point in asking so.
Let's say we can model the radiation coming from a very compact object, such as a BH with an accretion disc or any ...
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How to obtain a luminosity from an SED
I have a spectral energy distribution (flux densities measured at several frequencies), and have fitted a 'greybody' model to these points.
I am confused about how I use this information to determine ...
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What units are used for the Stefan-Boltzmann law?
I have a star with given temperature in Kelvin and radius in solar radii. I tried to calculate the luminosity of the star using Stefan Boltzmann's law, and got an absurd number (over 1 million). What ...
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Increase in Luminosity of the star
The Luminosity of a star is proportional to the 4 th power of its temperature and square of its radius. Also the mass-luminosity relationship says that the luminosity of star is proportional to ...
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Luminosity of Neowise
So, I have been trying to figure out the bolometric luminosity of the comet C/2020 F3 (Neowise) on the 22nd of June, 2020. At that time, Neowise was $1.4$ AU away from Earth and had an apparent ...
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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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What is meant by the notation $A^{\times{B}}_{\div{C}}$; where A,B,C are real numbers?
I have come across a few papers using the notation $A^{\times{B}}_{\div{C}}$; where A,B,C are real number. For example, $3000^{\times{3}}_{\div{4}}$.
An example can be Eqn (4) in Stern & Laor (...
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Converting Light curve to Luminosity
So I'm currently working around a specific variable star, α Ori and I want to determine it's luminosity...I do only have the light curve (driven from V-optical photometric band - Johnson V from AAVSO)....
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Strip Brightness in a Spherical System
My question concerns the following problem, published in Galactic Dynamics by Binney and Tremaine and based on a work by Schwarzschild.
Specifically, I am having difficulties in deriving the given ...
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How do I calculate the surface temperature of a star from luminosity? [duplicate]
How do I calculate the surface temperature of a star from luminosity? I've been trying to delve into speculative solar systems for a bit, and I've heard the surface temperature of a star can be ...
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How does the Eddington limit make the gravitational field of stars asymmetric?
This answer to Is the gravitational field of the sun uniform? says:
Very large stars are asymmetric due to being close to the Eddington limit. The Sun is too small of a star to have the kind of ...
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Is there a relation between mass, radius, and luminosity in deuterium-burning brown dwarfs?
I'm a worldbuilder and my setting has a lot of brown dwarfs.
While I'm trying to keep my setting as science-compliant as possible, I can't seem to find any resources for brown dwarfs like there are ...
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