Questions tagged [mass]

Questions regarding the property of astronomical objects that determines their inertial resistance and gravitational interaction with other bodies.

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Neutral vs ionized mean molecular weights

I am confused about the calculation of mean molecular weights, especially for ionized particles. From my understanding, the mean molecular weight $\mu$ is the average mass per the number of particles: ...
justauser's user avatar
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5 votes
1 answer
95 views

What is the minimum amount of mass needed for geologic activity

I have heard sometimes that "X is too small to have an atmosphere/geologic activity" so that got me wondering: Is there a minimum mass or volume needed for an (old) object to have geologic ...
Stephen's user avatar
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2 votes
0 answers
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Which star has the highest estimated mass-loss rate? [duplicate]

As far as I know, stars like RSGs and LBVs have the highest mass loss rates. There is Eta Carinae (0.00039 solar masses/yr), NML Cygni (0.00042 - 0.00048 solar masses/yr), WOH G64 (0.00072 solar ...
Migmanychion's user avatar
5 votes
1 answer
73 views

What are the effects of mass concentration along a planet's axis of rotation?

Reading about geological history of Mars and coming across the Martian dichotomy, which is about having the two hemispheres' geography differ in elevation by 1 to 3 km. Does this mean that Mars' ...
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23 votes
3 answers
3k views

From an outsider's perspective, how can a black hole grow if nothing ever crosses the event horizon?

Due to time dilation, an outside observer never sees a falling object actually cross the event horizon. I'm not referring to the optical illusion of red-shifted light making objects appear to fade ...
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3 votes
2 answers
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Is the object mass distribution different for galaxies of different diameter?

Let's say we compare two elliptic/spiral galaxies with the bigger having a diameter 100 times the smaller. Now we count every separated object inside them and classify them into mass categories e.g. $...
J. Doe's user avatar
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1 vote
1 answer
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How to turn find velocity dispersion from radial velocity

In the above given picture Vi is the velocity of the i-th galaxy in the cluster while Vm is the mean velocity of a galaxy in the cluster. and V i,r is the radial velocity of the i-th galaxy and V m,r ...
Moiz khokhar's user avatar
1 vote
0 answers
53 views

Large dataset of galaxies redshift, mass, and metallicity?

I'm curious if there is a standard dataset for redshift-mass or redshift-metallicity like there is for redshift-distance with Pantheon+SH0ES. https://github.com/PantheonPlusSH0ES/DataRelease/tree/main/...
MikeHelland's user avatar
3 votes
1 answer
139 views

Do all orbits emit gravitational waves?

In principle, all orbits in the universe should progressively decay due to the emission of gravitational waves. However, does this always happen? Are there any kind of orbits that do not decay as they ...
vengaq's user avatar
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What are the primary astrophysical implications of a proposed mass of about 11 M⊙ for the 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) ...
uhoh's user avatar
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Seeking Guidance & Tips for Collaboration on a Cosmological Project Involving Potential Energy Variation Due to Cosmic Expansion

I'm a student with a deep interest in cosmology and astrophysics. I've embarked on a project and am seeking some guidance, insights, or even ways that I could look for possible collaboration on this ...
Aaron Schramm's user avatar
3 votes
4 answers
8k views

Does the Earth constantly lose mass?

The Moon is orbiting the Earth in a circular motion. To keep any object in a circular motion we need energy. Hence, does the Earth lose energy by pulling the Moon? In that case, does the Earth's ...
Prajwal D M's user avatar
1 vote
0 answers
119 views

Mass range of a sub-brown dwarf

Sub-brown dwarfs are celestial object that have planetary mass or are termed "Planetary mass object/planemos". They do not lie in the range 13-80 MJ that defines "normal" brown ...
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14 votes
1 answer
2k views

What is going on with this (sub?) brown dwarf WISEPA J174124.26+255319.5?

In this Wikipedia article, it details about a T9 class brown dwarf named WISEPA J174124.26+255319.5. Apparently, this brown dwarf has 0.95 Jupiter masses, and 0.4 Jupiter radii (with rather low error)...
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12 votes
2 answers
1k views

How are the masses of solitary stars weighed?

How are the masses of solitary stars weighed? With binary stars you can measure the pull each applies to the other, but that isn't an option with solitary stars.
blademan9999's user avatar
3 votes
1 answer
112 views

What mass does an evaporating black hole have when it's schwarzschild radius equals the Planck length?

I am referring to Hawking radiation and the decrease in mass of the black hole with time
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3 votes
0 answers
102 views

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 ...
HugoF's user avatar
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1 answer
226 views

Mass Content of the Hubble Sphere

How does the mass encased within the Hubble sphere/volume (both proper and comoving) change with time?
Kontrola Faktů's user avatar
9 votes
1 answer
2k views

Is the Andromeda galaxy larger than the Milky Way or not?

The Wikipedia article on the Milky Way states that it has an estimated 100 to 400 billion stars. The one on the Andromeda states that it has about a trillion stars. With this, we can conclude that the ...
Rohit Pandey's user avatar
3 votes
1 answer
116 views

Binary - when mass transfer starts

How to estimate when the mass transfer will start? What is the characteristic of pre-mass transfer binaries?
Elena Greg's user avatar
4 votes
1 answer
247 views

Maximum mass of the observable universe

As I understand it, the maximum radius of the observable universe will be about 62.9 billion ly (at t = ∞). Does it mean that the observable universe will reach a maximum mass (baryonic + dark matter)?...
Kontrola Faktů's user avatar
3 votes
1 answer
405 views

What is mass-weighted age?

This seems to be a common term used in the field of stellar populations and galaxy evolution, but I can't find a good definition besides the fact that it is different from light-weighted age (a term I ...
CuriousCosmos's user avatar
3 votes
1 answer
221 views

How do you convert an uncertainty quoted in dex to a 1-sigma uncertainty?

The black hole mass measurement uncertainties from this paper https://arxiv.org/pdf/2006.15150.pdf are quoted in "dex" and are said to be equal to 0.4 dex. I have seen from certain papers ...
Os GS's user avatar
  • 33
3 votes
0 answers
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Mass resolution in cosmological simulations [duplicate]

I've been reading papers about different cosmological simulations and they all talk about the "mass resolution" of those. Can someone please explain what does "mass resolution" ...
schrodingal's user avatar
3 votes
1 answer
258 views

How can the upper limit for a star's mass be calculated?

I know there is a theoretical mass limit for stars around $300 M_\odot$. But I cannot find a way to calculate that number. I tried to use the "Eddington Limit", but I don't know if I'm on ...
Aegean's user avatar
  • 109
4 votes
0 answers
69 views

If the universe is a closed spacetime structure, can we assign a center of mass to it?

If we envision the universe like a balloon but in 3D, is it possible, in general, to assign a of global center of mass?
Felicia's user avatar
0 votes
1 answer
410 views

How to calculate metallicity of a star that is made of iron of 20kg and Hydrogen 1000 kg?

I want to know how to calculate star metallicity using only masses of metal and hydrogen of the star. I am attaching my working so far. I am not sure how to exactly calculate the log10(Fe/H) based on ...
Jerome's user avatar
  • 155
1 vote
0 answers
102 views

Why do we estimate the Minimum mass when we are dealing with exoplanets?

While solving astronomy problems dealing with exoplanets, I always see that the question asks for minimum mass instead of the mass. Why is that so and why is the calculated mass minimum mass? example ...
Hardek A.'s user avatar
4 votes
1 answer
281 views

Accurate formula for calculating the mass of an exoplanet using the transit method

A friend and I did some work on exoplanets with the help of a research institute (IEEC in Spain) for a major high school project. What we did was to "redetect" the exoplanet XO-6b through ...
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1 vote
0 answers
48 views

Approximately what fraction of the galaxy's stars are in the bulge? [closed]

In the text of the question it is said to consider density uniformly
MTMH's user avatar
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7 votes
1 answer
480 views

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 ...
Nownuri's user avatar
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1 vote
2 answers
234 views

Are there negative masses that attract each other but repel positive masses? [closed]

Is there law/rule in physics that precludes the existence of a negative mass, wherein similar negative masses attract but positive and negative masses repel? To keep this on-topic in Astronomy SE: Has ...
Riad's user avatar
  • 119
0 votes
2 answers
330 views

How is light unable to escape a black hole if photons are massless? [duplicate]

I understand light will follow the curved space that the BH is causing due to its mass. I also understand that mass attracts other mass but then photons are massless. So 0(photon) x m2 (the BH) is ...
Nuffsed81's user avatar
0 votes
2 answers
78 views

When calculating the mass of stars, is it considered that additional mass could be added because of pair-production?

I would like to know that, since stars emit a lot of photons where some of them could be producing electrons-positrons pairs, if its mass affects the calculations, and if because of this is different ...
Joako's user avatar
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3 votes
0 answers
76 views

How much mass to make a shperical object?

I was googling around for info for D&D campaign I am going to run. I was wondering about the mass required for a object to pull itself into a shperical shape and it seems that the answer varies ...
Joseph Williams's user avatar
2 votes
0 answers
56 views

What's the relationship between the mass of a star and the mass of its core?

What's the mathematical relationship between the mass of a star and the mass of its core? For simplicity's sake, I'm asking about the cores of main sequence stars at birth, and by "core" I ...
zucculent's user avatar
  • 1,718
0 votes
1 answer
163 views

What actually is the mass? [closed]

Since high school, I've been told that the definition of mass is "quantity of matter" (which is absolutely wrong, I guess). If mass is actually a quantity of matter and it is a measure of ...
Kavin Ishwaran's user avatar
1 vote
2 answers
177 views

is weight of two identical objects same when they have the same exact distance from earth's surface but one is on a mountain and the other on a plane? [closed]

Is the weight of two identical objects the same when they have the same exact distance from the earth's surface but one is on a mountain and the other on a plane? The distance between the plane and ...
user avatar
6 votes
2 answers
752 views

What is the (overall) half-mass radius of Milky Way

I am doing some simulation and I need the half-mass radius of Milky Way (total mass: including all objects, dark matter, nebula...), but I cannot find the value and I don't know how to calculate it. I ...
Jinning Liang's user avatar
1 vote
0 answers
82 views

Which KBOs would one have to merge in order to have more than half the Kuiper belt's mass?

I wonder how many and which Kuiper belt objects' masses would one have to merge so that the resulting mass is more than half the Kuiper belt's mass. The total mass of the Kuiper belt is reportedly ...
John's user avatar
  • 1,548
26 votes
3 answers
5k views

Is the sun's volume shrinking currently?

The Sun loses about 5.5 million tonnes of mass every second, does this mean Sun's volume is also going down? If so can we tell by how much every year? E: "by how much" I mean can we tell if ...
xenfoulis's user avatar
  • 479
2 votes
4 answers
296 views

If a black hole has the same mass as me, then why dont i suck everything at my center of mass?

So, a black hole is very dense that you can get really close to its center of mass that it has a strong pull, well, if i have the mass of a black hole that has a really small event horizon, why doesnt ...
Programmer's user avatar
1 vote
0 answers
58 views

How likely are triple planet systems?

Is it likely to ever discover three planets of similar mass revolving around a common barycenter, or would such a system be too unstable? Such triple planet system would look like a triangle once in a ...
Giovanni's user avatar
  • 145
1 vote
1 answer
1k views

If a black hole has a mass similar to a star, why does it have a different gravitational pull?

Say there is a black hole with 1 solar mass, having the sun's mass, it would have the same gravity as the sun, right? But it still has an event horizon, so why does it have such a strong gravitational ...
Anonymous's user avatar
1 vote
1 answer
1k views

Is there a formula to calculate any star mass from Luminosity, Radius, and/or Temperature (K)? [duplicate]

I know there is the Mass-Luminosity relationship, but I am wondering if there is a more accurate formula I can use based on the data points I have generated: Absolute Magnitude (based on class and ...
TyCobb's user avatar
  • 113
0 votes
1 answer
356 views

What is the density of the solar system per cubic light second outside the Jupiter ecliptic?

I have been unable to find any research on particle density over 1 cSecond above or below the ecliptic in regions with a gravitational field with an acceleration less than 1/1000 of meter per second ...
LOIS 16192's user avatar
6 votes
2 answers
296 views

Is there a way to calculate the mass of of a stellar remnant given the initial mass of the star?

Assume there is a star in a completely empty region of space, away from any outside influence. Is there a way to calculate the mass of a resulting stellar remnant, a white dwarf, neutron star, or ...
Max0815's user avatar
  • 1,862
3 votes
1 answer
256 views

Why don't we detect planets around OB stars and no terrestrial planets around A or early F stars?

Looking at an exoplanet database, I noticed that there are very few planets detected around main-sequence OBA stars, and most of them are gas giants/brown dwarfs. Why can't we detect low-mass planets ...
WarpPrime's user avatar
  • 6,633
0 votes
2 answers
377 views

How do we estimate the dimensions and mass distribution of a galaxy's dark matter halo, beyond the effective limits of its visible matter?

Current research suggests that the Milky Way's dark matter halo may extend up to about 10 - 15 times the size of the visible galaxy, and is believed to be roughly spherically symmetrical. But I don't ...
Stilez's user avatar
  • 1,022
1 vote
0 answers
83 views

Is is possible for a main sequence star to have 0.77 solar masses yet only be 0.54 solar radii?

I know ordinarily a star's mass and radius tend to be proportional, so a 0.5 solar masses star tends to be about 0.5 solar radii and have a density of 4.82 g/cm³, 3.42 or about three and a half times ...
Xi-K's user avatar
  • 403