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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Mass estimate for cluster NGC2516?

The Wikipedia entry on NGC2516 mentions a mass value in the range $[10^5 - 10^6]\; M_{\odot}$. This seems like a rather enormous value for an open cluster. In Jilinski et al. (2009) the authors state ...
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Will 1036 Ganymed's orbit be changed by its close encounter with Mars in 2176?

In 2176, the asteroid Ganymed will come as close as 0.02868 AU (4,290,000 km / 2,670,000 mi) from Mars. That's pretty close to Mars imho. Can Mars' gravity alter Ganymed's orbit significantly in 2176 ...
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Why doesn't star size distribution conform to space rock size distribution?

The number of space rocks is exponentially related to the size of the rocks. There are more small space rocks than big ones. Stars are most commonly the size of the sun, big and smaller stars are rare,...
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Relation between core mass and red giant mass?

Yes, the title might be confusing (I'd appreciate some more clarification on it :D ). I have an estimated mass of hydrogen in the core of a star, and how much hydrogen will be in the core when the ...
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What is the mass for a celestial body to definitely achieve hydrostatic equilibrium?

While these posts (attempt to) answer what the minimum mass is to be able to achieve an ellipsoidal shape, my question asks for the mass at which a body definitely collapses into an ellipsoid. Meaning,...
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Why are most discovered exoplanets heavier than Earth?

Looking at all discovered exoplanets (4393 exoplanets), I found than only 17 of them (less than one percent!) have masses less or equal to Earth's mass. Why so? Is it because it is very difficult to ...
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Minimum distance between planets

In our solar system, MOIDs (minimum orbital intersection distance) of different planets reach a minimum of ~30 million miles (Mercury and Venus). However, other star systems have more compact planets. ...
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What should the mass of a planet be in-order for its escape velocity to be near the speed of light? [duplicate]

What should the mass of a planet be in-order for its escape velocity to be the speed of light? Is it even possible? What will it look like from an outside viewer? Will it even be visible in the human ...
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What if a primordial black hole went through the Sun?

How much mass would the Sun lose to a primordial black hole that (initially) has 10 Earth masses, passing through or close to the center of the Sun at solar escape velocity? How massive would the Sun ...
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Do more massive stars become larger or smaller white dwarfs?

I wonder whether e.g. stars more massive than the Sun (but below the mass where they'd go supernova) would become larger or smaller white dwarfs than a white dwarf Sun. Since Procyon B is larger than ...
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How do we get to know the total mass of an atmosphere?

Since atmospheres don't end abruptly but gradually get thinner the higher you go, I wonder how we can get the total mass of an atmosphere if we don't know where exactly it ends. E.g. the Earth's ...
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Why doesn't smashing larger and larger bodies incrementally into a rocky planet create a star?

Let's start with a stationary Earth. If we smash a few Mercury-sized objects into the Earth, the Earth begins to accrete mass. Repeat this step with larger and larger objects, until we start impacting ...
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How much mass would have to be added to the Sun to significantly alter any of its characteristics?

While this might at first sound like an XKCD What If? question, let's proceed with it because astronomical objects do occasionally merge. How much mass would have to be added to the Sun to ...
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Relation between mass of gas, mass of stars and dark matter halo mass [duplicate]

As we all know that Mass of the galaxy can be written as the sum of the mass of gas(Mg), the mass of stars (Ms), and mass of dark matter halo(Mh), as M(galaxy)=Mg+Mh+Ms, But is there any formula which ...
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density of dark matter halo

I was surfing the net for knowing the actual density of dark matter halo for a particular Mh(Mass of the halo) and finally, I got two equations: for pseudo-isothermal halo and by NFW-profile So, ...
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Relation between absolute magnitude of UV and star formation rate

I surfed the internet and searched a lot of sites, so far I got this but unable to find the formula which relates only Muv and the Ψ as I don't know the value of parameters Auv and μ(z). If there ...
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List of galaxies with their dark matter halo

Where can one find the list of galaxies with their dark halo masses, I've searched several sites but I found no such proper list where the masses of their dark matter halo is compiled? Can anybody ...
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Where can I find a database on the masses of different galaxies?

I want to get the data for masses of galaxies, more information about them can only be helpful. Can anyone point me to a site where I can get this sort of information?
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Calculate mass of exoplanet from transit method

Is there any way to calculate (or at least estimate) mass of an exoplanet from transit method? I know that mass can be calculated with radial velocity method, however I would like to create program ...
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How was the mass of Venus determined?

The mass of Venus seems rather complicated to determine to me: Venus doesn't have any satellites, so you can't just apply Kepler's third law (like you would with Jupiter or Saturn for instance) to ...
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GW190521 black hole merger total mass calculation and missing mass, how does this happen?

I have just read an article about that black hole merge event (it's in Italian): Sette miliardi di anni fa, due mostri si unirono What made me curious is that the article tell that a 66 solar mass ...
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How to find the mass of a planet not knowing the gravitational constant?

So I found this problem, I know the gravity of earth $g_0$, I found the orbital speed of one satellite using this equation $\frac{GM_em_s}{(R_e+h)^2}=m_sa$ ($M_e$ is the mass of earth, $m_s$ is the ...
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How likely does a body more massive than Eris exist beyond the Kuiper belt?

Other than the hypothetical Planet IX, is it likely if there's a (dwarf) planet more massive than Eris orbiting between Eris and Planet IX? Michael Brown seems to have found it likely. As far as we ...
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How did we measure the mass of the universe?

In an wiki article, observable universe, it was mentioned that, Mass (ordinary matter) 1.5×10^53 kg I wonder how did we measure the mass of our observable universe?
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How to calculate the orbital period and the density of a planetary body?

I'm a student studying in 9th grade, I am making this fictional habitable planet named "Darwin B" for a planet making competition. It orbits a sun-like star at a distance of 1.15 AU or 172 ...
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Why don't or (can't) stars be more than 325 or so times the mass of the sun? What limits their size?

Is there a particular reason(s) why stars cannot grow as massive as they want to? And why doesn't this limit apply to supermassive black holes?
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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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How do OGLE-III and GAIA measure the mass of free microlensing black holes?

What is the "hypothesized lower mass gap" between 2.5 and 5 solar masses? eventually links to Constraining the masses of microlensing black holes and the mass gap with Gaia DR2. The angle of ...
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Size and mass of comet ATLAS (C/2019 Y4)

I read some news about this new comet and some unreliable sources said it is twice as big as Jupiter. I tried to find a reliable estimation of its size or mass, but I couldn't find anything. Would you ...
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How does energy (from fusion reactions still inside the sun) still have gravitational attraction?

In this answer they say: While the conversion of mass matter† to energy in the Sun's core now represents a loss of mass proper matter, it turns out that that energy (trapped in the Sun and slowly ...
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Why isn't Eris considered a planet despite being the body of dominant mass?

The 2006 definition of a planet states that a planet is a celestial body that (a) is in orbit around the Sun (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it ...
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Estimating Galactic Mass of Andromeda

So I need to estimate the mass of the andromeda galaxy using: $$ M = \frac{v^2r}{G}$$ where $v$ is the rotational velocity, $r$ the galaxy's radius and $G$ Netwon's gravitational constant. I'm told ...
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Why does the star formation rate correlate with the total stellar mass in star forming galaxies?

The so-called "Main Sequence" of star-forming galaxies (e.g., Brinchmann et al. 2004; Noeske et al. 2007) clearly points to a linear relation between the stellar mass of galaxies and their star ...
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Moon's unusual gravity

We know that the Moon's gravity is about one-sixth that of Earth. Then I recently read that the mass of the Moon is about one-eightieth the mass of Earth. Since gravity depends on the mass of the 2 ...
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If we've only observed Oumuamua as a single pixel, how can we know its shape?

On a separate Oumuamua question (Oumuamua alien space junk?), I was confused how shape could be inferred from a single pixel, per another user's (@Uwe) comment. It was suggested I ask this question ...
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How would I define mass in a space

I always heard that mass is a measure of inertia during my school days. Is this applicable to bodies which are in space ? Suppose there is space craft in a space; how would I define mass ? I read ...
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How did they estimate the mass of Sgr A*'s companion G2 without knowing what it was?

Gizmodo.com's Astronomers Spot Unprecedented Flashes From Our Galaxy's Black Hole mentions Sgr A*'s companion gas cloud G2. That Wikipedia article says: First noticed as something unusual in ...
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Could anything consume a small black hole?

Whenever I read about black holes, it is normally involving how they devour anything that comes too close... regardless of how big anything is. But what if it were a really small black hole vs ...
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Black hole's gravity

Is gravity relative to volume, or size of an object? Since a black hole is a massive star that collapses on its weight, how comes the same sun's mass, when it becomes a black hole, provides gravity ...
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Comet mass loss

As the comet orbits around the Sun, I gather that its tail loses mass due to solar wind and tidal waves. Approximately, from what distance (with respect to Sun) will the mass loss begin?
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How is stellar mass of a galaxy obtained?

I believe there is a difference between the mass calculated using the orbital speed and the stellar mass of the galaxy. So how is the stellar mass calculated? Thank you :)
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Mass of Photon and Black holes [duplicate]

The gravity caused by a black hole is said to be so strong such that even light(photons) can not escape from it. since gravity exist only in between objects with mass, How does a black hole attract a ...
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Is blue light not traveling faster then red light in space?

I just can't understand why light and other massless particles are not traveling at different speeds? Gravity effects anything with a mass but light has no mass but a black hole, and weak lensing ...
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1answer
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Existence of a mass-volume astronomical chart?

I've been wanting to make a mass-volume (or mass-radius) chart for astronomical objects ranging from asteroids to supermassive black holes on a log-log scale. A sort of 'Hertzsprung-Russel' type ...
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What does it mean when there are two plus-or-minus signs for a measurement?

As far as I know, the plus-or-minus sign is used to indicate the statistical margin of error of a measurement. But what does it mean when there are two plus-or-minus signs in the same measurement? ...
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How to determine the mass of a galaxy?

I am having a slight disagreement with my professor. We can measure the mass of a distant star cluster from: A.Its color B.Its radius C.Its metallicity D.Smearing of lines in its total spectrum My ...
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Mass of a potential black hole in a binary system

So I've been given the velocity curve, parallax and apparent magnitude of a star in a binary system with what is potentially a black hole. I've calculated from the apparent magnitude and parallax that ...
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1answer
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Smallest mass of star to be a black hole? [duplicate]

It seems to me that I forgot the smallest mass of a star and its angular momentum in order to form a black hole. So I know that electron degeneracy pressure is overcome if the core is 1.4 solar ...
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Does the Sun twinkle?

Does our solar system have enough bodies in orbit to appear to twinkle to another distant solar system viewed from the side? https://en.wikipedia.org/wiki/List_of_asteroid-discovering_observatories ...
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Doppler Spectroscopy - Finding mass of an exoplanet

An astronomer, T observed the spectrum of a distant star X. The spectral lines were observed to have tiny blueshifts and redshifts regularly with a period of 1.27 years. T concluded that the star is ...