Hot answers tagged

17

Planets and stars, no. Globular clusters and galaxies, yes. Small scales To condense into such relatively compact objects as planets, stars, and even the more diffuse star-forming clouds, particles need to be able to dissipate their energy. If they don't do this, their velocities prohibit them from forming anything. "Normal" particles, i.e. atoms, do this ...


13

It doesn't matter if the body is made of gas, rocks, liquid or plasma, the four states of matter all have mass. So, as we know, mass create a gravitational field, and the more mass the stronger the gravity - and Jupiter has 317x Earth mass.


12

Comet Shoemaker–Levy 9 crashed into Jupiter a few years back. As well as these molecules, emission from heavy atoms such as iron, magnesium and silicon was detected, with abundances consistent with what would be found in a cometary nucleus. Those heavy elements are consistent with the comet being at least being partially composed of rock. So Jupiter is ...


10

The mass of the Sun is determined from Kepler's laws: $$\frac{4\pi^2\times(1\,\mathrm{AU})^3}{G\times(1\,\mathrm{year})^2}$$ Each term in this component contributes to both the value of the solar mass and our uncertainty. First, we know to very good precision that the (sidereal) year is 365.256363004 days. We have also defined the astronomical unit (AU) to ...


10

I assume you're asking about central supermassive black holes (SMBHs, one per galaxy), not stellar-mass black holes. The answer is yes, but what actually happens is the two SMBHs have to merge first, and then the resulting combined SMBH can sometimes be ejected from the combined (merged) galaxy. [Edited to add: Since you've updated the question with a ...


9

I concur with everyone else here (of course) that the gravity at the "surface" of Jupiter is entirely determined by the mass contained within that surface. The composition makes no difference. However I differ with some on the answer to the headline title question. We simply do not know whether Jupiter has a rocky core. A popular theory for the formation ...


9

Well, I wasn't going to answer but the other two answers are wrong, or at least incomplete. If you wish to make a black hole from a stellar-sized object, then there is no need to compress it to as small as the Schwarzschild radius (though that would certainly work and would certainly be the answer for smaller objects with negligible self-gravity). Instead, ...


9

I asked a somewhat similar question but just about the Earth. Here and in my question there's some links that you might be interested in. Jupiter for example is thought to have moved closer to the sun during the late heavy bombardment, then back outwards. So I suspect that through the wormhole didn't get that point quite right. Observations by the ...


8

The gap appears because of pair instability supernovae. In short, as one looks at such massive stellar cores at increasing temperatures, an ever-larger fraction of the photons are sufficiently energetic to spontaneously form electron-positron pairs. True, they soon recombine, but there is nevertheless a loss in (radiation) pressure, which causes contraction, ...


8

A succinct summary of supernova types is given in the following image based on Heger et al. (2003): Image courtesy of Wikipedia user Fulvio 314 under the Creative Commons Attribution-Share Alike 3.0 Unported license. The graph is based on the graph in Fig. 1 of the linked paper. The pair instability realm is upwards of ~100 solar masses, though it is ...


8

Your question body is different from your question title and it seems you really want to ask what you did in the question body so I'll address that. Short Answer: The simple power law which applies for larger asteroids and comets actually doesn't extend that well to smaller bodies and shouldn't be trusted too much in that range. Long Answer: You're right ...


8

The mass of an average galaxy appears to be totally dominated by dark matter, so your calculation would not give the galaxy mass. Even if all you wanted was the baryonic (non dark matter) mass then what you suggest will be very much a lower limit. For example you can look at this paper by Chabrier (2001), who estimates that gas forms less than half the ...


7

According to the standard ΛCDM cosmological model, the observable universe has a density of about $\rho = 2.5\!\times\!10^{-27}\;\mathrm{kg/m^3}$, with a cosmological consant of about $\Lambda = 1.3\!\times\!10^{-52}\;\mathrm{m^{-2}}$, is very close to spatially flat, and has a current proper radius of about $r = 14.3\,\mathrm{Gpc}$. From this, we can ...


7

This Wikipedia page does a decent job of describing the orbit-clearing criterion, based on the original paper by Stern & Levison (2002), which can be found here (PDF). In order to have cleared its orbit over a period of billions of years, an object needs a "Stern-Levison parameter" $\Lambda$ which is $> 1$; Pluto has $\Lambda \approx 3$-$4 \times 10^{...


7

The mass of a object does not increase when it collapses into a black hole. So a supermassive black hole must have started off quite small, and then grown. The formation and growth of supermassive black hole is not settled science. Supermassive black holes probably started as large stellar mass black holes (The very earliest stars could have been very large,...


7

There is no general consensus on this. Different evolutionary models give different results. The factors (in addition to the initial mass of the star) that effect the final black hole mass would be the rotation rate of the progenitor, its composition (or metallicity) and whether it was in a binary system or not and whether that binary system was able to ...


7

Your approach is completely correct, just note three things: Logarithmic distribution First, since the distribution of masses is logarithmic in nature (as is most other things), be sure to bin them logarithmically. Otherwise you will oversample (undersample) the bins at the low-(high-)mass end. Comoving densities Second, to be able to compare mass ...


7

Photons are massless. This doesn't depend on their energy, so doesn't depend on their frequency or wavelength. Massless particles travel at the speed of light. Even if we abandon particles and look at classical electrodynamics, we find that the speed of an electromagnetic wave (in vacuum) has a fixed value. It doesn't depend on wavelength. Gravitational ...


6

The article you've read is not quite accurate/correct. A more correct pictue is as follows: A star may approach a super-massive black hole (SMBH) so closely that the tidal forces of the SMBH tear it appart. The distance to the SMBH at which this happens is often referred to as the tidal radius. For a (non-rotating) SMBH with a mass in excess of about $10^8$...


6

What id like to know, in what distance do they have to be from each other to create only one gravitational influence. At whichever point you decide to call them two objects rather than one object. It's a completely arbitrary choice that depends on you rather than gravitational physics. What's going on is that gravity can be described by a mass density ...


6

The Schwarzschild radius of a black hole is probably the closest we can get to your question. $$ r_s = (2G/c^2) \cdot m \mbox{, with }\ 2G/c^2 = 2.95\ \mbox{km}/\mbox{solar mass}. $$ This means, that the Schwarzschild radius for a given mass is proportional to that mass. The radius shouldn't be taken too literal in the physical sense, because space is ...


6

I don't have enough reputation to comment... I think this might help you understand the formation or binary and more stars systems. This of course is not the only possible method but it might explain the systems with big mass differences. As the initial rotation speed increases (marked in the videos as beta) you will see how the protoplanetary disk breaks ...


6

Here you can find a list of all the natural satellites in our Solar System. You can check one by one (good luck!) OR you can check this webpage, and just add the terms. Please, keep in mind that the latter website is kind of unknown, so double-check at least some of the masses, before to trust it. Perhaps, you can cross check with this list as well, and ...


6

According to Newton's Law of Universal Gravitation, you simply need interacting masses in order to generate a gravitational force between them. Gases have mass and they therefore can contribute to gravity. So even if Jupiter is entirely gaseous, it is so incredibly massive besides (so much gas!), that it has a much stronger gravitational pull than Earth. ...


6

It's not completely clear what you are asking, but if this is a multi-choice quiz, then the only option that could be correct is (a). (b) Is not correct, because a white dwarf that just passes the Chandrasekhar mass is comfortably below the maximum mass that is supportable by a neutron star. So neutronisation followed by neutron degeneracy pressure and the ...


6

You don't have to guesstimate to come up with the answer. What you do is look at the dynamics of stars with respect to the Galactic plane - in particular, the velocity dispersions of stars with known distances from the plane, combined with a reasonable assessment of where the Sun is with respect to the plane (close), yields an almost model-independent ...


6

I'll shamelessly reference an answer I wrote on Worldbuilding to an almost identical question. Lammer et al. (2014) suggested that "super-Earths" with masses of $2$-$5M_\oplus$1 could retain massive hydrogen/helium envelopes, up to $\sim10^{25}$ kilograms. Above this, up to about $10M_\odot$ or more, "mini-Neptunes" exist, possibly composed of volatiles and ...


6

As you say, making black holes quickly in the early Universe is a major unsolved problem in astrophysics. There are various hypotheses, of which two roughly correspond to supermassive stars. All basically involve trying to give the black hole a headstart in mass. There isn't really enough time to grow a $100\,M_\odot$ black hole to $10^9\,M_\odot$, so the ...


6

There are three factors that all play into this: The Jupiter/Sun mass ratio The Jupiter/Sun distance The Sun's radius The barycenter of any pair of orbiting masses lies on the line connecting their centers of mass, and its position depends on the masses of the two objects. If two objects have the same mass, their barycenter will lie halfway between them. ...


6

A Black Hole (BH) is an object of General Relativity (GR), not of Newtonian physics, so the answer involves both. First Newton: As another answer notes, the acceleration due to gravity depends on the mass of the body divided by the square of the distance from it. At a given distance (say, ten million miles) the acceleration due to gravity is simply ...


Only top voted, non community-wiki answers of a minimum length are eligible