A current explanation of Mars lack of atmosphere seems to be largely attributed to the lack of a magnetic field. The Sun emits a 'Solar wind' of neutral density plasma (mostly ionized hydrogen) with a density (strength) that obeys inverse square law. The Earth's atmosphere is protected from these very energetic particles (~400 km/s) by Earth's magnetic field at the magneto-pause. The solar charged particle flux interacts with Earths magnetic field to deflect the particles (Lorentz force). Since Mars has appreciably no magnetic field it's often said that Mars atmosphere has no protection from solar wind; and that is the reason Mars has very thin atmosphere, blown away by 400 km/s solar wind. The explanation is plausible. Mercury has ~zero atmosphere as well, but it is also has low gravity plus solar wind 15.5 times that of Mars ((1.523/0.387)^2) plus Mercury is very hot.
Venus has nearly the same non-existent magnetic field as Mars. Yet Venus has an atmosphere about 90 times more dense than Earth's. Consider also that Venus has solar wind 1.9x Earth's and 4.4x more dense ((1.523/.723)^2) than Mars. So why is the Mars lack of atmosphere explanation on it's head at Venus? While it is true Mars has lower gravity than Venus, it is also much colder than Venus. To escape a planet, atmospheric molecules must attain escape velocity (at high altitude where mean free path is long) by means of thermal velocity. The colder the atmosphere, the slower the gas particles travel. So Venus should find it easier to shed atmospheric molecules than Mars on two counts: solar-wind density (kinetic collisions) and mean molecular temperature.
Maybe it would be useful to site Venus '4.4x worse solar wind & no magnetic field' accompanied by the dense Venusian atmosphere when offering the 'solar wind and no magnetic field' explanation for Mars scant atmosphere?
In a given stellar neighborhood, which would consume more matter over the same period of time, a 5 solar mass STAR or a 5 solar mass BLACK HOLE? The BH event horizon would be 18.4 miles in diameter. For sake of argument say the star photosphere is greater than 1-million miles in diameter.
ANSWER: The star by a landslide. The equal mass star and BH have identical gravity wells outside their horizons (photosphere & event). That means, as a function of time, that accretion gravitational trajectories are identical for all candidate-4-consumption particles. Those particles that intersect the stars large area photosphere get added to the stars mass. All material that passed within the same 500,000 miles radius of the BH would have hit the star but missed the BH except for the tiny 18 mile EH diameter. The ratio of star-to-BH target area is greater than 3 billion to one And if my theory on 'Escape From BH Event Horizon' is the correct one, the BH may have a real problem trying to grow. Only radial in-fall to the singularity would have a chance of accretion the BH's mass. So much for 'voracious BH appetite'. Please question assertions about black hole appetites.
1) If my contention is correct that "Mass CAN ESCAPE" a black hole (but light cannot), the source of Quasar's brilliant display of energy could simply be the result of hyper-energetic ejecta resulting from the collision of black hole singularities in a very busy neighborhood. A corollary may be that singularities inside EH's actually have a finite size; which fact would enhance probability of 'singularity' collisions. And, indeed, eliminate the incomprehensible infinity of the zero volume 'point' singularity.
2) Time travel to the future would be available. Have to run some time dilation numbers vs BHB size. Update your collision insurance. Galactic BH Binaries may present the ultimate Disneyland ride.
3) My 'escape from BH' proposition would get rid of another nagging physics problem; Lost Info (LI) to a BH. And this information not lost solution would not require the 'event horizon' to be a 'hologram' that stores the information as has been proposed as one (LI) solution.
4) If Gravity Frame Dragging (GFD) exists (evidence is found in careful orbital (velocity) measurements during near earth fly-bys), GFD would represent communication and indeed an energy transfer method that a spinning Black Hole has to talk to the 'outside world', Frame dragging would transfer BH angular momentum and energy to bodies outside of the event horizon. Note, That energy and momentum 'came from inside' the EH. With mass=energy equivalence, is energy getting out like mass getting out?
5) And when it is said the BH 'Jet' is a result of the BH 'eating' too fast, that statement seems to be in opposition to spaghettification; gravity gradient pulls matter apart which would increase separation of particles rather than causing choking of the particles being gorged.
*) Please put the above thoughts in your physics/astronomical 'pipes', give them due consideration while 'smoking' them. And thanks...
There is a YouTube Video I question. A 16 solar mass Black Hole M33 X7 is described as being orbited by a star like the sun. The link is:
The video states that a star orbiting the BH is being gradually consumed where gas pulled off the star spirals down to the BH and is heated to extreme temperatures. It assumes that X-ray seen from this source (by Chandra) is caused by heating of the gas by the extreme gravity near the event horizon.
1) The star has a 'hill sphere' inside of which the gravitational attraction of the star exceeds that of the black hole. If the star's 'hill sphere' is inside the star's surface, the star would be quickly consumed by the black hole. If the star's 'hill sphere' is outside the star's surface, I would say the only star gas available to the black hole's gravity would be that ejected from the star by ordinary stellar mechanism of stellar wind. I object to the notion of the black hole pulling gas off the star into a death spiral; this description attributes a capability to black hole gravity that I believe does not exist. For sure; a black hole cannot suspend physics outside the event horizon.
2) When matter approaches a black hole's gravity well, does not spaghettification occur? What is the cogent, salient, relevant mechanism of 'spaghettification? It is the gravity's gradient that stretches matter out. Lets say you are falling feet first into a black hole; this event is correctly described many times on the Science channel; as you are approaching, your body goes into TENSION. At first you are just uncomfortable from being stretched, but as you get closer and closer to the black hole, it tugs much harder on your feet than your head. Finally, you are ripped apart, your feet accelerate ahead of your body, your head lags the furthest behind. That is spaghettification. Finally your whole body is pulled apart into molecules. Now if Chandra is watching your body stretch out, just when is your head going to hit your feet so hard that X-rays are produced by the collision? NEVER, until you reach the singularity well inside the event horizon. So Chandra is NOT going to see X-rays coming off your body atoms as they are spaghettified. Nor is Chandra going to see X-rays coming off of in-falling gas that is also being pulled apart by gravity gradient.
#1: I would submit that any gas off an orbiting companion star was ejected by that star as stellar wind, not pulled off by black hole gravity. AND
#2 If Chandra were to see X-ray light coming from some of that gas mass it is because there is another source of in-falling matter from an opposing direction causing high closing velocity that produces hyper-energy collisions that produce the X-rays seen by Chandra.
While it is true that gravity can cause extreme in-fall velocity and velocity is nothing but temperature, all matter from a single source (star) would be moving the same direction. Thermodynamically, That is to say the matter would have an extreme total temperature but near zero static temperature. Further, all matter from a single source would be mutually receding; no X-ray producing high relative velocity collisions would be eminent. So:
I think the black hole cannot pull gas out of the stellar companion's 'hill sphere' and heat it to enormous temperature producing X-ray emission as it swirls inward toward the event horizon. This inadequate scenario as described in the video just messes with my head and leaves me wanting.
There is conflicting information. YouTube says companion star is sun-like; Wiki says companion star is 70 solar mass
(SM) and the 15.7-SM X-7 BH orbits the 70-SM star every 3.45 days. A 'sun-like' star of ~1-SM would orbit the 16-SM BH
in one year at 2.51 AU; this would have given astronomers two orbits (2 years) to track 'sun-like' star. But optical
(diffraction limited) telescopes could not resolve the orbit or wobble of either the 15.7 vs 70 or 15.7 vs 1-SM orbits
at 3E+6 LY distant M33, I don't know how they could have made the conclusions on mass. And I don't know which, if either,
reports (YouTube, Wiki) are correct or in near agreement. I computed;
Hubble Gemini can resolve about
3E-7 8.9E-8 radians; a 235E+6 mile orbit (easiest case to resolve) would subtend 1.3E-11 radians. No
chance seeing 1.3E-11 radian star orbit with 8.9E-8 radian telescope.
Google Astronomy Magazine: M33 X-7 yields 2 links, 22-Oct-07 and 22-Oct-2010. Astronomy Magazine gets, in MHO, the usual high marks. The above '10 link has a good discussion that does not mess with my mind. Wiki is close; the YouTube video is a big question mark in my book.
Perhaps Astronomy Magazine Bob Berman's "Strange Universe" cerebral and witty article June-2011 P-14 (while not discussing M33 X-7) takes a whack at "High confidence" folding into presentations such as the YouTube video.
So, I'm here to complain when Astro sources make assertions that physics principles or just common sense would discredit, I would work to diminish jaz-e'm-up fanciful astro-license from appearing in articles.
The above table outlines the M33 X-7 orbital parameters to aid the minds eye in grasping the physical reality. Assumptions made are: 1) Orbits Are Circular 2) Stellar Density of 70-SM star Set EQ to the SUN. Since the BH orbits 4.46 times further from the barycenter it is fair to view the HB as orbiting the Stellar partner. The 8th table entry shows the binary CG separation needed to produce the 3.45 day period, about 11.5 million miles (about 1/3 Mercury's orbit distance from the Sun.
Diameter of the Star (my guess) found from D=860000*(70^(1/3)); ratio of Sun diameter times cube root of Star's 70SM. I 'stuck' a yellow Sun in for size reference to the 70SM star. Gravity at the stellar surface would be about 3740 f/s/s (vertical tics are 1000 f/s/s). Vertical green axis line denotes system CG (barycenter). The red line represents gravitational acceleration versus distance between the binary partners. The LT_blue dashed arc is the stellar 'hill sphere' radius; matter to the left is attracted toward the star. Matter to the right is attracted toward the BH. A circular orbit for the BH would therefore put it's orbit distance well outside the stellar_70 'hill sphere' which means that in-falling stellar material would consist entirely of stellar wind.
Since the BH is orbiting the star, new stellar wind particles would constantly approach the BH accretion disk from different angles relative to the accretion disk material direction which would give rise to hyper- energy particle collisions giving rise to X-rays seen by Chandra.
I still do not know how stellar mass was determined, certainly not by observing the BH orbit. BH orbit diameter is too small (~19E+6 miles) and M33 too far 3E+6 LY distant to optically resolve by a long shot, even with the 8m Gemini primary mirror. Maybe stellar mass was determined by color temperature?, and orbital speed by red-blue doppler? The 4.3E6 SM BH at center of Milkyway was sized by tracking a 16 year period star S2 orbiting the galactic BH. We are ~111 times closer to Milkyway center than M33 and the 16 year star's orbit, as I recall, is about 10.7 LD or 9000X larger than X-7's orbit. That is a 1,000,000x resolution advantage for observing the much closer BH in Sagittarius A.