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7

This is more of a question of human perception, than astronomy. I was going to answer your question with this: "One, it just needs to be close to Earth." But, I decided it wasn't THAT funny. Anyway, stars are essentially point sources as far as our eyes are concerned. Typical visual resolution is about 0.02° or 0.0003 radians. Assuming from horizon to ...


7

No, stars do not have a rocky core. They start as clouds of gas, become gravitationally unstable and collapse. Some planets are thought to start this way too - though probably not the ones in our solar system, because the outer three three giant planets have solid cores and Jupiter is likely to also. The two modes of giant planet formation are reviewed in ...


7

Let me make some more general points to clear up some misconceptions. The Sun orbits around the Milky Way at a speed of around 230 km/s with respect to the Galactic centre (GC), taking around 200 million years to complete a circuit. Stars at a similar radius to the Sun from the GC orbit at similar, but not identical speeds and may have peculiar motions ...


6

The constellations change slowly, over thousands of years, due to the proper motion of the stars with respect to the Sun. The main cause of these motions is the orbit of the stars around the centre of our Galaxy (with or without dark matter). This video shows these changes for the constellation of Ursa Major over 400,000 years. Another way the ...


5

The short answer is pela's comment: more mass equals shorter life. For a bit of a longer explanation... The only way the life of the star could be prolonged is if the new material can be transported to the core. This requires convection. Most stars are not fully convective, having distinct layers of either convective or radiative zones. The net effect of ...


5

Star S2 reaches maximum velocities of 5,000 km/s according to this ESO page. The orbital period is given as a little over 15 years and this paper gives a peri-center (closest approach to the black hole) of 17 light hours. There's another star in the area called S0-102 which has a shorter period, but its orbit is less eccentric - so its closest approach to ...


4

Think of when the planet is at the "side" - there's a little bit of light from the planet (ie, reflecting off the planet) shining towards us. Could it be due to that little bit of light - when the planet is behind the star, it no longer reflects towards us? Maybe that's the effect you have in mind?


4

Globular clusters formed whilst the gas of the proto Milky Way was still approximately spherically distributed. The gas forms a dissipative system that loses energy and collapses (within the first billion years) to a disk whilst conserving angular momentum. Formed stars and clusters are essentially collisionless so the halo stars continue to have a ...


4

The lines show as either peaks above the black body emission (for emission lines) or troughs below the black body emission (for absorption lines). Though stars more often have absorption lines and nebulae emission.


4

Regarding the title: Yes. Does this mean that the star started off as a planet? Yes, a star could technically start out as a planet, if it accreted enough mass. However, this is extremely unlikely, since the planet would need to be 80x the mass of Jupiter for it to undergo nucleosynthesis. Stars require hydrogen fusion and earth has little H. Could ...


3

A star does not start off as a planet; you have a large cloud of gas that is collapsing in on itself due to gravity. The majority of the gas goes towards creating the star (more than 99% in the case of our Solar System). However, gravitational collapses can occur several places in the gas cloud, and some of the gas will contribute towards the collapse of far ...


2

The initial stars were made of hydrogen and helium. These enriched the interstellar medium (ISM) with some chemical elements right across the periodic table, when massive primordial stars ended their lives as supernovae. Subsequent generations of stars continue to enrich the ISM, if their lives are short enough. So the general gist of what you suggest is ...


2

After looking into the various wrappers and ways Python and IDL work with FORTRAN I came to the conclusion that it is more of a preference which language you use. However as people continuously add astronomy support to Python this may change, but as of now, it seems to be a question of preference.


2

I think your star is an 8th magnitude star in Aries: properly catalogued as HD 14610. It is an F5 white dwarf, a little larger and brighter than the sun, but about 300ly away, and too dim to see without a telescope. It is located at RA 02h 22m 01s, dec +15* 59' 30'' An image from the sky surveys: http://simbad.u-strasbg.fr/simbad/sim-id?Ident=HD++14610 (...


1

There's a little bit too much sophistry in some of the answers to this question. While it is true a photon doesn't experience time, the OP was asking about light emitted from Proxima Centuri as observed from Earth. Since PC is 4 light-years away, the light took 4 years to reach us - since neither we nor the Centuri system are traveling, relative to each ...


1

Just to add, while I think Rob Jeffries answer covers it. Now is it expected that in future more stars will be made of more heavy elements or are there causes/laws which prohibit stars forming of e.g. stars made of elements without hydrogen. While this is unlikely to happen because Hydrogen will stick around as the most abundant element for a very ...



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