If the sun were replaced by a star with twice the mass. Could the earth orbit stay the same? why?

Question

If the sun were replaced by a star with twice the mass. Could the earth orbit stay the same? why?

Answer 1

The orbit would stay the same only if the velocity increased.

Since the new star would also be a great deal hotter, it wouldn't matter much, because we'd be inside hot side of the 'life' zone and we'd fry.

Answer 2

Depends where and what Earth is doing at the "moment" you replace the Sun with the new massive star.

The orbital speed of a body, at a given distance from a larger one, is proportional to the mass of the larger body.

Let us assume that the change is instantaneous.

Then at the exact second of the change, the Earth (still going at its "previous" speed, finds itself going only at half the speed needed to stay on its "previous" orbit, given that the central mass is now doubled.

It will start falling towards the more massive star (while still keeping its sideways velocity).  As it falls, it gains more speed, until it gains so much that it is now going too fast for the new distance.  It starts "climbing".

The Earth will end up in an elliptical orbit, where the apastron (furthest point from the new star) is our old orbital distance and our periastron (closest point) is somewhere between the present orbit of Venus and Mercury.

This would give us an average orbital speed of 1.41 times our present orbital speed (square root of 2) and a orbital distance smaller than our present one (the elliptical orbit would have a smaller circumference).

Our "year" would be down around 8 months (this is a very rough approximation).

At first, there would be little effect on Earth's rotation and Moon's orbit.  

However, since the star's tidal effect would be greater (and even more so at periastron), the slowdown of our spin rate would increase a bit (making days longer a tiny bit faster than it is now -- one second every 40,000 years), and the difference between Moon's perigee and apogee (closest and furthest distance from Earth) would increase -- Moon's orbit would get more elliptical due to the star's tidal effect.

Answer 3

I think the solar system would be swallowed up by the sheer power & strength and gravitational strength. But if this doesn't not matter the heat will be searing high and the days will be longer. The planet will take longer 2 orbit.

Answer 4

No.

Since gravity is directly proportional to mass, the force of gravitation between the Earth and the new Sun would be twice as large. Therefore, the gravitational orbit would be only half as large.

Answer 5

many things may effect on Earth`s orbit .

if the size of the new sun is more than sun ,too .then there would be more slope in space and according to 3rd rule of cepler, the earth`s orbit would be bigger  if we want to imagine thespeed of turning  ,not to change.

but Earth orbit can stay the same if earth turn faster.

and if the mass takes place in the same size ,then there would be not a special change in orbit.

Answer 6

If you apply Newton's Law of gravity to planetary orbits, you will be able to derive what are known as Kepler's Laws which describe how objects like planets (and satellites) orbit around much more massive objects (like stars and planets).

In a simplified form (but ok for this question), Kepler's third law of motion tells us:

MP^2 = K R^3

where M is the mass of the central object (here, the sun), P is the period of the orbit (one year for the earth) and R is the distance of the planet from the star.

Written in another form, this equation tells us:

P^2=R^3/M

if you doubled the mass of M (so that the denominator on the right becomes 2M), then you notice that the period of orbit will become smaller.  If you doubled the mass of the sun, the EArth could orbit at its current distance, but would do so in a period that is approximately 0.71 times the current period (i.e., about 7/10 of a year)

Answer 7

If the sun were to double its mass, its gravitational pull would be greater. The earth fell into orbit with the sun under perfect conditions.. meaning its inertia (at the time of the big bang?) just happened to be equal to the pull from the sun so that it fell into orbit. So if the sun doubled its mass, the earth would still orbit the sun, but slowly get pulled closer and closer to the sun as it orbited until they collided or the earth was thrown out of orbit. So, no. It would not orbit the same.