First-ever evidence of comets beyond the solar system orbiting a sun-like star

Just as we have grown accustomed to stories of increasingly small planets being discovered around distant stars, along comes a new study that ups the ante.

This week, for the first time ever, scientists have announced evidence of icy comets orbiting a sun-like star about 160 light-years from Earth. Consider them the first known exocomets.

The work will be published in Monthly Notices of the Royal Astronomical Society.

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nice

dv said:

nice

S’pose so, but it would be pretty surprising if other solar systems didn’t have comets, wouldn’t it?

The Rev Dodgson said:

dv said:

nice

S’pose so, but it would be pretty surprising if other solar systems didn’t have comets, wouldn’t it?

That would be downright spooky but it is nice that they have detected this.

The Rev Dodgson said:

dv said:

nice

S’pose so, but it would be pretty surprising if other solar systems didn’t have comets, wouldn’t it?

Tends to go against the numbers.

Comets are continuously being ejected from the Solar System at a great rate, about half of all non-periodic comets are in this category.

So if the Milky Way were in steady state equilibrium we ought to be seeing comets entering the solar system from outside at the same rate as comets are leaving the solar system. The Milky Way has had 5 billion of years to come to equilibrium, and it should have reached equilibrium in about 100 million years or less.

So where are all the extra-solar comets that should be entering the Solar System? They would be very easy to spot because their speed relative to the solar system should be about 15 km/s, very easy to see because of the strongly eccentric hyperbolic trajectory.

Astronomers have not seen a single one.

mollwollfumble said:

Comets are continuously being ejected from the Solar System at a great rate, about half of all non-periodic comets are in this category.

So if the Milky Way were in steady state equilibrium we ought to be seeing comets entering the solar system from outside at the same rate as comets are leaving the solar system. The Milky Way has had 5 billion of years to come to equilibrium, and it should have reached equilibrium in about 100 million years or less.

So where are all the extra-solar comets that should be entering the Solar System? They would be very easy to spot because their speed relative to the solar system should be about 15 km/s, very easy to see because of the strongly eccentric hyperbolic trajectory.

Astronomers have not seen a single one.

To be fair we haven’t been watching for very long, a number of centuries at the most and perhaps even shorter if it requires modern telescopes to detect them.