HD 26965b: Super-Earth Found Just 16 Light-Years Away

Sci News ^ | July 30, 2018 | Natali Anderson

[ETL]

Designated HD 26965b, the newly-detected alien world has a mass of 8.47 Earth masses and is located a mere 16 light-years away.

This planet revolves around the bright K-class dwarf star HD 26965 once every 42.4 days.

The host star is approximately 6.9 billion years old, has a mass about 78% of the Sun’s and a radius 87% as large.

“HD 26965 is the primary of a very widely separated triple system. The other two companions are an M4 dwarf and a white dwarf,” said University of Florida astronomer Bo Ma and co-authors.

“This star is a very bright metal poor star with an absolute magnitude of V=4.4. This makes it the second brightest star in the night sky with a super-Earth detection so far, just behind HD 20794 (V=4.3).”

“One interesting fact is that HD 20794 has a similar metallicity as HD 26965, which is consistent with the finding that smaller planets are detected around stars with wide-ranging metallicities.”

“With a minimum mass of 8.4 Earth masses, HD 26965b likely possesses a gaseous atmosphere based on other planets with known masses and radii,” they added.

“However, we note that Kepler-10c has a similar mass and orbit, is hosted by a similar, low-metallicity star, and does not possess an envelope, so HD 26965b may be a similar type of world.”

HD 26965b was found using the ‘wobble’ method, called radial velocity, by the Dharma Planet Survey (DPS).

This method watches for the telltale jitters of stars as they are pulled back and forth by the gravitational tugs of an orbiting planet; the size of the wobble reveals the mass of the planet.

[wally_bert]

Hope those stations are ethanol free.

[SuperLuminal]

"... located a mere 16 light-years away."

Hmmm... At warp 8.8 the trip will only take 5-years...We need warp 20 to avoid a long boring trip...

[ETL]

but this doesn’t take dilation into account. Instead, because the distance has been dilated we will reach the star in only 14.1 years.

The *time* would dilate. The distance would contract (shrink).

[Deplorable American1776]

Environmentalists and other Liberals...I’ll start a GoFundMe campaign for you to move to it ... Okay?

[ETL]

Are there any gas stations along the way? I don’t think I can make it on one tank of gas.

Lol! I thought you were going to say you don't think you could make it without a p*ss stopm

[Dark Knight]

Lord Kelvin was an absolute zero!!!

DK

[dead]

At our current top spacecraft speed, we could get there in about 320,000 years.

[Cementjungle]

Didn’t even think of that... lol

[King Moonracer]

High mass and gravity means Fenachrone

[jmacusa]

A single light year is six trillion miles. 16 light years. Hmmmm? I’m not good at math. But yeah. You’re right. We ain’t getting there anytime soon.

[jmacusa]

“Pack a lunch’’ Yes. And make sure everyone goes to the bathroom before we leave.

[William Tell]

"8x mass probably means THOUSANDS of g’s higher gravitational acceleration, if it keeps the same relative density as earth, or thereabouts."

Actually, the gravity does not rise as fast as the mass.

For this example, the mass ratio is 8.47.

Assuming identical density then the planet would have a radius which exceeds that of earth by the cube root of the mass ratio, or 8.47^-1/3 = 2.04

Gravitational force is calculated as F = G*m1*m2/r²

IF m1 (the mass of a planet) increases by a factor of 8.47 and the radius increases by 2.04, then the resulting gravitational force increases by 8.47/(2.04)² = 2.04

Hey, look at that! We now have a rule of thumb for gravitation. Assuming identical densities, the gravity of a planet changes proportional to the radius change.

Let's try this out on Mars. From Wikipedia, the radius of Mars is smaller than that of Earth by a factor of 2106/3959, or 0.53

We should expect the gravity at the surface of Mars to be, then, 0.53 times Earth's gravity. But (also from Wikipedia) we find that Mars has a surface gravity of just 0.376 times that of Earth. What went wrong?

The answer is given by looking at the densities of the two planets. Earth has a density of 5.51 and Mars has a density of 3.93 or only 71% And sure enough, if we multiply the gravity we calculated times the density percentage, we get 0.53 * 0.71 = 0.376

The initial density assumption was wrong but when taken into account we get the right answer.

Let's try Jupiter. The radius ratio is 11.209 times that of Earth. Is the gravity 11.2 times that of Earth? No! It is only 2.528 times that of Earth.

Let's calculate the ratio of densities. The density of Jupiter is 1326 kg/m³ or 1.326 gm/cm³

Earth's density was 5.51, so the ratio of densities is 1.326/5.51 or 0.241

So, if we multiply our initial "rule of thumb" value of 11.209 by 0.241 we get gravity at the surface of Jupiter of 2.70 times that of Earth, close to the Wikipedia value of 2.528

We're still off by a factor of 2.70/2.528 or about 7% hign. Let's all see if we can find the missing mass (or is it mysteriously excess radius?)

[SunkenCiv]

Thanks ETL.

· join · view topics · view or post blog · bookmark · post new topic · subscribe ·

Google news searches: exoplanet · exosolar · extrasolar ·

[Rock N Jones]

Well the human brain with 100 billion neurons to shape human observation and perception that we live in a vast universe with stars billions of light years away.

[kjam22]

You’re the only other person besides myself I’ve encountered that believes there is no such thing as time!

We are the enlightened ones

[backwoods-engineer]

Good analysis. I tried to scale the gravity by the mass, assuming the density would stay the same. Of course, I used the equation for volume of a sphere, which has a cube in it. Somehow, my calculations were off.