astronomy

Guest, 3 godziny temu w Newly discovered 'cosmic unicorn' is a spinning dead star that defies physics: 'We have a real mystery on our hands'

Jasmine’s subtle beauty lies in its ability to arugula plant spacing bloom repeatedly with little fuss. It can handle summer heat gracefully and brings natural softness to rock gardens, pathways, or balconies.

Guest, 4 godziny temu w Newly discovered 'cosmic unicorn' is a spinning dead star that defies physics: 'We have a real mystery on our hands'

Radiates class with its well-blended composition. Projects a clean yet warm trail that suits both office wear and blu by ajmal personal moments.

three_trains_in_a_trenchcoat, 2 dni temu w Friday Night Stargazing 2025-07-18

okay, report:

• good lord, Antares and Vega are offensively bright once you adjust to the dark.

• M4!! HOLY GUACAMOLE WOW! M4 by itself made being out tonight worth it!

• M80: cool, felt cool to find it, but it looks like any of the other tighter globs and I didn't want to mess with switching to one of my narrow AFOV higher power eyepieces on my manual dob. May revisit once I invest in a higher power eyepiece with a decent AFOV.

• Epsilon Lyrae: hmm, am I maybe just not using enough mag? looks like a regular double star to me.

• Took the telescope for a slew through Sagittarius, for a laugh, was not disappointed. Breathtaking amount of stars there.

• Was all aboard the strugglebus making sense of Hercules's constellation. Didn't help that he was at the zenith, which made using the dob weird when looking for M13 and made looking at the constellation annoying after staring straight up like a turkey for minutes.

• Took some time to re-acquaint myself with Draco, Cygnus, and Aquila.

• Didn't pick out any more DSOs, in part because I got annoyed with blowing out my night vision, even with the red light, on my charts.

• I've been fairly serious about the hobby for about 9 months now, and it seems like I saw way more satellites out tonight than I did when I stopped back in May. Bruh, the little bastards were everywhere.

Bluetreefrog, 4 dni temu w For the first time, astronomers witness the dawn of a new solar system

There’s so much cool stuff happening in Astronomy at the moment.

crazyminner, 5 dni temu w This Earth-sized Exoplanet is On a Death Spiral

How fast is that in kilometers per hour?

kichae, 5 dni temu (edited 5 dni temu)

The paper doesn’t calculate the radius of the star’s Roche limit, instead opting to calculate the orbital period of the Roche limit. I’ve never done a Roche limit calculation for stars, but I have for planets/moons, and I’m not seeing anything that suggests it’s different than for planets. So, I think I did this correctly (excepting typos):

The star’s Roche limit is about 1.5 million km from its centre (~1 million km above its surface), and the planet’s orbit is about 2 million km from the star’s centre. Assuming a circular orbit, which should be the case at these distances, the orbit has a circumference of about 12.7 million km, and the planet is whipping around at a speed of about 2.3 million km/h, or 0.2% the speed of light.

HurlingDurling, 5 dni temu

So much math here that my head is already overheating. I need to find the time to learn all this math. Kudos to you internet stranger on your examplary calculations.

kichae, 5 dni temu

The numbers are big, so it can be intimidating, but the math isn’t too bad. It’s a little bit of multiplication and division. The most daunting bit is a cube-root, which you can find on most scientific calculators these days.

It’s hunting down the numbers you need to use that’s the trick, and making sure they’re all in the right units.

The equation for the Roche limit is the most complex math, but that’s just something you look up:

Roche Limit = 2.44 x {the radius of the star} x cube-root(( {the mass of the planet} / {the radius of the planet}^3 ) / ( {the mass of the star} / {the radius of the star}^3 ))

All of the things in the braces are also just values you look up.

Typotyper, 4 dni temu

The article mentions the star being a dwarf. Are dwarf stars older and in a degrading state. Would the star have had less gravitational force when younger.

How would a plant form that close if the gravitational pull from the star was this strong.

kichae, 4 dni temu

Dwarf stars are technically any star that is in its core phase of life. They are dwarves in comparison to giant stars. The sun is a G-type dwarf star, for instance.

The star is a K-type dwarf, which means it is cooler and smaller than the sun (stars are labelled froom hottest/most massive coolest least hot/least massive: O, B, A, F, G, K, and M for historical reasons).

Planet formation is a complicated and still somewhat young field of study. Planets being close to their stars was a real shock 20 years ago when we stared finding them. The best models we have for this is planetary migration, where the planets form farther aewy from the star, but friction/drag forces from the nebula from which they formed causes them to slow down and fall into smaller orbits.

This planet continues to see its orbit degrade for even more complex reasons, related to both drag – it is interacting with the star’s atmosphere, which is causing it to slow – and tidal effects. When you’re close enough to a massive, rotating body that the differences in gravitational pull strength due to things like variations in density become significant, the rotating body will force you into an orbit that matches its rotation length. If you’re already orbiting faster than it is spinning, that means it will slow you down. But slowing down will cause your orbit to shrink, which shortens the time it takes you to complete an orbit, which will make the central body slow you down more, which will shrink your orbit, which…

Typotyper, 3 dni temu

So you’re saying as our own system ages the planets will get pulled in and eaten up.

Would Jupiter being a gas giant get slowed down equally to the outer planets or would it eat some planets on its own.

Maybe eat is too much imagery. Would it accelerate those planets decline.

kichae, 3 dni temu

typotyper@sh.itjust.works said in How fast is that in kilometers per hour?: So you’re saying as our own system ages the planets will get pulled in and eaten up.

Not in the same way, no. None of our planets are touching the Sun’s atmosphere in the same way this planet is, and none of them are orbiting at rates that are faster than the Sun’s rotation. If anything, tidal interactions would want to speed up the planet’s orbits, and push them into higher orbits.

But eventually the Sun will become a red giant star, which will change some of these relationships. We will see competing effects then: The Sun will begin shedding its outer layers, which will create a higher drag environment for the planets (that were not swallowed during the Sun’s expansion) which would tend towards inward migration, but this will also lower the Sun’s mass, which will lend itself toward an outward migration.

typotyper@sh.itjust.works said in How fast is that in kilometers per hour?: Would Jupiter being a gas giant get slowed down equally to the outer planets or would it eat some planets on its own.

All of the outer planets are gas giants.

Jupiter is not currently migrating inward, nor are any of the other planets. If inward migration happens after the Sun becomes a red giant, those other outer planets will not get anywhere close to it. As a red giant, the Sun will approximately fill Earth’s orbit. Jupiter’s orbit is 5x larger than this; Saturn’s is 10x larger, and by the time the Sun actually grows this large, all of the planets’ orbits will be even larger than they are today, thanks to gradual mass loss.

None of the outer planets are expected to fall into the Sun at any point in time.

Typotyper, 3 dni temu

Thanks for the answers (and time). It’s cool to learn these things.

I could ask another 100 questions and still not understand half of it.

buggy-pull-buggy, 10 dni temu w Citizen Astronomers Help Confirm New Temperate Jupiter

That is pretty f'n sweet

Olap, 18 dni temu w New interstellar object candidate heading toward the sun

fosstodon.org/ - this scientist reckons 0.2AU to Mars. Still 30m km. And thus about 100x further than the moon. But it only took Armstrong three days to do that distance!

Could we slingshot between the earth and the moon a probe to reach it’s relative solar velocity and chase it down? Does anyone know the bounds of that?

Pronell, 18 dni temu w Exoplanets that cling too tightly to their stars trigger their own doom: 'This is a completely new phenomenon'

This is phrased like the planets have some choice. It’s weird.

Geodad, 18 dni temu w A rare chance to see two exploding stars is happening in the southern sky

These never seem to happen in the northern hemisphere.

Or maybe they do, and there’s so much light pollution that they never bother to report on them.

Evil_Shrubbery, 18 dni temu

wiki/History_of_supernova_observation

Animation showing the sky position of supernovae discovered since 1885. Some recent survey contributions are highlighted in color.

https://lemmy.zip/api/v3/image_proxy?url=https%3A%2F%2Fupload.wikimedia.org%2Fwikipedia%2Fen%2Fa%2Fac%2FSN_Discoveries_1885-2019.gif

SweetCitrusBuzz, 19 dni temu w Scientists look to black holes to know exactly where we are in the Universe. But phones and Wi-Fi are blocking the view

Yeah, we need fewer satellites really.

As for the rest, that’s not easily solved.

pennomi, 20 dni temu w Scientists look to black holes to know exactly where we are in the Universe. But phones and Wi-Fi are blocking the view

I still think they should build out a lunar crater radio telescope out there on the dark side of the moon. The radio silence and scale would be impossible to get any other way.

ogmios, 20 dni temu

scale

That’s an interesting thought I hadn’t considered. The Webb is about as quiet as we’re going to get anywhere near our orbit, but a lunar compound could very easily be much larger, and would be a great deal easier to service/upgrade.

pennomi, 20 dni temu

The dark side of the moon is shielded from the planet’s radio by the whole moon. So it’s a pretty attractive place to set up.

Plus, several candidate craters have favorable geometry for a massive radio telescope.

It truly is one of my favorite proposals.

quediuspayu, 20 dni temu

That’s the far side.

pennomi, 20 dni temu

Yes the far side of the moon is colloquially (and incorrectly) called the dark side of the moon. Thanks for the correction.

agamemnonymous, 20 dni temu w Scientists look to black holes to know exactly where we are in the Universe. But phones and Wi-Fi are blocking the view

I get the actual issue, but that title sounds hilariously boomer.

al_Kaholic, 20 dni temu w Scientists look to black holes to know exactly where we are in the Universe. But phones and Wi-Fi are blocking the view

It’s starstink muskings up the sky.

ogmios, 20 dni temu w Scientists look to black holes to know exactly where we are in the Universe. But phones and Wi-Fi are blocking the view

And slowly, society began to awaken to the reality that theirs was a civilization ruled by Mammon, not men.

InternetCitizen2, 22 dni temu w NASA's been pulling out of major astronomy meetings — and scientists are feeling the effects

True shame.