Be Cool, Star

Unfortunately, I only have 1 reference article for this week’s blog, and it was listed as ‘Opinion’. So, if you don’t already, take this week’s blog with 2-3 grains of salt. I did try to follow the link to the original article in the Astronomical Journal, but I’m not subscribed to it, so couldn’t get past their first page. From the looks of some of the titles listed for their current issue, their articles are seriously geeky, which is why I sometimes have to rely on someone else to explain it to me. Having said all that, hand me an ice cube for my drink, and let’s get started.

NASA’s Spitzer space telescope (launched in 2003) has found 14 of the coldest stars known, but it’s expected that far more are waiting to be discovered. These 14 objects are hundreds of light-years away and are thought to have temperatures 350 to 620 degrees Fahrenheit. That’s bitterly cold for stars.

These are ‘failed stars’, also known as brown dwarfs, which have been known to exist for years. Spitzer and its sister, WISE, could recognize them by the hundreds before too long. Spitzer was assigned specific patches of space to study, but WISE has been tasked with studying the entire sky. WISE’s task is 40 times the size of Spitzer’s.

Brown dwarfs form like any other star, out of collapsing balls of gas and dust. But they are puny things, and never collect enough mass to ignite nuclear fusion and start shining. The smallest known so far are 5 to 10 times the mass of Jupiter, and there are giant gas planets of that mass around other stars. Without nuclear fusion, what little internal heat these bodies started with eventually faded away.

It’s possible that WISE could find an object about Neptune-sized (or bigger) in the far reaches of our solar system. Raise your hand if you’ve heard the story of Planet X, a large planet so far out we can’t see it, but it has some disruptive tendencies for the orbits of the outer planets, dwarf planets and other objects we know of. Some scientists speculate it might even be a brown dwarf companion to our sun.

So are these 14 examples of planets or stars? Well, they’re hot for one, and unbelievably cold for the other. I assume someone will decide what they are, eventually.

www.networkworld.com/article/2231137/nasa-finds-14-new--seriously-chilled-stars.html

Weird Planets 12

Good morning! This is the 12th day of your tour, and it’s the last day! So tomorrow you can either rest up or start home, it’s your choice. Now, we do have a number of planets to get through today, so everybody buckle up and let’s get going!

The first one is 51 Pegasi b. Now, don’t ask about the name; they only gave us clues about one naming method, and have completely ignored any other methods that may have been used. Anyway, 51 Pegasi b is gigantic, about half the mass of Jupiter. Yet it completes its orbit in 4 days, so it’s tucked right in close, like so many seem to be. This was the first confirmed exo-planet orbiting a sun-like star, and that’s its claim to fame.

Here is system HR 8799. We aren’t here to see any one planet in this system, but the entire system. This was the first exoplanet system that was directly imaged. As you can see, the system contains a debris disk and 4 massive planets, at least.

Now this - and I keep asking for the name, but they never give it to me - was once called the Oldest Alien Planet. It is 12.7 billion years old, so it formed more than 8 billion years before Earth and only 2 billion years after the Big Bang. Its discovery made people start thinking that planets are very common in the universe and that life may have begun far sooner than anybody had ever imagined. I’m still waiting to hear from one of those civilizations that got started so much earlier than us.

Here we are, only 420 light-years away from Earth, at the Coku Tau-4 system. See the big dusty disk going around the star? Scientists think this system has the universe’s youngest star, less than 1 million years old. They haven’t actually found it yet, but if you look closely, you can see a big hole in that disk. That hole is 10 times the size of Earth’s orbit around the sun, and they surmise it’s been made by this planet cleaning up the dust as it rolls around its orbit.

This is Hat-P-1. Huge, isn’t it? It is 1.76 times bigger than Jupiter, but only has 1/2 Jupiter’s mass. It’s lighter than a ball of cork would be! What’s holding it together? I have no idea. Known as one of the Puffiest Planets known, it could float in water, if it could find a tub big enough.

This Super-Neptune, called Hat-P-11b, is 4.7 times the size of Earth, but has 25 times Earth’s mass. If you weighed 100 pounds on Earth, here you’d weigh 2,500 pounds. Doesn’t sound very inviting to me. And it’s puny star is 3/4 the size of our sun, and cooler. On the other hand, 11b’s orbit is so close to that star, it only takes 4.88 days to complete an orbit, and the surface temperature is around 1100°F. Nope, still doesn’t sound inviting.

Now here’s a fun one. Most planets orbit in the same plane as their star’s equator. But XO-3b’s orbit is at a 37-degree angle to the star’s equator. How did that happen? The only other planet that’s been known to have such a tilted orbit was Pluto. But it got demoted to dwarf planet, and its eccentricities are of no interest anymore. So tilted orbits are an oddity. I’ve heard a rumor that one planet orbits backwards to its star’s rotation. But I don’t know where it is, or else we’d squeeze that in today, too.

Okay, watch carefully, or you’re going to miss this planet. SWEEPS-10 is only 740,000 miles from its parent star. It zips around so fast, a SWEEPS-10 year is only 10 hours long. This puts it in a classification called Ultra Short Period Planets. Those are the fastest planets, where their orbits last less than a day.

Take a good look, this is the last planet of the day, and of our tour. COROT-exo-3b is the densest exoplanet known to man at this time. As you can see, it’s about the same size as Jupiter, but it’s mass is 20 times Jupiter’s. That makes it about twice as dense as lead. But it might not even be a planet. Scientists are also considering the possibility that it’s a brown dwarf, or failed star.

Please watch your step as you disembark. Thank you for taking our tour, and for sticking with it for the entire 12 legs. I know the tour is called ‘Weird Planets’, but actually, this was only a sampling. If we had tried to show you all the weird planets out there, we could be at it for years. Have safe journeys home!

[At last! I don’t know what I’ll be doing next week, but it will probably have nothing to do with planets, weird or not!]

https://www.nasa/gove/feature/jpl/20-intriguing-expoplanets

www.space.com/159-strangest-alien-planets.html

Weird Planets 8

Good morning. I am your replacement driver and tour guide. Your previous driver, um, has been... has been asked to stay home today.

Hope you had a large breakfast, because we’re going to visit several ‘HD’ systems on this leg, and it could be a long time until supper. Everybody buckled in? If not, get that way, ‘cause we’re headed out.

Okay, on the right side is HD 106906 b. It’s 11 times the size of Jupiter. Yes, it does have a parent star. It’s one of those bright bits of light ahead of us. This planet’s distance from its star is 650 times as Earth’s distance from our sun, so I can’t blame you for asking. Despite being so remote from its star, the average temperature on the surface is 1500° Celsius, which is 2,732° Fahrenheit. That’s pretty toasty warm, in my mind. Scientists say it shouldn’t exist at all, being so large and so far from its parent. Where did it get enough material that far out? But however it came to exist, it’s only 13 Million years old. Just a baby, really, since the universe is over 14 Billion years. So maybe it just hasn’t had a chance to cool off since it came into being?

Now, right over here is Osiris, more formally known as HD 209458 b, which was the first planet to be seen as it crossed in front of its star. It’s also the first planet to have its light directly detected. Its discovery showed that transit observations were possible, which opened up a whole new realm of exoplanet discovery.

The planet ahead of us is HD 189733 b. It’s about the size of Jupiter, and has been studied quite a bit ever since scientists discovered it transiting its star while they studied that star using X-ray frequencies. This is also one of the first planets to have its atmosphere ‘sniffed’ to determine its composition. I don’t remember the full list, but I do remember that the atmosphere contains methane. No, that doesn’t necessarily mean there’s cows on that planet. Methane can be produced naturally. It doesn’t have to be a biological byproduct.

Now we come to HD 114762 b, which was discovered in 1989. This is the first discovered planet to be orbiting a sun-like star. However, because its mass is - as seems so popular - 11 times that of Jupiter, and because it only takes 84 days to complete an orbit, it was initially thought to be a brown dwarf. But it’s not. As a comparison, tiny little Mercury takes 88 days to complete an orbit around our sun.

I have to ask you to please be quiet as I approach this one. If it was up to me, we wouldn’t even bother with this one. Too dangerous, if you ask me; you never quite know what to expect from HD 80606 b. It’s orbit is so eccentric-- Oh! Hang on! ... Whew! That was close. I think we’ll be safe now, at least for a few minutes. Besides its highly eccentric orbit, HD 80606 b also displays plenty of storms and atmospheric heating, and you can plainly see how fast it rotates.

Okay, that’s our tour for today. I’ll take you back to base so you can get some supper. I know I’m ready for it. No, I’m sorry, I don’t know who will be your next driver and tour guide. No, I don’t know where you’ll be taken, either. From the looks of it, you still have quite a number of planets to visit. We are all qualified drivers and tour guides, ma’am, otherwise, we wouldn’t have the job.

http://www.express.co.uk/news/science/643662/The-10-weirdest-planets-to-have-been-discovered-so-far

https://www.nasa.gov/feature/jpl/20-intriguing-exoplanets

www.space.com/159-strangest-alien-planets.html

Weird Planets 6

Some of these planets look familiar, which is how they get their nicknames. Is it a surprise that someone has imagined planets similar to actual exoplanets?

HD 188753 is sometimes called Tatooine. It is a Jupiter-sized planet located 149 light-years away from us… in a triple star system. One list explained that this meant the planet orbited a star, which orbited another star, which orbited a third star. They could be right that HD 188753 is set up this way, but it is not the only configuration available to 3 stars and 1 planet. How many other configurations can you come up with?

Whatever the configuration of this system, the gravitational fields would be complex, so scientists were surprised to find planets could be created in such a gravity maelstrom. Dr Maciej Konacki of CalTech feels the view from this planet would be spectacular, with ‘occasional’ triple sunsets. Yes, that’s possible; it depends on the distance between the triplet stars. Some ‘companion’ stars are so far apart that each appears as only a bright point to the other. But this Tatooine would definitely be hot; it completes an orbit around its star in 3.5 Earth days, so it is snuggled up real close.

CoRoT-7b was the first exoplanet to be dubbed a ‘Super Earth’. That means it’s a rocky planet, not a gaseous one. Knowing that other rocky planets exist, scientists can look for potentially habitable planets that reside in a star’s ‘Goldilocks’ zone.

However, this particular planet does not look like a pleasant place, as it is tidally locked to its star, meaning the same side always faces the star, and the temperature on that face is around 4,000° F. If you want to visit, consider that it may be the rocky core of a vaporized gas giant where it rains rocks. Be sure you take a strong umbrella with you!

Kepler-10b is the first rocky planet discovered by the Kepler equipment. It is the smallest known exoplanet; an Earth-sized world that may have a lava ocean on its surface. I love a hot tub, but that’s too hot.

OGLE-2005-BLG-390 is the first ‘cold super Earth’ exoplanet discovered, nicknamed Hoth. The thought is that it began to accumulate a Jupiter-like core of rock and ice, but didn’t stop with just a core. It is 5.5 times the mass of Earth, has a surface temperature of -364° Fahrenheit, and orbits a red dwarf star some 28,000 light-years away.

Well, on this trip, we’ve gone from Tatooine to Hoth. Have we gotten all the ‘extremes’ done? I’m not sure. But next week, we’ll start zipping through the planets that only appeared on 1 list. Bring your seat belt!

http://www.express.co.uk/news/science/643662/The-10-weirdest-planets-to-have-been-discovered-so-far

https://www.nasa.gov/feature/jpl/20-intriguing-exoplanets

www.space.com/159-strangest-alien-planets.html

Planets Around Failed Stars

Stars can (but don’t necessarily) have a family of planets surrounding them. Planets can (but don’t necessarily) have moons surrounding them. What about the so-called ‘failed stars’? Do they have anything as a family?

Jupiter is sometimes called a failed star. If it had just a bit more mass, fusion could start, goes the argument. Well, not really. It would take 13 Jupiters combined to have enough mass to reach the minimum needed for a brown dwarf, AKA failed star. Also, Jupiter was created within the disk of dust that surrounded our infant sun, which is how planets are made, not stars. Not even failed stars. So we can’t take any clues from Jupiter about the possibility of planets around dwarf stars.

Okay, so exactly what is a failed star? A close apparent brown-dwarf-type object to Earth is SIMP0136. It lies 21 light-years away and is 13 times the mass of Jupiter. Theoretically, it could be a brown dwarf. Brown dwarves form like other stars, but fail to get big enough. They may have some fusion of deuterium for a relatively short time inside them, but it doesn’t last. Any light they produce tends to be in the red and infrared spectrums, so despite being called brown dwarves, they would probably appear magenta or possibly red-orange. And the older the brown dwarf is, the more it cools and contracts, until it can seem to be just another planet. Scientists have recently decided SIMP0136 is just a planet, after all. A rogue planet, big enough and close enough for them to study its weather patterns.

It could have gone the other way. The size of brown dwarves range from a minimum of 13 Jupiter masses to a maximum of 80 Jupiter masses. If it managed to gather more than 80X Jupiter’s mass, it would have made it to actual stardom.

Because brown dwarves are a type of star, at least some of them do have a family of planets, such as 2M1207b and MOA-2007-BLG-192Lb. This makes sense, because brown dwarves form the same way as other stars, just in the middle of a smaller dust cloud. Once the center of the cloud collapses into a proto-brown-dwarf, the remainder of the cloud thins into a rotating disk of dust, which would normally form planets. It is thought that this disk would not extend far, since the entire cloud was small to begin with, so any resulting planets would be fairly close to the brown dwarf. It is also believed that these planets would be rocky, like Earth and Mars, rather than gas giants like Jupiter, because most of the gas would be taken by the brown dwarf. So, let's look at some known brown dwarf systems:

170 light years from Earth, planet 2M1207b orbits a brown dwarf. Its mass is somewhere between 3X and 10X that of Jupiter, and it orbits its primary at approximately the same distance as Pluto from our sun. Although there is some indication of water, it is not likely to be habitable.

Occasionally shortened to MOA-192 b, MOA-2007-BLG-192Lb is about 3,000 light-years away. This small planet is 3.3X Earth’s mass, and circles a small brown dwarf in an orbit approximately 2/3 the size of Earth’s orbit around the sun. It is believed to have lots of ice and gases, more like Neptune than Earth.

And then there’s the quadruplets: a small brown dwarf (2MASS J04414489+2301513, with a mass 20X that of Jupiter) has a companion (5X to 10X the mass of Jupiter) that could be either a planet or a sub-brown dwarf. There are also two other brown dwarves in close association. All four objects together only have 26% the mass of our sun, making it the quad system with the least mass. It is 470 light years away.

So yes, it is entirely possible - almost probable - that ‘failed stars’ will have planets. Or possibly siblings, as in the quad system.

http://www.iflscience.com/space/one-of-earths-closest-failed-stars-may-actually-be-a-rogue-planet/

http://now.space/posts/gas-giant-planets-small-failed-stars-is-there-a-difference/

https://en.wikipedia.org/wiki/Brown_dwarf

https://en.wikipedia.org/wiki/2M1207b

https://en.wikipedia.org/wiki/MOA-2007-BLG-192Lb

https://en.wikipedia.org/wiki/2MASS_J04414489%2B2301513