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Irishman

macrumors 68040
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Nov 2, 2006
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The Galaxy is a Crowded Place – A Series

One of the things that mankind’s search for exoplanets – planets located outside our own solar system – has shown us is that there are a lot more of them out there than we initially thought.

As of this morning, we've found 1,774 exoplanets, a good chunk of them (962) found by the Kepler mission! They have a backlog of about 3,845 planet candidates for it to work through. Way back in 1989, we found the first exoplanet – HD114762 b (nicknamed Latham’s Planet, after its discoverer) – because of its great mass (10.98 Jupiter masses). That mass causes it to exert a small tug on its star due to its radial velocity, making the star “wobble”. HD114762 b is situated 128.7 light years from Earth, with a surface temperature of about 487K.

So, I thought it would be fascinating to explore our galactic neighborhood, beginning with those closest to us, working our way further into the galaxy.

Of course, as many of us know, that means we’ll start with Alpha Centauri B b:

For long-time Star Trek fans, it probably won’t come as a surprise that we found a planet around the closest star to us. They probably will be surprised by how recently that discovery happened – two years ago in 2012! Alpha Centauri B b is interesting because it’s an Earth-mass planet (1.13 Earth masses) extremely close to its star (only .0400 AU) away. That means it whips around its star (1.227 solar masses), with a very short year (3.23 days)! It makes sense that we found this planet by the same radial velocity “wobble” indicator as referenced above. Alpha Centauri B b is 4.37 light years from Earth, and is, so far, the only planet in its system.

Well, that’s it for this time! A huge part of my decision to keep the series going will be reader feedback. If it’s something you find useful, entertaining, or informative, please let me know here in the thread! If noone’s digging it but me, I’ll get that message quickly.
 

Macman45

macrumors G5
Jul 29, 2011
13,197
135
Somewhere Back In The Long Ago
Interesting stuff. I find it hard to comprehend the sheer size and quantity of what mankind has ALREADY found. A year of 3.62 days is strange, but the " wobble " in a planets orbit is said to indicate the possibility of life, based on what we know about our own solar system, and of course Earth.

Who knows how long it will take to discover life elsewhere, but I am firmly of the opinion that it must exist...we are currently bound by our own laws of physics, meaning we are unable to reach any further than Mars, and that's a huge stretch.

I'd like to see a mission to the Red Planet in my lifetime, but I'm not holding my breathe....it's such a tough job with the existing technology.
 

Scepticalscribe

macrumors Ivy Bridge
Jul 29, 2008
63,834
46,282
In a coffee shop.
Thanks a lot for starting a thread on such a wonderfully interesting topic and for your OP. And, please, do, continue to post and add further data and material.

Yes, I do find this sort of information both entertaining and informative; above all, I find it extremely thought-provoking, and awesomely absorbing. As a kid, I loved Star Trek (the original); as an adult, STNG was one of my few must-sees on TV.

Indeed, I used to watch the moon landings, entranced, and read - nay devoured - books and articles on this topic. I'll still read about, or watch programmes about such stuff.
 

localoid

macrumors 68020
Feb 20, 2007
2,447
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America's Third World
The surface temperature of Alpha Centauri Bb is estimated to be about 1,200 °C.

Kepler-186f, on the other hand, is the most earth-like, potentially habitable, exoplanet that's been found to date, although it is much further away from the earth, @ 500 light-years from earth.

Exoplanets have been found in a habitable zone before, however Kephler-186f is first Earth-sized planet that's been found (the others were 40 percent larger than Earth).

 

Scepticalscribe

macrumors Ivy Bridge
Jul 29, 2008
63,834
46,282
In a coffee shop.
The surface temperature of Alpha Centauri Bb is estimated to be about 1,200 °C.

Kepler-186f, on the other hand, is the most earth-like, potentially habitable, exoplanet that's been found to date, although it is much further away from the earth, @ 500 light-years from earth.

Exoplanets have been found in a habitable zone before, however Kephler-186f is first Earth-sized planet that's been found (the others were 40 percent larger than Earth).

YouTube: video

Great clip and terrific story - thanks for posting it, and I hadn't seen that particular news report.

I must say that I love this term 'The Goldilocks Zone' which is used in this context - it is brilliant; beautifully descriptive, immediately comprehensible and utterly unforgettable.
 

localoid

macrumors 68020
Feb 20, 2007
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America's Third World
The Space Sunflower...

Soon, we may get an even better look at Earth-like rocky planets orbiting around nearby stars, by using a spaceship that uses a giant starshade, that's being developed by NASA's Jet Propulsion Laboratory in Pasadena, Calif.


Great clip and terrific story - thanks for posting it, and I hadn't seen that particular news report.

I must say that I love this term 'The Goldilocks Zone' which is used in this context - it is brilliant; beautifully descriptive, immediately comprehensible and utterly unforgettable.

Thanks. "Goldilocks Zone" certainly rolls off the tongue easier than the "Circumstellar Habitable Zone" (CHZ), doesn't it? ;)
 
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SandboxGeneral

Moderator emeritus
Sep 8, 2010
26,482
10,051
Detroit
Oh I love this stuff! I did a little reading about Kepler 22b a couple of years ago and, at the time, I believe, it was the most Earth-like exoplanet known.

It's in what is called the habitable zone around it's sun and the average surface temperature is 72℉ or 22℃. It's located about 600 light years away from Earth and was discovered in 2009.

I even wrote a little article on my website with references to it. Though there are some holes in my research and missing ideas I still want to add, I still thought it was a good write.

http://www.space.com/24128-kepler-22b.html

Kepler-22b is a planet orbiting in the habitable zone of its sun-like star, Kepler-22, which is located roughly 600 light-years from Earth. With a radius of about 2.4 times that of Earth, astronomers noted after its discovery in 2011 that the planet's temperatures about the same. If the greenhouse effect is the same as well, scientists estimated its surface temperature is a life-friendly 72 degrees Fahrenheit (22 degrees Celsius).

Although the planet is larger than Earth, astronomers hailed the discovery as a step to Kepler's goal of discovering Earth-size planets in the habitable zones of their respective stars.

"We're getting closer and closer to discovering the so-called 'Goldilocks planet,'" Pete Worden, director of NASA's Ames Research Center in Moffett Field, Calif., said during the 2011 press conference announcing its discovery.
 

Huntn

macrumors Core
May 5, 2008
23,396
26,521
The Misty Mountains
Oh I love this stuff! I did a little reading about Kepler 22b a couple of years ago and, at the time, I believe, it was the most Earth-like exoplanet known.

It's in what is called the habitable zone around it's sun and the average surface temperature is 72℉ or 22℃. It's located about 600 light years away from Earth and was discovered in 2009.

I even wrote a little article on my website with references to it. Though there are some holes in my research and missing ideas I still want to add, I still thought it was a good write.

http://www.space.com/24128-kepler-22b.html

It makes me wonder what are the odds that the development of planets in the "life sweet spot" would lead to a predominantly O2 atmosphere? It's fiction, but I am reminded of Pandora. :)
 

SandboxGeneral

Moderator emeritus
Sep 8, 2010
26,482
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Detroit
It makes me wonder what are the odds that the development of planets in the "life sweet spot" would lead to a predominantly O2 atmosphere? It's fiction, but I am reminded of Pandora. :)

I like to believe, that given the vastness of not only our galaxy, but the universe as a whole, or even the multi-verse, that there has to be other habitable planets that could sustain life as we know it to be.

It's just a matter of finding it, not that we'd likely ever be able to actually visit it even if we could travel at light speed.
 

localoid

macrumors 68020
Feb 20, 2007
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America's Third World
The Fermi paradox is the apparent contradiction between high estimates of the probability of the existence of extraterrestrial civilizations and the lack of evidence for, or contact with, such civilizations.

One of the hypothetical explanations for the paradox is that "it is the nature of intelligent life to destroy itself".

In the following video, Michio Kaku ponders the question of whether humankind will destroy itself before we're able to achieve inter-stellar/galactic explorer status.

 

Huntn

macrumors Core
May 5, 2008
23,396
26,521
The Misty Mountains
The Fermi paradox is the apparent contradiction between high estimates of the probability of the existence of extraterrestrial civilizations and the lack of evidence for, or contact with, such civilizations.

One of the hypothetical explanations for the paradox is that "it is the nature of intelligent life to destroy itself".

In the following video, Michio Kaku ponders the question of whether humankind will destroy itself before we're able to achieve inter-stellar/galactic explorer status.

YouTube: video

Great video! I can easily see Type 0 civilizations blowing themselves up. I vote for Star Trek Next Generation, a society built on a "we is greater than me" standard, a socialist utopia. If we want to advance to a type 1 civilization, this is the only path I see. I don't want to turn this into a PRSI discussion, so I'll stop there. :)
 

Scepticalscribe

macrumors Ivy Bridge
Jul 29, 2008
63,834
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In a coffee shop.
Great video! I can easily see Type 0 civilizations blowing themselves up. I vote for Star Trek Next Generation, a society built on a "we is greater than me" standard, a socialist utopia. If we want to advance to a type 1 civilization, this is the only path I see. I don't want to turn this into a PRSI discussion, so I'll stop there. :)

Yes, agree with you completely. Actually, I find myself rather partial to the 'world view' (and 'universe building' concepts) of STNG; a positive, inclusive, thoughtful perspective on the universe
 

Irishman

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Nov 2, 2006
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The Galaxy is a Crowded Place – A Series (Part 2)

The Galaxy is a Crowded Place – A Series (Part 2)

Welcome back. As of today, we’re up to 1,776 exoplanets, and next on our list for the series is epsilon Eridani b:

Epsilon Eridani b orbits its gas giant star about 10.44 light years from Earth, at a distance of 3.39 AUs from that host star, and has a 2,502-day year. Its surface temperature is 111.8 K. As of right now, it’s the only known planet in its system, and was discovered quite recently in 2000. It was found using the same radial velocity technique as was Alpha Centauri B b, as it was measured exerting a gravitational tug on Epsilon Eridani, a K2 V-type star.

As far as supporting life, due to its distance from its type of star (3.39 AU), it is well beyond the “Goldilocks Zone” there – which is between .65 – 1.21 AU from the star. Sadly, this means no life as we know it can exist on Epsilon Eridani b.

Thanks so much for the feedback thus far! It’s clear that you guys are enjoying it as much as I am, so I’ll soldier on with the series.
 

localoid

macrumors 68020
Feb 20, 2007
2,447
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America's Third World
Thought I'd post this video, which takes a look at how astronomers find exoplanets, and what it means to call them Earth-like. It also traces the history of planetary science back three thousand years and examine Earth's changing status in the cosmos -- earth was once the center of the universe, now it's just another rock in the sky.

 

Irishman

macrumors 68040
Original poster
Nov 2, 2006
3,388
842
The Galaxy is a Crowded Place – A Series (Part 3)

This time we’ll be taking a slight detour on our trip through the galaxy, on our search for exoplanets, in what is proving to be a very crowded galaxy. Just a week ago, I would have been making a different kind of post in my series to highlight the exoplanets that are the closest to our star. But due to the rapid advance of science, a new discovery was announced just a few days ago that has changed that.

What is it?

The answer is Kapteyn b. Kapteyn’s star is named – as is tradition – after its discover, the Dutch astronomer Jacobus Kapteyn. There are several qualities about Kapteyn b that make it special: 1) Its proximity to Earth, which is 12.75 light years, and 2) Its age, which is roughly 11 billion years old. To put it into perspective, the Earth is about 5 billion years old. Life on Kapteyn b has had over twice as long to evolve, 3) Its mass is 4.8 Earth masses, which puts it into the category of super-earths, 4) Its orbit around its M1.0 type star is 48.62 days, which puts it within its Goldilocks zone of .07-.15 AUs. This delicate combination of qualities make Kapteyn a place which should keep our attention for a long time to come.

Kapteyn b isn’t alone in its system. We have - so far - found a second planet, called Kapteyn c, another super earth that is 7.0 Earth masses, orbits further away – 121 days - from its host star, and thus, too far outside of its habitable zone to support life as we know it.

Both Kapteyn b and Kapteyn c were found in 2014 using the tried and true radial velocity method.

Here is a good starter link to more of the methodology of how we learned what we know about these planets. http://phl.upr.edu/press-releases/kapteyn
 

SandboxGeneral

Moderator emeritus
Sep 8, 2010
26,482
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Detroit
I just read an interesting article on io9.com about this binary star system.

We've Discovered a Binary Star System Whose Planet Is in Stable Orbit

It may not be anything like Tatooine of Star Wars, but this discovery is still incredible. We've found a frozen, rocky planet orbiting one of its two parent binary stars in a stable Earth-like orbit. This significantly expands our sense of where life can emerge in the galaxy.

Binary star systems are quite common. So common, in fact, that they may account for as many as 50% of all stellar systems, though more conservative estimates place the figure at about a third. Regardless, the presence of so many binary stars likely imposes a profound constraint on galactic habitability; gravitational perturbations from a companion star can interfere in the formation and long-term stability of planets.

Prior to this study, all the planets discovered thus far in binary systems have been gas giants, including a binary system with more than one planet.

It's possible, of course, that the moons of these exoplanets are habitable , but astronomers have no idea if rocky Earth-like planets in stable Earth-like orbits can form in these systems — though models suggest it is possible.
It now appears the simulations were right. Using a gravitational microlensing technique, an international team of astronomers led by Andrew Gould of Ohio State University has discovered a large terrestrial planet in a binary system.

An Entire New Population of Exoplanets
Called OGLE-2013-BLG-0341LBb, the planet is located 3,000 light-years from Earth. It's about twice our planet's mass and is situated about 0.8 AU from its preferential host star. That's just slightly closer than Earth's distance to the Sun. But because its host star is only about 10% to 15% the mass of our Sun, it shines 400 times less brightly; this world is cold, dark, and likely uninhabited. At around 60 Kelvin (-352 degrees Fahrenheit or -213 Celsius), it's even colder than Jupiter's icy moon Europa.

But that's not the interesting part. What's exciting here is the planet's curious behavior. It orbits just one member of a pair of stars, practically ignoring the more massive companion star (spinning in what's called an "S-type" orbit). Planets that orbit both members of a stellar pair — called circumbinary planets — are quite common (they spin around in "P-type" orbits). Despite the close proximity of the two stars, OGLE-2013-BLG-0341LBb largely maintains its 0.8 AU distance, which is very good news for astrobiologists.

While this world is likely uninhabitable, its existence suggests the presence of an entirely new population of planets around these sorts of binary orientations — some of which may host planets that reside within the star's habitable zone. This study proves that terrestrial planets can form in orbits similar to Earth's — even in a binary system where the stars are not very far apart. In this case, the second star in the system is only 15 AU away — about the distance of Saturn from our Sun. But this binary companion is also very dim.

Importantly, however, binary star systems composed of dim stars like these are the most common type of star system in our galaxy. This discovery therefore suggests that there may be many more terrestrial planets out there that we thought— some potentially capable of harboring life.

The Power Of Microlensing
To make the discovery, Gould's team used a technique that's not often used to detect exoplanets. It's called gravitational microlensing, an optical phenomenon where light emanating from a distant object gets warped and distended by the gravity of another nearby object. This warping can create a magnification effect, making celestial objects, like planets and galaxies, easier to find.

Searching for planets within binary systems is tricky for most techniques because the light from the second star complicates the interpretation of the data. But in gravitational microlensing, astronomers don't even look at the light from the star-planet system. They just observe how its gravity affects light from a more distant, unrelated, star. Microlensing is thus offering astronomers a powerful new new tool to search for planets in binary star systems.

"Now we know that with gravitational microlensing, it's actually possible to infer the existence of a planet — and to know its mass, and its distance from a star — without directly detecting the dimming due to the planet," noted Gould in a statement. "We thought we could do that in principle, but now that we have empirical evidence, we can use this method to find planets in the future."
 
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