Starship Asterisk*

by **neufer** » Wed Sep 05, 2012 1:38 pm

owlice wrote:
Kathleen (kat330) writes that she has now recorded her paean to Gliese 581g; it can be heard here.

http://en.wikipedia.org/wiki/Gliese_581_g wrote:
[img3=""Eyeball Earth" Gliese 581g model"]http://upload.wikimedia.org/wikipedia/c ... hSmall.gif[/img3]
<<Whether or not a tide-locked planet with the orbital characteristics of Gliese 581g is actually habitable depends on the composition of the atmosphere and the nature of the planetary surface. A comprehensive modeling study...identified two habitable states for a water-rich planet. If the planet has a very thin atmosphere, a thick ice crust forms over most of the surface, but the substellar point remains hot enough to yield a region of thin ice or even episodically open water. If the planet has an atmosphere with Earthlike pressures, containing approximately 20% carbon dioxide, then the greenhouse effect is sufficiently strong to maintain a pool of open water under the substellar point with temperatures comparable to the Earth's tropics. This state has been dubbed "Eyeball Earth" by the author. According to [Gliese 581 g discoverer & Zarmina hubby Steven S.] Vogt, the long lifetime of red dwarfs improves the chances of life being present. "It's pretty hard to stop life once you give it the right conditions", he said. "Life on other planets doesn't mean E.T. Even a simple single-cell bacteria or the equivalent of shower mold would shake perceptions about the uniqueness of life on Earth.">>

by **owlice** » Wed Sep 05, 2012 12:15 pm

Kathleen (kat330) writes that she has now recorded her paean to Gliese 581g; it can be heard here.

by **Daddyo** » Sat Oct 16, 2010 5:21 pm

Thanks Chris.

I was trying to visualize how there could be strong air currents when the planet is stationary. I think it's because the cold dense air wants to creep under the hot lower density air, the cold air heats eventually and rises to the top. This ends up being a big loop that should be pretty messy at the dark/light termination ring around the planet. But it outta become calmer towards the extremes, maybe dead-calm at the extreme ends. Couldn't this still mean very hot arid temperatures for the air at the near point? Does the air there only get conductive cooling from the rest of the atmosphere? I wonder how hot a temperature would be required to boil it off into space.

Nice poem btw.

by **owlice** » Sun Oct 10, 2010 6:37 pm

Hiya, Kathleen! I can't vet the facts; just wanted to say that I'm glad you posted! Welcome to Asterisk!

by **kat330** » Sun Oct 10, 2010 6:27 pm

I was inspired by the October 1st APOD to write the below paean to Gliese 581g. It fits the melody of Cat Stevens' "Sad Lisa." [Since maybe some are too young to be familiar with it, here's a link to a youtube performance:]

Click to play embedded YouTube video.

I'd appreciate any feedback, but especially I'd like to hear if any "fact" I've woven into the lyrics is embarrassingly inaccurate. Also, I really want to share this with astronomy wonks and the like, so if you can suggest blogs or other sites where it might be an appropriate fit, I'd be grateful. Thank you, and I hope you enjoy!

Take and give care,
Kathleen

Glad(?) Gliese [to the melody of Cat Stevens' "Sad Lisa" from “Tea for the Tillerman”]

She orbits Gliese five eighty-one, a red dwarf sun
getting cooler, and Zarmina's her new ruler.
Floating in Libra in the night sky,
g, please don't be shy.
You're a plus lass Milky Waying triple our Terra's mass.
Gliese Gliese, g, Gliese Gliese.

Although she's dense, her gravity's right. We think she might
(in fact oughta) hold a load of liquid water.
A wormhole to g, string theory or beam --
we only can dream
now. This new plan, it can mean a future for all of man.
Gliese Gliese, g, Gliese Gliese.

She's twenty light years far away, but still one day
we may live there, praying this time we will give care.
g-whiz, you're a gem formed from the big bang
(and our doppelganger).
Please take us, when our Earth must finally forsake us.
Gliese Gliese, g, Gliese Gliese.

(c) Kathleen A. Martin
New Albany, Indiana
October 10, 2010

by **Chris Peterson** » Wed Oct 06, 2010 11:57 pm

Daddyo wrote:Would a planet that is tidally locked be more apt to boil off it's atmosphere through the hot point facing it's sun? I wonder if that has been modeled for this or if that is not a significant factor. I also wonder about the likelyhood of having no wind to transport water/clouds to support life (except near shorelines).

No. Since the planet is in the habitable zone, it isn't going to get that hot. We are probably looking at something like tropical desert temperatures on the sun side, and arctic temperatures on the dark side. This will result in major air current systems, so there will probably be some serious weather. But no loss of atmosphere.

by **Daddyo** » Wed Oct 06, 2010 6:53 pm

Would a planet that is tidally locked be more apt to boil off it's atmosphere through the hot point facing it's sun? I wonder if that has been modeled for this or if that is not a significant factor. I also wonder about the likelyhood of having no wind to transport water/clouds to support life (except near shorelines).

by **Beyond** » Tue Oct 05, 2010 6:59 pm

"The Wrap of Khan?" Give that man a Tribble.

by **neufer** » Tue Oct 05, 2010 5:45 pm

Ann wrote:Design by Zarmina Khan. Maybe that's how they dress on Zarmina's world?

(Hey, I can see Captian Picard welcome these ladies on board the good ship Enterprise as ambassadors for Zarmina's world! How surprised the ambassadors will be when they realize that we had figured out the name of their planet even before we even knew if it was inhabited or not!)

The Wrap of Khan?

by **Ann** » Tue Oct 05, 2010 4:50 pm

Design by Zarmina Khan. Maybe that's how they dress on Zarmina's world?

(Hey, I can see Captian Picard welcome these ladies on board the good ship Enterprise as ambassadors for Zarmina's world! How surprised the ambassadors will be when they realize that we had figured out the name of their planet even before we even knew if it was inhabited or not!)

Ann

by **neufer** » Tue Oct 05, 2010 4:36 pm

Zarmina Voit

by **bystander** » Tue Oct 05, 2010 5:48 am

APOD Robot wrote: Zarmina s World

... the planet is designated Gliese 581g, but Vogt's more personal name is Zarmina's world, after his wife ...

A Tour de Force of Planetary Discovery
Centauri Dreams | 04 Oct 2010

Steven Vogt (UC-Santa Cruz) is suddenly the buzz of the blogosphere, though not in ways he might have intended. The designer of the HIRES spectrometer that made the detection of Gliese 581g possible, Vogt can claim pride of place as the discoverer of the first near-Earth mass planet found in the habitable zone of its star. But he’s also taking his lumps for saying that he could all but guarantee life on that planet. An unwise call, as many commenters here have noted. Perhaps even more unwise is his hope to name the new planet after his wife, Zarmina.

Centauri Dreams has nothing against the notion of naming celestial objects for loved ones, but caution should always be the byword. Suppose, for example, that Mrs. Vogt, fed up with publicity and tired of the company of astronomers, should surprise her husband by leaving him. Vogt’s ex would be forever enshrined in the celestial sphere, a taunting presence whenever the poor man thought of the Gl 581 system.

by **Chris Peterson** » Tue Oct 05, 2010 5:35 am

Ann wrote:So how seriously should we take this Dave Goldberg? What are his credentials? How good is he seeing into the future and understanding what needs to be done for humans to achieve near-speead of light space travel?

I'd say he's living in a fantasy world. The technology required to achieve 92% of c for any craft, let alone a manned one, and to protect that craft from the conditions encountered in interstellar space at such speeds, is well beyond anything we even have on paper. It would require an investment in basic science and then advanced engineering that would dwarf all of the space program to date- and this in a world that is barely limping economically, and shows no sign of real improvement anytime soon.

Science issues aside, our society is simply not constructed along lines that would allow an expensive, international project of decades duration, which has no real economic (or national security) payback that can be foreseen in advance.

by **Ann** » Tue Oct 05, 2010 4:23 am

bystander wrote:
durant1928 wrote:Using our fastest rocket-propelled space craft, approximately how long would a one-way trip to Zarmina take ? Let's be realistic about extraterrestrial colonization !
So, How Long Would It Take to Travel to That Exciting New Exoplanet?
Discover Blogs | Discoblog | 04 Oct 2010
... (David) McConville puts the trip at about 180,000 years. Bummer. But that’s assuming that humans only have access to current technology.

Dave Goldberg, coauthor of A User’s Guide to the Universe, took a more optimistic approach. In a blog post, he assumed an average travel speed of 92 percent of the speed of light, and figured that the trip could be accomplished in 22.4 years of Earth-time. Better yet, the time dilation effect described in Einstein’s theory of relativity would shorten the trip from the perspective of the bold travelers on their way to Gliese 581g. To them, the trip would only seem to take 6.1 years.

So how seriously should we take this Dave Goldberg? What are his credentials? How good is he seeing into the future and understanding what needs to be done for humans to achieve near-speed of light space travel?

I have a book from 1964 at home, Beyond the Solar System by Willie Ley, foreword by Wernher von Braun. (There are some nice illustrations by Cheseley Bonestell in it too, and one not so nice, where he paints B-type star Pleione as a highly flattened red ellipse!!!!)

Anyway. In the first chapter of his book (which was written before the Moon landings, remember), Willie Ley discusses what it would take to send humans to Alpha Centauri. Ley discusses his contemporary early 1960s technology, and notes that it is woefully inadequate at sending people on a 4.3 light year trip to Alpha Centauri. But, he writes:

It is fairly generally acknowledged that technological knowledge roughly doubles every 7 years. Some experts insist that this rate will increase so that a few decades from now it may take only 5 years for a doubling of the technological knowledge. But even if we count only the current rate of doubling every 7 years, a time interval of half a century should result in a total amount of technological knowledge 250 times as large as it is today. Surely this will be enough to attack the problems posed by the desire to undertake an interstellar expedition.

In other words, just wait half a century and the inevitable cumulative increase of technological knowledge will make the problems regarding interstellar travelling take care of themselves. Remember that Willie Ley wrote his text in 1964, and now it is October 2010; if we want to uphold Ley's promise to have people setting off for Alpha Centauri in half a century from 1964, we only have a little more than three years to prepare the spaceship. We'd better find ourselves some suitable astronauts and tell them to start packing.

In regard of what Willie Ley said, I feel confident that Dave Goldberg knows what he is talking about and knows how to solve the various problems concerning a 22.4 years Earth time/6.1 years personal time journey to Gliese 581.

Ann

by **bystander** » Mon Oct 04, 2010 8:27 pm

durant1928 wrote:Using our fastest rocket-propelled space craft, approximately how long would a one-way trip to Zarmina take ? Let's be realistic about extraterrestrial colonization !

So, How Long Would It Take to Travel to That Exciting New Exoplanet?
Discover Blogs | Discoblog | 04 Oct 2010

... (David) McConville puts the trip at about 180,000 years. Bummer. But that’s assuming that humans only have access to current technology.

Dave Goldberg, coauthor of A User’s Guide to the Universe, took a more optimistic approach. In a blog post, he assumed an average travel speed of 92 percent of the speed of light, and figured that the trip could be accomplished in 22.4 years of Earth-time. Better yet, the time dilation effect described in Einstein’s theory of relativity would shorten the trip from the perspective of the bold travelers on their way to Gliese 581g. To them, the trip would only seem to take 6.1 years.

by **neufer** » Sun Oct 03, 2010 5:10 pm

Chris Peterson wrote:
neufer wrote:The sun is really only needed to keep water in a liquid state near the surface.
Many earth ecosystems don't rely on the sun for their energy source.
Certainly. My comments were directed towards the observation that the artist rendering
suggested the planet is heavily populated by something like chlorophyll-based life.

Yeah, well, they definitely need to get a new artist for lots of reasons.

by **Chris Peterson** » Sun Oct 03, 2010 4:27 pm

neufer wrote:The sun is really only needed to keep water in a liquid state near the surface.
Many earth ecosystems don't rely on the sun for their energy source.

Certainly. My comments were directed towards the observation that the artist rendering suggested the planet is heavily populated by something like chlorophyll-based life.

by **neufer** » Sun Oct 03, 2010 4:23 pm

Chris Peterson wrote:
dahowa wrote:I notice that the artist has included a healthy amount of green on the planet. Not only is it shown as livable, but alive!
I'd think, however, that the shifted spectral output of the star (compared with the Sun) might result in the evolution of entirely different pigments for photosynthesis. On the other hand, photosynthesis in most plants on Earth is adapted for absorbing red and near IR light, so perhaps you'd find a very similar process on a planet in the Gliese 581 system. You'd expect Earth plants to do very well there.

The sun is really only needed to keep water in a liquid state near the surface.

Many earth ecosystems don't rely on the sun for their energy source.

http://en.wikipedia.org/wiki/Photosynthesis wrote:
<<Not all wavelengths of light can support photosynthesis. The photosynthetic action spectrum depends on the type of accessory pigments present. For example, in green plants, the action spectrum resembles the absorption spectrum for chlorophylls and carotenoids with peaks for violet-blue and red light. In red algae, the action spectrum overlaps with the absorption spectrum of phycobilins for blue-green light, which allows these algae to grow in deeper waters that filter out the longer wavelengths used by green plants. The non-absorbed part of the light spectrum is what gives photosynthetic organisms their color (e.g., green plants, red algae, purple bacteria) and is the least effective for photosynthesis in the respective organisms.
Z scheme

by **Chris Peterson** » Sun Oct 03, 2010 3:26 pm

dahowa wrote:I notice that the artist has included a healthy amount of green on the planet. Not only is it shown as livable, but alive!

I'd think, however, that the shifted spectral output of the star (compared with the Sun) might result in the evolution of entirely different pigments for photosynthesis. On the other hand, photosynthesis in most plants on Earth is adapted for absorbing red and near IR light, so perhaps you'd find a very similar process on a planet in the Gliese 581 system. You'd expect Earth plants to do very well there.

by **dahowa** » Sun Oct 03, 2010 3:06 pm

I notice that the artist has included a healthy amount of green on the planet. Not only is it shown as livable, but alive!

by **Chris Peterson** » Sun Oct 03, 2010 4:24 am

Ann wrote:My software gives a GSC measurement for this star, but there is a Hipparcos measurement, too. Hipparcos says that the maximum V luminosity of Gliese 581 is 10.49, and its minimum V luminosity is 10.60. Could it be that the variability has anything to do with the many planets of Gliese 581?

I don't see any connection there.

My software also quotes "Johnson", whose measurement gives a V luminosity of 10.57 for this star.

"Johnson" just defines a particular set of photometric filters, commonly used. This lets people know the type of filter, which allows for conversion of magnitude to different scales.

Yes, but the given V magnitudes (10.49, 10.57, 10.60) are not absolute magnitudes. They are the V magnitudes measured for this star at its distance from us, which is, according to the Hipparcos measurements, 20.45 ± 0.29 light-years. But the absolute magnitude for a star describes how bright it would be if it was seen from a distance of ten parsecs. I can never remember exactly how much ten parsecs is, but I know that it is a little more than thirty light years.

Good catch. I looked at the Hipparcos catalog, and the stated value ("Hpmag") is indeed the apparent magnitude. Taking the Hipparcos parallax (0.16091 arcsec) gives a distance of 6.22 parsecs, which allows for conversion to an absolute magnitude (based on 10 pc) of 11.6.

Chris, I think I'm right here. I think that the absolute V luminosity of Gliese 581 is about 11.50.

Pretty close. But the GSC value is apparent, so it is simply in error.

by **Ann** » Sun Oct 03, 2010 2:59 am

Chris Peterson wrote:
Ann wrote:Interesting. According to my astronomy software, Gliese 581 has an absolute V magnitude of 11.584. That is a whole magnitude fainter than the paper you refer to. Someone must have made a significant mistake here.
What software? Most of it uses a mix of catalogs, and most catalogs do not contain very accurate photometric data. I do a lot of photometry, and generally cannot rely on standard catalogs to provide accurate photometric references.

The Hipparcos catalog, which is pretty good photometrically, gives V=10.5759±0.004. An error of a full magnitude might suggest your software is using GSC data, which has notoriously poor photometric values.

Wait, Chris! I think I have figured it out!

My software gives a GSC measurement for this star, but there is a Hipparcos measurement, too. Hipparcos says that the maximum V luminosity of Gliese 581 is 10.49, and its minimum V luminosity is 10.60. Could it be that the variability has anything to do with the many planets of Gliese 581?

My software also quotes "Johnson", whose measurement gives a V luminosity of 10.57 for this star.

Yes, but the given V magnitudes (10.49, 10.57, 10.60) are not absolute magnitudes. They are the V magnitudes measured for this star at its distance from us, which is, according to the Hipparcos measurements, 20.45 ± 0.29 light-years. But the absolute magnitude for a star describes how bright it would be if it was seen from a distance of ten parsecs. I can never remember exactly how much ten parsecs is, but I know that it is a little more than thirty light years.

So the V luminosity of Gliese 581 is about 10.55 at a distance of about 20 light-years. But if it had been seen at a distance of about 30 light-years, then its V luminosity would probably have been about 11.50 after all.

Chris, I think I'm right here. I think that the absolute V luminosity of Gliese 581 is about 11.50.

Ann

by **NoelC** » Sun Oct 03, 2010 1:36 am

Food for thought...

If we, at the very dawn of technological advance - at the virtual instant of scientific advancement beyond satisfying basic needs - can already detect extrasolar planets capable of supporting life, what can we imagine a civilization out there of, say, 1 million years of advancement can see of us?

Could the others out there - perhaps after having constructed a telescope with an aperture the size of a planetary orbit - be studying our society close-up... Reading headlines on papers tossed in front lawns (okay, so the news might not be too fresh after traversing some tens of light years, but they might find it interesting)... Mapping our planet for their own Google Earth app... Planning their invasion...

-Noel

by **emc** » Sat Oct 02, 2010 9:13 pm

Craig Willford wrote:A Red Dwarf and a Red Giant are very different stars.

A Red Dwarf is a small star (smaller than our Sun) so that the nuclear furnace cooks more slowly because of decreased pressures at its core. As a consequence it is cooler and only red.

A Red Giant is a star in the final stages of life. It has used up much of its nuclear fuel and has switched to a different nuclear process, making even heavier elements than Helium. In the process, it bloats its surface far from its core and makes the star huge (and red).

Zarmina's world's star is reputed to be the former. It could be a young red dwarf or an old red dwarf. That info. hasn't been provided to us in this APOD entry.

Hi Craig, Thank you for clearing up my stupid assumption regarding red stars. I should have done a little research before posting but I got caught up in the moment when I thought I had something interesting and fun to say.

There are a lot of bright and shiny people reading and posting in Asterisk*… it's intimidating... I try too hard sometimes to NOT be boring.

by **Chris Peterson** » Sat Oct 02, 2010 5:24 pm

Ann wrote:I didn't quite get that, Chris. Do you mean that there is a greater chance for life to develop on a tidally locked planet than on a planet that isn't tidally locked, like the Earth? Why would it be easier for life to develop on a tidally locked planet?

I simply mean that there is an argument to be made for that. A geographically small, environmentally dynamic region may be just the sort of thing required for the development and early evolution of life. It has been suggested that life on Earth began in ocean tidal zones for precisely the same reason.

I'm not saying I either agree or disagree with this theory, only that it has been offered up by people who study such things, and is taken seriously. Any discussion concerning the conditions under which life can develop is necessarily speculative.

Starship Asterisk*

APOD: Zarmina s World (2010 Oct 01)

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