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"These suggest that the planet candidate is on an eccentric (e~0.4)Frozen solid, I should think.
orbit significantly inclined with respect to Alpha Cen AB orbital
plane (i mutual ~50 degrees, or ~130 degrees). Based on the photometry
and orbital properties, the planet candidate could have a temperature
of 225 K, a radius of 1-1.1 (Jupiter) and a mass between 90-150 (Earth), >consistent with RV limits."
https://arxiv.org/abs/2508.03814
For people not familiar with the Kelvin temperature scale, 225 K is the >temperature of a very cold giraffe.
On Sat, 9 Aug 2025 08:36:41 -0400 (EDT), jdnicoll@panix.com (James
Nicoll) wrote:
"These suggest that the planet candidate is on an eccentric (e~0.4)
orbit significantly inclined with respect to Alpha Cen AB orbital
plane (i mutual ~50 degrees, or ~130 degrees). Based on the photometry
and orbital properties, the planet candidate could have a temperature
of 225 K, a radius of 1-1.1 (Jupiter) and a mass between 90-150 (Earth), >>consistent with RV limits."
https://arxiv.org/abs/2508.03814
For people not familiar with the Kelvin temperature scale, 225 K is the >>temperature of a very cold giraffe.
Frozen solid, I should think.
And I am sure the planet candidate could be a lot of things. Those
proposed here, presumably, have at least some sort of data to support
them.
After all, I /could/ have wings. But I don't.
Perhaps "might have" would be better than "could have", although I
suppose it doesn't make much difference any more.
"These suggest that the planet candidate is on an eccentric (e~0.4)
orbit significantly inclined with respect to Alpha Cen AB orbital
plane (i mutual ~50 degrees, or ~130 degrees). Based on the photometry
and orbital properties, the planet candidate could have a temperature
of 225 K, a radius of 1-1.1 (Jupiter) and a mass between 90-150 (Earth), consistent with RV limits."
https://arxiv.org/abs/2508.03814
For people not familiar with the Kelvin temperature scale, 225 K is the temperature of a very cold giraffe.
For people not familiar with the Kelvin temperature scale, 225 K is the temperature of a very cold giraffe.
"These suggest that the planet candidate is on an eccentric (e~0.4)
orbit significantly inclined with respect to Alpha Cen AB orbital
plane (i mutual ~50 degrees, or ~130 degrees). Based on the photometry
and orbital properties, the planet candidate could have a temperature
of 225 K, a radius of 1-1.1 (Jupiter) and a mass between 90-150 (Earth), consistent with RV limits."
https://arxiv.org/abs/2508.03814
For people not familiar with the Kelvin temperature scale, 225 K is the temperature of a very cold giraffe.
"These suggest that the planet candidate is on an eccentric (e~0.4)
orbit significantly inclined with respect to Alpha Cen AB orbital
plane (i mutual ~50 degrees, or ~130 degrees). Based on the photometry
and orbital properties, the planet candidate could have a temperature
of 225 K, a radius of 1-1.1 (Jupiter) and a mass between 90-150 (Earth), consistent with RV limits."
https://arxiv.org/abs/2508.03814
For people not familiar with the Kelvin temperature scale, 225 K is the temperature of a very cold giraffe.
Jupiter "should" emit at 105K but actually emits at 125. This much
larger hypothesized planet may well have a much greater output.
William Hyde <wthyde1953@gmail.com> wrote or quoted:
Jupiter "should" emit at 105K but actually emits at 125. This much
larger hypothesized planet may well have a much greater output.
The tidal flexing kneads of one moon of Jupiter, Europa's,
interior gives it a source of heat, possibly allowing its
ocean to stay liquid below the surface.
BTW: Have you all checked out the mars "corals"? An image
search for "mars" and "coral-shaped" for images about a
week or less old should do!
It is conceivable that a moon of this planet could have a strong enough greenhouse effect to be habitable, but it would probably need to be too large to be realistic.
That's a lot of ifs, but not too many for an SF novel.
I did a brief search for the amount of tidal heating and came up with no >hard numbers, but an estimate of less than one W/M**. Do you know. . .
anything more concrete?
It's frustrating how many of these sources talk around the figure you
need to know. These non-climate people!
In article <unqe9k93p83m8ai52b8s70tvfduqv4b73v@4ax.com>,Yeah, I think I got a wee bit unreasonable there.
Paul S Person <psperson@old.netcom.invalid> wrote:
On Sat, 9 Aug 2025 08:36:41 -0400 (EDT), jdnicoll@panix.com (James
Nicoll) wrote:
"These suggest that the planet candidate is on an eccentric (e~0.4)
orbit significantly inclined with respect to Alpha Cen AB orbital
plane (i mutual ~50 degrees, or ~130 degrees). Based on the photometry >>>and orbital properties, the planet candidate could have a temperature
of 225 K, a radius of 1-1.1 (Jupiter) and a mass between 90-150 (Earth), >>>consistent with RV limits."
https://arxiv.org/abs/2508.03814
For people not familiar with the Kelvin temperature scale, 225 K is the >>>temperature of a very cold giraffe.
Frozen solid, I should think.
And I am sure the planet candidate could be a lot of things. Those
proposed here, presumably, have at least some sort of data to support
them.
After all, I /could/ have wings. But I don't.
Perhaps "might have" would be better than "could have", although I
suppose it doesn't make much difference any more.
It's very early days, thus the "this interpretation fits the data",
not "this is what Alpha Centauri A is like".
It's about as cold as Mars, I think.Online calculators show -54.67 F (-48.15 C).
On 2025-08-09, William Hyde <wthyde1953@gmail.com> wrote:
It is conceivable that a moon of this planet could have a strong enough
greenhouse effect to be habitable, but it would probably need to be too
large to be realistic.
You could have tidal heating and a subsurface ocean under an ice
crust...
That's a lot of ifs, but not too many for an SF novel.
One of the Alpha Centaurian worlds in Charles Pellegrino's
_Flying to Valhalla_ (1993) is an ice world with a subsurface ocean.
*leafs through the book*
Not a moon of a giant planet though, but it does get tidal heating
from a very large moon of its own--think Pluto-Charon.
Gur angvirf nera'g fcnpr snevat lrg, ohg gurl pbzr hc guebhtu gur
vpr naq dhvpxyl qvfnffrzoyr gur cebor frag qbja, ng juvpu cbvag bhe cebgntbavfgf pbafvqre vg cehqrag gb Xrffyre-flaqebzr gurz, jvgu
nagvznfggre ab yrff.
In article <unqe9k93p83m8ai52b8s70tvfduqv4b73v@4ax.com>,
Paul S Person <psperson@old.netcom.invalid> wrote:
On Sat, 9 Aug 2025 08:36:41 -0400 (EDT), jdnicoll@panix.com (James
Nicoll) wrote:
"These suggest that the planet candidate is on an eccentric (e~0.4)
orbit significantly inclined with respect to Alpha Cen AB orbital
plane (i mutual ~50 degrees, or ~130 degrees). Based on the photometry
and orbital properties, the planet candidate could have a temperature
of 225 K, a radius of 1-1.1 (Jupiter) and a mass between 90-150 (Earth), >>> consistent with RV limits."
For people not familiar with the Kelvin temperature scale, 225 K is the
temperature of a very cold giraffe.
Frozen solid, I should think.
It's about as cold as Mars, I think.
On 8/9/2025 7:36 AM, James Nicoll wrote:
"These suggest that the planet candidate is on an eccentric (e~0.4)
orbit significantly inclined with respect to Alpha Cen AB orbital
plane (i mutual ~50 degrees, or ~130 degrees).-a Based on the photometry
and orbital properties, the planet candidate could have a temperature
of 225 K, a radius of-a 1-1.1 (Jupiter) and a mass between 90-150 (Earth), >> consistent with RV limits."
https://arxiv.org/abs/2508.03814
For people not familiar with the Kelvin temperature scale, 225 K is the
temperature of a very cold giraffe.
The freezing point of water at one atmosphere is 273.15 K.
So 225 K is very, very cold, -48 C.
That temperature occurs routinely in mostly the Dakotas and Minnesota in the lower 48 of the USA but not for very long.
On Sat, 9 Aug 2025 16:15:16 -0000 (UTC), jdnicoll@panix.com (James
Nicoll) wrote:
In article <unqe9k93p83m8ai52b8s70tvfduqv4b73v@4ax.com>,
Paul S Person <psperson@old.netcom.invalid> wrote:
On Sat, 9 Aug 2025 08:36:41 -0400 (EDT), jdnicoll@panix.com (James
Nicoll) wrote:
"These suggest that the planet candidate is on an eccentric (e~0.4)
orbit significantly inclined with respect to Alpha Cen AB orbital
plane (i mutual ~50 degrees, or ~130 degrees). Based on the photometry >>>> and orbital properties, the planet candidate could have a temperature
of 225 K, a radius of 1-1.1 (Jupiter) and a mass between 90-150 (Earth), >>>> consistent with RV limits."
https://arxiv.org/abs/2508.03814
For people not familiar with the Kelvin temperature scale, 225 K is the >>>> temperature of a very cold giraffe.
Frozen solid, I should think.
And I am sure the planet candidate could be a lot of things. Those
proposed here, presumably, have at least some sort of data to support
them.
After all, I /could/ have wings. But I don't.
Perhaps "might have" would be better than "could have", although I
suppose it doesn't make much difference any more.
It's very early days, thus the "this interpretation fits the data",
not "this is what Alpha Centauri A is like".
Yeah, I think I got a wee bit unreasonable there.
It's about as cold as Mars, I think.
Online calculators show -54.67 F (-48.15 C).
Mars I don't know about. Online calculators I can find.
One of the Alpha Centaurian worlds in Charles Pellegrino's
_Flying to Valhalla_ (1993) is an ice world with a subsurface ocean.
Gur angvirf nera'g fcnpr snevat lrg, ohg gurl pbzr hc guebhtu gur
vpr naq dhvpxyl qvfnffrzoyr gur cebor frag qbja, ng juvpu cbvag bhe
cebgntbavfgf pbafvqre vg cehqrag gb Xrffyre-flaqebzr gurz, jvgu
nagvznfggre ab yrff.
That wasn't nice of them.
On 2025-08-10, William Hyde <wthyde1953@gmail.com> wrote:
One of the Alpha Centaurian worlds in Charles Pellegrino's
_Flying to Valhalla_ (1993) is an ice world with a subsurface ocean.
Gur angvirf nera'g fcnpr snevat lrg, ohg gurl pbzr hc guebhtu gur
vpr naq dhvpxyl qvfnffrzoyr gur cebor frag qbja, ng juvpu cbvag bhe
cebgntbavfgf pbafvqre vg cehqrag gb Xrffyre-flaqebzr gurz, jvgu
nagvznfggre ab yrff.
That wasn't nice of them.
From the preface:
| Pellegrino, Powell and Asimov's Three Laws of Alien Behavior:
|
| Law No. 1: Their survival will be more important than our survival.
| If an alien species has to choose between them and us, they won't
| choose us. It is difficult to imagine a contrary case; species
| don't survive by being self-sacrificing.
|
| Law No. 2: Wimps don't become top dogs.
| No species makes it to the top by being passive. The species in
| charge of any given planet will be highly intelligent, alert,
| aggressive, and ruthless when necessary.
|
| Law No. 3: They will assume that the first two laws apply to us.
In his next novel, _The Killing Star_ (1995), Pellegrino followed
through on this thinking by suggesting that pre-emptively exterminating
your cosmic neighbors is the reasonable thing to do. Since a book
that effectively advocates genocide might raise issues with readers
and more importantly editors, he put humanity at the receiving end.
AKA, the 'Dark Forest' variant on the Fermi Paradox.
The freezing point of water at one atmosphere is 273.15 K.
So 225 K is very, very cold, -48 C.
That temperature occurs routinely in mostly the Dakotas and Minnesota in
the lower 48 of the USA but not for very long.
-48C is -54.4F. The coldest that the Twin Cities got during my time there
was -27F in January 1994.[1] Fortunately, I was in Europe for most of that >month. The folks I was working with were going to be coming to the Cities
the following month, so I spent a lot of our breaks telling them horror >stories about what they were in for.
Since the Twin Cities aren't Minnesota, let's look at "the nation's icebox," >International Falls, Minnesota. We see that the record low was -55F, a
record set in 1909.[2]