Five planets around 55 Cancri

[ajtribick]

In case anyone hasn't seen this yet, there are now five planets known in orbit around the star 55 Cancri, all apparently on near-circular orbits (though the eccentricity of 55 Cnc f could be anywhere in the range 0-0.4).

The newly-discovered planet is a >45 Earth mass planet right in the habitable zone. Too bad for those hoping for terrestrials there (...I guess this means that Danzig is going to need a bit of adjustment...)

Press release
Extrasolar Planets Encyclopaedia

[Cham]

Poor Grant, the planet discoveries will soon accelerate, and how would he be able to keep up with the rate of discoveries ?

Right now, there are about 260 known exoplanets, all of them (minus one or two) are already included in Celestia's CVS database. But what about the - not far away - future ? In, say, 5 years, we may have about a thousand of exoplanets all around of us !

EDIT : What is really funny here, is that this system (55 Cnc = RHO1 Cnc) is actually studied **right now, at this exact hour, while I'm writing this message** by my own astronomy students in their computer lab. Few minutes ago, I even had to announce them that a fifth planet is actually moving around that star. Talk about a funny coincidence !

[granthutchison]

The revised 55 Cnc system is available on the CVS tree now:

http://celestia.cvs.sourceforge.net/celestia/celestia/data/extrasolar.ssc

Grant

[ajtribick]

The revised 55 Cnc system is available on the CVS tree now:

Thanks for that

[eburacum45]

I had already placed a fictional terrestrial planet (Danzig) in that space for the Orion's Arm scenario, so I've had to make that planet a moon of 55 Cancri f.

Here is the new moon in orbit around the f planet.
http://img127.imageshack.us/img127/2995/danzigiy4.png

A moon in this location could conceivably be habitable, although it would be tidally locked.

[edasich]

I visit this forum quite seldom.

Anyway...I called Rho1 Cancri f "Ripheus"...

*nobody cares*

[BobHegwood]

I visit this forum quite seldom.

Anyway...I called Rho1 Cancri f "Ripheus"...

*nobody cares*

Actually, I DO care... Although I have NO training in physics and/or
astronomy, I have a deep interest in these topics. Go figure... Folks
who have no interest in the topics are missing some of the most
exciting things in the universe.

Take care, Bob

[ajtribick]

I'm almost tempted to do an add-on for this system now... maybe I'll use a Lovecraftian nomenclature (don't think that's been done in a Celestia add-on yet)...

[LordFerret]

I had heard a short blurb of this on the news, but I missed the details. I think this is great! Was this the discovery made by the observations made aboard the shuttle/ISS?

I just noticed the Wikipedia extrasolar planets page is already updated!

I'm also looking forward to hearing more about observations of Epsilon Eridani b which are supposed to be (hopefully will be) made this December by the Hubble.

The planet is expected to reach periastron in 2007, when it could potentially be observed by the Hubble telescope.[1] The most favourable time for such an observation is estimated to be late December 2007.[2]

http://en.wikipedia.org/wiki/Epsilon_Eridani_b


PS - Thank you Grant.

[MKruer]

Grant Is there a way to create the Sagittarius A* system (OK its not a system per say but it has the dynamics of one. )

I don't know if there is enough information. I know that they were tracking a dozen or so stars in orbit, but I can't find any data on them. Also I think the 16K limit might become an issue.

http://en.wikipedia.org/wiki/Sagittarius_A*

Edit:

Here is a better view of the system dynamics
http://zephyr46.tripod.com/cartography/id12.html

[ajtribick]

Something about the 55 Cancri system that's odd is the way that planets c and f somehow avoided accreting enough gas to become jovian-mass planets, and ended up with sub-Saturn mass.

I wonder if these planets might be super-Neptunes, mainly composed of ice and rock with only a small fraction of their mass in a gaseous envelope, rather than mini-Saturns.

[edasich]

I'm almost tempted to do an add-on for this system now... maybe I'll use a Lovecraftian nomenclature (don't think that's been done in a Celestia add-on yet)...

I'd advise to use Lovecraftian nomenclature for something laying in Cetus or Piscis Austrinus constellation, anyway no problem

[eburacum45]

I've made images of all the (known) planets in the 55 Cancri system now, using the Sudarsky classification system and a bit of imagination (which in my case is the least reliable part).

Here is the 'f' planet, with an imaginary Earth-like moon; it is a class II planet, with thick water vapour. This is different to the image I posted earlier, which was too blue. I based the earlier image on this picture which is probably much too blue and dark.

Here is the 'e' planet, which is probably hot enough to have clouds of silicate vapour in the atmosphere. I've imagined that such a planet might look a little yellowish- this might not be correct, but the planet's clouds might have all sorts of impurities that give it colour.

Here is the next planet out, 'b',, which is not hot enough to have silicate clouds, but too hot for water clouds (Sudarsky class III). Such a planet would probably be mostly given colour by Rayleigh scattering- the same process which makes our sky blue.

The next planet, 'c', is cool enough for water clouds, (Sudarsky class II) although I've added a lot of blue to the default Celestia texture to suggest that it is quite hot.

The outermost planet known so far, 'd',, is probably a Sudarsky class I planet, like Saturn or Jupiter. Obviously there is a lot of variation within these classes, as Saturn and Jupiter look very different to me, but they both have the distintive yellowish cast of a Class I planet.

Thanks to Grant, who has sorted these planets into classes for Celestia users, And Chaos for the original textures (although I've adapted them somewhat).

[ajtribick]

Interesting work eburacum45.

A point to note about the outermost planet is that its temperature may be kept too warm to be a class I planet because of internal heating. Indeed, one of the Sudarsky papers assigns planet "d" to class II (and planet "b" to class IV). That paper also seems to peg some of the boundary temperatures of some of the classes at different temperatures - e.g. class II appears to start at ~250 K rather than the ~350 K in the previous paper. The extrasolar planets in Celestia are still using the ~350 K boundary.

[eburacum45]

That's interesting.

These planets may be as much as a billion years older than our own gas giants, so will be a little cooler and more contracted. But perhaps Sudarsky has already considered that...

[ajtribick]

Using the brown dwarf/giant planet calculator, the temperature from internal heating for a 5.5 billion year old planet of 3.835 Jupiter masses comes out as 178 K, which is above the ~150 K boundary for water clouds. How accurate all this is, I don't know.

[eburacum45]

That does sound rather convincing. I'll give the matter some more thought.