PDA

View Full Version : Giant Planet or Failed Star?



Fraser
2006-Sep-07, 11:42 PM
The Hubble Space Telescope has helped astronomers uncover an object right at the dividing line between stars and planets. The object, known as CHXR 73 B, weighs in at about 12 times the mass of Jupiter, and orbits a larger red dwarf star. The two objects are separated by 200 times the distance of the Earth to the Sun, so astronomers don't think they both formed out of the same disk of gas and dust.

Read the full blog entry (http://www.universetoday.com/2006/09/07/giant-planet-or-failed-star/)

pantzov
2006-Sep-08, 04:36 AM
allow me to direct your attention to the following quote taken from the article:

"Some astronomers suggest that an extrasolar object’s mass determines whether it is a planet. Luhman and others advocate that an object is only a planet if it formed from the disk of gas and dust that commonly encircles a newborn star."

funny eh? in the first case, because an object is extrasolar, it therefore falls under different guidelines as to whether or not it is a "true" planet than objects in our own system do. in the second case an enormous object (larger than jupiter even) could be trapped by a star and (i am asuming) even sustain a permanent orbit but still not be considered a planet because it came from somewhere else.

ever since the pluto ** the definition of what constitutes a planet is becomming more and more retarded.

Ronald Brak
2006-Sep-08, 08:23 AM
I will go with whatever definition science-fiction writers use.

antoniseb
2006-Sep-08, 05:21 PM
ever since the pluto ** the definition of what constitutes a planet is becomming more and more retarded.

It is interesting that no matter what definition you give, there will be examples in this universe which are close to the boundary. For the case given in this story, I'd call the smaller object a planet because it is too close to the star to have formed independently. Perhaps it formed as a parallel core during the collapse of the star-forming cloud, but it certainly isn't a captured object.

None-the-less, the scientific definition of the word planet will get further refined as to what is too large, and what is too small, and what is in the wrong environment, and what is the wrong composition, and what has the wrong history to be counted.

CharlesBell
2006-Sep-08, 05:46 PM
I would like to know how these super sharp images are taken by HST.

http://hubblesite.org/newscenter/newsdesk/archive/releases/2006/31/

They must be able to correct for the seeing and get image resolution down below 0.1 arc sec.

The image field of view is only 4 arc secs across. Thats about half the width of Uranus' disk.

I would love to have that kind of technology.

The image is supposed to be a 40 minute exposure taken February 10 2005 with infrared filters:

with F775W (SDSS i) and F850LP(SDSS z)

Would anyone know what stellar catalog CHXR 73 A and B are in?

GBendt
2006-Sep-08, 07:57 PM
Hi Charles,
The Hubble Space Telescope is out in space, and in space there is no seeing problem. That´s why the Hubble Telescope was put there.
I tried to find out where the star CHXR 73 A is located. CHXR73 is a young T-Tauri type star in the constellation Chamaeleon, with a magnitude of 15,3, in a star forming region called CHA 1 (Google is great!!).
Where did you find the information on image field size and exposure time?

Regards,

Günther

Blob
2006-Sep-08, 08:18 PM
Hum,
it is in the constellation Chamaeleon.

Position (2000): R.A. 11h 063m 29s.3 Dec. -77° 37' 34".0

Faint members of the Chamaeleon I cloud
http://www.eso.org/~fcomeron/cham.ps

MSFletcher
2006-Sep-10, 11:06 PM
As well as the current ruckus around deciding whether a given object is a planet, star or something else, I notice we have a second issue with emotive terminology.

The original article referred to the object as a possibly a "failed star".

Surely it would be more correct to refer to this type of object as "a star that has experienced delayed success"?

rosshenry
2006-Sep-11, 05:32 PM
I will go with whatever definition science-fiction writers use.

Which Science Fiction Writers? Up until now they all called Pluto a planet. Shall we wait until a couple of years have passed to see what the consenses is?

I suspect that the vast majority will follow the International ruling. Pluto as a planet is the past. Pluto as a Dwarf planet in the future. SF is about the future.

antoniseb
2006-Sep-11, 06:35 PM
Surely it would be more correct to refer to this type of object as "a star that has experienced delayed success"?

Welcome to the BAUT forum MSFletcher.

The term 'failed star' has been around a while, and was used to describe Jupiter. I suspect you are right that it is being misused, and that the adjective 'failed' makes it sound like it isn't living up to expectations.

For most of the objects that get this label, there is no chance that they will someday become an object getting energy from fusing Hydrogen into Helium. I expect that at some point in the near future, there will be a concensus as to what to call the whole range of objects from cosmic dust up to, but not including M8.5 red dwarfs. For now, there is some variability, which to some degree depends on the audience of whoever is writing.

RUF
2006-Sep-13, 09:20 PM
The original article referred to the object as a possibly a "failed star".

Surely it would be more correct to refer to this type of object as "a star that has experienced delayed success"?

Oh my, PC:cry:

Pluto should not be called a dwarf planet...it should be a "size-challenged planet":silenced:

antoniseb
2006-Sep-13, 10:35 PM
it should be a "size-challenged planet"
Or perhaps a compact efficient planet.