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parallaxicality
2006-Oct-08, 10:04 AM
I'm trying to get to grips with the distinction between "solar system," "planetary system" and "star system."

The Universal Book of Astronomy defines a "planetary system" as:

A system of celestial bodies in orbit around a star including planets, moons, asteroids, comets, and dust.

This definition would exclude the parent star.

Collins Dictionary clarifies this distinction:

... A system of planets and other bodies, such as comets and meteroids, that orbits a star. The Sun and its planetary system together comprise the solar system.

The McGraw Hill dictionary of Astronomy defines a "stellar system" as:

A gravitational system of stars.

Chambers 21st Century Dictionary defines a "star system" as:

a group of stars thought of collectively

OED Concise defines "solar system" as

the sun together with the planets, asteroids and comets etc. that orbit around it.

According to these definitions, therefore, there are three separate concepts being defined here:

1. Planetary system: the substellar objects in orbit around a star.

2. Star system or stellar system: a group of stars garvitationally bound to one another

3. Solar system: our Sun, together with its planetary system.

There has been some outcry about the generic use of the word "solar system" to define other stars in conjuction with their planetary systems, since "solar" should technically apply only to our own Sun, but there doesn't appear to be a suitable generic term, describing exactly that concept, that is applicable to other stars. Is there a scientifically accepted defintion?

Ken G
2006-Oct-08, 10:30 AM
That's quite interesting that there's no definition like what you want. I certainly would have said "stellar system", in analogy with solar system, but obviously the dictionaries don't see it that way. All I can say is, I have never ever heard the term "stellar system" used to mean a collection of gravitationally bound stars unless they were a multiple star system-- like a binary or ternary star system, which is just like a solar system with a few suns. If you have a large number of weakly bound stars, it is a "cluster", not a "stellar system". I think perhaps the definitions are in error-- unless they are attempting to basically mean binary star systems, etc., which would include the planets and debris as well, and should also be extended to single stars and their orbital debris.

Jeff Root
2006-Oct-08, 12:15 PM
Another source you could look in would be the Facts on File
Dictionary of Astronomy.

I just looked in three introductory astronomy textbooks which
each have extensive glossaries, but only the term "solar system"
had an entry in any of them, and it is what you have as (3).
There hasn't been much need of a generic term except in science
fiction until fairly recently.

-- Jeff, in Minneapolis

antoniseb
2006-Oct-08, 12:42 PM
I understand why you are excluding Planetary System, though it does seem to be the choice in most papers. I sometimes see the term Stellar System used here as well.

The difficulty, of course, is that we've been observing these things for a short time, and no one has been charged with creating the 'official' terminology. We're lucky their trying to resolve what the term Planet includes.

CuddlySkyGazer
2006-Oct-08, 01:01 PM
No, there is no generic equivalent for solar system. It's never been needed, but it is now, which is why people are casting around for a term. It will come in time through usage.

One possibility is that a star and its planetary system will be known as a solar system, with ours being the Solar System, and others being individually known as the Sirius System, 51 Pegasi System, etc (note the capitalisation when used as a proper noun). This is similar to the distinction between a moon and the Moon.

I know, sol is Latin for sun, but this is the same as geology. Some people think the science is only geology on Earth, and is something else on the Moon and elsewhere, because geo comes from the Latin for earth. But geology is an English word, and solar system is an English term.

StupendousMan
2006-Oct-08, 05:46 PM
All I can say is, I have never ever heard the term "stellar system" used to mean a collection of gravitationally bound stars unless they were a multiple star system-- like a binary or ternary star system, which is just like a solar system with a few suns.

A quick search with ADS

http://adsabs.harvard.edu/abstract_service.html

shows that the phrase "stellar system" is used frequently to mean "two or three stars bound together gravitationally == multiple star", and also to mean "large cluster of stars bound together gravitationally == galaxy or globular cluster."

Ken G
2006-Oct-09, 01:33 AM
It certainly sounds like the terminology on this is in a bit of a mess at present.

Jeff Root
2006-Oct-09, 05:07 AM
It doesn't sound like a mess to me.

-- Jeff, in Minneapolis

astromark
2006-Oct-09, 05:46 AM
According to these definitions, therefore, there are three separate concepts being defined here:

1. Planetary system: the substellar objects in orbit around a star.

2. Star system or stellar system: a group of stars garvitationally bound to one another

3. Solar system: our Sun, together with its planetary system.

[/QUOTE]

It looks right from here.

and then . . .


One possibility is that a star and its planetary system will be known as a solar system, with ours being the Solar System, and others being individually known as the Sirius System, 51 Pegasi System, etc (note the capitalisation when used as a proper noun). This is similar to the distinction between a moon and the Moon.

I know, sol is Latin for sun, but this is the same as geology. Some people think the science is only geology on Earth, and is something else on the Moon and elsewhere, because geo comes from the Latin for earth. But geology is an English word, and solar system is an English term.

Thanks for this, all good stuff.

Does any of this not make sence,?
I think our langage is well up to this subject and its explanations.

Ken G
2006-Oct-10, 06:59 AM
That all sounds good, but the question is begged: what will be the generic name for the class of things that include the Solar System, the Sirius System, etc.? To me, that name should be "stellar system", and that phrase should not be included as synonymous with "cluster". To do so would make a mess, and be foolish anyway-- why do we need synonyms in one situation when no name exists for the other?