What Constitutes being a DSO?.

[LukeSkywatcher]

We all talk about them,we all observe them,but what is the official definition of them?. Are they objects outside of our galaxy?. Do they have to be a certain distance from Earth to be considered as DSO?. 

I consider nebulae as DSO. I dont consider the planets in  our solar system as DSO.

[Littleguy80]

I believe the definition is anything outside of the solar system 

[ollypenrice]

7 minutes ago, Littleguy80 said:

I believe the definition is anything outside of the solar system 

That's about it. If they are an absolute beggar to image the definition is confirmed!

Olly

[Charic]

Olly, that would make them  Difficult to See Objects. 

[LukeSkywatcher]

30 minutes ago, Littleguy80 said:

I believe the definition is anything outside of the solar system 

Kuiper belt objects...(asteroids)....they are within our solar system (AFAIK)............. so why are they classed as DSO?. 

I  may be wrong.

[Littleguy80]

31 minutes ago, LukeSkywatcher said:

Kuiper belt objects...(asteroids)....they are within our solar system (AFAIK)............. so why are they classed as DSO?. 

I  may be wrong.

I suspect they're technically not DSO's but get labelled as such because they're difficult to find. It's pretty common for classifications to be applied incorrectly

[Ouroboros]

So technically are all  stars deep sky objects? I must say I think most people think of nebulae and galaxies etc when they are referring to DSO. 

[Stu]

35 minutes ago, LukeSkywatcher said:

so why are they classed as DSO?. 

They aren't, as far as I'm aware. They are in the solar system. DSOs are anything outside of the solar system so stars, doubles stars, open clusters, globular clusters, planetary nebulae, nebulae, galaxies etc etc I guess even planets around distant stars are DSOs....

[Pondus]

30 minutes ago, Ouroboros said:

So technically are all  stars deep sky objects? I must say I think most people think of nebulae and galaxies etc when they are referring to DSO. 

I really dont think individual stars are classified as dso`s.

 

 

[Stu]

8 minutes ago, Pondus said:

I really dont think individual stars are classified as dso`s.

 

 

I think that makes sense. Perhaps Doubles and Triples are though? A bit of a grey area here I would say.

[Pondus]

4 minutes ago, Stu said:

I think that makes sense. Perhaps Doubles and Triples are though? A bit of a grey area here I would say.

An individual star is not a dso. Unless it explodes...

[Littleguy80]

I think the definition is pretty simple. An object in deep space. This would include stars. However, by convention, we tend to use it to mean objects like galaxies and nebula. As the conventional use of the term breaks with the technical definition we have a grey area...and the subject of a discussion  

[frugal]

You get a similar conversation if you ask a biologist "what is a fruit?"

[michaelmorris]

To me, this is just a matter of semantics and is of little consequence - but hear goes anyway ?

A galaxy, nebula, supernova remnant, open cluster, globular cluster or similar extended non-solar system object.

 

[swamp thing]

15 hours ago, Stu said:

I guess even planets around distant stars are DSOs....

Well they would certainly qualify as difficult to see objects  

[SilverAstro]

15 hours ago, frugal said:

You get a similar conversation if you ask a biologist "what is a fruit?"

Enough to give anyone the pip, and cause the conversation to sag a little, or even drupe.

15 hours ago, Pondus said:

An individual star is not a dso. Unless it explodes...

but then it would be a Dead Stellar Object ?

I think there lurks in Paul's question a fundamental problem - there is not, I dont think, an  official   definition. It is a custom&usage type thingumy, is it not ?

 

[LukeSkywatcher]

So essentially anything outside of our solar system. Good enough for me. Thanks all.

[Moonshane]

Wiki suggests a common sense description

Deep-sky objects are astronomical objects other than individual stars and Solar System objects (such as Sun, Moon, planets, comets, etc.).^[1][2] The classification is used for the most part by amateur astronomers to denote visually observed faint naked eye and telescopic objects such as star clusters, nebulae and galaxies.

[LukeSkywatcher]

So comets are not considered DSO. I know they enter our solar system, but spend most of the time out in deep space. I guess they are a grey area.

[Stu]

15 minutes ago, LukeSkywatcher said:

So comets are not considered DSO. I know they enter our solar system, but spend most of the time out in deep space. I guess they are a grey area.

Comets generally orbit the sun don't they, which makes them part of the solar system.

[Moonshane]

Yep, they originate from the Oort cloud part of our system. They are generally thought to contain solar system matter in its original form.

[LukeSkywatcher]

4 hours ago, Stu said:

Comets generally orbit the sun don't they, which makes them part of the solar system.

For a brief time, yes. 

[LukeSkywatcher]

1 hour ago, Moonshane said:

Yep, they originate from the Oort cloud part of our system. They are generally thought to contain solar system matter in its original form.

I forgot about the Oort cloud , which is part of our solar system, so indeed comets are/should not be classed as dso. 

[niallk]

It's a good question... just like what is a planet.  The definition of these things is somewhat subjective!

To me, I've always (rightly or wrongly) thought of DSOs as observable objects, historically known/believed not to be stellar, but their true nature was not understood.

As a kid, I had a wonderful old encyclopedia which was my grandfather's dating from 1910 or so, and it described the mysterious nebulae - what we now know of as galaxies.  I'd love to find it again!  It predated plate tectonics as well, describing land bridges to explain animal population distributions.

I love old science books - and seeing how knowledge has advanced over just a couple of generations.

[Stu]

18 minutes ago, LukeSkywatcher said:

For a brief time, yes. 

There are many short period comets orbiting the sun. It is the long period ones which tend to be more dramatic but then clear off for.....long periods....