How big is a nebula?

[Maladominus]

How big is a nebula?

From the many nebula pictures I've seen from NASA, I assume that even a small cloud covers MANY MANY stars (and their respective solar systems). Does a nebula cover an entire sector? Several sectors? Does a small nebula only blanket a subsector?

Curious.

 

[FlightCommanderSolitude]

My "Atlas of the Universe" notes that the Orion Nebula is "about 30 light-years across", which would make it roughly the width of a subsector.

 

[Ptah]

Good question, here's a big one, about 800 light years across.
http://www.guidescope.net/galaxies/lmc.htm

A 200 light year one (and a great site):
http://hubblesite.org/newscenter/newsdesk/archive/releases/2000/06/image/a

Orion fits nicely here at 30 light years.

On the smaller side, what are called Planetary Nebula are much smaller. Say 0.5 to 3 light years.

 

[FlightCommanderSolitude]

Wow, that makes the LMC over five sectors across.

 

[parmasson]

That means they come in three sizes:
Huge (1 subsector or less)
Super Huge (1 subsector +)
Really Super Huge (don’t worry about it)

 

[Maladominus]

Well, in canon Traveller.... we have the Dark Nebula Sector (home of the Aslans). Unless stated canonically otherwise, I'm going to assume that the entire sector was named after a nebula BECAUSE that nebula probably blankets much of the sector.

Besides the Aslan's Dark Nebula, what other canonical nebula do we have in the OTU?

Related question: what effects would a Nebula have on starship travel?

And thanks for the above responses!

 

[Black Globe Generator]

Originally posted by Maladominus:
Besides the Aslan's Dark Nebula, what other canonical nebula do we have in the OTU?

The Glimmerdrift Reaches are so named due to a nebulosity, according to the original Judges Guild sector guidebook.

(Note that the JG sector maps were originally "approved for Traveller but were subsequently decanonized.)

 

[TempMal]

Originally posted by FlightCommanderSolitude:
My "Atlas of the Universe" notes that the Orion Nebula is "about 30 light-years across", which would make it roughly the width of a subsector.

That's just the part you can see. IIRC the Orion Nebula is the lit part of a massive cloud of gas and dust call the Orion Cloud. There's other nebulae in there too: the Horsehead Nebula, Barnard's Loop. It's several hundred lightyears across, and if it was all lit it would cover all of Orion.

http://www.seds.org/messier/more/oricloud.html

Nebulae are huge though - the stellar nursery types would generally be on the order of subsectors or sectors in diameter. Supernova remnants may be smaller, depending on their age. The Crab Nebula, which formed as a result of a supernova explosion seen in 1054AD, is now about 10 lightyears in diameter.

More info can be found on a lot of nebulae here:

http://www.seds.org/messier/data3.html


ISTR that the Helix nebula should be in Traveller's Known Space somewhere.

Wow, that makes the LMC over five sectors across.

Er, no. The LMC is a small galaxy about 10,000 lightyears in radius. With a diameter of 20 kilolightyears - about 6,000 parsecs - that's a darn sight bigger than a mere five sectors

.

 

[archhealer]

Which all brings to question... how does being in a nebula affect what sort of stars one finds? Would they tendt o be younger?

 

[TempMal]

If you're in a stellar nursery (like Orion) then many would be very young.

If you're in a supernova remnant then you'd have the old core of the star (neutron star/pulsar or black hole).

If you're in a planetary nebula (what's left when a sun-type star turns into a red giant and puffs out it's outer layers at the end of its life) then you'd have a white dwarf in the middle.

You may also have other stars wandering into the structure if it's big enough, as they orbit the centre of the galaxy.

As I said elsewhere, nebulae are barely visible (if at all) when you're up close to them. From afar they look bright because they are illuminated by several stars and that area of illumination is packed into a small volume of the sky. But as you approach them, that same amount of illumination is spread out over a wider area of sky - so the nebulosity actually dims as you approach it.

 

[aramis]

Canonical: Trin's Veil (Spinward Marches), specific canon size unknown. Density apparently pretty darned high as nebulae run...

 

[FlightCommanderSolitude]

Er, no. The LMC is a small galaxy ...

Oops, I meant the Tarantula Nebula, described on that same page.

 

[Scarecrow]

Originally posted by TempMal:
As I said elsewhere, nebulae are barely visible (if at all) when you're up close to them.

So they ain't like the Mutara nebula from Wrath of Khan then? No surprise there.

What would they be like to fly through? Virtually non-existant? How big are nebulae particles and how close together?

Crow

PS - excellent topic!

 

[Ptah]

Originally posted by Scarecrow:

What would they be like to fly through? Virtually non-existant? How big are nebulae particles and how close together?

I think you would hardly notice them. Some of the highest number densities of particles in a nebula I've seen are about 10^4 per cm^3, to give you an idea of how thin that is, it corresponds to a pressure of about 8x10^-14 torr (1 atm=760 torr). The best vacuums I believe we can pull on earth are in the 10^-12 torr range and those are hard to get. A typical vacuum intrument (outside of surface science studies) is more in the 10^-6 to 10^-9 range.

However, if the nebula is big enough, you may not be able to see it immediately around you but if you look in any direction (of course depending of it is emissive, reflective, etc.) it may limit your horizon after you look through enough of the gas; it's just the horizon might be a few light years off.

This is where knowing science can be a bad thing, I just can't buy sci-fi where they "fly into the nebula" to hide from enemies and it is this thick billowing cloud.

 

[Fritz_Brown]

Could you have clouds like those called nebulae (in other, lesser, sci-fi realms, natch), though? What phenomena would that require?

 

[Ptah]

Originally posted by Fritz88:
Could you have clouds like those called nebulae (in other, lesser, sci-fi realms, natch), though? What phenomena would that require?

The first thing that pops to mind is maybe an accretion disk around a star forming planets or maybe gas "condensing" to form a star. At some point, especially in the later, I'd imagine that you might have this "billowing" cloud. Add a star nearby for light and viola [sic]. Such star formation occurs in some nebula, hence the misnomer.

My suspension of disbelief has been saved! After all, I do like the special effects of the nebula fights.

 

[aramis]

Accretion disks, Fritz...

 

[archhealer]

There are also, on a much smaller scale than nebulae, dust clouds in space, clouds of actual particles and gasses that drift, usually in orbit around a star. Frequently the remnants of planetoids that no longer exist, or sometimes material that has been caught by the star. These would be more likely to be dense enough to be visible, but might also be thick enough to in the long term have an affect on a ship's hull, through abrasion.