Orion Nebula Gets New Milepost Marker, Now Closer

twilight30 writes "Discovery News is reporting that 'One of the most famous and scrutinized heavenly objects is 10 to 20 percent closer than we thought, say two teams of radio astronomers who have made some of the most precise cosmic distance measurements ever, with a telescope nearly as big as Earth. The Orion Nebula is the closest major stellar nursery to Earth, so it has been heavily studied to learn about the lives of stars. Its distance from Earth, however, has long been a matter of uncertainty, with an estimate made about 25 years ago in need of revision.'"

Comments

"a telescope nearly as big as Earth"

[Anonymous Coward]

That's nothing. They needed a computer nearly the size of Jupiter to process the data.

Re:"a telescope nearly as big as Earth"

[opus]

The VLBA was aimed at one of the few radio-wave emitting stars in Orion, which was viewed twice in a single a year. The almost 200-million-mile width of Earth's orbit around the sun allowed the VLBA to serve as one eye, then again as the other eye six months later.

Wouldn't that be a telescope 200-million-miles wide, using the same poetic license that led them to say they used a telescope as big as the earth.

Re:"a telescope nearly as big as Earth"

[SnoopJeDi]

Not to mention if you consider that the awful comparison seems to suggest Gravitational Lensing.

Re:"a telescope nearly as big as Earth"

[glavenoid]

Wrong again. The 2 points, ~200 million miles apart were used as points in a measure of parallax. The virtual aperture of the VLBA scope is ~5000 miles diameter, which isn't *quite* "nearly as big as earth". Still a pretty big aperture, even though it's not a complete circular area, the resolution provided is apparently sufficient to measure the stellar (nebular?) parallax wrt M42.

What I find more interesting in this article is the close relationship alluded to between the trapezium and the nebula...

..with a telescope _AS BIG AS the EARTH" ?

[syrinje]

I wonder what they mounted it on! And yes, I did not RTFA - this is /., you insensitive clod

Re:..with a telescope _AS BIG AS the EARTH" ?

[Anonymous Coward]

It's an interferometer. It's not one telescope the size of earth but many smaller telescopes each collecting samples along a line with a length of about the diameter of Earth. The samples can be processed to give a picture with the resolution of a telescope the diameter of Earth (but it still only captures a small amount of em waves).

Re:..with a telescope _AS BIG AS the EARTH" ?

[jnik]

Actually, we've been doing it for a decade.

Re:question:

[The_Mystic_For_Real]

Or maybe the nebula is just moving 20% closer every six months!

Fortunately it will get caught in Xeno's paradox.

Re:question:

[Mahjub Sa'aden]

Very good question. I can only reply by pointing to the scalar polarisation effect negating the red/blue doppler shift you mention. Couple that with Newtonian dynamics in question, and you have a very good correction mechanism along the theta axis. Not to mention that the wibble-wobble isn't nearly as unstable as once thought.

Wow, I'm full of shit.

Re:question:

[siddesu]

the sun travels around the galactic center at about 20km/s. even assuming than sun and orion nebula travel away from each other at this speed, for 6 months they'd have moved away at about 6 billion km. this is about 0.00068 light years. since the distance is estimated at 1250+ l.y. give or take 50-60, the error due to the relative movement of the two objects seems accounted for.

Re:You thieving bastard!

[Mahjub Sa'aden]

Well, frankly, I just made a bunch of stuff up.

Unlike String Theory, a rigorously testable... oh wait.

summary

[evwah]

how the summary should have gone: /summary
the orion nebula is ___ light years away /end summary

end of story :P

Expanding Universe...

[CODiNE]

Let's just wait a little longer and we won't have to reprint all those textbooks.

Next Apolcalyptic Movie

[mrbluze]

"Impacted" Plot: In the year 2050 the Earth almost crashes into the Orion Nebula, only to be rescued from destruction by two nerdy radio astronomers from Parkes Observatory in the middle of nowhere in Australia, who, whilst trying to find a cure for constipation from eating too much McDongles(TM) Impact McBurglettes, find that by injecting massive amounts of First Fleet Enema into the Nebula they can cut a path through the Nebula. The romantic part of the movie is where the local district nurse shows up and a tense love triangle is set up between herself and the astronomers.. etc..etc

Re:question:

[servognome]

but if the Orion Nebula is undergoing rapid beta expansion, the measurements would be invalid. I don't know of any way to correct for this phenomenon...

Release it and figure it out in Service Pack 1.

Re:Three Dimensional Object

[CaptainPatent]

Aren't they measuring the distance to stars within a three-dimensional object? I would guess that they could pick two stars that appear close together along our line of sight and come up with wildly different distances. Now perhaps if they measured the distance to one of the Trapezium stars (a very bright formation thought to lie at the "heart" of the nebula) they could come up with some meaningful measurement of distance. Just thought of something else. Let's find a really large repository for data and create a three-dimensional map of the nebula. Don't try to shove this single star data down my throat! It is true that the nebula is three dimensional, but it is nowhere near 1/10th the distance from earth to the orion nebula. The margin of error associated with the "front" of the nebula with the "back" or "center" of the nebula is a fraction of a fraction of a percent. (and I purposely used relative terms to demonstrate where error can lie)

Additionally, they did not use line of sight. They were using radio telescopes making them able to "see" the star at the center of the nebula without necessarily having a true line-of-sight.

Closer than we thought...

[LordP]

Measured incorrectly, or has the Orion Nebula just been sneaking closing over the last 25 years?

Re:Closer than we thought...

[jamesh]

Hmmm... 10 to 20 percent closer in 25 years... (gets out calculator)... that means that it will be here in 125 to 250 years!!!

I for one welcome our invading Orion Nebula overlords.

Re:Closer than we thought...

[davburns]

Bower and his colleagues came up with a distance of 1,270 light-years, give or take 76 light-years. That compares with the previous estimate of 1,565 light-years, give or take 266.

There's still overlap in the uncertainties of the measurements. So it wasn't incorrectly measured, just measured with a 17% error margin. The only ones who are incorrect are the people who quote the estimate without including the uncertainty.

Telescope warning

[autophile]

Warning: Objects in telescope are closer than they appear.

--Rob

That's easy...

[SteveFoerster]

...four elephants standing on the back of a turtle.

Translation

[Anonymous Coward]

>One of the most famous and scrutinized heavenly objects is 10 to 20 percent closer than we thought

In other words, Natalie Portman moved from Boston to New York.

Re:question:

[Mahjub Sa'aden]

Apparently that manoeuvre also eliminates apostrophes. Who knew.

Re:Stellar parallax?

[glavenoid]

Yep. That's exactly what it is. Not exactly revolutionary, but interesting nonetheless...

Oh My GOD!

[grumling]

It's coming right at us!

Looks like I picked the wrong week to stop sniffing glue...

-Steve McCroskey

Combine the measurements for increased accuracy

[SirBruce]

The old measurement was 1,565 +/- 266 LY.

Bower's new measurement is 1,270 +/- 76 LY.

Assuming both error bars are correct, then by combining the two measurements we get between 1,299 LY and 1,346 LY.

Reid's new measurement is 1,350 +/- 23 LY.

So combining again, we can conclude the Orion Nebula is between 1,327 and 1,346 LY away, or 1,336.5 LY +/- 9.5 LY.

nah, not true

[someone1234]

This won't save your ass when the distance is only 1mm :)