Please explain it – HOW and WHY!

trumpler 15 is a young open cluster of stars, all of which are presumably the same age. according to current theories of star formation and accounting for metallicity, a certain percentage of those stars should have been high mass/luminosity, but those high mass stars are not seen. this should not be surprising, because high mass stars have short lifespans, and high enough mass stars can die within a few million years of birth.

but then why does Phil prelude the missing star discussion with this comment: “About 900 of the stars in Trumpler 15 are massive enough to produce X-rays…” at first, he’s saying those stars are there – he even counted them. but then he’s talking about the stars not being there.

so the question this raises in my mind is, are there about 900 stars in trumpler 15 that should be producing x-rays, but aren’t?

@11.Keith Harwood — I think I’m going to use “friggin yuge” as my adjective of choice this week.

Current estimates sugest that the “primary” star (once the secondary) still has around 80 solar masses, while tehsecondary (once the primary) has perhaps 60. The two may have been born with 200 solar masses! Winds from the rapidly evolving stars collide, heat and radiate X-rays. Whether one star or two, Eta Carinae will explode. If the star is indeed double, the invisible secondary will go first (as it is farthest along its evolutionary path). The wisdom is that Eta Car will produce a hypernova, a grander version of the supernova in which the stellar core collapses to produce a black hole.

- Page 77, Kaler, Copernicus Books, 2002. [Emphasis added. Any tyupos almost certainly mine.]

The now 60 mass star would be lower in mass than its companion due to the “Algol paradox” where the more massive stars evolves and loses mass quicker – including mass exchange to its partner. The 60 solar mass star is now a Wolf-Rayet type star and its 80 solar mass comrade is a B-type supergiant. The “whether” and “if” are interesting and obviously imply some degree of uncertainty remains.

Eta Carinae is one of – if not the – brightest star in our whole galaxy witha luminosity an incmprehensible five million times that of our Suns’s (& can you imagine something even just *twice* as bright?) and it is a personal favourite of mine – despite which I’m hoping to see it die by going supernova in my lifetime!

I’m pretty sure we now think Eta Carinae *is* indeed a binary of two supermassive stars.

See :

http://stars.astro.illinois.edu/sow/etacar.html

Via Kaler’s Stars website or via wikipedia here :

http://en.wikipedia.org/wiki/Eta_Carinae

with a photographic star map of Carina here :

http://stars.astro.illinois.edu/sow/car-t.html

if that helps.

Supernovae popping off “like firecrackers” – yeah there’s just a leeetttle bit of diffenrce in the scale of the blast there!

enchandrasekharlimitenate.

Nice one – but I’d like to hear you say it ten times in a row real fast!

Carina has been cranking out supernovae over the past few million years.

Plus it will be for a while yet I bet – wonder how long Eta Carinae has left and how many more night’s it will grace our skies for before it explodes too – and what magnitudes it will rise and fall to during its remaining time?

The most massive stars only live a few million years before going boom, and the cluster is roughly 8 million years old — plenty of time for those stars to have gone supernova.

Gone in 8 million years! Wow.

In stellar terms that’s not long at all so those must have been very supermassive and thus very short-lived stars indeed. Can we work out roughly how massive and what spectral types they once were from that?

Concerning the “missing” massive stars, i think the point is that these stars must have been formed in the nebula but are not detected now so they’ve gone. They were never detected, not that they were detected by one means and not by another.

That just sounds so … degenerate. (rimshot)

But then, of course, I have another question. I’m old and cranky and full of questions. With all those stars of assorted sizes all packed into space perhaps not much larger than four light years, what gravitational effect do they have on each other? It would seem to me that stars that size in so small an arena gravity might do some interesting things.

Or maybe are we detecting the existence of these stars indirectly (like gravity lensing, or watching existing stars orbit around black space)? Or is there something really obvious that I’m just completely missing?

“About 900 of the stars in Trumpler 15 are massive enough to produce X-rays and be seen by Chandra, and the highest mass of these stars should be cranking out lots of the highest-energy X-rays. However, this high-energy emission isn’t seen. Those stars should be there, but aren’t. The conclusion is clear: those stars are gone. The most massive stars only live a few million years before going boom, and the cluster is roughly 8 million years old — plenty of time for those stars to have gone supernova. In other words, Trumpler 15 is has been seeing some action lately.”

If the massive stars are gone, how were they detected in the first place? Do you mean that the stars were found in visible light but not in X-Ray, so they must be supernovae remnants? Have I misunderstood something?

Fascinating stuff as usual. Keep up the good work!