catdynamics | February 24, 2009our topic for today is to find the best paper on globulars published since the workshop started
sadly I'm only up to 2007 on astro-ph
My nomination of this paper failed to win the prize, due to the excessive integrity of the judge
PS: I WON!
WOO HOO!
Ok, it was the razzie.
But I like it.
The Munchkin, He Likes It!
we then somehow started discussing MOND and why measurements of accelerations in globular clusters all seem to give values of about 10-10...
bother
we then went on to discuss a Larson paper, no equations, no figures, lots of ideas
brilliant
seriously: no equations and no figures…
catdynamics | February 24, 2009What Julianne said.
It is not like going out into the Real World is a very promising career track right now.
catdynamics | February 24, 2009is the Light of an Oncoming Train
classic
haven't had gratuitous youtube blogging for a while
Pugh! Pugh!
Barney, McGrew!
Cuthbert, Dibble, Grub!
catdynamics | February 24, 2009NASA's Orbiting Carbon Observatory had a launch failure.
Taurus launch out of Vandenberg last night, tried to stay up to see if I could see the launch - often possible from the area - but I crashed before scheduled launch time.
Apparently payload failed to separate after stage burnout and the whole lot crashed near one of the poles (south pole - thought that was what they said but wasn't sure till I saw the formal press release).
Total loss.
I guess we know what NASA's SMD will use their $400M stimulus for now - that should just about buy a replacement.
It is a bad loss, the OCO, or…
catdynamics | February 23, 2009In the Good Old Days, Globular Clusters were simple things: spherical, relaxed, coeval and homogenous.
Not so much anymore.
The thorny issue of multiple populations keeps coming up at the workshop.
They're there, something is going on, but what, and how, and Y?
M13 embiggen
Guest author
Natalie Hinkel from ASU put some notes together from the sessions I missed earlier this month, and I post them below, with her permission, with light edits and addition of figures and links by me - any error is mine:
See, here is Good Old M54 (from Chaboyer) - simple.
Multiple Populations: A Summary…
catdynamics | February 23, 2009ipsos custodes?
The guardians of the finances, to be specific.
I infer, reading on the Net, that US Treasury Secretary Geithner has not got round to nominating under and assistant secretaries for the various Treasury Offices.
So, they are either vacant, or staffed by holdovers from the previous administration.
Awkward that.
They might want to do something about that, rather fast.
I hear, from a friend of a friend who has a cousin whose brother-in-law knows this girl who...
anyway, apparently US Treasury officials had it suggested to them that too much of the modern banking system and its…
catdynamics | February 23, 2009apparently citigroup is pushing for a deal whereby the US government's current preferred stock holding in the company would be converted to common stock
the catch is that for about $45 billion in preferred stock the US would get less than 50% of the company, to avoid the stigma nationalization the appearance of pre-privatization, which is puzzling, since the total capital value of the company is only about $10 billion
current shareholders would lose 90% or more of their current depleted holding, but the capitalization of the company would be boosted by almost a factor of ten - a comparable…
catdynamics | February 23, 2009New week, and a new set of topics for us to contemplate.
This week we hear from the grad students, who will tell us what it is they have actually been doing all this time, scientifically...
Tom is here! For a flying visit.
We may go post-Newtonian, and we may meander back through stellar evolution for a bit.
So - where, cosmologically, and when, do globulars form?
Is the mass-metallicity relation for galaxies a clue? Should we look to dwarf galaxies with masses less than 1010 solar masses as cites for most or all of globular formation? How long can we delay globular formation?
How dense…
catdynamics | February 20, 2009I've never seen a green star
I hope to never see one
but I can tell you anyhow
I'd rather model it than observe it...
if you have a bunch of stars of some age, or range of ages, and composition
with the stars all different mass over some range of masses, and
maybe some binaries and peculiar stars and interacting stars, and
bit of dust, then
what colour are they?
In particular if you are looking at a big clump of stars from far away
the easy thing to do is to see the slightly fuzzy blob, plop some filters
on your aperture and measure the colour - the difference in brightness in a small number…
catdynamics | February 20, 2009Yesterday we talked about triples.
It is an interesting thing that as we seem to not find any binaries in clusters, we do find triples... hmm.
First Rosemary discussed stability of triples - dynamical stability of isolated triples to internal spontaneous ejection - looking at analytic criteria for overlapping resonances to second order in the disturbing function
then Ivanova and meself talked - first Ivanova skated through the theoretical zoo of dynamically formed triples, stable and not, finishing with a teaser about 4U1820-303, then I talked about The Triple.
PSR1620-26 in M4 - The Triple…
catdynamics | February 20, 2009the disbursement of the stimulus funding through the science agencies is going to get real interesting
some disparate word has reached me on the stimulus funding
first, the NSF divisions won't hear for a while, like next month, how much they individually get to push out the door (NIH might be different since the bill specifies the funding goes pro-rate to the divisions).
But, the clock on getting the money disbursed is already counting, they basically have 120 days to dispose of the money from the signing of the bill.
Now, some calls for proposal are in current evaluation (oh to have a…
catdynamics | February 19, 2009I think I am having flashbacks
youtube, To The Rescue!
This was important mood music at a tender age...
late night parties with cider and harsh red wine in North Oxford.
catdynamics | February 19, 2009Say it is not so:
Brio near bankruptcy
Brio, yes, Brio makes proper toys, out of wood.
Not junky injection molded plastic crap.
Wah.
catdynamics | February 19, 2009word going around that Hubble servicing mission scheduled for May is in danger of being reconsidered because of higher mission risk
haven't seen the memo, but it went around:
due to the Iridium vs Kosmos collision there is concern that higher debris levels in LEO make SM4 too risky, and it is to be re-evaluated and possibly postponed, again, or canceled.
that kinda sux
if someone has the memo, do pass it along, there's a good chap
here's the satellite collision story, in case you missed it - was all over the news media
This is going to be a real problem, because there is still no…
catdynamics | February 19, 2009While I was galavanting about the southland yesterday, the program moved on and
John compared N-body and Monte Carlo (video and podcast)
and Sverre and Rainer continued with the theme (video and podcast)
today we move onto triples
'cause you got to know that if two stars are good, three stars are more better...
theoretically a lot of stars are binaries, (cf Matthew's latest)
Hogeveen Monte Carlo'd observed binaries to try to invert the q distribution and concluded the secondary mass function is a steep function of q, suggesting a lot of unobserved low mass secondaries
someone needs to redo…
catdynamics | February 17, 2009long weekend over, and we're back at it.
today's topic is GRBs
and what, you might ask, do they have to do with clusters...?
Well, Bob, as you know, there are two types of gamma-ray bursters, or maybe three depending on how you count
type I and type II the long and the short
"Some say" that short gamma-ray bursts are, clearly, coalescing binary neutron stars, spiraling into contact through gravitational radiation emission.
This can, clearly, happen in globular clusters, as evidenced by PSR M15C, and taking a single data point, inverting the rate, and throwing in some theoretical…
catdynamics | February 13, 2009ok, thomas.loc.gov now has the final version of the stimulus bill as being put to the vote to be sent to Obama - this is the House/Senate conference compromise plus extra bits the Speaker's office insisted upon after being unhappy with the Senate prematurely announcing agreement.
It is good for science, as good as can be expected. Maybe a bit too good in that we might pay a price later.
Interesting clause on executive compensation limitations.
PS: Bill has now passed senate and house and goes to President Obama for signature.
Not that I'm a worrywart or anything.
Ok, this particular…
catdynamics | February 12, 2009Latest on white dwarfs in globulars from Brad, John and Stefan.
White Dwarfs in Globular Clusters - Hansen - video and podcast
White Dwarfs in Globular Clusters - Fregeau and Rosswog - video and podcast
As we learned this morning, white dwarf cooling gives an absolute age indicator, essentially from ab initio physics calculations.
So you can independently measure cluster ages if you have very good photometry of very faint stars in very crowded regions. And we do.
cf NGC6397 - had a bit too much of M4 for now...
NB: white dwarf cooling age for NGC6397 is 11.5 Gyrs +/- 0.5
which is 1.2…