catdynamics | March 26, 2009intense and dense afternoon as we get the current state of the art about neutron star natal kicks, theory and observational constraints
Chevy supernova!
Vicky - on NS-NS constraints (video and podcast)
need >~ 2.1-2.3 solar mass He cores to get to iron and classic type II SNe
stable mass transfer may lower this limit
electron capture supernovae, in binaries, may limit on core masses right before SNe town to ~ 1.45 solar masses or more
evidence other than presence in globulars for subpopulation of neutron stars having low kick speeds: high mass x-ray binaries with e < 0.2 and…
catdynamics | March 26, 2009Phil tutors us today on neutron star formation and retention in globulars.
So we expect neutron stars to be made in globular clusters.
Massive metal poor stars should undergo supernovae and make neutron stars for a mass range of ~ 8-15-or-20 solar masses, maybe more or less, and depending a little bit on whether they are in a tight binary.
More massive stars may, or may not, make stellar mass black holes. But we are not here to talk about black holes, at least not this part of this morning.
So, when type II supernovae go bang (and we're not totally sure yet of the details of how that works,…
catdynamics | March 25, 2009Tom leads today, talking some more about Intermediate Mass Black Holes and possible evidence for black holes in globulars.
NGC 4472 in x-rays
ok, so there is probably a black hole in a globular in NGC 4472, and this, and the discovery paper
and very nice it is too
variable point x-ray source (well, XMM detection...) in a globular
at about 20 times Eddington luminousity, for a neutron star, in a high state
seen a transition to factor 7 lower state, mostly due to deficit of sub keV component, indicative of local foreground absorption
interesting... someone give them some XMM and/or Chandra…
catdynamics | March 24, 2009so The Intersection has followed several other of the top ranked science blogs to the Discoverblog hive
all well and good, and good luck to them at Bob's place (not no, not that Bob, Jr).
he dated Ann Coulter - wow, one learns the strangest things on the Nets
Anyway, the Baad Astronomer and his fans gave them a rousing welcome, and Drug Monkey and Comrade Physio Prof took exception.
Oh, the fight is the usual - the fans overcome by their lust for the hot sexy scientist (photo - not suitable for K-12 readers)...
Maybe Sheril should address the issue. If she feels like it.
'course the…
catdynamics | March 24, 2009you'd think that clusters that are bigger ought to be more massive, and vica versa.
ah, but are they? Arunav discusses
cf figure 2 in Kissler-Patig et al 2006
which was by all accounts a most invigorating and energetic discussion
but I missed 95% of it, as my paymasters required my presence in another realm
for the afternoon's entertainment
Andreas (video and podcast) discusses modeling of tidal tails, specifically Pal 5
Pal 5
and
Mario (video and podcast) discusses the ongoing hunt for evidence for IMBHs in galactic globulars
NGC 2298
yup, that NGC 2298
catdynamics | March 23, 2009What if, Geithner is a Good Guy, who has a Real Secret Plan which the bailout is intended to effect, and which will do enormous public good?
I mean, we can hope, right?
That he is not just another Goldman Sachs frontman who has confused What is Good for Goldman being in the US or World Interest?
Right?
Brad deLong defends the Geithner plan to relieve the banks of their pile of crap
ok, so lets take the first assumption for granted: that a patient investor, not beholden to next quarter's cash flow or mark-to-market capitalization accounting, really can pick up systematically undervalued…
catdynamics | March 23, 2009Astrophysicists like to quantify their estimates. One way to do that is to offer bets, with odds, on hypotheses or models being correct. There have been some famous bets, with spectacular odds.
We now have a new one, and a very daring one too.
Prof. Cole Miller gave today's Director's Blackboard talk:
Black Holes in Dense Star Clusters (video and podcast)
The main focus of the talk are the much speculated about "Intermediate Mass Black Holes" - black holes too massive to have descended from single stars, but not really the "Supermassive Black Holes" found in the centers of (most) galaxies.…
catdynamics | March 23, 2009Carnival of Space #95 at Orbital Hub.
Actually an interesting assortment of posts this week.
catdynamics | March 23, 2009the sun is back, and so is the intrepid gang of globularists here at the Kavli institute
apparently this week is gravitational radiation sources, with primary focus on intermediate mass black holes - including evidence hinting at their possible presence, and the possible fun things we can do with them
blackboard lunch today is on IMBHs, and will be webcast in due course as will an unusually high proportion of this weeks talks
PS: Cole left up a handy dandy gravitational radiation tutorial (pdf)
catdynamics | March 22, 2009ever wondered what age the universe is at redshift 6.7?
or how many nanoJanskys there are coming in the R band from a 23rd magnitude star?
well, a couple of web based calculators will tell you, rapidly and precisely
in cosmology, it is easy to get a crude estimate of time lapsed since the Big Bang, given the measured redshift, by assuming a pseudo-Euclidean universe, but often the precise time actually matters.
But, for a ΛCDM cosmology, the redshift-age formula is messy
Fortunately, Ned Wrigh at UCLAt has a handy dandy web Cosmology Calculator, which will give you the answer at the press…
catdynamics | March 20, 2009the root cause of the failure of AIG FP is that they were off by an order of magnitude as to what the risk was they were betting against
"The Seed Of Ruin Is Planted
- That year, JP Morgan approached AIG, proposing that, for a fee, AIG insure JP Morgan's complex corporate debt, in case of default. According to computer models devised by Gary Gorton, a Yale Business Professor and consultant to the unit, there was a 99.85 percent chance that AIGFP would never have to pay out on these deals. Essentially, this would happen only if the economy went into a full-blown depression, in which case, the…
catdynamics | March 20, 2009here is something that ought to keep you awake screaming in terror
From St Louis Fed (pdf)
click to embiggen
Aargh!
h/t CR
catdynamics | March 20, 2009I am in an all day meeting with bio/geo types, as one does, and as I sit here a random thought struck me, since us astronomers will insist on asteroids as the universal explanation for all things
we have a nice medium sized impact structure in Chesapeake Bay,
the ripples seem to have come as far as Pennsylvania, possibly responsible for the rather bothersome acid rock that almost ruined our most recent local attempts to stimulate through the I-99 construction
anyway, the Chesapeake Bay impact structure is about 35 Myrs old.
In fact, at a glance from an outsider, it seems to coincide within…
catdynamics | March 19, 2009
Bit behind with KITP program events, mostly due to my deplorable inability to be in two or more places at the same time.
Bit on multiple populations, and then gravitational radiation sources.
Franca d'Antona's talk on multiple stellar populations is here - thought we knew simple main sequence stars?
Hah!
Worried?
You ought to be...
I'll be getting back to multiple populations and why some of us are worried later.
Richard on gravitational waves here follow by Ilya here
Another topic due to get heated.
More on that next week.
catdynamics | March 19, 2009Nice article over at Universe Today on
The Sun As A White Dwarf Star and why it might become a DAZ.
Good stuff.
Even though I say it meself.
catdynamics | March 18, 2009there has been a lot going on in the world in recent year, and people are outraged,
sort of
actually, given the sheer outrageousness of the various finanicial and political misdeeds of the last few years, the level of outrage is surprisingly low
people are jaded, and this is reflected in many anecdotal interviews
why is that?
do the shenanigans at AIG leave a bad taste in your mouth?
do you feel nauseated by the bank bailout?
do you feel the bile rise when you read the headlines?
do you "taste a bit of vomit" when you read the latest breaking news?
well, you should: in a rather fascinating…
catdynamics | March 18, 2009A couple of years ago I received a copy of Chris Mooney's "Storm World" and packed it in my carry-on to read on travel.
This month I finally read it, and about time too.
Storm World
Hurricanes, Politics and the Battle Over Global Warming
by Chris Mooney
Harcourt Inc
ISBN 978-0-15-101287-9
Storm World follows Chris's debut work, The Republican War on Science, and was written in the immediate aftermath of Hurricane Katrina and the 2005 Atlantic Hurricane season.
It is a timely, well written and very interesting book.
The approach is largely historical and from the perspective of following the…
catdynamics | March 17, 2009New York Attorney General Cuomo writes a letter to Congress.
He is not amused at American International Group.
Cuomo, in his capacity as overseer on NY insurance companies has been making enquiries, and kindly asked AIG not to distribute bonuses to its finance group last year out of the deferred compensation fund, which they agreed to, something to do with de facto bankrupt companies not being allowed to pay bonuses,
so they paid to bonuses out of the retention fund instead
duh.
Cuomo would like to know who and how much.
AIG is stalling.
NY State lawyers seem somewhat dubious about the…
catdynamics | March 17, 2009stars do turn, sometimes fast enough to be noticeably flattened
this may have consequences
Like So
there are two issues related to stellar rotation contemplated this morning:
Altair
now, way flatter than that...
self-enrichment - back to the good old O/Na anti-correlation
evidence for H burning at high T
trick is not so much to burn the H, but to get the ashes out...
can do that either with AGB stars, yes, it is the dreaded "third dredge up", or just boring old hot bottom burning... ok, don't ever google that.
AGB dredge up (from Eskridge's online lecture notes at MNSU)
anyway, to get…