#29 MTU – My observer friend at Jodrell has never heard any one speak of a possible planet in the twenty years she has been working on the crab. Pulsar timing wasn’t so exact in 1970.

So no planet then & wiki got it wrong? Oh well, thanks for that anyhow.

@41. r0blar Says:

” In other words, put the Crab pulsar where the Sun is now, and we’d be cooked in seconds just from gamma rays.”
I think in about 8 minutes.

LOL. Good point, gotta allow for the travel time light minutes betwixt Earth & Sun.

@42. Anchor :

Thanks for that informative comment & links.

I’m afraid that your explanation of the changes in the structures you point out between December 1993 and last Saturday doesn’t quite square with what’s already been seen. In 1996, for example, a Crab pulsar MOVIE sequence composed of eight images taken by the Hubble WFPC2 every few days OVER A PERIOD OF ONLY A FEW WEEKS shows the structures near the pulsar changing very dramatically. The researchers on that observation attributed the changes to an ionized pulsar wind interacting with the intense magnetic field.

That sequence can be found here:

http://hubblesite.org/newscenter/archive/releases/1996/22/video/a/

As the team leader Jeff Hester observed, “Watching the wisps move outward through the nebula is a lot like watching waves crashing on the beach — except that in the Crab the waves are a light-year long and are moving through space at half the speed of light…You don’t learn about ocean waves by staring at a snapshot. By their nature waves on the ocean are ever-changing. You learn about ocean waves by sitting on the beach and watching as they roll ashore. This Hubble ‘movie’ of the Crab is so significant because for the first time we are watching as these ‘waves’ from the Crab come rolling in.”

The release story also notes: “The most dynamical feature in the inner part of the Crab is the point where one of the polar jets runs into the surrounding material forming a shock front. The shape and position of this feature shifts about so rapidly that the astronomers describe it as a “dancing sprite,” or “a cat on a hot plate.” The equatorial wind appears as a series of wisp-like features that steepen, brighten, then fade as they move away from the pulsar to well out into the main body of the nebula.”

Comparable changes were also observed in x-rays by the Chandra Observatory in a sequence of 7 exposures taken between November of 2000 and April 2001.

http://chandra.harvard.edu/photo/2002/0052/

In other words, one doesn’t need to invoke some particular energetic event to explain what we’ve been seeing since 1993 – you don’t need 17 years: these changes have already been noted on a timescale of DAYS.

A more plausible scenario is to assume that the pulsar suffers from a more or less constant rain of gas and dust from the supernova remnant falling onto its surface, with charged particles strongly funneled onto the magnetic poles. The more or less steady release of energy “rolls outward” in the form of dynamic shockwaves in an otherwise constant pulsar wind, mediated by the rapidly-rotating magnetic field rooted in the pulsar.

Elsewhere, a number of theorists have suggested that much of the pulsed emission observed from the Crab and other young pulsars comes not only from the canonical ‘rotating lighthouse-beam effect’ as the dipolar magnetic field sweeps across our line of sight, but is also generated at a region some distance from the pulsar where charged particles are accelerated to near the speed of light inducing synchrotronic emission. They suggest that the ring-like structures that appear to be off-set from the position of the pulsar are the regions where the magnetic field beams pile up packets of charged particles and accelerates them to near-light speeds as the magnetic axis whips around like a natural particle accelerator.

The “dancing sprites” observed above the ROTATIONAL (as opposed to the magnetic) axis of the pulsar are interpreted as a plasma confined within the relatively narrow compass of the magnetic dipole region (i.e., the ring you indicate) where the outflowing pulsar wind is also preferentially confined to produce polar jets that interacts with the SN remnant that would otherwise be compelled to fall into the pulsar. The pulsar “jets” blowing outwards prevents them from falling in, while the jets inject them with energy and dynamic shocks that make them ‘dance’ in place, somewhat analogous to a ping pong ball that bobbles about on a vertical stream of air.

I think in about 8 minutes

Q.E.2.

My observer friend at Jodrell has never heard any one speak of a possible planet in the twenty years she has been working on the crab. Pulsar timing wasn’t so exact in 1970

So much for my thought that whatever the event was it may cause a glitch in the pulsar…

Pretty much so. One of my astrophysics lecturers was fond of saying, “Astrophysics can be divided into two parts – the Crab Nebula and everything else.” That was nearly 30 years ago, but I’m told the saying still applies today.

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

& I’ve also asked this as a question on the Bad Astronomy Universe Today (BAUT) forum here :

http://www.bautforum.com/showthread.php/108314-Crab-Pulsar-PLANET-!

Which I hope is okay netiquette~wise. My apologies if not. I’ve mentioned & linked this thread there too btw. I’ll check back on both threads there & here for more.

***************

PS. I post as ‘StevoR’ there & ‘Messier Tidy Upper’ here, sorry if that causes any confusion or problems. I guess I should make it consistent but.. long story, anyhow.

I may, of course, be mistaken..

I’ve just noted Wikipedia suggests that the Crab Pulsar (under its entry) may have an orbiting planet :

***

“In 1970, astronomer Curtis Michel proposed the presence of a planetary companion to explain certain variations observed in pulsar timing[16]. The hypothesized object would have a mass of 0.00001 Solar masses (i.e 0.01 Jupiter masses or 3.3 Earth masses) and be located at 0.3 Astronomical Units from the pulsar.”

(Brackets original.)

***

Which raises a few questions like :

1. Has anybody confirmed or rebutted this idea since?

2. If true then wouldn’t this be the first exoplanet ever discovered?

&
3. How come I’ve never heard of this before – why has it seemingly been kept so quiet? Has anybody else here heard of that before and can anybody here enlighten us on this Crab pulsar possible planet (!) further?

Here at Jodrell Bank Observatory we have been (almost) continuously monitoring the Crab Pulsar for over forty years. I have just been talking to one of the observers and she assures me that there has been no unusual activity – no flux change, profile change, timing chaneg etc – recently.

(Sorry I’m not Woof but I’ll still answer that ‘un, after all we haven’t got an infinite amount of time to wait. Meow. )

http://en.wikipedia.org/wiki/SN_1054

&

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

BTW. Proxima Centauri is Wiki’s featured article today too I see.

Here’s a thought – a marshmellow of neutron star matter may or may not be infinitely delicious but given the amount of material it sure would be filling!

As explosively filling as that final after-dinner mint in the Monty Python sketch ..

There is just one thing though ..

The Crab Supernova – which produced that first Messier object (M1) the Crab Nebula and the Crab Pulsar there – took place in 1054 didn’t it?

So 1054 + 1000 = 2054 not 2010 so it has not quite been 1,000 years yet – even my maths can work that much out!

The energies involved and the bizarre nature of it though are just staggering to contemplate. I don’t know if anyone can fully grok how extreme these objects are but the BA sure does a nice job of trying to describe them for us.

Only if you drop it into an infinite cup of hot chocolate.