At intermediate densities, around 10¹⁴ g/cm³ just below nuclear density, matter may form complex nuclear pasta phases. Competition between short range attractive nuclear, and long range repulsive Coulomb, interactions can lead to clusters with many different non-spherical shapes including long rods or flat plates. Because pasta may form at high densities, it could represent as much as half the mass of the neutron star crust. The complex shapes in nuclear pasta have sizes of tens of Fermis [10^-15 meters, about the size scale of atomic nuclei].

The article is just full of great quotes; “Semiclassical nuclear pasta model”; “The complex physics of frustration”‘; “[the model] can describe nuclear pasta in a flexible way”. Plus the physics is absolutely wild.

What I worked on was detecting metals such as carbon, oxygen, neon and sulphur in an HII region (DR 21). Detecting hydrogen and helium in the HII region is simple; the lines are strong and spaced far apart from each other. We could see clearly after a three minute scan. The rest of the elements we were looking for were much weaker and much closer together. Weaker, because there’s simply not as much of the heavier elements. They’re closer together in frequency, because the greater number of protons in the each atom means that the transitions have similar energies. There’s a big energy difference between an atom with one proton and an atom with two protons, but not so much when it’’s between 6 and 7, or 8 protons. So you end up with closely spaced lines, which are then blured together by the thermal velocities too. If the region is in thermodynamic equilibrium, some of the atoms will be blue shifted and some will be red shifted just by the doppler shift, due to random motions within the cloud. This broadening is proprtional to temperature, so it doesn’t help that the HII regions are at 10,000 K.

Enough theory, let’s see data. Here’s the spectrum straight off the telescope (but after calibration, really):

There’s the full spectrum, 12.5MHz wide. The two biggest bumps are hydrogen lines. In the center is the helium line, and between the two blue ticks is the smeared carbon, oxygen, and nitrogen lines. Now let’s look at just the interesting bits:

Here I’ve removed the neighboring hydrogen and helium lines (which is simple because the lines are mostly gaussian). The is definitely something non-gaussian in this plot though. The three or four metal lines have been blended together. Extracting information about the individual lines is going to be tricky. You can already see that the lines on the left are stronger, since the peak is asymmetric. Beyond that I haven’t had a chance to look at it much, so I’ll have to save the details of the analysis for later.

Late this afternoon I discovered that the angle of these two peaks shifted around as a function of fluctuation size scale (Sorry, it’s difficult to explain that much clearer). That’s completely unphysical. So there’s probably just some calibration issue, and that’s it. No funky physics, no fun paper. Psh.

The light blue line on the left of the screen is from the lander. This picture was taken just after the lander separated and began its decent, so it’s still moving fast. In the few minutes afterwards the line swept over to the right side of the screen as the parachute deployed and slowed down Phoenix. There were a few more slight manuvres, the JPL people called out that the lander was on the surface, and then the radio shut off just as planned. Everything went flawlessly as far as anyone could tell here in Green Bank.

We then had about two hours to wait until pictures would start arriving. In the mean time we could watch a few other transmissions take place. We watched one of the orbiters relay data down to Phoenix, and could follow the doppler shift on that as the orbiter crossed the surface. After that we just waited around with the NRAO and JPL people, watching NASA TV to see the first pictures when they arrived. They were definitely worth waiting for, and I’m sure most people have already seen them by now (they’re on the JPL site if you haven’t). Once we saw the first images there was definitely champagne opened in the control room.

The part of this that’s interesting to me is that Phoenix has no antennas or transmitters capable of relaying data back to (or from) Earth. The mission relies entirely on relaying data through two Mars satellites, the Mars Reconnaissance Orbiter and the Mars Odyssey probe. All the data from the probe must go through one of these satellites, which have larger antennas and more powerful transmitters than Phoenix.

But there is a third option. Nasa could just point the largest steerable radio telescope at Mars and try to listen in on Phoenix directly. And that’s what they’ll be doing in Green Bank this evening. The GBT will be tracking the decent of the probe to the surface, and should be able to track the doppler shift as the probe decelerates. They won’t be able to decode any data, since the signal will be too weak, but they will still get the first indication that the probe has landed on the surface and is transmitting to the orbiters.

So my plan for the night is to hopefully watch this from the GBT control room. Unfortunately I won’t have easy access to a computer to relay details immediately, but I will try to get some pictures and hopefully have something interesting to relate about the event afterwards. We’ll see how it all goes. Entry starts at 7:38pm EDT (Today!), so be watching NASA TV.

From my window I can see:

We eventually made it to Atlanta, where much to our surprise, our flight to Cleveland was merely four-hours delayed, not canceled. Waited around til the new departure time of 12:30. They then announced a gate change, and sent all the passengers from two separate flights to a gate at the far end of the terminal. The confused employee at the new gate knew nothing of either flight, nor why about two hundred people had suddenly appeared at her gate. Calls were made to the tower. Both planes were then sent back to their original gates at the other end of the terminal, which just topped off the hilarity.

And then they canceled the flight. Turns out the pilots for the flight had flown as long as they are legally allowed to in one day. Everyone runs from the gate to the nearest long line they can find. Most people picked the line for hotel vouchers or for flight rescheduling; we picked the line for taxis. Found a hotel, and went to bed around 2am.

Woke up at 7:30, since we were on standby for a flight at 9-something. Didn’t make that one. Didn’t make the one at 12:50. The rest in the afternoon are full. I finally ended up with a ticket at 9:55pm. So I have plenty of time in the crown room to kill.

That story was dull, so hopefully this picture will make it better:

Kitt Peak attacks.

But we’re in an isolated observatory, how are we going to get another one? Well, we have spares of everything., including this motor. So we uncovered an identical motor, already here in the observatory. So we managed to work around the shipping failure, and got the motor installed. Much wiring then ensued, along with the disassembly of the gearbox the motor attaches to. The gearbox is another Warner and Swasey 1941 original, and was probably part of a battleship gun turret before it was a telescope drive. So even the covers on the gearbox are half-inch thick steel. Removing huge hunks of steel that are mounted ten feet off the ground is not particularly easy. Plus we repeatedly assembled the gears in the wrong order, so fixing the gearbox turned out to be an entire night of work (we probably started around 7pm, gave up at midnight, and spent another hour the next morning).

I don’t have many pretty pictures to post, but here’s the motor:

Random story time: the most recent visitors to the Schmidt before us were here in early July. When they left, they set the dishwasher to run. Reasonable thing to do, except that we have semi-frequent power outages. So before the dishwasher could run, the power failed, and the dishwasher wasn’t smart enough to resume cleaning. So the dirty dishes sat there for a month. I opened the dishwasher yesterday to find quite a colony of mold taking over all the plates. Not just spots, this was enough mold to make a hearty meal. So we just ran the cycle a few times with as much detergent as we could fit in, and that restored the plates to a mostly sanitary state. But the bottom line is that I don’t feel as bad for leaving dirty dishes all over the kitchen of my suite in Cleveland. They may have been dirty, but they weren’t nearly as bad as these plates.

That picture was taken on the Case 9.5 inch telescope on top of A.W. Smith, connected to a Nikon D40 camera. The cluster has a magnitude of 5.8, so it would be a naked-eye object if we were not in the middle of Cleveland. But we are, so we have to use a telescope and a thirty-second exposure to get a decent shot of it. That’s the longest exposure the camera can handle, as the noise becomes more and more significant. I could combine several images together to get one nice shot, but that is rather obnoxious to do with consumer cameras (The bayer filter, which gives you color information, causes most of the frustration. And IRAF doesn’t handle three-color images very well, so that adds to the difficulty).

Now, to explain what is actually in the image. It’s the Hercules globular cluster, also known as Messier 13. It’s a group of stars in our galaxy that all formed from the same cloud of gas at roughly the same time. It’s 8 kiloparsecs away from us (26,000 light years), which is about one sixth of the diameter of the Milky Way.

Hopefully I’ll have some better pictures from Kitt Peak to put up soon. I still have all the data for an image of M101; I just need to make it into a nice picture.