Invited talk

The dean of Denison University’s Physics & Astronomy department was so kind as to invite me to give a talk about my research. The audience was a mix of undergraduate students (Denison doesn’t have graduate programs) and faculty members, so I had to include quite a bit of simple introduction (for the undergrads) before diving in deeper (for the faculty). Also, my current project is very much a work in progress, so it was a challenge to make a coherent whole out of all the loose parts. Based on the reactions afterwards, I did quite well. No one fell asleep, there were a few good questions at the end, and I got several compliments on both my research and the talk itself. That’s one to put on my CV!

Leiden, NL - Granville, OH

It’s 6:15am Eastern Standard Time as I start typing this. Yesterday, at 6:15am Central European Time, 30 hours ago, I had just left my apartment in Leiden to get a bus to the train station, a train to Amsterdam Schiphol airport, an air plane to New York JFK airport, and an air plane to Columbus International Airport, where someone would pick me up and bring me to my final destination: Granville, Ohio.

All of that worked out, sort of.

The bus was on time and I got to the train station at 6:25am. I wanted to get the 6:30 train, so I’d be at Schiphol at 6:50: two and a half hours before my 9:20 flight. The airline actually recommends coming three hours before departure, but you never need more than two, so I figured a half-hour buffer would be enough.

I bought the train ticket and walked to the platform, where the 6:30 train was announced to have a 20-minute delay. Not a brilliant start for a long day of travelling, but if things at Schiphol weren’t extremely slow, this delay would be no problem. Besides, it was only a 13-minute delay, because the regular 6:43 train was on time. (Leiden-Schiphol has a very frequent train connection.)

At 7:00am sharp, I entered Schiphol’s main hall and looked up my flight on the monitors to see where I had to check in. There came a bigger problem: my flight was delayed by over four hours to 1:25pm. That wasn’t good! I had an almost five-hour stopover at JFK, of which about 40 minutes were now left. That wouldn’t be enough to get off the plane, go through immigration, get my luggage, go through customs, recheck the luggage, and board the plane. So, off to the Delta information desk to see how they might solve this.

Me: “Good morning. I was supposed to fly to Columbus through New York JFK, but with this four-hour delay, I’m going to miss my connection at JFK.”

Delta lady: “Don’t worry, sir. We’ve already changed you to the 10:10am flight to Atlanta, where you’ll have a connecting flight to Columbus. You’ll now arrive at 6:54pm EST instead of 6:50pm.”

Now that’s what I call excellent service! It did seem to be a bit of an odd move, though, because I also heard about people being changed from the Atlanta flight to the New York flight because of bad weather in Atlanta. (As it turned out, the weather wasn’t so bad there at all.) For a man standing next to me at the check-in desk, this meant he wouldn’t get to his final destination until the next day, instead of that evening.

After a rather lengthy check-in procedure (the computer had some difficulty with my new itinerary), I got to the gate in plenty of time. From there on, the journey was about as good as can be for a 10-hour flight, a three-hour stopover and another one-hour flight. The security check at Schiphol was no more stringent than previously, despite the new rules regarding batteries. In fact, no one ever even asked if I had spare batteries in my checked luggage (which I didn’t) or if any spare batteries in my carry-on bag were protected against short-circuiting (which they were).

The air plane was a Boeing 767, with a two-three-two seating arrangement. I had an isle seat in the centre section, sacrificing some view (it was cloudy anyway) for the chance to stretch at least one leg. And… the seat to my right stayed empty, so I had plenty of room for my other leg as well. Ten hours is still a long time to spend in a big tin can, but the good amount of leg space made it tolerable.

Getting into the US went a fair bit faster than I had anticipated based on stories from others. Waiting included, I was through immigration in maybe 20 minutes. Rechecking my luggage and taking my carry-on bag through security didn’t pose any problems either. (Again, not a single question about spare batteries.) Of course, all of that left me with quite some time to kill at the gate. Fortunately, the chairs at Atlanta’s Hartsfield-Jackson are very comfortable.

The low clouds caused some delay in taking off, as the traffic tower had to wait each time until they could see the next incoming plane before outgoing planes were allowed to get on the runway. When it was our turn, there were still a dozen planes awaiting theirs behind us. I had an another isle seat on this Boeing 737, and again the chair next to me remained empty. In addition, I was at one of the emergency exits, so now I had more leg space than I could ever fill.

We landed at Columbus International at exactly 6:54pm. Steve Doty, the assistant professor I’m visiting at Denison University, and his son Matt were waiting for me exactly where Steve had said they would. They brought me to a lovely Bed & Breakfast in Granville, where I went to bed at 9pm EST (3am CET). What with the jetlag, I awoke at 5am and gave up trying to get more sleep at 5:30am. After a shower and a breakfast, I discovered that this place has a wireless connection, allowing me to type this. Steve will pick me up around 10:40 (he’s teaching until 10:30), so I’ll have a look around town until then. The weather looks nice, if a bit chilly.

I’ll be in Granville for the next two weeks and a bit. Steve has been a frequent visitor of Leiden Observatory, most recently for five months in 2006. We started collaborating on a few projects back then, and we’re at a point now where it was a good idea to get together again. I’m looking forward to doing that and to staying here for a while. If the first day is any indication, I’ll have a great time.

Astronomy in Garching

I just got back from a five-day trip to the town of Garching, north of Munich, in Germany, where I was visiting my thesis advisor. Couldn’t I have visited her in Leiden, where her office is two doors down the hall from mine? Yes and no. Her husband, who was also a professor of astronomy in Leiden, moved to Garching a few months ago to become the new director general of the European Southern Observatory (ESO). (ESO is the organization that develops and runs major telescopes such as the VLT [images or text] and ALMA [images or text].) In order to still spend some time together, my advisor took up a part-time professorship at the Max Planck Institute for Extraterrestrial Physics (MPE), literally across the street from the ESO headquarters. The reason for my visit was that she had much more time for me this week than in any other week when we’re both in Leiden. In Garching, there simply aren’t any other students or faculty to demand her attention. (Actually, there was one: I travelled to Garching with another student from Leiden.)

The visit was scientifically successful. We pretty much got around to doing everything that we wanted to. There was also plenty of time to enjoy being in a new place and meet new people. Garching itself isn’t much of a tourist attraction, but had enough to keep us going for five days. I went to Munich itself on Thursday with my fellow traveller, and spent a couple of nice hours there.

Some further random observations:

• Travelling to Garching took some more time than expected. We were scheduled to depart Amsterdam at 11:20am on Monday, but the airplane had a delay coming in from Brussels, so we had to wait until 1:00pm. From there on, the journey went fast and smoothly.
• Travelling back from Garching took even more time. The scheduled departure time was 8:45pm, but fog and cold weather caused delays on almost all flights from Munich airport. In fact, many flights were cancelled. We took off with another 90-minute delay and landed in Amsterdam at half past midnight. The luggage came slowly, so we missed the 1:00am train to Leiden and had to wait for the next one at 2:00am. Of course, when we got to Leiden at 2:20, there were no buses anymore, so I had to walk for another fifteen minutes to get home. In hindsight, we should have just taken a taxi from the airport and reclaimed the fare from the Observatory as travel expenses. Oh well… it was a lovely night for a walk.
• The VLT is located in Chili’s Atacama desert, a very dry and barren place all year around. In winter, the surroundings of the ESO headquarters are almost as barren. The difference is in colour: Atacama has red sand, Garching has brownish grey farmlands.
• The ticket machines for the Munich subway don’t accept credit cards or 50-euro notes. On Thursday, that made for some difficulty in getting from the MPE into Munich. I only had two 50-euro notes and some coins, but not enough to pay the 11.80 euro two-way, two-person fare. My fellow traveller was almost out of cash. Of course, there were no ATMs near the MPE, or anyone to change a 50-euro note into smaller units. We ended up walking back to Garching proper to get smaller change at a supermarket. Our advisor just happened to be there as well, and she was very surprised to still see us in Garching.
• It never got above freezing while we were in Garching, marking the longest period of sub-zero weather I’ve been in in quite a few years. It was nice to endure some real winter weather again.
• I’ve heard from a reliable source where the finale of the next James Bond film will be shot. It’s supposed to be a secret, though, so I’ll not divulge any details. Okay, just this one: it’s not Garching!
• A seagull just came swimming backwards through the canal in front of my appartment. It looked very odd, but I’m sure it had a good reason for doing it.

Schnee

It’s snowing!

Not in Leiden, obviously, but it is on the Königstuhl mountain next to the city of Heidelberg, Germany. Near the top of this 567-metre high mountain (1859 ft.) lies the Max Planck Institute for Astronomy (MPIA), where I’m visiting a colleague for a week.

We already got some snow yesterday morning, but at only half an inch, it wasn’t too exciting. The more interesting bit yesterday was the dense fog hovering over the upper part of the mountain. The clouds were hanging so low that they covered the MPIA, and much of the Königstuhl, like a thick grey blanket. With visibility down to about 50 metres (160 ft.), the bus driver must have had a hard time hauling his vehicle up the slopes. Making it even tougher is the fact that some of the roads are essentially single lane, and the bus can only pass oncoming traffic at specific passing places. That can be tricky already in clear weather. Fortunately, no accidents occurred.

This morning, as we started up the mountain, there was quite a bit of white visible amongst the greens and browns of the forest at the top. Ascending further, it turned out to be a lot more than yesterday. A good four inches had fallen overnight, making for a truly beautiful landscape. The road was still in good condition, as it had been well cleared and salted. The clouds are hanging higher than yesterday, so I have a great view from my office now. It’s a shame I have to work today.

Payment check

I will be attending a conference on chemistry in space in Hong Kong next year. Yesterday I filled in the registration form and payed the conference fee online with my credit card. I also signed up for an optional tour of Hong Kong at the end of the conference, and payed that one as well. Within a few minutes, I got an email from the conference organizers confirming the receipt of my registration and payment.

Half an hour later, my cell phone rang. It was my credit card company! They wanted to know if I had just made two payments to an address in Hong Kong. Apparently, the transactions had set off their alarm bells. They quoted the sums and I told them everything was in order.

Now, on the one hand, I’m glad they keep an eye out for suspicious transactions. The world seems to be full nowadays of people robbing bank accounts and abusing credit cards through the internet. I’d rather not have that happen to me. On the other hand, it’s a weird feeling that my credit card company (though certainly well-intentioned) keeps such close tabs on what I’m using my credit card for. It’s a question that’s been asked many times: how much privacy are we willing to give up for extra security? Pretty much everything we do nowadays is recorded, or can be. Phone calls, email, travelling, shopping, browsing the internet, making payments: it’s difficult to do any of that without leaving a trace. It’s something most people take for granted. I know I do. And do I care? No, not really. Not enough to try and do something about it, anyway. I just hope the powers that be use all the data they’ve gathered about me wisely.

Two co-authored papers accepted

Two papers on which I’m the third author recently got accepted for publication in Astronomy & Astrophysics, the major European journal for all astronomical and astrochemical research. Both of them make use of the infrared emission model for polycyclic aromatic hydrocarbons (PAHs) that I developed over the past three years. My own (first-authored) paper, describing this model in more detail, was published in A&A earlier this year.

The first of the two new papers, “Dust sedimentation in protoplanetary disks with PAHs”, looks into the effects of dust settling on PAH emission from protoplanetary disks. Dust tends to fall towards the midplane of a protoplanetary disk due to gravity, and larger dust grains do so more quickly than smaller ones. Since PAHs can be considered very small grains, they should stay up at higher altitudes for longer times than the rest of the dust. This is expected to enhance the PAH emission features with respect to the continuum emission. However, this enhancement is not found in observations. The paper discusses turbulence and coagulations as possible answers to this discrepancy. The research was led by Kees Dullemond, who did his PhD in Leiden and is now at the Max-Planck-Institut fü Astronomie in Heidelberg, Germany.

The other paper was written primarily by Vincent Geers, a fellow PhD student here in Leiden. He will graduate next Tuesday and this paper is the basis for one of the chapters of his thesis. Titled “Spatially extended PAHs in circumstellar disks around T Tauri and Herbig Ae stars”, it describes highly detailed observations of PAH emission from protoplanetary disks around solar-type stars. Vincent found that the PAH emission is extended on a scale similar to the size of these disks. This shows that PAHs are present throughout the disk and emit everywhere, as predicted by theoretical models.

The abstracts and full texts are available from my list of publications.

Lunar eclipse

There was a total lunar eclipse last night, but the moon was almost eclipsed too much. The sky had been going from almost fully clear to almost fully overcast and back throughout the afternoon and early evening. No one knew for sure whether the moon would be visible during the eclipse, which would last from 10.30pm to 2.11 am, with the total phase occurring between 11.44pm and 0.58am.

We got a good start, with only a few scattered clouds at 10.30pm. The shadow of the Earth was clearly visible on the moon’s lower left, slowly creeping across the rest of the surface. I was out with my bike, camera and tripod, trying to get a few pictures in between the clouds, and meanwhile riding around looking for a good (dark) location to catch the total phase from. That brought me to parts of Leiden I’d never been before, including what I later discovered to be a bike racing track.

With some ten minutes to go before totality (where the moon is entirely in the Earth’s shadow), I set up my tripod on an empty parking lot just outside the city limits. The illuminated part of the moon continued to shrink and shrink and shrink… and then disappeared entirely.

Behind a pack of clouds.

At 11.42pm, two minutes before totality, a seemingly endless stretch of clouds came in from the west and obscured the moon. I felt robbed. Granted, a lunar eclipse is not nearly as spectacular as a solar eclipse, but I’d never seen one before (contrary to a solar eclipse; I saw the 1999 total eclipse in Belgium) and I was looking forward to seeing the moon turn a dark brownish red. Alas, no such luck. To make matters worse, it started raining and I had wondered off quite far from home. I was soaked to my underpants by the time I got back, but I wasn’t about to give up just yet.

The rain subsided a bit, so I changed into a dry jacket and a dry pair of shoes, and went out again. Before long it had stopped raining again and the clouds got a bit thinner. Eventually they broke altogether and I got a ten-minute window to behold the fully eclipsed, dark red moon. After that the clouds returned and it started raining again, but I didn’t care. I’d seen the eclipse.

The partially eclipsed moon at 11.04, 11.14 and 11.30pm (40, 30 and 14 minutes before totality) and the fully eclipsed moon at 0.39am (55 minutes into the 74-minute total phase). The poor quality is due to the limited capabilities of my camera.

Clouds came in again around 0.45am to make the rest of the eclipse invisible from Leiden.

Hubble goes blind

Bad news for astronomers and fans of gorgeous astronomy pictures. The most important camera on the Hubble Space Telescope, the Advanced Camera for Surveys (ACS), has broken down. Again. It’s the third outage in less than a year and the problem seems to be worse than the last two times. A NASA Anomaly Review Board will try to determine what happened and whether the camera can be turned back on.

More details are available in the article “Telescope News: Advanced Camera for Surveys Suspends Operations” on the Hubble website (retrieved Jan. 30, 2007):

Hubble’s Advanced Camera for Surveys (ACS), the instrument whose work has dominated the telescope’s observation program, is currently not operating.

On Jan. 27, Hubble went into a self-protective hibernation called “safe mode.” This happens whenever Hubble’s computers measure a serious anomaly in the spacecraft’s operation. A pressure sensor located in the section of the telescope that houses the science instruments had detected a rise in pressure. At the same time, an electrical fuse blew in the ACS, probably as the result of a short circuit.

Hubble is currently out of safe mode and functioning normally. Science operations will resume this week.

Hubble still has significant science capabilities. The Near Infrared Camera and Multi-Object Spectrograph (NICMOS), the Wide Field Planetary Camera 2 (WFPC2), and the Fine Guidance Sensors (FGS) are all working. ACS was installed in 2002 and has met its expected lifespan of five years.

NASA has convened an Anomaly Review Board to attempt to identify the precise cause of the ACS problem and determine whether it is safe to return ACS to operation. It will also help establish whether there is any prospect for repairing ACS, if it cannot be turned back on, during the upcoming mission to service Hubble in 2008.

In the likelihood that ACS remains inoperative, several steps will allow NASA to proceed with the best possible science program with the telescope.

Observations that had been scheduled for the still-working instruments will be moved, when possible, into the time slots left empty by ACS’s breakdown. All the current ACS programs will be reviewed to determine which observations might be transferred to other instruments — most likely WFPC2.

Paper accepted

My first paper, which I submitted late November last year and which got a favourable referee rapport just before Christmas, has now been accepted for publication in Astronomy & Astrophysics. A preprint is available on arXiv.org as of yesterday, under ID astro-ph/0701606.

Stars rock for rock star

Did you know that Brian May, guitarist of Queen, used to be, in a way, a colleague of mine? Or rather, that he still is one?

May was working on a PhD in astronomy at the Imperial College London in the 1970s, but quit when Queen rose to fame. He was studying zodiacal light, the faint glow that is visible above the horizon under favourable circumstances after twilight or before dawn. It is produced by sunlight reflecting off dust particles within the solar system. (May can undoubtedly tell you much more about it than I can.) As part of his thesis work, May performed observations on Tenerife, resulting in his co-authoring two scientific papers (one, two). Even more interesting, the first of these two was published in the very prestigious Nature journal.

As of last year, May is once again working on his thesis, hoping to finally earn his astronomy doctorate after a thirty-year break. It’d be cool if he succeeds!