Friday, July 18, 2014

What would a brown dwarf look like?

I've been studying brown dwarf stars for almost three years now.  They are fascinating objects, more massive and hotter than planets but smaller and cooler than stars, with clouds of hot sand and molten iron vapor in their atmospheres.  They glow brightest at infrared wavelengths that the human eye can't see, and we usually study them at these wavelengths.  Recently, however, I've been working on a project studying them at the extreme red edge of the optical -- that is, at wavelengths near those that we can see (it turns out we can learn some unique information about their clouds at these wavelengths).  This has led me to produce an image something like what a human might see, if we could look at a brown dwarf through a powerful enough telescope (or get close enough).  It still isn't quite right, because it makes use of some information from light at wavelengths just a bit too long for our eyes to detect, but it's the closest that I know of to a true-color view of a brown dwarf:

The brown dwarf (called WISE 0819-0335) is the tiny red star in the center.  And that's the main impression a brown dwarf would make, if you could see one with your own eyes through a powerful enough telescope: it would be faint, and deep-red.  Has anyone done this?  I don't know, but I think not.  You'd have to put an eyepiece in one of the most powerful telescopes in the world (which normally use only electronic imaging equipment). Even then you'd only have a chance at seeing the very brightest brown dwarfs, and they'd probably be too faint for color vision -- you'd just see a faint grayish star.  We'd need even bigger telescopes (or better yet, a starship) to see this kind of view for real.

What if you could get really close to the brown dwarf -- close enough that it would appear not just as a red-hued point of light but as a huge orb out the windows of your starship?  It would still look deep-red, and unlike the Sun and most other stars seen up close, it would be dim enough that you could stare at it without hurting your eyes.  According to some of the latest research on brown dwarfs (including my own), it would probably have dramatic cloud features.  Thick, high-altitude clouds would glow only dimly, while through huge rents in them you would see down into the hotter, much brighter deep regions of the brown dwarf.  Powerful winds and possibly storms full of lightning would be constantly churning and shifting the glowing clouds.  It would be worth a journey of a few light years to see.

Thursday, July 10, 2014

The Late Unlamented Winter

Last winter was great and all... we had lots of good times.  But still -- thank God it's over, and three cheers for summer.

In summer you have to be careful about ticks.  Lyme disease is a serious concern here.  But not as serious as the road to Toronto back in February!

I sweat every day on my walk to work now.  But you can stand still outside and enjoy it.  Not so much on the walk when the picture above was taken.

A few nights ago, 9 year-old Petra came downstairs at about 10:30pm and told me that she and her brother had decided to sue me for not putting an air conditioner in their room. They have one now, thanks to a friend from church to whom I told this story... I wasn't trying for charity, honest, I just thought it was funny... but I am grateful for the air conditioner -- and that our house no longer looks like the above picture.

A couple of weeks ago we went boating.  Toward the end of the day the children were tired and I was a little warm, so I jumped off the boat to amuse them (forgetting to take my hat off).  The weather was a little different from when I took this picture back in February.

OK, so maybe that should be four cheers for summer.  Anyway, thank God for warmth and resurgent life and outdoor fun.  Winter is good too, and I will be ready for it to come back... maybe sometime in 2016.

Wednesday, July 2, 2014

Driving in D.C.

I spent last weekend in Washington, D.C. with my wife and our five children.  We were there as part of a larger family gathering to celebrate my father in law’s 60th birthday.  The celebration was very well planned (none of it by me!) and involved not only a nice dinner and cake but also visits to the National Mall and various Smithsonian museums.  You may ask what museums can hold the attention of five children with ages ranging from two months to nine years.  The answer is that the two-month-old doesn’t count, and you can keep the rest interested for quite a long time where there are a sufficient number of such things as rockets, space capsules, dinosaurs, and pickled giant squids.  The important thing is to move quickly from one exhibit to the next, and explain them each one in a brief and accessible way.  It’s rather exhausting for the parents, but it’s good mental exercise.

But all this, though more significant in the broad scheme of things, is only context for the real topic of this post: driving in D. C.  I did most of it, because I am slightly less stressed by dangerous driving situations, and because my wife is a much better navigator than I am.  I drove so aggressively that I was disturbed by my own conduct.  I didn’t understand why I was driving like this until my wife took over for a little while – and was forced off a highway exit she didn’t want to take by someone who accelerated to remain in her blind spot (I don’t think they were purposely malicious – just unobservant and unhelpful on a crowded road).  Anyway, I realized I was driving aggressively because other ways of driving didn’t work.

Still, I am painfully aware how thin the line is between aggressive and stupid.  I am alert and observant behind the wheel, and have excellent intuitive judgment of velocities and tolerances.  My quick, almost subconscious decisions are rarely at fault.  Nevertheless I intensely dislike suddenly realizing that I have staked thousands of dollars on a split-second decision whose rational basis I cannot articulate.  The fact that the decision was good does not comfort me – how do I know the next one will be?

The reader may be wondering why I have talked about staking money rather than the incomparably more serious risk of human lives.  The answer is that I drive with tight tolerances only when the stakes do not involve a high-momentum crash.  I risk totaling my car, not my children.  Nonetheless it is a car the children need, that I cannot afford to replace, and there could be some injuries even in a lower-velocity accident.

The most disturbing moment came when I pulled in front of a black pickup to make a left turn into a gas station on the way home. That was the only time I was honked at. I was making my intentions clear, but the driver of the pickup was not slowing down to let me in.  I saw that I had enough space, and I gunned the engine and took it.  It was only afterwards that I tried to estimate how close our rear bumper had come to the pickup’s front bumper and couldn’t do it.  Surely it was feet rather than inches… wasn’t it?  Why didn’t I let the left turn go, make a U-turn later, and come back?  The answer is that I was sure – intuitively, not rationally – that what I was doing would work.  I am not happy with answers like that.

There are other questions, though.  We needed the gas.  U-turns are dangerous too.  What would have happened if I had given up on turning there?

I have to recognize the uncomfortable reality that I cannot guarantee my family’s safety, even when I am literally at the wheel and it seems that I am most completely in control of it.  Much less can I guard effectively against other things: falling trees, malicious strangers, cancer, and the children’s own foolish decisions.  I have the responsibility to do what I can: to think carefully about how I drive, prune trees, and teach good decision-making.  Still the Proverb remains true: “Unless the Lord guard a city, the watchmen stay awake in vain.”  God promises care to his people, and I trust him.  The fact that he does not promise protection against any particular catastrophe troubles me.  But he promises his presence and care in both peace and disaster, and that must be enough.  We reached the end of the journey safely.  Why?  Because I am a good driver?  No. Because he is a good God.

Saturday, June 7, 2014

How I Weathered the Tsunami

Although it was slightly edited afterwards, this post was actually written in Chile on April 1, the day of the large earthquake near Iquique.  Nothing about it is an April Fool’s joke, however.

 I was eating dinner this evening at a nice restaurant right on the ocean in Vina del Mar, Chile.  My Spanish is disgracefully non-existent, so when the waiter came up and said something to me, I thought at first that he was telling me the restaurant would be closing soon.  Then he repeated himself and I caught the words ‘tsunami’ and ‘alerta’.  Several things came into my mind immediately: the reality of tsunamis in Chile, the considerable distance from where I was to any really high ground, and the right thing to do if a tsunami were imminent: start running right away on my best guess at an efficient route to a reachable topographic highpoint. 

 I also felt something I have sometimes felt before in situations of unexpected physical danger. It is almost the opposite of panic, and is more like a thwarted denial. Not wanting to change my previous plans, but recognizing that denial could be fatal, I accept the duty to preserve my life with a sort of annoyed reluctance. If I put it into words, I might say, “How annoying that I will now have to run for my life when I had intended to spend the evening processing data… but it can’t be helped.”

 Anyway, having reached this point in my thoughts about half a second after hearing the word ‘tsunami’, I jumped to my feet so quickly that the chair grated loudly on the floor. The waiter and some of his nearby coworkers laughed at me, and told me to relax.  I remembered one other fact about tsunamis: there can be hours of warning.

 So I sat down and finished my dinner, since this was clearly what the waiters expected and what others in the restaurant were doing.  I was able to do this calmly, but I felt impatient to get back to my hotel (just across the street) and get the full story from a receptionist who spoke English.

 I paid and tipped and crossed the street – and learned that the warning was triggered by an earthquake near Iquique. I pictured this in my mind: Iquique is a city in far northern Chile, well over five hundred miles from here. The tsunami will have to propagate along the Chilean shoreline to reach us, being diffracted and weakened by the land all the way. It is very different from the scenario I imagined earlier: a seaborne warning system alerting us to a large undersea earthquake straight offshore from here.  So I do not expect a tsunami.

 However, as I write this, I am on the eighth floor terrace of my hotel, where I was told to go for safety. I am here only out of deference to the authorities. Besides being skeptical about the likelihood of any sort of tsunami tonight, I am convinced that if one did arrive that could flood my room on the sixth floor, it would also wash away the whole hotel.  But this will be a pretty good place from which to watch (and, of course, photograph) a tsunami, in the unlikely event that even a small one appears. And it’s a good place to write a blog post.  I’m going to wait until the warning interval expires to write the final paragraph, which will describe what the tsunami was like or else confirm that it never arrived.

 Epilogue: There was no tsunami, not even any noticeable change in the wave pattern on the beach.  This is what I expected, once I knew where the earthquake had been.  Amusingly, when I went to the same restaurant again the next night, about five different waiters there came by and made comforting or commiserating comments about how I had panicked the night before.  Of course, even in English I could not hope to communicate that I had only appeared to panic.  I just smiled and laughed with them at my last night’s behavior. The things that really can throw me into heart-pounding, hand-trembling panic are quite different: missed flights and sudden instrument failures, for example.

A Perfect Night and a Surprise

March 30:

Although clouds had little effect on my observations at the end of last night, sunrise on March 30 shows rapidly increasing sky cover that soon fills the sky over the with torn clouds. I copy my data to a backup hard drive and go to sleep around 8 AM.

 I wake up near 11. My observatory dorm room is dark, but my body knows it is not night.  I have a thousand things to think and worry about.  Worse still, the wind is howling around the dorm.  Especially since the instrument failure last night, I really need data tonight.  That wind could stop it.  If the wind is too strong, above about forty-five miles per hour, we will not even be allowed to open the dome.

 I have slept only three hours.  I desperately need more sleep, but the wind is in my soul.  My body tenses up with every gust.  I pray for sleep.  I try to lie still and relax, to give my up anxiety to God.  I tell myself what is obvious: that worry is destructive; that if anxiety about bad weather keeps me awake, I will not be able to observe as efficiently even if I have good weather. Worse still, I do not expect to sleep at all tomorrow: I have to travel by car, airplane, and bus to Vina del Mar, an unfamiliar city hundreds of miles to the south.

 I have fought this battle many times at other observatories, and have seldom won it. I usually cannot go back to sleep once I have woken up in the daytime. There is too much to think about, and my over-active mind does not let me sleep.  The effects of sleep deprivation accumulate from night to night: at the end of week-long observing runs I have sometimes been almost delirious.

 Not today.  Sometime after noon, my prayers are answered, and I sleep well. I sleep through the hours when the afternoon calibrations are taken, but with this telescope that does not matter: the daytime staff take a flawless set of calibration images without me.  I wake up in time for dinner, and go to the door of my room.

 This is the moment of truth.  There is no sound of wind now, but last time I saw the sky it was hopelessly cloudy.  The tiny, blurry window near my toilet looks blue, but that doesn’t mean much.  I pray for good weather for the thousandth time. I take a deep breath, and I open the door.

 Blue and clear.  Clear from the Andean peaks in the east down to the west horizon, where a sheet of clouds far below us always shrouds the Pacific Ocean.  Clear.  My heart is singing, full of thanks and praise.

 Except that the seeing is slightly poorer, this night is everything I hoped last night would be.  DECam performs perfectly.  So does the telescope.

 Far into the night, I use the third workstation to check an image, and I see something strange.  The now-familiar starfield is there, but several bright parallel streaks span the entire image.   This is so unusual that even the telescope operator is surprised. “What is that?” he asked, looking over from his own workstation.

 I am wrestling with the same problem myself, but I have come up with a guess. “I think it is an airplane,” I say.  We are both staring closely at the monitor now.  The steady lights of a commercial airliner would make the streaks we see, but airliners also have flashing lights.  If it is an airliner, why don’t we see them?  I realize suddenly that there are three or four extremely bright stars in this image that are not in any of the others. The new stars lie at regularly spaced intervals along the streaks. “See,” I say to the telescope operator, “these are flashes.”  We are both amused and pleased.  The streaks and starbursts affect only a small fraction of the image area: they will not hurt my science.  And now we are some of the first people in the world to have observed an airliner through a 4 meter telescope.

 Dawn comes.  I squeeze the last dregs out of the night as before, and then hurry to finish backing up my data before I need to catch my ride back to the town of La Serena.  I am exhausted, but giddy with delight.  It worked. No matter what happens in the future, I will always have these two nights where God filled my hands with asteroids.  It actually worked.

Dreams and Nightmares

March 29: My first night actually observing with DECam has the almost unreal quality of a dream come true. While I’ve done equally exciting science with even bigger telescopes in the past, this project is more fully my own than any I have attempted before with such a powerful telescope. Tonight, given good weather and working equipment, I am going to image asteroids fainter than any human has ever measured before. And I have good weather and working equipment.

 Good weather and working equipment.  World-class telescopes such as the Blanco and instruments like DECam are painstakingly maintained by engineers and technicians at least as skilled as the astronomers who use them – but even so, they are complex, one-of-a-kind systems.  A million different things can go wrong, even under a perfect sky.  I have seen many bizarre failures in the twelve years since I did my first astronomical research at a major observatory. I cannot forget the vast number of things that all have to work together for any night’s observations to be a success. Even though the alignment of good weather with perfectly functioning instruments is the norm at a fine observatory such as this one, it feels like a miracle every time. I thank God, and I honor the human genius and the diligent work by many that makes my work possible.

 As I prepare to begin tonight’s observations, I post on Facebook the cryptic status update I decided on weeks ago if this happened: “Tonight is the night when I cup my hands, and God fills them full of asteroids.”

 The data are coming in, one beautiful image after another.  The sky is clear, and the seeing is good.  Pessimistic and skeptical person than I am, I have a hard time believing this is actually happening.  I am still looking for something I might be doing wrong, something that I have to fix in order for this night really to be as good as it seems.  But my plans are meticulously laid, and they are unfolding beautifully.  God is pouring the asteroid-rich data into my lap. The reality is sinking in.  I am smiling a lot.

 While DECam is flawlessly executing my observing scripts, I have time to work on the huge challenge of processing this data. I started weeks ago, downloading publically available example images from DECam and teaching myself how to work with them.  DECam images are huge.  After processing into the format I need for asteroid searches, each image is 3.5 GB.  I have two 4 TB backup hard drives, but even this is barely enough.  I am continually running into problems doing things that are easy with smaller images. So far I have always been able to write more computer code to solve them.  Over the next few weeks, I will be racing against time to accurately measure the brightest asteroids in the data before it is too late for other observers to follow them up. Without follow-up observations, their positions will soon become uncertain.  Future observers will not know where to point their telescopes to see my asteroids, and the asteroids will join the thousands of objects that have been seen and followed over one night or a few nights but then lost.  This is not a disaster scientifically: my main objective is to study the statistics of extremely faint asteroids, and I can do that perfectly well with objects that later become lost.  It is unsatisfying, however, not to make full discoveries of at least a few asteroids when the data are this good.  I am determined to do it if I can.

 But it is also necessary to enjoy the moments of observing.  I look around the control room in leisure moments near midnight.  It is a large, well-lit room with a white linoleum floor. Three sets of doors open out from it at somewhat odd angles, giving it the shape not of rectangle but of a round-ish irregular polygon.  One set leads to the exit from the observatory, another set to the refrigerator and rudimentary kitchen area, and a third to a computer room where mere astronomers like me are not allowed – a room that is unexpectedly about to become extremely important.  The actual observing floor is several stories above us, where the huge telescope moves slowly in the starlight, responding with magnificent precision to our computerized commands.

 There are three major workstations in the control room, each with six to eight widescreen monitors stacked in double rows.  I am at the observer’s station.  My monitors are filled with more status information than I can possibly process mentally.  Fortunately, as long as everything is going smoothly, most of it doesn’t matter at all.  Fifteen feet to my right is the telescope operator’s station, similarly well supplied with data displays I suspect are as complex as those in the cockpit of a Space Shuttle.  He has to understand his displays much better than I do mine.  My job is only to make this telescope do excellent science, provided it is working.  His job is to make it work. There is also a man in the room whose official title I forget, but who is effectively an instrument specialist.  He is the one I can appeal to for immediate rescue if something seems to be going wrong with DECam.  He doesn’t have his own workstation, but will help me with mine if something happens that I don’t understand or can’t fix.  At present, thankfully, he has nothing to do. The telescope operator and instrument specialist are both experts in complex systems of which I have only the most basic understanding.  I have enormous respect for them, as for their counterparts at the other observatories I have used throughout the world.

 There is a third workstation which I have the privilege of using if I want.  It is for quick-look processing of DECam data.  Sometimes I display an image on it, to check the starfield and admire the handful of stunning spiral galaxies I am capturing without even meaning to.  I also use it now and then to evaluate the seeing – that is, the extent to which turbulence in the earth’s atmosphere is blurring my images. I think the seeing is very good tonight.  The images are blurred only a little more than one arcsecond, which is about the size of a bacterium held at arm’s length.  I comment on this aloud.  “We can do better,” says the instrument specialist.  He doesn’t mean that he or anyone has control of the atmospheric turbulence, but rather that this excellent site in the desolate foothills of the Andes sometimes produces even better seeing than we have tonight. I hope that tomorrow night we will indeed do even better.

 At 1:30 AM DECam abruptly stops working. I and the instrument specialist try to fix it. We restart some components of the control software.  Then we restart the whole thing. It doesn’t work.

 We call for reinforcements.  The experts work on the system, trying things I don’t understand, ruling out possible causes of the problem one by one.  3 AM. Outside the  southern Milky Way shines magnificently in a perfect, moonless sky above our useless telescope. I feel physically sick, breathless with the value of what I am losing, moment by moment.

 One does not complain in such situations. It will not help the experts frantically working to solve the problem.  Everyone knows that observing is a gamble that can be lost, and one does not whine about losing however great the stakes.

 One can pray, though.  I would like to pray aloud, as much to affirm to myself that God is in control as to make any request of him. I am afraid of distracting those working on the problem, however, so I kneel silently a few feet behind the observer’s workstation.

 The problem has been traced now to a serious hardware failure: one of the computers behind the forbidden door has crashed.  Restarting it could fix the problem, but would more likely create a cascade of other issues, as the effects of the restart propagated through the interconnected systems.  A senior member of the observatory staff is on the way.  He may give us the go ahead to restart the computer.  He arrives at about 3:45.  Internally, I have already given up the rest of the night for lost.

 But it isn’t! The new system expert finds a workaround for the ailing computer, and we are back online at 4 AM! Chile lies far west in its time zone, so sunrise will be after eight.  There are three more usable hours in the night, and the total time lost was only two and a half hours. Once again, I thank God, and I silently bless the technicians who work around the clock to keep the world’s most powerful telescopes running. 

 The night is no longer perfectly clear, but the clouds stay away from my primary science field until it is getting too low to observe anyway.  The loss of 2.5 hours of perfect weather remains painful, but the night’s data set is excellent.  In the last hour before dawn, with my primary science field setting in the west, I point the telescope instead to the positions of two very small near-earth asteroids that recently made a close pass by Earth and are now receding into the distance without having been observed by anyone.  If the images I am taking do show them, I will have helped save them from being lost.

 No man can hinder the dawn, and it is a fitting end even to the most precious night. The sky brightness in my images rises abruptly, the stars fade into the noise, and I tell the telescope operator I am finished observing and ready to close the dome.

 In my notebook I write down the parameters of the last exposure, including the sky background value that showed me the night’s observations were certainly over. Let there be no doubt that I used this night down to the last dregs. Underneath the data on the last exposure, I write in my notebook, “So ends a stomach-churning nail-biter of a night, which nevertheless turns out to be basically successful. Thank you, my Lord!”

Brief explanation

My situation with this blog has been a bit silly.  Not only have I not been finding time to write new posts, but I have not made time even to edit and publish the several long blog posts that I wrote more than a month ago about my experiences traveling in Chile -- and that trip is now more than two months ago.  I am going to post all of those blog updates in quick succession now, in the hopes that they will make interesting reading even though they describe events that are now more than two months past.