Class hours: MWF 10-11 am
Class location: 176 S. Mudd

Class mechanics (You might want to read this, important information here!)

Syllabus

• Week 1: Introduction to the solar system, exoplanet detection techniques.
• Week 2: Properties of other planetary systems.
• Week 3: Star formation; stars with disks.
• Week 4: Physics of viscous accretion disks, growth of dust to planetesimals.
• Week 5: Formation of terrestrial and giant planets.
• Week 6: Disk dissipation/lifetime, Solar formation environment?
• Week 7: Solar system dynamics, especially the small bodies in the outer solar system.
• Week 8: Small bodies in the outer and inner solar system.
• Week 9: Exo-Kuiper and Zodiacal Belts (short week, Thanksgiving).
• Week 10: Additional solar system constraints, wrapping up.

• Monday, 26 September: Pages 1-14 of Armitage provide a short introduction to various important properties of the solar system. For more detailed reading, The solar system and its place in the galaxy. is a nice (but long!) introduction to what is in the solar system. You need only read sections I and II, though III and IV make interesting introductions to the remainder of the class. There are many textbooks one can consult nowadays, one of the more readable is The New Solar System, edited by Beatty, Petersen, and Chaikin (Sky Publishing). For reference, here is the classic paper on binary star distributions from Duquennoy and Mayor that presaged many of the results to come on extrasolar planets. For a true classic, try Kant's 1755 attempt at describing the universe and its origin. Laplace has his say a few years later. Finally, for those with an interest in planetary astronomy and the sometimes rocky history of science, the discoveries of Neptune and Pluto make for an interesting story.
• Wednesday, 28 September: How can we detect extrasolar planets? Here you should consult pages 15-29 of Armitage. For a look back at how things have developed, a now rather dated but still detailed look at the possibilities before the onslaught of actual detections can be found in the Towards other planetary systems. report written in NASAese a few years before the discovery of the first extrasolar planets. It is a long report, but you only need read the following sections: 3.1, 3.2 through The potential role of ground-based astrometry in TOPS ; 3.3; 3.4; 4.1 - 4.4 to get a sense of things. I will work on making a smaller file with just the pages necessary. What we'll concentrate on is the potential discovery space with indirect techniques, as summarized in Figure 3.1. So, think a bit about this figure and the pages that follow. A glossier draft of the 2006 roadmap from NASA that is primarily meant for public policy makers can be found here, which updates the planet detection story/strategies and which does have a decent listing of the sometimes bewildering array of upcoming and potential NASA/ESA missions related to exoplanetary science near the end. Chapter 5 is most relevant to today's discussion, but I include Chapter 4 and the technology roadmap for completeness and those interested.
I will update these files with additional suggested chapters/reading from the Exoplanets book over the next few days.
• Friday, 28 September: The architecture of extrasolar planetary systems. I. A short overview of the statistical properties of extrasolar planetary systems is provided in pages 29-33 of Armitage, and there is no shortage of review articles here. For example, Statistical properties of extrasolar planets ; is a review with most of the important known properties of extrasolar planets as derived from radial velocity studies. Here is a more recent update from our own John Johnson that covers transit-based results as well. This field is moving very quickly, and so if you are interested in keeping up-to-date you should peruse http://exoplanet.eu or one of the other extrasolar planet web sites on occassion! For information junkies, I recommend the Exoplanet Data Explorer, where you can get up to the date information and make plots of all sorts of things like the mass distribution, orbits, eccentricities, and the like for the presently known exoplanets. Recent topics of interest in extrasolar planet research that we'll think about include the stellar metallicity/planet correlation (see Marcy review above) and the discovery of a "super-Earths" toward several systems, especially those around M-type stars (such as GJ 1214b). NEW!!! A summary of the HARPS survey has just been posted on astro-ph, and announces a nearly 50 percent detection rate for planets in orbits up to only 100 days!
• Monday, 03 Oct: The architecture of extrasolar planetary systems. II. The rare cases where extrasolar planets transit in front of their stars tell us a great deal about them. For an excellent review of the practice and science of exo-planetary science, see the recent review by Josh Winn (MIT). An interesting case study is presented by the super-Earth core to a Jovian planet. Diagrams of the proposed interior structure of this `hot Saturn' and its comparison to Jupiter may be found at http://tauceti.sfsu.edu/n2k/hd149links.html. Recently, IR observations of the `secondary eclipse' of transiting planets by their stars have resulted in the first detection of the thermal emission from an extrasolar planet. The impressive pace of advancement with Spitzer observations is apparent in the report of the full `light curve' of an extrasolar planet less than two years later. Finally, for a summary of the over 1000 planet candidates from the first few months of the Kepler mission, point your browser here.
• Wednesday, 05 Oct: What else can you learn from transits? These events also provide the best opportunity to characterize the atmospheres of extrasolar hot Jupiters, as is described in the nice work using HST NICMOS on HD 189733. Direct imaging of planets has a now reasonably lengthy history of announcments followed by retractions, but the late-2008 detections of co-moving and apparently orbiting companions to HR 8799 and Fomalhaut may herald the opening of the floodgates.
• Friday, 07 Oct: Another area likely to see significant growth in future years is microlensing. We'll go over the basics of the technique in this lecture, and look into possible future missions/searches. While follow-up is not possible in this case, microlensing offers the immediate ability to search for Earth-mass planets in the so-called habitable zone (white paper to the Asro2010 panel).
• Monday, 10 Oct: From molecular clouds to stars. The basics of star formation. Gotta have stars if you're gonna have planets, unless they are free floating, of course. To get a feeling for how dynamic this process is, the beautiful simulations by Matthew Bate at the University of Exeter are hard to beat!
• Wednesday, 12 Oct: Young circumstellar disks and their evolution: a review . This review examines the properties of circumstellar disks and how they evolve. Over the next couple of weeks, the Armitage text will cover the physics of disks nicely, but not the observational constraints on disk structure and evolution. On larger spatial scales, for example, outflows from young stars play a pivotal role in the evolution of molecular clouds, yet are not well understood. We'll come back to outflow models when we talk about meteorites and the early solar system, for now I have mounted the Protostars & Planets V prerpints for your convenience. There are several articles on disks and outflows here. For the latter, the observational papers by Bally (optical/IR approaches) and Arce (mm-wave and radio techniques) are the most accessible. Skim them to get a feeling for what can and cannot be learned at present.
• Friday, 14 Oct: Disk statistics and timescales. Imaging disks is hard, and so much of what we know about them comes from spatially unresolved measurements of their Spectral Energy Distributions, or SEDs. Interpreting these has become an ever-more complex art, and pages 36-47 of Armitage are a good place to start your reading. For peer-reviewed treatments with varying levels of sophistication, the paper by Chiang and Goldreich is the classic reference. This is an extensive, and dense paper, so concentrate only on sections 1 and 2, and take a quick look at section 4 through 4.1.3 on spectral features in the infrared (see also the remaining sections of Chapter 2 in Armitage, which provides a more extensive derivation of many of the formulae in Chiang and Goldreich). Finally, images in optically thick lines can provide access to the disk velocity fields, inclincation, etc. This is a terse paper, so mainly think about why the emission patterns in Figure 1 have the shapes that they do! The most appropriate PP V review is that by Dullemond et al. Such observations are possible for only a handful of objects. So, most of our information on dissipation timescales comes from observations of the dust. At millimeter-wavelengths, a good paper to start with is: A survey for circumstellar disks around young stellar objects, This is an update of the classic early paper by Beckwith and collaborators. The goal is to learn something about the masses of the detected disks. There is a lot of detail you don't need here, so concentrate on the motivations for this kind of work and why long wavelengths give access to the disk mass. By combining optically thick and optically thin tracers of the disk, astronomers can investigate the timescales associated with disk dispersal. Lynne Hillenbrand has written an updated account of disk dissipation time scales and how they can be assessed.
• Monday, 17 Oct: OK, here's where it all happens. First we need to think a bit more deeply about the structure and transport properties of circumstellar disks. We will use primarily the Armitage text, Chapter 3, but the older Formation of Planets review by Steven Ruden has some good material as well. The latter review is nice, but terse in places, so I'll append to the various days some additional peer-reviewed articles. These are often quite dense and specialized. I do not expect you to read them in detail, but provide them so that if you are interested in such processes and topics you have a place to get started. For today's discussion, what we really care about is the overall structure and transport in the disk. For today, it's pages 68-87 of Armitage (and up to section 3 of Ruden). One interesting discussion about the possible impact of magnetic fields on disk transport that is outlined in Armitage was first raised in this article on layered accretion. There are also several relevant chapters in the Protostars and Planets V preprint proceedings mounted on the class web site that you can peruse at your leisure.
• Wednesday, Friday 19, 21 Oct: Geoff on NSF travel.
• Monday, 24 Oct: Now that we've looked at "basic" disk physics, we need to think about how dust grows into planetesimals. This is described in the beginning of Chapter 4 of Armitage (through section 3 of Ruden). Recent simulations of such processes suggest rapid growth and sedimentation in disks is likely unless collisions regenerate small dust grains, but we'll see there are serious issues in getting up to >km size scales. Recent theoretical work has suggested a possible "out" by using turbulence to directly bypass the meter-sized `migration barrier,' as is described in the simulations by Johansen et al.
• Wednesday, 26 Oct: How do we grow larger bodies? Gravitional interactions are the key here, as discussed in Chapter 5 of Armitage (and through the end of section 4 in Ruden). The processes by which oligarchs grow and then interact may be found in this article by our own Peter Goldreich and Re'em Sari.
• Friday, 28 Oct: Gas giants via core-accretion and disk instabilities. Go through Chapter 6 of Armitage. A nice analytical analysis of the core mass needed to drive gas accretion can be found in Stevenson 1982, Planet. Space Sci. 30, 755-764. This is not available electronically, so here is a scanned version. A rather more pedagogical discussion can be found in section III.C. of the Armitage notes, and I have posted to recent articles by Jack Lissauer and colleagues on dust settling and core-accretion timescales followed by the role of gap formation and angular momentum in the formation of Jovian satellite systems. Finally, we're not going to talk much about disk instability models in this class, but in the interests of full disclosure Alan Boss's recent 3-D simulations of this process and it's likely dependence on metallicity, etc. are worth a look. The paper cited is lengthy with lots of figures, but the overview of instability versus core-accretion models, hot Jupiter formation, and the like is worth a skim.
• Monday, 31 Oct: Planet migration. For this lecture, the appropriate Armitage section is 7.1. Here, since we are dealing with planet-disk (and planet-planet) interactions, I have mounted some nice animations of gap formation and planet migration from Frederic Masset's planet formation/simulation pages. For those interested in the gory fluid dynamics details, here's an ApJ article describing gap formation/Linblad resonances. The appropriate review notes are section IV.A. of Armitage. Many of the analyses of migration that find high rates use linearity assumptions. For a recent simulation that may well offer a more realistic model, point your browser here.
• Wednesday, 02 Nov: Planet-disk interactions and migration, part two.
• Friday, 04 Nov: Find out about gas dissipation and migration. What might this say about Uranus and Neptune? Other sources of information about this topic would be the Dullemond et al. chapter in PP V referenced above, and a recent paper by Alexander et al. that compares "toy disk models" of the photoevaporation process with what is known about disk masses and ages. See also section 3.6 of Armitage.
• Monday, 07 Nov: What about planetary dynamics in our own solar system? The first of two class sessions on the small body population beyond Neptune (the Edgeworth-Kuiper belt). The theme here will be observations. A good introduction can be found in is Mike Brown's Physics Today article which is (or at least should be) a relatively easy read. The pretty Physics Today preprint version may be found here. The second Kuiper Belt paper, also from Mike for the newly minted Comets II book, goes in to more detail, so read it second.
• Wednesday, 09 Nov: Now we need to think about the formation and destruction of small bodies in the outer Solar System. The dynamical properties of the Kuiper Belt are strongly influenced by the outer giant planets. A view advanced a few years ago suggested that Uranus and Neptune formed between Jupiter and Saturn.
• Friday, 11 Nov: More recent approaches, termed the Nice model utilizes a crossing of the 1:2 mean motion resonance of Saturn and Jupiter that attempts to get around problems with the timescales associated with the oligarchic growth of cores in the outer solar system and explain some unusual dynamical properties of the outer solar system. A quick overview of this model may be found in section IV.B. of Armitage. Our own Konstantin Batygin and Mike Brown have surveyed the possible gas and ice giant configurations that are compatible with Nice-like outcomes, as described here. We'll also talk a bit about the largest icy bodies known far from home. Here's a link for those interested in learning more, for example, about the discovery and implications of the detached KBO Sedna.
• Monday, 14 Nov: What about Kuiper belt-like structures around other stars? We can `see' them through the dust they create. The nearest and most extended can be imaged, but in terms of statistics and timescales the best data come from the Spitzer Space Telescope. A first survey of (mostly A) nearby stars shows dramatic scatter on top of an overall decline (for a press release describing this work, point your browser here. Concentrate on the Introduction, Figure 1, and the Discussion. Spitzer has also enabled the first search for Kuiper belt analogs around systems known to harbor planets.
• Wednesday, 16 Nov: Comets! This paper on the formation of the Oort cloud and the delivery of comets goes into more detail than we have time for, so read and understanding sections 1-3 and take a look at 6-7. Any information comets retain about their origins is contained in their chemical composition. Here is a brief review of the volatile composition of comets, useful mainly for its table of detected species and references to other reviews. Skim the intro and conclusions. The Stardust mission has been telling us quite a bit about the dust in one particular comet. For an overview of what's been discovered to date, the best place to look is the March 2006 press release.
• Friday, 18 Nov: We're working our way in, so next read about The formation and evolution of the asteroid belt. An interesting update to the kinds of calculations presented here is that considering the delivery of water to growing planets and the habitable zones around stars. This is also the parent body region for meteorites. More recent, large scale simulations include a more radical proposal in which the giant planets undergo substantial radial migration during the gas-rich disk phase, called the "Grand Tack" scenario (since Jupiter and Saturn first migrate inward, then outward).
• Monday, 21 Nov: Student Affairs retreat for Geoff, no class.
• Wednesday, 23 Nov: Chondritic meteorites can give us insight into many details of solar system formation. But what do they mean??? Here is a short overview of the ties between chondrites and the disk in which they formed. Here I have mounted a more thorough, but introductory review of chondrite properties and implications. Finally, short-lived isotopes have much to tell us about the early solar system. When combined with astronomical observations, this helps us to think about The cradle of the solar system, As we saw earlier, the lifetime of disks and the means by which they are dispersed can depend on their environment. Thus, the question arisis: Can we determine in what sort of cloud the solar system formed? The [very] short paper cited above argues that it was not in regions like Taurus that form primarily Sun-like stars in relative isolation. This paper is dense with ideas, so please read carefully.
• Friday, 25 Nov: The day after Thanksgiving, Institute holiday.
• Monday, 28 Nov: Further solar system constraints. Thanks to recent Hf/W isotopic studies, our understanding of the timescales associated with the formation of the Earth has some new constraints. The Nature papers that present the raw data on which this short overview rests may be found here. These studies have also illuminted dynmanical simulations of the giant impact the formed the Earth/Moon system. In this article by Robin Canup (Icarus 168, 433) it's most important to read the Introduction and Key Constraints sections. For those interested, Robin has also written a nice Science article on a collisional origin for Pluto/Charon. What does all this mean for the early Earth? What do planet formation theories tell us about the origin of life? What defines the so-called "habitable zone"?
• Wednesday, 30 Nov: We've been thinking about the dynamics in our own solar system for a bit, let's revisit extrasolar planets and think about the potential dynamics that shaped the observed exo-planetary systems. Perhaps the most unusual is the first one discovered, Ups And. For those interested in how such calculations can be used to examine the stability of and chaos in our own planetary system, read here. Planet-planet interactions are discussed in section 7.4 of the Armitage text.
• Friday, 02 Dec: Wrapping up. Finish up exo-planetary dynamics and think a bit about what the future might hold.




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Homework (Plese leave homeworks in TA's mailbox, 1st floor of S. Mudd) Will be updated as class moves along.
• Problem Set 1, due Oct. 6
• Problem Set 2, due Oct. 13
• Problem Set 3, due Oct. 27
• Problem Set 4, due Nov. 3
• Problem Set 5, due Nov. 10
• Problem Set 6, due Nov 17
• Problem Set 7, due Dec. 1
• Final, due Dec. 9