Observing How Habitable Conditions Develop (Or Not) in Protoplanetary Disks

1. Observing How Habitable Conditions Develop (Or Not) in Protoplanetary Disks ? Colette Salyk National Optical Astronomy Observatory Credit: JPL-Caltech/T. Pyle (SSC) Credit: NASA

2. Why studying protoplanetarydisks is important for understanding habitability • Planet formation “laboratory” – ground truth for our ideas about how planets form and habitability develops

3. Even if you don’t care how planets form…

4. Planet detection remains difficult at large distances, and characterization even more so Milky way diameter: 40 kpc (120,000 light years) Microlensing planets: 5 kpc Kepler planets: 2 kpc Imaged planets: 0.2 kpc Credit: Exoplanet app

5. Why studying protoplanetarydisks is important for understanding habitability • Planet formation “laboratory” – ground truth for our ideas about how planets form and habitability develops • Understanding formation process allows us to extrapolate to the rest of the galaxy/universe

6. Overview of what we do and don’t know about protoplanetary disks • Current studies of development of Goldilocks properties: • Location • Planet size and type • Chemistry

7. Opaque disks in Orion (Hubble) Composed of gas and (opaque) dust, Few 100 AU in size 1800 AU CO velocity in HD 163296 (ALMA) de Gregorio-Monsalvo et al. 2013

8. Spitzer spectra of Si-O stretch Small (but evolved) dust, consistent with olivine composition Data Models Kessler-Silacci et al. 2006 Chondrule from American Museum of Natural History meteorite collection

9. Spitzer spectra of Si-O stretch Small (but evolved) dust, consistent with olivine composition Data Models Kessler-Silacci et al. 2006 Chondrule from American Museum of Natural History meteorite collection

10. Protoplanetary disks are ubiquitous* Kraus & Ireland, 2011 *around sun-like stars in nearby star-forming regions

11. Protoplanetary disks last a few Myr Kraus & Ireland, 2011

12. Masses are consistent with Minimum Mass Solar Nebula, or slightly lower Ophiuchus data from Andrews et al. 2007

13. Masses are consistent with Minimum Mass Solar Nebula, or slightly lower ∨ small Ophiuchus data from Andrews et al. 2007

14. Active research related to habitability • Planet size and location: Snow lines and disk dispersal • Chemistry: Chemical inventories of planet forming regions

15. What processes determine planetary size and location?

16. What processes determine planetary size and location? Terrestrial planets Gas giants

17. The “snow line” – an increase in solid surface density Terrestrial planets Gas giants

18. What is the expected location of the snow line?

19. What is the expected location of the snow line?

20. The “snow line” Habitable zone Terrestrial planets Gas giants

21. Multi-wavelength observations of water vapor measure snow line locations ice line K. Pontoppidan

22. First measured locations of snow lines in disks Meijerink+ 2009 Zhang+ 2013

23. First measured locations of snow lines in disks See poster by Sandra Blevins for an update! Meijerink+ 2009 Zhang+ 2013

24. Planet type affected by disk dispersal Terrestrial planets Gas giants Ice giants (super Earths?)

25. Dispersal of disk gas also affects planet migration Snapshot of disk surface density with planet undergoing migration Hot Jupiters # of planets 1 10 100 Orbital Period [days] P. Armitage

26. How do disks evolve/disperse? B wind Disk winds accretion Blandford & Payne 1982 Pudritz & Norman 1983 Cartoon inspired by Bai et al. 2013

27. Molecular emission lineshapes and images – evidence for disk winds? Vibrational CO ALMA CO velocity field Flux Velocity Pontoppidan+ 2009; also Bast+ 2011 Salyk+ in prep Brown+ 2013

28. How do disks evolve/disperse? Photoevaporative winds wind FUV EUV X-ray

29. How do disks evolve/disperse? Photoevaporative winds wind ? FUV EUV X-ray Main open question: How quickly do disks dissipate at each disk radius?

30. Observations of photoevaporation tracers measure location and mass-loss [Ne II] emission from two disks + models Pascucci & Sterzik 2009

31. Chemistry: Chemical inventories of planet forming regions

32. CI chondrite abundances vs. solar abundances • (R ~ 4 AU) Solar data from Grevesse et al. 2010 Chondrite data from Allegre et al. 2001

33. Earth abundances vs. solar abundances • (R = 1 AU) Solar data from Grevesse et al. 2010 Chondrite data from Allegre et al. 2001

34. Earth abundances vs. solar abundances • (R = 1 AU) CO, CO2, organics, graphite? N2, HCN, NH3, organics? Solar data from Grevesse et al. 2010 Chondrite data from Allegre et al. 2001

35. What is the correct chemical pathway? Inheritance or reset? Maximum “reset” Maximum “Inheritance”

36. Resemblance between cometary and cloud ice compositions = an inheritance assumption Cloud abundance % relative to water Cometary abundance % relative to water Data from Mumma & Charnley 2011 (and references therein)

37. Evidence for reset in the solar system: CAIs and chondrules Chondrule Calcium Aluminum-rich Inclusion (CAI) Thin sections from the American Museum of Natural History meteorite collection

38. The study of chemistry in inner disks was enabled by the Spitzer InfraRed Spectrograph (IRS) Carr & Najita 2008 Also, Salyk+ 2008

39. O,C,N inventory in inner disks is being measured O C N Fraction Pontoppidan+ 2014

40. Evidence for reset in disks: O,C,N inventory different from birth cloud Salyk et al. 2011; Öberg et al. 2011

41. Evidence for reset in disks: Variability in disk chemistry Banzatti et al. 2012 See poster by Andrea Banzatti

42. Current: Partial chemical inventory, evidence for reset Yet to come: Chemical differences between disks, and as a function of radius

43. Conclusions • Basic protoplanetary disk properties have been characterized • Studies of development of Goldilocks properties ongoing: • Location • Planet size and type • Chemistry Measuring snow lines Observing disk evolution/dispersal Chemical inventory in planet-forming regions, evidence for reset, details yet to come Questions about observing disks?