What can X-rays tell us about planet formation? Eric Feigelson (Penn State). Hydrodynamical simulation of Jovian planet formation in a disk around a T Tauri star. Our knowledge of planet formation has recently grown in many ways. Protoplanetary disks: Gas & ice (mol spec & comets)
Hydrodynamical simulation of Jovian planet formation in a
disk around a T Tauri star
Gas & ice (mol spec & comets)
Dust (IR photom & spec, vis silhouette, meteorites)
Larger solids (meteorites, beta Pic comets)
Dynamics from ~110 extrasolar Doppler planets
Hot Jovian planet properties from transits
None yet, though possible today for nearby young Jovians
Mag field lines
Flare MeV particles
Feigelson IAU Symp 219 2003
Dead zone calculations for cosmic ray and X-ray ionization in disks with different viscosities. Here, only ~1 keV X-rays are used, not the more energetic X-rays seen with Chandra.
Matsumura & Pudritz 2003
Competition between standard planet-disk torques (which produce rapid Type I inward migration) and torques from turbulent density structures. Turbulence randomizes migration, and may accelerate or inhibit planetary growth.
Papaloizou et al. 2003; Laughlin et al. 2003; Winters et al. 2003; Rice & Armitage 2003; Menou & Goodman 2004
Magnetic field is restricted to outer
Reynolds stress which causes
MHD turbulence also avoids inner
But Maxwell stress (vertical motions)
induced by non-axisymmetric density
waves from the outer zone are
present in dead zone
Time (tens of orbits)
3-D MHD calculation Fleming & Stone 2003
When central temperature
of dead zone exceeds T~800K,
ionization may rise to support
MHD turbulence. This would
produce a burst of accretion.
Are these FU Orionis outbursts?
Armitage, Livio & Pringle 2001
2a. A Solar System enigma: in disks with different viscosities. Here, only ~1 keV X-rays are used, not the more energetic X-rays seen with Chandra. Why do the most ancient solid materials of the solar nebula show evidence of MeV irradiation?Excess short-lived radionuclides in carbonaceous chondrite calcium-aluminum inclusions (CAIs)
Isotope t (Myr) Abund
10Be/Be 2.6 9x10-4
26Al/Al 1.1 5x10-5
41Ca/Ca 0.1 1x10-8
53Mn/Mn 5.3 4x10-5
… … …
Possibly 7Be (t = 53 days)
Lee et al. 1998
McKeegan et al. 2000
Cameron & Truran 1977, Wasserburg et al. 1994, Arnould et al. 1997
Hoyle et al. 1962, Clayton et al. 1977, Feigelson 1982, Shu et al. 1997, Lee et al. 1998
Local spallation also explains spallogenic 21Ne in some free-floating grainsCaffee et al. 1987, Woolum & Hohenberg 1993, Rao et al. 1997
Chandra measurements of X-ray flare rates in Orion Nebula
solar analogs directly support the local spallation
origin of meteoritic isotopic anomalies
Feigelson et al. 2002 (see also Feigelson 1982)
2b. Another Solar System enigma: in disks with different viscosities. Here, only ~1 keV X-rays are used, not the more energetic X-rays seen with Chandra.
What melted meteoritic chondrules?
The causes of the flash melting of meteoritic chondrules and CAIs has been a major problem for >100 years. Meteoritic literature appears surprisingly unaware of X-ray/radio flare findings. Feigelson 1982, Feigelson & Montmerle 1999
Shu et al. (1997, 2001) develop a (controversial) model for flash melting of CAIs by X-ray from magnetic flares.
Calculation of chemical reactions
and physical state of various
layers of an X-irradiated disk
Semanov, Weibe, Henning 2004
(also Aikawa & Herbst 2001)
Astronomical studies of older (5-20 Myr) disks can elucidate
longevities of the gaseous, dusty and planetisimal disk phases.
Particularly important for Jovian planet formation. Major obstacle
is the lack of large, disk-unbiased samples of older PMS stars.
Disk signatures are weak and stars have dispersed far from clouds. Feigelson 1996 Review: Hillenbrand 2001
These older PMS stars are mostly found via their X-ray emission.
We are pursuing a Chandra snapshot survey to find nearby
examples of older PMS stars. Feigelson, Lawson & Garmire 2003
JHKL photometry shows inner disks around 2/3 of stars and & hi-res optical spectroscopy show accretion
endures in 1/3 of stars at ~10 Myr in
sparse cluster environments.
ROSAT discovered the nearest open cluster
found in the 20th century: 26 Li-rich, rapidly
rotating stars, B9 to M5.5 (+ BDs?).
D=97 pc, q=0.5 pc, t=9 Myr.
Lawson et al. 2002, Lyo et al. 2003
Lawson et al. 2004
Mamajek et al. 1999 & 2000,
Lawson et al. 2001, Lyo et al. 2004