X-rays and planet formation. X-rays from young stars Magnetic reconnection flaring Some results from COUP & XEST Do X-ray flares influence planet formation? Evidence for X-ray irradiation of disks Implications of flare irradiation. Eric Feigelson (Penn State).
Eric Feigelson (Penn State)
From Stars to Planets Apr 2007
Orion Nebula cluster & proplyd
Star formation occurs in molecular cloud cores at T~10-100 K. Planet formation occurs in disks at T ~100-1000 K. This is neutral material (meV).
But high energy radiation is present in planet formation environments: keV photons & MeV particles are produced in violent magnetic reconnection flares.
Does this influence disk processes?
(heating, ionization, chemistry, turbulence, viscosity, shocks, melting & spallation of solids)
Theory looks good
Is there evidence for X-ray/flare effects in disks, extrasolar planets & meteorites?
Fe 6.4 keV & NeII 12.81mm, meteorites
Protostars & Planets V review article 2007
Feigelson, Townsley, Guedel & Stassun
ApJ Suppl Special Issue October 2005 + others 2006-07
Special Issue As&Ap 2007
The Chandra Orion environments: keV photons & MeV particles are produced in violent magnetic reconnection flares.
of the Orion Nebula
1616 COUP sources:
849 low-NH ONC stars
559 high-NH stars, incl.
75 new members
159 probable AGN
Getman & 22 others 2005 COUP #1 & #2
COUP: The Movie environments: keV photons & MeV particles are produced in violent magnetic reconnection flares.
Age ~ 10 Myr
Mass ~ 1 Mo
log Lp = 32.6 erg/s
X-ray cts / ks
Time (13.2 days)
Wolk et al. 2005 COUP #5
X-ray luminosity fn environments: keV photons & MeV particles are produced in violent magnetic reconnection flares.
spans 28 < logLx < 32 erg/s
Correlation with stellar mass plus scatter
There is no X-ray
quiet population for
All X-ray sources are
dominated by flares
Guedel et al. XEST #1
Pre-main sequence X-rays are generally not environments: keV photons & MeV particles are produced in violent magnetic reconnection flares.
produced by the accretion process
~15-day light curve
Optical accretion event
No relation seen between X-ray flares and accretion variations in ~800 Orion stars. Stassun et al. 2006/7 COUP #15/16
No difference in X-ray flaring of ~100 Class II vs. Class III Taurus stars.
Stelzer et al. XEST #11
X-ray Sun -- Yohkoh
Yokohama & Shibata 1998
Both smaller (<1 R*) and giant (~10 R*) loops are inferred from COUP
Flaccomio et al. 2005 Favata et al. 2005 COUP #6 & 7
Resulting X-ray corona
Jardine et al. 2006
X-ray levels are
during Class I-II-III
but drop greatly on
the main sequence
Preibisch & Feigelson 2005 COUP #4
Imanishi et al. 2001, Tsujimoto et al. 2005, Favata et al. 2005
Glassgold et al. 2006, Pascucci et al. 2007
YLW 16A: protostar in Oph
Imanishi et al. 2001
Tsujimoto & 7 others
2005 COUP #8
of gas content of
Kastner & 7 others
2005 COUP #9
Mag field lines
Flare MeV particles
Feigelson 2003, 2005
YSO X-ray ionization rate dominates CRs in the
disk by 108 for 1Mo PMS star at 1 AU:
z = 6x10-9 (Lx/2x1030 erg s-1) (r/1 AU)-2 s-1
The ionization fraction is uncertain due to recombination processes. Hard (5-15 keV) X-rays should penetrate 1-100 g/cm2.
Igea & Glassgold 1997 & 1999; Fromang et al. 2002; Matsumura &
Pudritz 2003 & 2006; Alexander et al. 2004; Salmeron & Wardle 2005;
Ilgner & Nelson 2006; Glassgold et al. 2007; Nomura et al. 2007
Reviews: Glassgold et al. 2000 PPIV & 2006; Balbus ARAA 2003;
Dutrey et al. PPV 2007; Bergin et al. PPV 2007
X-ray ionization of the gaseous disk protoplanetary disks
Atomic excitation calculation of J1/2 J3/2 [NeII] 12.81 mm line from ionized outer layer of disks around 5-10AU
Glassgold et al. 2006
Spitzer FEPS Legacy reports [Ne II] line in 4 older, X-ray
bright T Tauri stars
Pascucci et al. 2007
X-rays MRI MHD turbulence inhomogeneities producing
gravitational torques which overwhelm the Goldreich-Tremaine torque,
so protoplanets undergo random walks rather than secular Type I
migration. Gap formation suppressed.
Laughlin et al. 2004 and other groups
Evidence: Fe fluor lines Absorption
consequences: Ionization Turbulence
Chondrule melting Outflows
Planetary systems form in protoplanetary disks
cool dark disks
which are irradiated by 10 8violent
magnetic reconnection flares