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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).

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X rays and planet formation l.jpg

X-rays andplanet formation

  • X-rays from young starsMagnetic 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)

From Stars to Planets Apr 2007


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X-rays and star/planet formation

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).


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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


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Some useful references environments: keV photons & MeV particles are produced in violent magnetic reconnection flares.

  • X-rays from young stars & stellar clusters

    Protostars & Planets V review article 2007

    Feigelson, Townsley, Guedel & Stassun

  • ~20 papers from COUP

    ApJ Suppl Special Issue October 2005 + others 2006-07

  • ~15 papers from XEST

    Special Issue As&Ap 2007

  • ~5 papers/month on X-rays SFRs & disks


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The Chandra Orion environments: keV photons & MeV particles are produced in violent magnetic reconnection flares.

Ultradeep Project

13-day observation

of the Orion Nebula

1616 COUP sources:

849 low-NH ONC stars

559 high-NH stars, incl.

75 new members

16foreground stars

159 probable AGN

23 uncertain

Getman & 22 others 2005 COUP #1 & #2


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COUP: The Movie environments: keV photons & MeV particles are produced in violent magnetic reconnection flares.


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Extraordinary flares in environments: keV photons & MeV particles are produced in violent magnetic reconnection flares. Orion pre-main sequence stars

1

2

JW 738

K=10.5

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


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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

M<3 Mo

All X-ray sources are

dominated by flares

Guedel et al. XEST #1


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Characteristics of PMS flaring environments: keV photons & MeV particles are produced in violent magnetic reconnection flares.

  • Orion flares are typically 102 stronger than >X9 solar

  • flares releasing 1035-1036 ergs (0.5-8 keV). Many

  • smaller flares (powerlaw distribution like Sun/stars).

  • Flares occur every few days and last ~2-20 hrs

  • Flares unrelated to accretion variations and are

  • independent of presence of disks

  • Flare lightcurve & spectral evolution are usually

  • similar to solar/stellar flares

  • X-ray energies often extend to >10 keV


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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

X-ray flares

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


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Solar/stellar X-rays arise from magnetic reconnection events in the corona

X-ray Sun -- Yohkoh

Yokohama & Shibata 1998


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T Tauri X-rays arise from a complex reconnecting magnetosphere

Both smaller (<1 R*) and giant (~10 R*) loops are inferred from COUP

Flaccomio et al. 2005 Favata et al. 2005 COUP #6 & 7

Open accreting

field lines

Closed plasma-filled

field lines

Resulting X-ray corona

(without flares)

Jardine et al. 2006


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X-ray emission elevated throughout planet formation epoch magnetosphere

1 Mo

X-ray levels are

roughly constant

during Class I-II-III

phases

but drop greatly on

the main sequence

0.5 Mo

0.2 Mo

Preibisch & Feigelson 2005 COUP #4


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Three lines of evidence that X-rays irradiate protoplanetary disks

  • Some systems show evidence of X-ray reflection off of the disk: the fluorescent 6.4 keV iron line

    Imanishi et al. 2001, Tsujimoto et al. 2005, Favata et al. 2005

  • Some systems show soft X-ray absorption attributable to gas in the disks Kastner et al. 2005

  • Some systems show [NeII] IR line

    Glassgold et al. 2006, Pascucci et al. 2007


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Iron fluorescent line protoplanetary disksCold disk reflects flare X-rays

COUP spectra

YLW 16A: protostar in Oph

Imanishi et al. 2001

Tsujimoto & 7 others

2005 COUP #8


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X-ray absorption by gas protoplanetary disksin edge-on Orion proplyds

First measurement

of gas content of

UV-irradiated

photoevaporating

disks?

Kastner & 7 others

2005 COUP #9


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X-ray influence on planet formation protoplanetary disks

Mag field lines

Cosmic rays

Flare X-rays

Proto-Jupiter

Proto-Earth

Flare MeV particles

Dead zone

Ionized MHD

turbulent zone

Feigelson 2003, 2005


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X-rays & disk ionization protoplanetary disks

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


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Plausible X-ray/flare effects protoplanetary diskson protoplanetary disks

  • PMS X-ray ionization will heat gas and change chemistry in disk outer layers.

  • PMS X-rays may be an important ionization source at the base of bipolar outflows.

  • X-ray ionization is likely to induce MRI turbulence affecting accretion, planetesimal formation, migration, ...

  • Flares may help explain enigmas in the meteoritic record: short-lived radionuclides, chondrule flash melting


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X-ray ionization of the gaseous disk protoplanetary disks

PREDICTION

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

DETECTION

Spitzer FEPS Legacy reports [Ne II] line in 4 older, X-ray

bright T Tauri stars

Pascucci et al. 2007


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Protoplanet migration in a turbulent disk protoplanetary disks

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


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Conclusions protoplanetary disks

  • The X-ray studies of young stars show that powerful magnetic flares are ubiquitous throughout the epoch of planet formation. The astrophysics resembles solar flares

  • X-rays can efficiently irradiate protoplanetary disks

    Evidence: Fe fluor lines Absorption

    Possible

    consequences: Ionization Turbulence

    Heating Chemistry

    Chondrule melting Outflows

    CAI isotopes

    Therefore …..


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Planetary systems form in protoplanetary disks

cool dark disks

….

which are irradiated by 10 8violent

magnetic reconnection flares


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