What can x rays tell us about planet formation eric feigelson penn state
Download
1 / 16

What can X-rays tell us about planet formation? Eric Feigelson (Penn State) - PowerPoint PPT Presentation


  • 166 Views
  • Uploaded on

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)

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'What can X-rays tell us about planet formation? Eric Feigelson (Penn State)' - ophira


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
What can x rays tell us about planet formation eric feigelson penn state

What can X-rays tell usabout 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
Our knowledge of planet formation has recently grown in many ways

  • Protoplanetary disks:

    Gas & ice (mol spec & comets)

    Dust (IR photom & spec, vis silhouette, meteorites)

    Larger solids (meteorites, beta Pic comets)

  • Planetary systems:

    Dynamics from ~110 extrasolar Doppler planets

    Hot Jovian planet properties from transits

  • Planetary imagery:

    None yet, though possible today for nearby young Jovians

  • Theoretical modeling of the above observations


  • X-ray effects on protoplanetary disks ways

  • While protoplanetary disks are far too cool to emit X-rays,

  • high energy studies may provide crucial indirectinsights

  • into planet formation:

    • Young stellar X-rays will ionize the disks, inducing MHD turbulence which affects Jovian planet formation & migration

    • Magnetic flaring in young stars may help explain two enigmas in meteoritic studies:the production of short-lived isotopes in disk solids via spallation, and the flash melting of chondrules or CAIs.

    • X-rays will change disk chemistry & heating

    • 4. X-ray selected older PMS starsprovide important samples to measure the distribution of disk longevities


High energy processes & protoplanetary disks ways

Mag field lines

Cosmic rays

Flare X-rays

Proto-Jupiter

Proto-Earth

Flare MeV particles

Dead zone

Ionized MHD

turbulent zone

Feigelson IAU Symp 219 2003


1. X-ray ionization of protoplanetary disks ways

  • X-rays from magnetic reconnection events will penetrate

  • to surprising depths into the disk. Ionizing radiation incident

  • on a cold disk produces an outer MHD-turbulent layer via the

  • magneto-rotational instability. The inner midplane remains a

  • neutral laminar `dead zone’.

    • Conductivity, ambipolar diffusion, and dynamos will affect the

    • extent of the turbulent zone. Cosmic ray ionization is also

    • important. The balance between X-ray and cosmic ray

    • ionization depends on: Lx & spectrum, X-ray flare geometry,

    • penetration of low-E cosmic rays in cloud, and recombination

    • rate within the disk.

  • Gammie 1996, Glassgold et al. 1997, Igea & Glassgold 1999

  • Fromang et al. 2002, Blackman & Tan 2003, Salmeron & Wardle 2003

  • Matsumura & Pudritz 2003

  • Review:

  • Glassgold, Feigelson & Montmerle in Protostars & Planets IV 2000


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


Turbulent disk structures produce random walk rather than rapid inward migration
Turbulent disk structures produce random walk in disks with different viscosities. Here, only ~1 keV X-rays are used, not the more energetic X-rays seen with Chandra.rather than rapid inward migration

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


Dead zone may be active
Dead zone may be active in disks with different viscosities. Here, only ~1 keV X-rays are used, not the more energetic X-rays seen with Chandra.

Magnetic field is restricted to outer

layers, |z/H|>0.4

Reynolds stress which causes

MHD turbulence also avoids inner

dead zone

But Maxwell stress (vertical motions)

induced by non-axisymmetric density

waves from the outer zone are

present in dead zone

2

z/H

-2

Time (tens of orbits)

3-D MHD calculation Fleming & Stone 2003


Turbulent disks may exhibit periodic accretion episodes
Turbulent disks may exhibit periodic accretion episodes in disks with different viscosities. Here, only ~1 keV X-rays are used, not the more energetic X-rays seen with Chandra.

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


Excess short lived radionuclides in carbonaceous chondrite calcium aluminum inclusions cais

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)

Allende meteorite

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)

CAIs

Chondrules

Lee et al. 1998

McKeegan et al. 2000


Explanations for short lived isotopes
Explanations for short-lived isotopes in disks with different viscosities. Here, only ~1 keV X-rays are used, not the more energetic X-rays seen with Chandra.

  • Injection of recently synthesized stellar material: AGB red giant winds, Wolf-Rayet winds, or supernova remnnant

    Cameron & Truran 1977, Wasserburg et al. 1994, Arnould et al. 1997

  • Spallogenic nuclear reactions by MeV particles impacting the solar nebula

    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.


Dead zone

Reynolds number

Calculation of chemical reactions

and physical state of various

layers of an X-irradiated disk

Semanov, Weibe, Henning 2004

(also Aikawa & Herbst 2001)


4 longevities of protoplanetary disks
4. Longevities of protoplanetary disks chemistry in disk

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


The h cha cluster
The chemistry in diskh Cha cluster

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


Summary
Summary chemistry in disk

  • Flares may have important effects on protoplanetary disks:

    • ionization & disk dynamics

    • irradiation & melting of solids (meteoritics)

    • chemistry & heating

  • X-rays help determine disk longevities.


ad