Adwin Boogert

Geoff Blake

Caltech/OVRO

Caltech/OVRO

High Resolution 4.7 m Keck/NIRSPEC

Spectra of Protostars

R=25,000 in 0.43” wide slit; v=12 km/s at 4.7 m

M band sensitivity: S/N=50 at M=5.6 magn in 900 seconds on source

3 partial orders on 10242 array.

Instantaneous coverage 0.07 m per order.

4 settings needed to cover best part of atmospheric M band

NIRSPEC is powerful instrument for M band observations, although it is not optimized for M band

NIRSPEC at Keck II

The Atmosphere at 4.7 m at R=25,000

The Atmosphere at 4.7 m at R=25,000

Program start-up involved well known Herbig AeBe, T Tauri and Class I protostars in multiple settings.

Efficiency and success rate increase significantly with larger sample of sources in only one setting, initially. Follow-up in other settings on most interesting sources.

In second stage of program a flux limited sample drawn from the SIRTF/IRS c2d source list: M<7 magn, Dec > -30 degrees.

Differences with VLT/ISAAC:

NIRSPEC only Dec > -30, so no R CrA, Cham, Lupus :(

NIRSPEC has higher spectral resolution (25000 vs. 10000)

Keck/NIRSPEC cannot observe sources without optical guide star closeby (4 arcmin), i.e. cannot do most embedded 'icy' sources. Bias toward more evolved sources with emission lines.

Source Sample

R=25,000 4.7 m Spectra Trace Wide Variety of Phenomena

R=25,000 4.7 m Spectra c2d/IRS YSOs

Status:● 2.5 good nights in spring/summer 2002 in which about 25 sources done. ●Another run next week.

:

L1489 IRS with Keck/NIRSPEC

Inventory:Inventory:

●deep deep 1212CO gas absorption CO gas absorption lines with red shifted wingslines with red shifted wings

●gas phase gas phase 1313COCO

●gas phase Cgas phase C1818OO

●complex CO ice bandcomplex CO ice band

●nono strong “XCN” strong “XCN”

●nono strong H I Pf strong H I Pf ●nono CO emission CO emission

HCO+ 3-2 OVRO/BIMA:

The Shrinking Disk of L1489 IRS

●Class I SEDClass I SED

●L=3.7 LL=3.7 Lsunsun

●MMdiskdisk=0.02 M=0.02 Msunsun

●Large flattened structure in millimeter Large flattened structure in millimeter continuum+line emission.continuum+line emission.

●Continuum and lines Continuum and lines cannot be fitted with cannot be fitted with same inside-out collapse modelsame inside-out collapse model

●Instead, velocity structure indicates large Instead, velocity structure indicates large 2000 AU radius close to 2000 AU radius close to edge-on diskedge-on disk, in , in almost Keplerian rotation withalmost Keplerian rotation with infall infall component.component.

Hogerheijde, ApJ 553, 618 (2001)Hogerheijde, ApJ 553, 618 (2001)

HCO+ 3-2 OVRO/BIMA:

The Shrinking Disk of L1489 IRS

L1489 IRS disk characterized by power law ‘flared disk’ model:

●Fits lines, continuum and velocity structure.

●T = 34(R/1000AU)-0.4 [K]

●n = n0(R/1000AU)-1.5.exp(-z2/h2) [kg/cm3]

●h = R/2 ‘flaring’

●Vin = 1.3(R/100AU)-0.5 [km/s] in addition to Keplerian rotation around 0.65 Msun central star

L1489 IRS represents short lived (<20,000 yr) transition phase in which disk shrinks to few 100 AU TTauri disk?

Hogerheijde, ApJ 553, 618 (2001)Hogerheijde, ApJ 553, 618 (2001)

CO Keck/NIRSPEC:

Boogert et al., ApJ 568,761 (2002)Boogert et al., ApJ 568,761 (2002)

The Shrinking Disk of L1489 IRS!

●To first order, 4.7 To first order, 4.7 m CO spectra m CO spectra

confirm confirm infalling motioninfalling motion of disk of disk..●CO lines confine T and n structure of CO lines confine T and n structure of disk. disk. ●Introduce power law for density along Introduce power law for density along pencilpencil absorption beam: absorption beam:● n(n(ll)) = n = n00((ll/1000 AU)/1000 AU)-p-p

CO Keck/NIRSPEC:

BoogertBoogert et al., ApJ 568,761 (2002)et al., ApJ 568,761 (2002)

The Shrinking Disk of L1489 IRS!

●To first order, 4.7 To first order, 4.7 m CO spectra m CO spectra

confirm confirm infalling motioninfalling motion of disk of disk..●CO lines confine T and n structure of CO lines confine T and n structure of disk. disk. ●Introduce power law for density along Introduce power law for density along pencilpencil absorption beam: absorption beam:● n(n(ll)) = n = n00((ll/1000 AU)/1000 AU)-p-p

●we find: p=0.55we find: p=0.55●……scale height increases more than scale height increases more than linear, very flared disklinear, very flared disk●Too much warm gas at high velocityToo much warm gas at high velocity

CO Keck/NIRSPEC:

Boogert et al., ApJ 568,761 (2002)Boogert et al., ApJ 568,761 (2002)

The Shrinking Disk of L1489 IRS!

●Modelled depth in better agreement if Modelled depth in better agreement if 50% of observed continuum from 50% of observed continuum from scattered light, not absorbed by CO.scattered light, not absorbed by CO.●Still too much warm gas at high Still too much warm gas at high

velocity.velocity.●Only partial collapse of disk, e.g. a Only partial collapse of disk, e.g. a

surface layer and outer parts?surface layer and outer parts?●Supported by low luminosity and Supported by low luminosity and

weakness of H I emission lines (weak weakness of H I emission lines (weak

accretion shock):accretion shock):●0.02 M0.02 Msunsun disk collapse in 20000 yr disk collapse in 20000 yr

gives Mgives Maccacc=10=10-6-6 M Msunsun/yr or L/yr or Laccacc=7 L=7 Lsunsun, ,

while L=3.7 Lwhile L=3.7 Lsunsun..