1. Infrared study of a star forming region, L1251B
Jeong-Eun Lee
Sejong University

2. IGRINS for protostars
High spatial and spectral resolution studies of inflow & outflow close to protostars are lacking.
With IGRINS, we can study statistically sample of protostars and explore
how key molecules such as CO, H2O, and H2 form and are destroyed at high temperatures
the complex kinematics in the inner tens of AU such as infall, outflow, and rotation
how does the star build up mass and what role does angular momentum play on small scales

3. L1251B: an example case
L1251, d=300pc
L1251B
13CO 1-0 map

4. L1251B : a group of low mass protostars
IRS2
IRS1
IRS4
IRS-NW
IRAS

5. Gas Distribution (OVRO)
Contours: H2CO
Gray: 1 mm continuum
Thick contours: N2H+
Thin contours: HCO+
Gray: 3 mm continuum
P-V diagram
IRS1
IRS2
Lee et al. 2007

6. Spitzer Infrared Spectrograph (IRS)
Four separate 128x128 arrays with angular resolution of 3 to 10
Total wavelength coverage: 5.3 – 42 μm
Short-Low (SL; μm, λ/Δλ ~90)
Long-Low (LL;12-40 μm, λ/Δλ ~90)
Short-High (SH; μm, λ/Δλ ~600)
Long-High (LH; μm, λ/Δλ ~600)
Covered all of the H2 pure rotational lines from S(0) (28.2 μm) to S(7) (5.52 μm) as well as various ice features

7. IRS Spectra of L1251B
H2O ice
H2O ice

8. H2O ice

9. IRS Mapping of L1251B
SL module
SH module

10. Ice Maps of CO2 and H2O
CO2 ice
H2O ice
Heated by shock
Heated by IRS1

11. IRS1 for XDR (?)

12. Fe II 17.9
Ne II 12.8

13. IRS1 for XDR (?) FeII, SiII, NeII, and SIII detected ionization energy
NeII 12.8 μm has a peak, but FeII 17.9 μm has a hole at IRS1.
Fe is possibly doubly ionized (FeIII !?)
ionization energy
X-ray flare observed with Chandra toward IRS1 (Simon 2009)
XSPEC Model;
NH = 2 x 1023 cm-2 (Av = 100 mag) → XDR ?
LX = erg s-1 Fe
Fe+ Si Ne
S++
7.9 eV
16.2 eV
8.2 eV
21.6 eV
23.3 eV
Need high spectral resolution observations of Fe III

14. Outflows & Shocks

15. Outflows & Shocks
H2 S(1)
Fe II 26
CO 2-1

16. Outflows & Shocks outflow around IRS2 – only ionic lines
→ a dissociative shock ??
FeII 6D7/2-6D9/2 (25.98 μm)
SiII 2P03/2-2P01/2 (34.81 μm)
outflow at NW– strong H2 emission + ionic lines
→ various shock properties??
NeII 2P01/2-2P03/2 (12.8 μm) and SIII 3P2-3P1 (33.5 μm) peak at IRS2 with no elongated emission, so possibly related to infall or outflow very close to the protostar??
Need high spectral & spatial resolution observations

17. Summary
The Spitzer IRS mapping of L1251B revealed a few interesting results!!
Direct detection of ice evaporation from mapping of solid state features:
CO2 ice is heated above 30 K by IRS1.
H2O ice is heated above 100 K by the shock.
IRS1 may generate an internal XDR (if this is true, this is the first detection of a XDR by a low mass Class0 source!!)
The distribution of the H2 and ionic emission imply various shock velocities in this region.

18. What can IGRINS do for protostars?
High velocity resolution observations of CO, H2O, H2, Fe II, and Fe III transitions
Each of this tracer proves slight different physical regimes
With high spatial and spectral resoution we can survey a large sample of protostars selected from Spitzer
Characterize the kinematics of infall/outflow seen in each tracer and explore dynamical evolution
If rotation is detected we can study the angular momentum in the innermost regions near young forming star
Comparison of source luminosity and outflow characteristics in a large sample can set constraints on accretion timescales

19. Thank you.

20. This slide shows the LH spectra toward the same sources
This slide shows the LH spectra toward the same sources. SI, FeII, SIII, and Si II lines were detected in some sources.