Ionized components in star
forming regions byspectroscopic observations
Masao Saito (NRO=>NAOJ TMT Project)

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Introduction:
Star-formation & magnetic fields

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Scientific Background• Star Formation• Wide coverage of density and temperature (too general comments)• Magnetic field – important role – how at earliest stage?
• Jet/outflow – magnetic field involved – launching mechanism?
• Atomic/ionized component. – less dense ionized regions• Planet Formation (ALMA)• High resolution is a key.
• New radical ideas may be needed ([N II])

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Formation of Stars and Planets

Magnetic field
Angular momentum
in a core scale
BcoreRcore2
Core scale
103-4 au
2017/3/2-3Magnetic field and removal
angular momentum in a
jet/outflow
BcoreRcore2 - BdiskRdisk2 -B*R*2
Jet/Disk scale
100-3 au
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Stellar scale4Antarctica 30 m telescope• Ground Based Telescope• Large Collecting Area
• Good Angular Resolution (afew arcsecs)• Potentially wide frequencycoverage• Antarctica Site• New atmospheric window• Advantage：inaccessible
windows from MK orAtacama• Disadvantage: Single dish• Targets:

Frequency vs Angular Resolution

543[“]

2100500

1500

2000

Frequency [GHz]• size >> angular resolution

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1000

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Complemental Instrument
High Resolution• Herschel• ALMA• NRO45m

ALMA

Antarctica 30m

10 mm

Herschel

NRO45m

0.1 mmBoundary
Betweenradio and IR

PLANCK

Low Resolution
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Target (2” resolution)
size

D=10 pc

D=150 pc

Debris Disk

100 au20 au

300 auProtoplanetary disk

100 au300 auLow-mass star

100-10000 au

300 auLow-mass jet/outflow

1-10000 au

2000 au

Hot core (IRDC)

100-10000 au

2000 au

0.1 pchigh-mass outflow

100-10000 au

2000 au

0.1 pcCloud (CCC)

1-5 pc

GMC (SNR)

10-100 pc

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D=1kpc

D=10 kpc

2000 au

0.1 pc2000 au

0.1 pc7

Measurement of Magnetic Field• See Momose-san’s
Presentation in continuum• Zeeman (HI, OH, CN)• Circular polarization measurement |B| along theline of sight.

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Measurement of Magnetic Field• Zeeman in reality• Extremely difficult (e.g. instrumentalcalibration)• E.g. Df ~ 64 Hz @100mG in CCS at 45
GHz << thermal broadening

64 Hz@100 mG

水野2014@NROUM
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Ionization Fraction

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南極30m級テラヘルツ望遠鏡によるサイエンス10Measurement of Ionization Fraction• If zero, no magnetic force is exerted.
• Ambipolar diffusion• Dense cores slippage of gas through the ambient magnetic field.
• Time scale critically depends on the ionization fraction.

• Ionization fraction x(e)=ne-/nH• ~ 10-7 from previous studies

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Measurement of Ionization Fraction:++
DCO /HCO

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南極30m級テラヘルツ望遠鏡によるサイエンス12• [e-] ~ 10 -7+-0.5 for lowmass dense cores(Willaims+98)• [e-] ~ 10 -6.9-7.3 for highmass dense cores(Bergin+99)• This method cannot be
apply to cold dense cores.
Williams+1998
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Cold Dense Cores: Depletion
Caselli+99

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Measurement of Ionization Fraction: H2D• H2D+ is a more direct probe of ionization fraction.
• H2D+ is more robust against depletion in dense cold cloud cores.
• It is not easy to observe at 372.421 GHz from ground based
telescopes.

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H2D+

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Measurement of Ionization Fraction: H2D• L1544: low-mass prestellar core

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Caselli+03

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+
Measurement of Ionization Fraction: H2D• x(H2D+)=N(H2D+)/N(H2) ~1x10−9• x(e) ~ 2 x 10-9
Caselli+03• x(H2D+) ~ x(e)• Applicable to colddense cores (IRDC) or
dead zone.
fD: CO depletion
factor2017/3/2-3

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Outflow

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Outflow components• Molecular• CO• HCO+• H2• Atomic• HI• [C I]• Ionized• [N II]

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Yıldız+15 CO(6-5) with APEX

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Bjerkeli+16

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Atomic and Molecular Component• Spatial Distribution• Momentum• Only few [C I] observations

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Lefloch+07 HH111

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Ionized Gas

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22Ionized Gas• [H II]• Halpha• Recombination Lines• [C II]• PDR• Coexist with H• [N II]• > 13.6 eV• Hard tracer

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[N II]

Goldsmith+15• Exclusively trace (embedded)
young massive star, not thewarm ionized medium• Template for extragalacticobjects• Applicable to jet/outflow orprotoplanetary disk?

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[N II] map of Carina• Corresponds to ionized region• Trace extended Low-density(ELD) ionized region.

Oberst+11 with SPIFI2017/3/2-3

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Proposed Observations

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+H2D Targets• Goal: To derive x(e) in dense cold cores at pre-stellar phase• Av ≳ 10 mag., or N(H) ≳ 5.8×1021 cm-2 & cold (T ≈ 10K) regions (tobe complimentary to near-IR and SPICA), Low-mass prestellar cores
and/or IRDCs• Same targets as Momose-san’s talk• dTA* = 0.3 K in TB• dn = 0.25 km/s
• Mapping area 120” with 2” sampling• Obstime ~ 60/4 x 60 x 60 x 3 sec ~ 45 hr
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[C I]/CO(7-6) Targets• Goal: To derive momentum of atomic component of young outflows• Low-mass Protostars• dTA* = 0.54 K in TB• dn = 1 km/s
• Mapping area 120” with 1” sampling• Obstime ~ 120/4 x 120 x 30 x 3 sec ~ 180 hr

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[N II] Targets• Goal: To reveal spatial distribution of hardness of ionization• Cluster Regions• dTA* = 2 K in TB• dn = 1 km/s
• => dt = 45 sec• Mapping area 70” with 0”.7 sampling• Obstime ~ 100/4 x 100 x 45 x 3 sec ~ 94 hr

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29System Requirement• Antenna ([N II] Observable at 1.5 THz)
• Pointing (<1/10 qFWHM) – overcoming disturbance and pointing jitter• Surface accuracy (< 16/l ~ 12 mm)• Rx• Frequency Coverage (373 GHz observable (currently at band edge?)• Sideband Rejection (> 10 dB) – Avoid noise from an imaging band
• IF bandwidth (> 10 GHz) CO/[C I] obs with HCO+
• Spectral dynamic range
1.5 THz with 3.5 GHz width ~ 115 GHz with 250 MHz• Gain Stability• Data Storage
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Calibration Requirement• Amplitude Calibration (not established > 1 THz)
• Absolute• Relative (repeatability)• Pointing/squint/focus• Pointing jitter?

• Surface/Efficiency

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Summary• Star Formation Study with the 30 m telescope• Ionization fraction (H2D+)• Atomic/molecular outflow ([C I]/CO)• [N II] observations• System requirements to be considered accordingly• Each science topic in the present talk is to be compared against othermethods in detail.
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