20”

S. Molinari – INAF/IFSI, RomeHi-GAL team

IFSI - Arcetri - Univ. Rome 1/2 - Univ. Lecce (Italy), CESR - OAMP - IAS - Saclay (France), RAL - Herts - Liverpool - Cardiff - UCL (UK), IPAC/SSC/JPL - Univ. Colorado - CfA (USA), Toronto - Calgary - U. Laval (Canada), MPIfR -

(Germany)et al.

Hi-GALThe Herschel infrared Galactic Plane Survey

Hi-GAL composite 47° > l > 36°

Hi-GalA Herschel Key-Project for the Far-IR mapping of the inner

Galactic Plane• -60°<l<60° - |b| <1°, i.e.

the GLIMPSE and MIPSGAL areas

• 5 bands 70-500m imaging using PACS and SPIRE in Parallel Mode with crossed-rasters

• Area already surveyed in continuum and spectroscopy over few wavelength decades

Galaxy-wide Census, Luminosity, Mass and SED of dust structures

at all scales from massive YSOs to Spiral

Arms

Hi-GALThe Herschel infrared Galactic Plane Survey

• The High-Mass Star Formation Timeline• Measure the star formation rate and history Galaxy-wide • Cold dust in the Galactic Plane and the Formation of Molecular

Clouds• Understanding star formation laws and the nature of thresholds as

a function of ISM properties across a full range of galactocentric radii metallicity and environmental conditions

• Determining the relative importance of global vs local, spontaneous vs triggering, agents that give rise to star formation.

• Build bottom-up recipes and prescriptions useful for Xgal science20”

Toward a Predictive Global Model of Galactic Star Formation

-70°< l < 70° |b|<1° - 70/160/250/350/500m – 343 hours

Hi-GAL 70/160/350 Composite – Molinari+ 10

W43

Motte, Schilke & Lis 2003PACS 160

The black circle is the ALMA Band 9 primary beam !!

Herschel is crucial for ALMA

The black circle is the ALMA Band 9 primary beam !!

Herschel is crucial for ALMA

Bally+ 10

G29.96-0.02 Beuther et al. 2007

1”

A Mass-Size power-law with exponent 1.33 is found to discriminate structures on the basis of their ability to form massive stars(Kauffmann et al. 2010)

The majority of sources are dense clumps which should be able to form M* > 10 M stars.

Nature of the compact sources

Nature of the compact sources

M=M J

The majority of the detected cores are gravitationally

supercritical

Jeans conditions for gravitational instability

€

MJ (MΘ) =T

10K

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− 12 Mean Clumps

Temperature

Nature of the compact sources

ZAMS

ACCRETION

Krumholz & McKee (2008)L/M due to accretion onto low-mass protostars, at given SFR and IMF

L/M where accretion radiation is sufficient to halt fragmentation of low-mass cores

≈1 g cm-2

A significant fraction of the clumps should be already forming high-mass protostars (M≥10M)

Molinari+ 2008

However…

The actual core surface density is significantly below what the Krumholz & McKee 08 theory predicts (Elia+ 10)

Other agents supporting against fragmentation, other than accretion radiation from low-mass protostars, must be at work.

Magnetic field is a possibility (Commerçon+ 10, although in a slightly different context)

l = 59° - SPIRE 250

The Filamentary Nature of Star FormationMolinari+ 10

Filament and compact objects

• Compact sources are mostly found associated to filamentary structure

• There is no apparent correlation between mass of compact sources and the column density of the hosting filament

• There is a strong suggestion for a threshold effect around AV≈1 Hollenbach et al. 1991

Filament fragmentationHeitsch et al. 2008

Local filaments density

Preliminary filament section measurements in the l=59° region give values between 0.5 and 1pc.

Local filaments temperature Conclusion: filaments form from

diffuse ISM and grow in column density until at AV≈1 heating and cooling go out of balance. Gravitational instability comes in and high-density fragments start to appear.

Is B important in filament fragmentation ?

Filaments hosting compact sources span a N(H2) range which is compatible with structures losing magnetic

support and starting to collapse

Filaments hosting compact sources span a N(H2) range which is compatible with structures losing magnetic

support and starting to collapse

M/=1

Fiege & Pudritz 2000

Census of Filaments (Schisano+, in prep.)

Automated Filament Detection

• Complete catalogue of filaments• Statistics of filaments length and cross-size• Multi-scale analysis to obtain hierarchical information

Properties of filaments and their relationship to cores/clumps

(Schisano+, in prep.)

Cross-matching to compact source catalogues to:• subtract flux of compact sources from the integral under the RoIs• Obtain statistics of filament/clump associations

• Subtract background from nearby regions• Fit greybodies to measure Masses and Temperatures• Cross-match to molecular line databases to (e.g. GRS) to obtain velocity dispersion: virial masses, confirm physical nature, …

The Earliest Stages of High-Mass SF : Shadows…

PACS 70

PACS 160

SPIRE 250

and Lights

Peretto+ 10D=3kpc

D=12 kpc

• ALMA will allow comprehensive studies of SF regions over the entire Galaxy, “unlocking” access to the same level of detail we currently have for nearest regions• Hi-GAL will constitute the essential input database for statistically significant studies of the earliest stages of massive SF and the lifetime of pre-stellar phase• ALMA will enable us to

• resolve the Jeans length Galaxy-wide• address the early fragmentation of clumps and filaments across a variety of Galactocentric distances, metallicities and environmental conditions (morphology, chemistry and dynamics)

Triggered Star Formation(5’x5’ field) – Zavagno+ 10

300° 298°

Hi-GAL coming along…SPIRE 250m

The future is bright

The outer Galaxy is unique to complete a large and otherwise uncharted parameters space:

• Get SFR, SFE, SFH vs R. Different SF thresholds ? Different S-K law ?

• Is the path from clouds to protostars the same ? Different timescales ? Different agents ?

• Build the bottom-up recipe of an entire Galaxy

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The HOTAC granted 278 hours in OT1 to cover another 120° longitude range centered on the anti-center. The greater Hi-GAL now covers 520 sq. deg.

Most of it will be accessible by ALMA !!

The future is bright

Hi-GAL is a goldmine for the Community to peruse !!

For your science….to plan ALMA science….to maximize ALMA science

Data are already public as they come out of the standard pipeline

The Hi-GAL Consortium will start incremental releases of high-quality products (images and catalogues) 6 months after the data

taking of 1st survey

The SDP tiles enhanced products will be released shortly

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