•Millimetre Astronomy Legacy Team

• 90 GHz survey

MALT 90

James Jackson (Boston University)

Kate Brooks, Jill Rathborne (ATNF), Jonathan Foster (Boston U), Gary Fuller (Manchester), Friedrich Wyrowski

(MPIfR), and 38 others….Great Barriers Townsville 2010

High-mass star formation: dense cores

Giant Molecular

Cloud

OH Masers

CH3OH + H2O Masers

High-massStarHII Region

High-massStar

Pre-UCHII + IRUCHIIHCHII + cm

Hot Molecular Core

mm onlyStarless Core

WarmCompact mid-IR sources4.5 m “green fuzzies”

Protostellar core

ColdDark in the mid- and far-IR

Starless core

Hot Core

Hot H II region embeddedStrong, extended mid-IR emissionStrong 8 m PAH emission

Slide courtesy of Kate Brooks

Image credit: NASA/JPL-Caltech/Univ. of WisconsinBlue - 3.6m, Green - 8m, Red - 24m

1.2 degrees

0.2

degr

ees

Cores in the Nessie Nebula

Image credit: NASA/JPL-Caltech/Univ. of WisconsinBlue - 3.6m, Green - 8m, Red - 24m

Cores in the Nessie Nebula

Cold core

Image credit: NASA/JPL-Caltech/Univ. of WisconsinBlue - 3.6m, Green - 8m, Red - 24m

Cores in the Nessie Nebula

Protostellar core

Image credit: NASA/JPL-Caltech/Univ. of WisconsinBlue - 3.6m, Green - 8m, Red - 24m

Cores in the Nessie Nebula

Stellar “H II region” core

MALT 90: The Millimetre Astronomy Legacy Team 90 GHz Survey MALT 90 will image 3,000 high-mass cores

with Mopra in key 90 GHz molecular lines, e.g. N2H+, HCO+, HCN, HNC…

The survey will be complete: all high-mass star forming cores (M > 200 M) to 10 kpc.

It will provide key information for Herschel and ATLASGAL studies

MALT 90 sources will be key targets for ALMA

ALMA will be able to image any core detected in MALT 90 at 1” angular resolution with excellent signal-to-noise

MALT 90 science goal:How do high-mass star-forming cores evolve?MALT 90 will provide

Kinematic distances Column densities Molecular chemical abundances Virial masses Core kinematics A large sample of the elusive youngest cores

Why 90 GHz ? Molecular lines at ~90

GHz require high densities for their excitation (n > 105 cm-3)

These lines are therefore sensitive ONLY to dense star-forming cores.

Dense core

13CO

C18O

CS

Image credit: NASA/JPL-Caltech/Univ. of WisconsinBlue - 3.6m, Green - 8m, Red - 24m

1.2 degrees

0.2

degr

ees

All of these cores are strong molecular line emitters easily detected by Mopra

Size ~100 pc x 0.5 pc

Mopra HNC (1-0) integrated emissionFor more on Nessie see Jackson et al. 2010

ApJL

The MALT 90 strategy

A blind fully-sampled 90 GHz Galactic plane survey is impractical 90 GHz emission is relatively weak Dense cores have a small solid angle

BUT submm thermal dust emission indicates cores The ATLASGAL 870 m survey of the Galactic

plane has now identified thousands of cores. ATLASGAL sources will be imaged with Mopra in

molecular lines.

ATLASGAL 0.87 mm

Spitzer/MIPS 24 m

Mopra HNC (1-0) integrated emission

Core classification : Spitzer GLIMPSE/MIPSGAL

Pre-stellar Protostellar H II region

Blue 3.6 m Green 8 m, Red 24 m Spitzer: GlIMPLSE?MIPSGAL

The primary goal of the MALT 90 GHz Survey is to characterize star-forming cores and to study their physical and chemical evolution

MALT 90 Survey Observing Parameters16 lines

3’ x 3’ maps

Two orthogonally scanned “on-the-fly” maps for each source

38” angular resolution

0.05 K sensitivity

0.1 km s-1 spectral resolution

ATNF Mopra 22 m

Selected linesIF Line Frequency

(MHz) Tracer

1 N2H+ 93,173.772 Density, chemically robust

2 13CS 92,494.303 Optical depth, Column density, VLSR

3 H41 92,034.475 Ionized gas

4 CH3CN 91,985.316 Hot core

5 HC3N 91,199.796 Hot core

6 13C34S 90,926.036 Optical depth, Column density, VLSR

7 HNC 90,663.572 Density; cold chemistry

8 HC13CCN 90,593.059 Hot core

9 HCO+ 89,188.526 Density

10 HCN 88,631.847 Density

11 HNCO 413 88,239.027 Hot core

12 HNCO 404 87,925.238 Hot core

13 C2H 87,316.925 Photodissociation region

14 SiO 86,847.010 Shock/outflow

15 H13CO+ 86,754.330 Optical depth, Column density, VLSR

16 H13CN 86,340.167 Optical depth, Column density, VLSR

Hot vs. Cold Core 90 GHz spectra

HCO+

N2H+

HNC

HCN

H13CO+

C2HH13CN

HC3N

CH3CN

HNCO

HCO+

N2H+

HNC

HCN

H13CO+

C2HH13CN

HC3N

CH3CN

HNCO

Hot Cold

Complex line profiles

Infall Outflow Self-absorption

HCO+ 1-0

Complex Chemistry: An N2H+ “only” source; associated with starless or protostellar cores

N2H+

HNCHCN

HCO+

Blue - 3.6m, Green - 4.5m, Red – 8 m from GLIMPSE survey

Complex Chemistry: An N2H+ “drop out”; typically associated with H II regions

N2H+

HNCHCN

HCO+

Blue - 3.6m, Green - 4.5m, Red – 8 m from GLIMPSE survey

A combination of N2H+ “only” and “drop out” morphologies

N2H+

HNCHCN

HCO+

Blue - 3.6m, Green - 4.5m, Red – 8 m from GLIMPSE survey

Source Velocities

Source: CfA-Columbia CO survey

CO l-v (position-velocity) diagram

VLS

R

Galactic Distribution of Cores: High-mass stars forming in spiral arms

Current status Observations began in July 2010 Over 600 sources mapped Data pipeline in place Analysis underway All data will be made public after

verification and calibration

MALT 90 Team Meeting

Tomorrow (Tuesday) from 12:00—13:30 New team members are welcome!

Summary

MALT 90 will map ~3000 dense, star-forming cores with the Mopra telescope in 16 different molecular lines near 90 GHz

ATLASGAL cores are the targets Spitzer GLIMPSE/MIPSGAL images will allow us

to classify cores: Pre-protostellar cores Protostellar cores HII regions

MALT 90 will be an enormous, systematic molecular line survey of dense cores and an excellent resource for

Herschel and ALMA.