Download eMERLIN_KP - Leeds Astrophysics

School of Physics
something
& Astronomy
FACULTY OF MATHEMATICS
OTHER
& PHYSICAL SCIENCES
e-MERLIN Key Project on Massive
Star Formation
Melvin Hoare
Jim Jackson (Boston University)
Gary Fuller (University of Manchester)
Janet Drew (Imperial College London)
Why Massive Star Formation?
• Underpins much of
astrophysics
• Pop III & Primeval galaxies
• Starbursts
• Galaxy evolution
• Feedback, Superwinds,
Chemical evolution
• Extreme environments
• SNe, GRBs
• NS, BH
Gemini Observatory - GMOS Team
Key Unsolved Questions
• What determines the
upper IMF?
• Accretion physics?
• Outflow physics?
• Evolutionary scheme?
Accretion Physics
Magnetically/turbulently controlled collapse or triggering?
Krumholz et al. (2005)
IRAM 30m 13CO 1-0 map
Spitzer 8mm image
Outflow Physics
Radiation or magnetically driven winds and outflows?
X-wind (Shu et al. 1997)
or disk wind (Ouyed et al. 2003)
Drew et al. (1998); Proga (2000)
Outflow Physics
Bipolar or cometary at the onset of the H II region phase
NGC 7538 IRS 1
Evolutionary Scheme
Massive pre-stellar core
Inactive IR Dark Cloud
Active IR Dark Cloud
Methanol masers
Hot molecular core
Massive young stellar object
Water masers
Hyper-compact H II region
Ultra-compact H II region
OB cluster
Context
• Exploitation of Galactic Plane surveys at a range of
wavelengths – many UK led
• Build on discoveries made with MERLIN and the VLA
• Currently only a few bright/nearby examples of the later
stages have been studied
Equatorial Winds and Jets
Blue/red contours 8/22 GHz VLA map
MERLIN 5 GHz 0.1" (image)
Image: SMA 850mm dust continuum
2mm speckle 0.2" (contours)
Patel et al. (2005)
Hoare (2002)
Galactic Plane Surveys
Survey

Beam
I/VPHAS+
H
0.7"
UKIDSS GPS
J,H,K
0.7"
0.02mJy
GLIMPSE
4-8 mm
2"
1
MSX
8-21 mm
20"
100
MIPSGAL
24, 70 mm
6, 20"
AKARI
50-200 mm
30-50"
400
Herschel
200-500 mm
17-34"
20
JCMT/APEX
450/850 mm
8-14"
4
GRS
13
46"
Molecular Gas
Arecibo/MMB
CH3OH
0.1"
Masers
IGPS
H I 21 cm
60"
Atomic Gas
CORNISH
5 GHz
1"
CO 1-0
Sens.
Probe
Nebulae, Em *
Stars & Nebulae
Hot Dust
Warm Dust
2
Cool Dust
Compact Ionized Gas
Key Project Sample
• Well selected sub-samples from the surveys that cover a
range of masses and evolutionary stages
UCHIIs
Transition objects?
MYSOs
HMCs/IRDCs
Key Project Outline
• Active IR Dark Clouds from GLIMPSE/MIPSGAL/GRS
• Methanol maser sources from Arecibo/MMB
• Massive YSOs from Red MSX Source survey
• Herbig Be stars from IPHAS
• UCHII regions from CORNISH survey
• Distance limited samples (e.g. < 7 kpc) to preserve physical
spatial resolution
Key Project Outline
• 20/40 from each category for full/half tracks at 4-8 GHz
• 1/16th BW on the methanol maser 6.7 GHz line
• Including Lovell gives 2-3 mJy/beam noise level
• 1000 hours in total
Why Key Project?
• Avoid piecemeal approach through PI programmes
• Good sample selection only way to unlock evolutionary
trends
• Builds co-operation between Galactic Plane survey teams
• Pools expertise within these teams
• Will answer key questions
• Onset of wind and H II region phases
• Driving mechanisms
Low-Mass YSO Key Project
NICMOS
WFPC2
VLA 8 GHz
Stellar Jets
• Key tests of MHD driving mechanisms
Shang et al. (2002; 2004)
6/1.5 AU resolution at 140 pc