RAMPS: The Radio Ammonia Mid-Plane Survey. James Jackson Institute for Astrophysical Research Boston University

Transcription

1 RAMPS: The Radio Ammonia Mid-Plane Survey James Jackson Institute for Astrophysical Research Boston University High Frequency Workshop, Green Bank, 21 September 2015

2 Collaborators (partial list) Taylor Hogge Ian Stephens Scott Whitaker Jonathan Foster Anish Roshi Boston University Boston University Boston University Yale NRAO

3 All (high-mass) stars form in clusters or groups from a single molecular clump Orion Trapezium cluster 4 high mass stars; ~3500 total stars 2 pc molecular clump 4500 M gas mass The clump is the fundamental unit of cluster formation. Hubble Space Telescope; near-ir Lada et al. 1997, Lada & Lada 2003

4 How do high-mass star-forming clumps evolve? Determine their evolutionary stage Characterize their physical properties: Temperature Density Column Density Kinematics Chemistry Fragmentation

5 0.2 degrees The evolutionary phases of high-mass star forming clumps 1.2 degrees The Nessie Nebula Jackson et al ApJ Letters Blue - 3.6µm, Green - 8µm, Red - 24µm Image credit: NASA/JPL-Caltech/Univ. of Wisconsin

6 Pre-stellar Early stage Cold pre-stellar clump Blue - 3.6µm, Green - 8µm, Red - 24µm Image credit: NASA/JPL-Caltech/Univ. of Wisconsin

7 Protostellar Intermediate stage Protostellar clump Blue - 3.6µm, Green - 8µm, Red - 24µm Image credit: NASA/JPL-Caltech/Univ. of Wisconsin

8 H II region Later stage Stellar H II region clump Blue - 3.6µm, Green - 8µm, Red - 24µm Image credit: NASA/JPL-Caltech/Univ. of Wisconsin

9 Photodissociation Region (PDR) Latest stage Photodissociation region (PDR) Blue - 3.6µm, Green - 8µm, Red - 24µm Image credit: NASA/JPL-Caltech/Univ. of Wisconsin

10 Temperature and Column Density Evolution (MALT90 targets) The Herschel data indicate evolution. The clumps dust temperature increases from 15 to 25 K. Column densities increase, then decrease Guzman et al. 2015

11 Dust continuum surveys of high-mass starforming regions: HiGAL, ATLASGAL, BGPS, Limitations: 1. Blend of many dust clouds along line of sight 2. Cannot establish distances or internal motions. 3. Opaque at mid-ir (and sometimes FIR) 4. Luminosity dominated by hottest dust. (L~T 4+β ) 5. Relatively poor angular resolution at optically thin submm/mm wavelengths Color: HiGAL Herschel images; Contours: GBT NH 3 (1,1) integrated intensity

12 Ammonia Inversion Lines NH 3 (1,1) NH 3 (2,2) Probe only dense star-forming gas Velocities yield kinematic distances and internal motions. Multiple NH 3 inversion lines at ~same frequency yields gas temperature. Relative intensity of hyperfine lines yields column densities.

13 The Radio Ammonia Mid-Plane Survey: RAMPS K-band Focal Plane Array on the GBT Lines: NH 3 (1,1); (2,2); (3,3); (4,4); (5,5) [7 beams] H 2 O maser (1 beam) CH 3 OH masers (1 beam) Blind survey Goal: l = 10 to 40 d, b = -0.5 to 0.5 d

14 Status Completed observations of 6.4 square degrees. Completed processing of NH 3 (1,1), NH 3 (2,2), and H 2 O maser data Upon verification, data cubes and moment maps will be available at NH 3 (3,3), (4,4), and (5,5) data will be available ~ December 2015

15 RAMPS NH 3 (1,1) integrated intensity 1 degree Blue represents 1 K km/s and red 20 K km/s

16 RAMPS NH 3 (1,1) integrated intensity

17 RAMPS (GBT KFPA) vs. HOPS (Mopra, Single pixel 13 mm ) RAMPS HOPS Walsh et al. 2008, 2010

18 Int. Intensity Velocity T rot Column Density

19 Int. Intensity Velocity T rot Column Density

20 Water Masers

21 Water masers 619 H 2 O Maser Sites Associations 60% star formation sites 26% evolved stars 14% unknown One source has 28 velocity components spread over ~120 km/s

22 The unusual source G Enormous linewidths V ~ 25 km/s ~10 x wider than typical sources Odd line shapes, especially in NH 3 (3,3) 2 nd moment (line width) image NH 3 (2,2)

23 The unusual source G Enormous linewidths V ~ 25 km/s ~10 x wider than typical sources Odd line shapes, especially in NH 3 (3,3) 2 nd moment (line width) image NH 3 (2,2)

24 Associated with filamentary Infrared Dark Cloud Blue - 3.6µm, Green - 8µm, Red - 24µm Contours RAMPS NH 3 2,2

25 RAMPS NH 3 spectra G Unrelated

26 Compact Array NH 3 1,1 and 2,

27 Compact Array NH 3 3,

28 G Minimum surface brightness of NH 3 (3,3) spike is ~8,000 K. It is a MASER. Very rare Likely shock-excited Powerful outflow Enormous linewidths indicate extremely turbulent, active, high-mass star-forming region in very early stage Important target for ALMA, JVLA,.

29 Summary RAMPS has completed mapping 6.4 square degrees along the galactic plane RAMPS has detected ~500 clumps in NH 3 and measured their temperature, column density, and velocity. RAMPS has detected 619 H 2 O maser sites. The unusual source G is an extreme example of a very young highmass star-forming region. Data will soon be posted at