1 / 15

Star Formation with the SKA

Star Formation with the SKA. HII Region RCW 38 (VLT & ATCA). Tyler Bourke - Harvard-Smithsonian CfA. Star Formation with the SKA. What we know (or think we know) What we don't know, but would really like to What the SKA can do for Star Formation Studies

heulwen-evans
Download Presentation

Star Formation with the SKA

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Star Formation with the SKA HII Region RCW 38 (VLT & ATCA) Tyler Bourke - Harvard-Smithsonian CfA

  2. Star Formation with the SKA What we know (or think we know) What we don't know, but would really like to What the SKA can do for Star Formation Studies (and why going to 24 GHz is important)

  3. What we know Stars form within the dense cores of Molecular Clouds Young Stars are surrounded by Circumstellar Disks Young Stars produce energetic Bipolar Outflows NH3

  4. Properties of Dense Cores n ~ 104 cm-3 M ~ 10 MO r ~ 0.1 pc T ~ 10 K aspect ratio ~ 2:1 B = ???? mG

  5. Young Stars have Disks • Mdisk ~ 0.02 MO ; r ~ 100 AU

  6. HL Tau - S ~ r-1 GM Aur - 1.3 mm cont. - 12CO 2-1

  7. Young Stars drive Outflows • - Large scale molecular component (CO) • - Narrow ionized components • (Herbig-Haro objects, radio jets) • - Neutral winds ? (HI)

  8. HH211 L1551 HI (VLA) HH1-2

  9. What we would like to know Magnetic field strengths in cores (THE best way our for theorists) The structure of circumstellar disks (small scale structure and dynamics) How are outflows driven? Where do they originate?

  10. Magnetic fields in dense cores • - EXTREMELY difficult to measure • (only viable method is the Zeeman effect) • - Zeeman splitting independent of n, but • Doppler width is not - best at low freq. • - THE most important unknown quantity • in any theory of star formation

  11. Magnetic Fields in Dense Cores mm lines - not bright in low-mass cores (CN 113 GHz) - frequency vs line-width problem - many, many hours per point OH lines (1.6 GHz) - best to date, but n < 103 cm-3 Zeeman With SKA sensitivity, CCS at 11 GHz may be best (CCS lines at 11, 22, 34 GHz) (SO at 13 GHz - maybe)

  12. Protostellar Disk Studies Multifrequency Continuum Studies - dust optically thin at cm wavelengths - separation of thermal and non-thermal components - probe the densest gas and the ionized component Complementary to ALMA

  13. Outflow Studies Continuum Studies - probe the inner regions where the jets originate (connection between jets and disks) - trace the ionized gas to larger distances (connection to optical/IR emission - full history) Line Studies - where does the HI originate (does some combination of neutral and ionized components drive the large scale CO outflow?) - Recombination lines for kinematics of the ionized gas

  14. 24 GHz - ammonia studies The only molecule that allows for the determination of both temperatureand number density, using the (1,1) and (2,2) inversion transitions near 23.7 Ghz, observed simulatenously with similar angular resolution - does not suffer from "funny" chemistry - widely detected in both low- and high-mass cores (CCS at 22 GHz as a bonus - 2 transitions for Zeeman work)

  15. NH3 (1,1) NH3 (2,2) NH3 (3,3) & SiO Qizhou Zhang et al.

More Related