Using masers to characterise possible HCHII regions and pre-UCHII region stages of star formation

1. Using masers to characterise possible HCHII regions and pre-UCHII region stages of star formation Shari Breen Bolton Fellow 8th September 2010

2. Masers as evolutionary traces of star formation? • Historically, attempts to construct a sequential timeline for the common maser species uncovered mixed/contradictory results • Typically derived from biased searches with poor sensitivities and positional accuracies or limited to ‘special’ sources • VLA study of water maser towards OH masers (Forster & Caswell 1989) found that the water masers appear first, followed by the OH emission • Different species of masers trace different physical conditions (e.g. Cragg et al. 2005) • Arise in different locations within e.g. GMCs Breen et al. 2007 CSIRO. Using masers to characterise possible HCHII and pre-UCHII region stages of star formation

3. Masers as evolutionary traces of star formation? • Walsh et al. (1998) found that 6.7 GHz methanol masers present before a detectable UCHII counterpart is present • Caswell (1997) found that those 6.7 GHz methanol masers with UCHII region counterparts preferentially associated with OH • Garay & Lizano (1999) concluded that water masers are present prior to emission from methanol maser emission • Beuther et al. (2002) found that more water masers where associated with cm radio continuum than methanol masers; methanol masers more sensitive to the ignition of the central object • Comparison between class I, class II methanol and OH masers with GLIMPSE point sources by Ellingsen (2006) supported an evolutionary scenario whereby class I sources are present first, followed by class II and finally OH masers CSIRO. Using masers to characterise possible HCHII and pre-UCHII region stages of star formation

4. Masers as evolutionary traces of star formation? • Fontani et al. (2010) suggest that both class I and class II sources become more prominent with evolution (although the observations leading to this conclusion have sensitivity biases) • Caswell & Breen (2010) suggested from a systematic water maser search that a class of source dominated by highly blue-shifted emission may precede the methanol masers • Ellingsen et al. 2007 present a ‘straw man’ model of the relative evolutionary phases that the different maser species are tracing CSIRO. Using masers to characterise possible HCHII and pre-UCHII region stages of star formation

5. Methanol, water and OH masers towards 1.2 mm dust clumps 6.7 GHz methanol (MMB) • Hill et al (2005) carried out 1.2 mm dust continuum observations towards 6.7 GHz methanol masers from Walsh et al. (1998), detecting 404 sources • Maser observations: • 6.7 GHz methanol masers known (since they were targets) • cm radio continuum known for most sources (e.g. Walsh et al. 1998) • 12.2 GHz observations towards 112 6.7 GHz methanol masers carried out with Parkes (5σ = ~0.11 Jy) • Water maser observations completed with the ATCA towards 294 of the 1.2 mm dust clumps • 12 GHz methanol masers towards MMB sources • Water maser towards OH and methanol masers OH (Caswell et al. 2010) 1.2 mm dust Hill et al. (2005) Water (Breen et al. 2010) 8 GHz cont (Walsh 1998) CSIRO. Using masers to characterise possible HCHII and pre-UCHII region stages of star formation

6. Methanol masers towards dust clumps • 6.7 GHz methanol masers targeted for 12 GHz methanol maser emission • 68 detections towards 112 sources (60 % detection rate) • Data split into 3 groups of presence/absence data in order to compare the dust clump properties from Hill et al. (e.g. mass, radius, mass, H2 number density, flux density…) • with and without 6.7 GHz methanol masers • 6.7 GHz with and without 12 GHz methanol masers • With and without radio continuum • 1.2 mm clumps with associated radio cont have higher values of mass, radius, peak and integrated flux density and lower values of density • 6.7 GHz methanol masers are associated with 1.2 mm dust clumps that have higher values of integrated and peak flux densities, mass and radius. • 6.7 GHz sources with higher luminosities are more likely to be associated with OH masers and have lower H2 number densities and have larger mass and radii CSIRO. Using masers to characterise possible HCHII and pre-UCHII region stages of star formation

7. Methanol masers towards dust clumps • 1.2 mm clumps both 6.7 and 12.2 GHz methanol masers are more likely to be associated with OH masers and have lower densities • The luminosity of 12.2 GHz methanol masers is not dependent on the presence of radio continuum 12 GHz sources are associated with the later stages of the 6.7 GHz lifetime CSIRO. Using masers to characterise possible HCHII and pre-UCHII region stages of star formation

8. 12 GHz methanol masers towards the MMB sources • Definitive, sensitive search for 12 GHz sources towards an unbiased sample of 6.7 GHz sources • 250 detections 43 % detection rate • Both flux density and velocity ranges of the methanol masers increase as they evolve • 6.7 GHz sources increase more rapidly than the 12 GHz sources • Lower luminosity 12 GHz sources are more variable and are rarely associated with OH masers • Complete searches of OH (Caswell 1998), 6.7 (MMB) and 12 GHz methanol masers allow relative lifetimes of sources to be derived CSIRO. Using masers to characterise possible HCHII and pre-UCHII region stages of star formation

9. Water masers towards dust clumps • 294 of the 404 Hill et al. (2005) sample targeted for water masers with the ATCA • 165 detections towards 128 clumps -> 44 % detection rate • Positions of the water masers are consistent with the peak positions of most of the dust clumps. • More dust clumps show ‘only water’ than ‘only methanol’ • Increase in both flux density and velocity range from mm only -> methanol -> methanol + cont CSIRO. Using masers to characterise possible HCHII and pre-UCHII region stages of star formation

10. Water masers towards OH masers • Breen et al. (2010) -> large catalogue of water masers • 379 water masers detected towards a complete sample of OH masers and a selection of methanol maser sources • 128 associated with both OH and methanol masers • 33 associated only with OH masers • 70 associated with methanol masers • 148 sources are solitary (these are also the most variable and weakest) CSIRO. Using masers to characterise possible HCHII and pre-UCHII region stages of star formation

11. Evolutionary scheme for the common maser species Best maser targets would be sources that exhibit only: water or methanol masers (or both) CSIRO. Using masers to characterise possible HCHII and pre-UCHII region stages of star formation

12. Contact Us Phone: 1300 363 400 or +61 3 9545 2176 Email: enquiries@csiro.au Web: www.csiro.au Thank you CSIRO Astronomy and Space Science Shari Breen Bolton Fellow Phone: 02 9372 4325 Email: Shari.Breen@csiro.au Web: www.atnf.csiro.au CSIRO. Using masers to characterise possible HCHII and pre-UCHII region stages of star formation

13. HCHII and Class I methanol masers Max Voronkov Software Scientist – ASKAP 08th September 2010

14. “Remote” talk, thanks to Kate for presenting…. Talk is about class I (or collisionally pumped) methanol masers Different maser species may trace different evolutionary stages Stages traced by class I masers are not fully understood • I am flying back to Australia right now • This presentation will cover just a few basic points

15. Evolutionary sequence traced by masers Image credit: Cormac Purcell Image credit: Simon Ellingsen • Ellingsen (2006): class I masers tend to be deeply embedded younger. Recent studies suggest that there are many old class I masers! • Multiple mechanisms responsible for these masers: outflows, ionisation shocks • Notable overlap with OH masers and UCHII regions • Earliest stage with these masers is not constraned (no blind surveys) Overlap with HCHII regions is likely!

16. Future plans (MMB follow up) MMB = Methanol Multibeam survey, unbiased survey of the 6.7 GHz (class II) masers • We plan to follow up southern MMB detections (6.7 GHz, class II) as well as sites with high mass star-formation activity traced by other means in class I maser transitions towards • Probably not in this semester, as the proposal grade is not great • Continuum at 7mm will be observed as a by-product with CABB • Expected noise levels (1 sigma) about 0.1 mJy • Can search for HCHII • Collaboration is certainly possible - talk to me in Townsville

17. Contact Us Phone: 1300 363 400 or +61 3 9545 2176 Email: enquiries@csiro.au Web: www.csiro.au Thank you Australia Telescope National Facility Max Voronkov Software Scientist (ASKAP) Phone: 02 9372 4427 Email: maxim.voronkov@csiro.au Web: http://www.narrabri.atnf.csiro.au/~vor010