Photo Credit: Levente Buzas, University of Victoria From Clumps to Cores to Protostars: The GBS First Look at Southern Orion A Steve Mairs - JCMT User’s Meeting - 南京 (Nanjing) 2017 with: Dr. Doug Johnstone, Dr. Helen Kirk, and the JCMT GBS Team Overview 1. Connecting Large and Small-scale Structures with the JCMT 2. The JCMT Gould Belt Survey (SCUBA-2) 3. Characterising Significant Structure 4. Connecting dust emission with Young Stellar Objects in Southern Orion A 850 μm beam 5. Summary 0.25 pc Mairs et al. 2016. MNRAS 461:4022 The JCMT Gould Belt Survey Star forming regions are complex and dynamic. A full understanding will require investigating the connection between many different size scales. SCUBA-2 provides the imperative, intermediate observing regime between the large-scale cloud and the small-scale protostellar physics The JCMT Gould Belt Survey is a consortium dedicated to studying ~20 nearby (<500 pc) star forming regions at submillimetre wavelengths Orion, Perseus, Taurus, Ophiuchus, IC5146, Lupus, Cepheus, Auriga, Serpens… Southern Orion A (850 μm; SCUBA-2) Identifying Structure SCUBA-2 Observes at 850 μm and 450 μm simultaneously Two Step Source Extraction: Islands: 3σ contours larger than one beam (~15”) Fragments: Identified using FellWalker (Berry 2015 A&C 10:22) Fragments are often smaller than islands. They highlight substructures within larger sources 2 Islands of interest 0.2 pc 2 Islands of interest Fragment Finding Algorithm 0.2 pc 5◦30000.000 − 36000.000 An Example of an interesting follow-up candidate Protostar M ~ 4MJ Class 0/I 42000.000 Disk Dec (J2000) Protostar M~ 3MJ Candidate 48000.000 YSO Catalogue From: Megeath et al 2012 Radius = 0.1 pc Starless 1 Mass = 16.5 M Stutz et al 2013 54000.000 40.00s 20.00s 36m00.00s 40.00s 20.00s 5h35m00.00s RA (J2000) YSO Distribution in Southern Orion A 120 1Beam Disks 100 Protostars Faint Candidates Red Candidates 80 Protostars correlated Fraction within 1 beam of peak: withDisks fragments = 3.9% 60 Proto = 48.1% Faint Proto = 3.7% Number Red Proto = 50.0% Disks more distributed 40 Number of YSOs Numberof across the map 20 > 2pc 0 ! 0.0 0.5 1.0 1.5 2.0 DistanceYSO Brightness from nearestDistance at 850 fragment (pc)μm (Jy/beam) peak (pc) Are we able to recreate this distribution with simple assumptions? A Toy Model for the YSO Distribution YSOs “Launched” in random directions from Jeans Unstable fragments The launch velocities are drawn from a Maxwell-Boltzmann distribution Class II Sources There appears to be an evolution in velocity dispersion from YSO Class 0 to Class II Summary 1. We have completed a First-Look Analysis of Southern Orion A using SCUBA-2. See: Mairs et al. 2016. MNRAS 461:4022 2. We have identified significant structures, Class II Sources performed an analysis on fragmentation, and highlighted interesting cases (Super-Jeans) 3. We investigated the dust emission’s relationship with Young Stellar Objects and created a simple model to recreate the YSO distribution 4. There is an apparent evolution Class II Sources in velocity dispersion from YSO Class 0 to Class II, though follow-up work is necessary 5. This analysis is being extended to other GBS regions by undergraduate James Lane.