Ionized regions & Star Formation
Annie ZAVAGNO Aix Marseille Université Institut Universitaire de France CONTEXT Interaction of high mass stars with their surrounding medium Do high mass stars promote star formation ?
Eagle Nebula: Herschel (70 160 250 µm) and XMM Newton (Xrays): ionizing stars Herschel: Hill et al. 2012 HOBYS - Xu, Zavagno+2019 HII regions and star formation 1) Instabilities in the compressed shell: Small-scale: 4) Radiation-driven Low/intermediate mass compression Star formation of pre-existing dense clumps
Deharveng et al. 2010 2) Instabilities in the compressed shell: 3) Ionizing radiation Large-scale: Massive Star formation acting on a turbulent 2nd generation HII regions medium: Clusters formation Pillar formation HII regions & (high mass) star formation
• Why is it important ? – Key role of high mass stars in galaxies’ evolution – Do HII regions promote the formation of high mass stars?
– ~ 7 000 ionized regions in the Galaxy (Armentrout +2019, L. Anderson’s Web site: http://astro.phys.wvu.edu/wise/)
• Radiative feedback: positive or negative impact on star formation? – From models à negative – From observations à positive Key roles of RadioNet for my work
Stars form in cold and dense molecular clouds à access in the radio and submillimeter range
RadioNet goals • Structuration of research & development activities in radioastronomy • Financial support for meetings (to organize and to attend) • Financial support for telescopes access • Formation of (young) researchers à optimal use of data – ARC Node use of ALMA archives à Zhang +2020 (PhD student)
Strong force for the coherent development of radioastronomy
10 pc
NGC 6334 NGC 6357 Herschel image of NGC 6357 and NGC 6334
70 microns, 160 microns, 350 microns
ArTéMiS-APEX+SPIRE and ALMA Vela C molecular cloud and the bipolar HII region RCW 36
Herschel images at 70 160 250 µm (Minier +2013)
Importance of bipolar HII region to study the radiative feedback on star formation
(Deharveng +2015, Samal +2018, Schneider +2018, Dewangan +2019, ….) STATISTICAL STUDIES WITH LARGE GALACTIC SURVEYS • Identify HII region Spitzer GLIMPSE Survey • YSO population
Herschel Hi-GAL Survey • Probe the cold neutral medium • Reveal the early stages of Star Formation DETAILED STUDIES WITH POINTED OBSERVATIONS RCW 120 Herschel HOBYS Zavagno + 2010
100 µm 160 µm 250 µm APEX ArTéMiS observations
Ionizing star Access to the telescope through RadioNet
Zavagno+2020 Result: Radiative compression RCW 120: APEX-ArTéMis and Herschel data (Zavagno+2020) Asymmetric intensity profile of filaments in the PDR
Shell’s interior
Compression ALMA Study of clumps fragmentation Probed scale: 0.025 pc (~ 5100 AU)
Bimodal fragmentation in high-mass star clumps (cores’ separation)
Zhang, Zavagno +2020 Accepted by A&A
RadioNet support Zhang à ARC Node in Grenoble
Formation of young researcher Optimal use of archival data Can Machine Learning do something for us? YES ! Star formation as a function of the environment
• Big data: Filaments, YSOs, cores, clumps, young stars
• BigSF project: building an empirical model of the Galactic Star Formation using Big Data and Machine Learning (PI: Zavagno)
• First results on Galactic Filaments (Zavagno+ in prep.) Filaments identified via supervised learning Filaments identified via classical extraction
N(H2) + segmented Region of Interest N(H2) + original Region of interest Smoother coverage of the filaments
A big thank to RadioNet for supporting and promoting Radio Astronomy