A planet in space Description automatically generated with low confidence Red supergiants Jacco van Loon Keele University Brno 2021 Map Description automatically generated Plan for this seminar: •What are red supergiants… and what are not? •Why should we care about red supergiants? •Mass loss from red supergiants •The peculiar (or typical?) case of Betelgeuse •Red supergiants as progenitors of supernovae •My favourite red supergiant • •Feel free to interrupt! We can discuss binary evolution… What are red supergiants? •Post-OB evolution (“inverse Henyey”), core He burning, convective mantle (“inverse Hayashi”) Chart, diagram, scatter chart Description automatically generated AGB Super-AGB … and what are not? •Yellow SuperGiants (Blue Loop stars ⇒ post-YSG RSGs?) SMC Ramachandran + 2019 •rotation •overshoot •binary interaction complications •(shell-burning) AGB or super-AGB stars red ⇔ low surface temperature A planet in space Description automatically generated with low confidence Earth’s orbit Main sequence Chart, line chart, scatter chart Description automatically generated •motions of few–tens km/s •dynamical timescales year(s) •rotation, convection, pulsation, collapse, binary motion, wind… supergiant ⇔ low surface gravity Elias, Frogel & Schwering 1986 (WOH G64 in the LMC) Sphere Why should we care about red supergiants? BSG: 10-6 M ⊙ /yr, 106 yr, 1000 km/s RSG: 10-5 M ⊙ /yr, 105 yr, 10 km/s free expansion: 1 kpc 1 pc Cone reality: sweep up ISM: 10 pc Red Torus Cone post-RSG BSG axisymmetric Chart, diagram Description automatically generated Chart, scatter chart Description automatically generated Wood + 1992 Marshall + 2004 Goldman + 2017 ⦿ •if dusty ! •if opacities known •if geometry known •alternatively model atomic line profiles Mass loss from red supergiants – method Mass loss from red supergiants – results Chart, scatter chart Description automatically generated Chart, diagram, scatter chart Description automatically generated 7 Goldman + 2017 van Loon + 1999 •RSG mass loss generally at nuclear burning rate •+ possible superwind no direct metallicity dependence Mass loss from red supergiants – mechanism? Chart, scatter chart Description automatically generated Diagram Description automatically generated Chart, scatter chart Description automatically generated van Loon + 2005 Marshall + 2004 Goldman + 2017 pulsation + dust driven mass loss? no direct metallicity dependence Energetically trivial cf. when gravity does work: •Roche Lobe overflow •Common Envelope •core collapse closing remark The peculiar (or typical?) case of Betelgeuse A picture containing light, star, outdoor object, rain Description automatically generated Herschel few pc – Decin 2011 A picture containing blurry, blur Description automatically generated A bright light in the dark Description automatically generated with medium confidence ALMA few au – O’Gorman 2017 ESO/VISIR – Kervella 2019 •runaway (whence?) •fast rotator (15 km/s) •not very dusty •chromosphere The Great Dimming of Betelgeuse Chart, line chart, scatter chart Description automatically generated Freytag Granulation? (Ren & Jiang 2020) A picture containing candle, light Description automatically generated ESO/SPHERE – Kervella Dust cloud? Convection cell? precursor? Diagram Description automatically generated A picture containing outdoor object, outdoor, light, star Description automatically generated Red supergiants as progenitors of supernovae before 1987 A picture containing worm, outdoor object, light, star Description automatically generated A picture containing text, light, red, traffic Description automatically generated Tanaka & Washimi 2002 Sanduleak -69o 202 Blue Supergiant !? HST Challis Matsuura + 2011 / many others RSG SN •post-red supergiant ! 0.5 pc Red supergiants as progenitors of neutron stars Chart, scatter chart Description automatically generated Hirata + 1987 neutrinos A picture containing worm Description automatically generated A picture containing text, outdoor object, star Description automatically generated A picture containing bubble, star Description automatically generated Zanardo + 2014 here? or here? ? Cigan + 2019 Greco + 2021 0.1-8 keV here! •neutrinos (black hole?) •source of dust heating •no pulsar detected evidence? so: where is the neutron star? Red supergiants as progenitors of supernovae (and possibly black holes) A screenshot of a computer Description automatically generated with low confidence Chart Description automatically generated Chart Description automatically generated SN2008bk: Mattila + 2010 Straniero 2019 Smartt 2015 data Davies & Beasor 2018 II-P II-L ? II-b ? II-L ? II-P •dust (Teff, BC) •matching model complications •mass loss •binary interaction •when does it go SN? My favourite RSG: WOH G64 in the LMC Graphical user interface Description automatically generated Diagram Description automatically generated Chart Description automatically generated Diagram Description automatically generated van Loon + 1999 Goldman + 2017 Marshall + 2004 van Loon + 1998 van Loon + 1996 Ohnaka + (in prep) •where is the dust? •why is it axisymmetric? •will it mimic SN1987A? questions 2000 au (Ohnaka + 2008) how to reconcile? A planet in space Description automatically generated with low confidence Děkuji