Roberta M Humphreys University of Minnesota

1. RSGs and AGBs in the Optical and Infrared -- Mass Loss, Circumstellar Ejecta and Episodic Events Roberta M Humphreys University of Minnesota m Cep VY CMa IRC +10420 NML Cyg ESO Workshop – Stellar End Products June 2015

2. A Little Bit of History – infrared, CS dust, RSGs, AGBs, masers and the OH/IR stars 10m silicate feature in RSGs (Woolf and Ney 1969) LPVs – oxygen and carbon-rich OH maser emission (Wilson & Barrett 1968) from LPVs, and very red supergiants, followed by H2O, SiO maser emission. Identified with strong infrared sources (Wilson, Barrett &Moran 1970, Hyland 1972) -- the OH/IR stars – RSGs, LPVs (AGBs) Mass loss mechanism ? -- radiation pressure on grains? pulsation (LPVs) convection (RSGs) But ---

3. The Upper HR Diagram The evidence for episodic high mass loss events

4. VY CMa -- the extreme red supergiant, powerful OH/IR source 10” Distance ~ 1.3 kpc Luminosity ~ 3 x 105 L sun Initial Mass ~ 30 M sun Mass Loss rate 2 -- 4 x 10-4 M sun / year Size ~ 8 -- 10 A.U., or ~ 1500 -- 2000 Rsun It is visible as a small red nebula ~ 10 arcsec across 1” = 1500 AU Due to multiple, asymmetric ejection episodes possibly from large-scale convective regions on the star. Smith, Humphreys, Davidson, Gehrz, & Schuster, 2001

5. Complex structure in ejecta Prominent arcs, numerous filaments and clumps of knots, overall mass loss rate 5 x 10-4 High Resolution, Long-Slit Spectroscopy --Keck HIRES Spectrograph NW Arc Arc 2 Arc 1 From surface brightness of NW arc mass ~ 3 x 10-3 Msun . With a dynamical timescale of ~ 3yrs, suggest a mass loss rate of 10-3 Humphreys, Davidson, Ruch & Wallerstein 2005 S Knots SW Knots/clump

6. 2D spectra of strong K I emission lines across the arcs NW Arc Arcs 1 and 2

7. Second epoch HST images Measure transverse velocities combined with radial velocities long slit spectra (Keck) of K I em line (resonant scattering) Total velocity, orientation, direction and age  3D morphology Feature Vel. Orientation Direction Age (yrs) km/s relative to sky of motion NW arc 46 22 degrees ~ west 500 Arc 1 68 -33 SW 800 Arc 2 64 -17 ~ south 460 SW knots 36 -25 ~ west 250 S knots 42 -27 SSE 157 SE loop 65 -21 SE 320 Humphreys, Helton & Jones, 2007, Jones, Humphreys, & Helton 2007

8. Results from LMIRCam (2 – 5mm) on the LBT with AO The SW clump – in the visible resolved into individual knots but very red and dusty. In the near-IR an unresolved knot . Clump is optically thick. Mass loss > 5 x 10-3Msun Shenoy, et al. 2013

9. SOFIA imaging 20 – 37 mm Note asymmetric shape. Outer ejecta at most about 1500 yrs old Ziurys et al 2007 noted molecules in red/blue outflows. 8.5 arcsec 37mm contours on HST visual image Shenoy et al. 2015 submitted

10. Asymmetric Mass Loss Events and the Origin of the Discrete Ejecta Arcs and Knots are spatially and kinematically distinct; ejected in different directions at different times; not aligned with any axis of symmetry. They represent localized, relatively massive (few x 10-3 Msun) ejections Large-scale surface activity -- starspots Surface asymmetries supergiants, AGBs – a Ori, a Sco, a Her, VX Sgr, NML Cyg, VX Sgr, IK Tau etc. (Tuthill et al. 1999, Monnier et al. 2004) Convective activity  Magnetic Fields200 – 400G (Vlemmings et al. 2005)

11. XMM observations (Montez, Kastner, Humphreys et al. 2015) set an upper limit on the X-ray flux and the surface magnetic field, f B <= 2 x 10-3G. VY CMa light curve (Robinson 1971)

12. Recent results on the iconic RSG – m Cep 9 -12 mm imaging MMT/MIRAC/AO Shenoy et al. 2015 submmited Mass loss for inner region – 3– 8 10-7 Msun/yr

13. SOFIA 11- 37 mm Shenoy et al. 2015 submitted Mass loss outer ejecta 6 x 10-7 Msun/yr Herschel 70mm (Cox et al 2012)

14. Post-RSGs ( and post-AGBs) and a dynamical instability

15. The Warm Hypergiants and post RSG evolution HD179821 – 11.7 um (Jura & Werner 1999) Post RSG or AGB? IRC+10420 IRAS 17163-3907 – 12mm (the fried egg) Lagedec et al 2011 Jones et al 1993 Oudmaijer et al 1994, 1996 Humphreys et al.1997, 2002 Other examples of post RSGs (r Cas, HR5171a, HR8752 etc.)

16. Variable A in M33 – a warm hypergiant ~ 45 years in eruption!

17. Var A – Spectrum and Circumstellar IR excess 45 years in “eruption” Cool dense wind Looked like an M supergiant Humphreys et al. 1987, 2006

18. Other supergiants NML Cyg (M6 I, OH/IR) -- extended CS ejecta (HST) S Per (M4 Ia, OH/IR) -- extended CS ejecta (HST/MIRAC/SOFIA) VX Sgr (M4 Ia –M8 , OH/IR) -- extended CS ejecta (HST) W Per (M3 Iab) -- null RW Cep (K0: Ia +) -- extended CS ejecta (MIRAC) RW Cyg (M3-4 Ia) -- extended CS ejecta (MIRAC) BD +24 3902 (M1 Ia+ ) -- extended CS ejecta (MIRAC) T Per (M2 Iab) -- extended CS ejecta (MIRAC)

19. Mass loss mechanism for RSGs? Pulsation Convection + ? A correlation among: Surface asymmetries (spots) -> convective cells? -> mass loss -> circumstellar dust/ejecta Enhanced surface activity -> high mass loss events -> complex CS ejecta

20. Some thoughts on the evolutionary state of the RSGs Why not more VY CMa’s ?

21. Evidence for increased mass loss, CS ejecta with higher luminosity and cooler temperatures (?) Clusters – RSG clusters (Figer, Davies, Clark) Stepenson2, N7419 (Negueruela) and even Per OB1 Do RSGs evolve through the red supergiant stage getting apparently cooler, more extended envelopes and high mass loss episodes? Like lower mass stars, could there be more than one RSG stage?  warm hypergiant  RSG again – extreme RSG (VY CMa) ?

22. Collaborators Kris Davidson Andrew Helton George Herbig Terry J. Jones Gerald Ruch Dinesh Shenoy Nathan Smith George Wallerstein Michael Schuster Massimo Marengo Kris Davidson Terry J. Jones Dinesh Shenoy Nathan Smith Chelsea Tiffany Terry J. Jones Massimo Marengo Dinesh Shenoy Michael Schuster