Luminous Hot Stars: The impact of HST
Mk34 (30 Dor)
Paul Crowther (University of Sheffield) Science with the HST IV: Looking to the Future Outline
• Massive stars - Introduction • Stellar winds - Metallicity dependent winds • Ejecta nebulae - Signatures of eruptions • Young star clusters - A plethora of hot stars • Starbursts knots - Templates for high-z galaxies • Progenitors of core-collapse Supernovae
2 Luminous Hot Stars?
o Incredibly rare though can individually be detected at large distances (Mpc for blue/red supergiants); o Short-lived (few Myr), so Lyman continuum photon output provide near instantaneous SFR diagnostic; o Dominant signature of massive stars in high-z galaxies; directly (far-UV continua) & indirectly (ionized gas, heated dust). Massive Stars?
L approx LEdd
L << LEdd Massive Stars?
-2 tMS propto M
L approx LEdd
-0.3 tMS propto M
L << LEdd
Crowther (2012) • Massive stars - Introduction • Stellar winds - Metallicity dependent winds • Ejecta nebulae - Signatures of eruptions • Young star clusters - A plethora of hot stars • Starbursts knots - Templates for high-z galaxies • Progenitors of core-collapse Supernovae Wind velocities Stellar Winds
LMC O2 dwarfs, giants, supergiants (Crowther+2014) Metallicity dependent Stellar winds?
1/2 Solar
NGC6611 (Galaxy) NGC 346 (SMC)
Solar 1/5 Solar
N11 (LMC) Evans+ (2005, 2006) Metallicity dependent winds P Cygni lines (HST)
Dmom = dM/dt * vinf * sqrt(R) H-alpha (VLT) HeI/II lines (VLT)
SMC LMC
MW
dM/dt propto Z0.8
(Mokiem+ 2007) Weak Winds; Clumped Winds Crowther+ (2002), Hillier+ (2003), Milky Fullerton+ (2006) Way (IUE)
SMC (HST/STIS)
Bouret+ (2003); Martins+ (2004) • Massive stars - Introduction • Stellar winds - Metallicity dependent winds • Ejecta nebulae - Signatures of eruptions • Young star clusters - A plethora of hot stars • Starbursts knots - Templates for high-z galaxies • Progenitors of core-collapse Supernovae Ejecta Nebulae Recent mass-loss history of evolved 120’’ (3pc@5kpc) massive stars revealed by ejecta nebula (Grosdidier+1998).
Central importance of eruptive mass-loss for massive stars highlighted by Smith (2014 ARA&A) " Carinae
#" Car `erupted’ in 19th Century, becoming 2nd brightest star in sky, forming the Homunculus, a dusty reflection nebula (10-20 Mo) illuminated by the star. Homunculus # Recent effort has focused upon nature of central star (120 + 30 Msun binary, 5.5yr period).
8.5’’ (0.1pc) # Extreme parameters for eta Car from STIS 0.1”x 0.1” spectrum: dM/ -3 dt=10 M◉/yr, HST imaging (100 AU 6 resolution) has revealed the L=5x10 L◉ expansion over 18 months (Hillier et al. (Morse et al. 1998). 2001). • Massive stars - Introduction • Stellar winds - Metallicity dependent winds • Ejecta nebulae - Signatures of eruptions • Young star clusters - A plethora of hot stars • Starbursts knots - Templates for high-z galaxies • Progenitors of core-collapse Supernovae Tarantula Nebula
LMC (Swift UVOT) Tarantula Nebula R136: central ‘star’ in the 30 Doradus region
Hunter+ (1995)
1985
De Marchi+ 1993
1980 A plethora of early O stars # HST/FOS (Massey & Hunter 1998) spectroscopy revealed a multitude of early O stars in R136. Total stellar mass of R136 probably 4 exceeds 5x10 M◉ WFC3/ERO
~30 pc
Excellent synergy with VLT Flames Tarantula Survey (VFTS: Multi- epoch spectroscopy of 800 OB stars in 30 Dor, Evans+ 2011) Hubble Tarantula Treasury Project Elena Sabbi (F336W)
100 pc NGC 3603
Milky Way cluster NGC 3603 also hosts many early O stars (Drissen+ 1993).
Follow up VLT spectroscopy revealed A1 the most massive (90 + 120 Msun ) binary currently known (Schnurr+ 2008). Key target in calibration of NIC focus tests(!) allowed Moffat+ still higher mass stars (2004) to identify A1 as an (Crowther+ 2010) eclipsing binary (3.77days) Galactic Centre clusters
Schneider+ 2014 Paschen alpha surveys NASA, ESA, and Q.D. Wang (U.Mass)
Arches
Sgr A* b Quintuplet l Half of stellar P-alpha emitters within GC region lie beyond the 3 bright clusters. Majority are evolved massive stars (Dong+ 2012) Paschen-alpha surveys
G305 star forming region: Davies+ (2012) HST/NICMOS • Massive stars - Introduction • Stellar winds - Metallicity dependent winds • Ejecta nebulae - Signatures of eruptions • Young star clusters - A plethora of hot stars • Starbursts knots - Templates for high-z galaxies • Progenitors of core-collapse Supernovae Starburst knots Local starburst galaxies, such as NGC 3125 (11Mpc) host young, high mass clusters
O Stars WR stars
UV evolutionary synthesis models suggest ~4 Myr for NGC3125-A1 (Hadfield & Crowther 2006; Wofford+ 2014). “My God.. its full of stars!” New UV+optical spectroscopy of every star in R136 to V=16 mag using HST/STIS (seventeen 52x0.2” slits)
Crowther+ 2014 R136 cluster dissected Crowther+ 2014
R136 composite UV spectrum resembles early O star + strong HeII 1640 emission. Emission from 6 stars with >100 Msun, with negligible emission from other ~100 massive stars) HeII 1640 from very massive stars?
HST/STIS (Wofford+ 2014)
Strong HeII 1640 emission might indicate very massive stars (>> 100 Msun) in NGC 3125-A1 Massive stars in metal- poor galaxies
STIS spectroscopy of knots in HII galaxy IZw18 (1/30 Zsun) reveals Wolf-Rayet star signatures (Brown+ HST/COS2002). Formation (Heap) via close Brown+ 2002 binary evolution? Ultraviolet OB templates?
Comprehensive OB templates for Milky Way from IUE. HST has added dozens of OB templates for the metal-poor SMC, although relatively few LMC stars have been obtained to date (approx ten O dwarfs in TOTAL) Lensed LBGs (105 O stars) MS 1512-cB58 (z~2.7, L*)
Pettini+ (2003)
J2135-0102 (z ~ 3.1, 2L*) Cosmic Eye
Quider+ (2010) • Massive stars - Introduction • Stellar winds - Metallicity dependent winds • Ejecta nebulae - Signatures of eruptions • Young star clusters - A plethora of hot stars • Starbursts knots - Templates for high-z galaxies • Progenitors of core-collapse Supernovae ccSNe statistics
PTF (Arcavi+ 2010)
LOSS (Smith+ 2010) SN2005cs Pre-SN Post-SN
Key role played by HST in establishing RSG progenitors for Type II-P SNe (Maund+ 2005) ccSNe progenitors?
II-P: 8-20 Msun (RSG),
II-L: 20-25 Msun (YSG),
Ib/c: 8-100+ Msun (single WR >25 Msun, He stars in binaries <25 Msun)
IIn: 25+ Msun (LBVs following giant eruptions) Smith+ 2010 GRB-Broad-lined Ic SNe
GRB980425/SN1998bw (Hammer+ 2006) GRB-SNe vs SNe hosts GRB-SNe originate from brighter regions of hosts than normal ccSNe (Fruchter+ 2006). Massive progenitors for broad-lined Ic
GRB! SN!
Ofek+ 2007; Smith+ 2007 Superluminous SNe
1999as% PTF09atu% PTF11rks%
2005ap% PTF09cnd% PTF11dij%
SCP06F6% 2009jh% CSS111230%
2007bi% 2010gx% PS1?12fo% UV# IR# UV# IR# UV# IR# From WFC3 imaging, SLSNe hosts (0.02 ! Mass ejections from other hot luminous stars have been discovered with HST such as Sher 25 (in NGC 3603), reminiscent of SN 1987A (Brandner et al. 1997). Ring Nebula SN1987A Bipolar outflows Sher 25 Dust formation in SN1987A 43 Indebetouw+ (2014) Without Hubble…? • No direct (UV) diagnostic of wind velocities from OB stars beyond Milky Way; • No spatially resolved view of Homunculus (template for CSM in luminous IIn SNe); • No Paschen-alpha surveys of luminous stars with powerful winds in Galactic Centre; • No spatially resolved UV spectroscopy of young high mass star clusters; • No identification of ccSNe progenitors from high resolution imaging of nearby galaxies; • No spatial location of GRB-SN or SLSNe in host galaxies 44 Massive close binaries • Recent studies have highlighted central role of close binary evolution • Very close binaries (weeks) from spectroscopic monitoring; long period systems (years) from conventional imaging. • HST/FGS helps to fill this gap (e.g. Nelan+ 2004 identified a companion to O2If* HD93129A, 55 mas = 140 AU apart) Sana+ (2012)