New Surprises from the

1. New Surprises from the Microsatellite … aka the Humble space telescope • MOST Parameters • telescope diameter 15 cm • launched 2003 June • tracker lost 2006, but… • still working better than ever • 3” pixels, 1” pointing stability • follow object up to 8 weeks • time resolution ~sec-min • 3 modes: Fabry (V = 0…6), direct (V = 6…12), guide-star (<2006) • CCD + B/V filter • Primary Science • Asteroseismology  structure, age • Exoplanets  sizes, atmospheres Tony Moffat & the MOST team • Luminous Hot-star Highlights • zeta Oph, O9.5Ve: Fig.1 • HD127756, B1/2Vne; HD217543, B3Vpe: SPBe stars, 30-40 NRP g- (+ poss r-) modes, excited by Fe opacity bump, v(rot) close to break-up (Cameron et al. 2008). • delta Ceti, B2IV: Fig.2. • HD163899, B2Ib/II: Fig.3. • HD 313926, B5: : largest eccentricity (e = 0.2) among short-period (3.5d) early-type binaries  v. young (Rucinski et al. 2007). • HD 163868, B5Ve: detection of ~60 modes, first r-modes (v. low freq.) & g-modes (Fe opacity bump) in a Be star  NRP important in Be stars? (Walker et al. 2005). • HD 163830, B5II/III: Fig.4. • beta CMi, B8Ve: 1st detection of non-radial (high-order) g-modes in a Be-star > B6  pulsations excited in all classical Be stars? Fe-bump @ 200kK, v(rot) ~ break-up, 3.5 M (Saio et al. 2007). • sigma Ori E, B2Vpe: being analyzed (Townsend et al.). • Rosette Nebula, 5 OB: to be analyzed. • WR123, WN8: Fig.5. • WR103, WC9d: Fig.6. • WR111, WC5: Fig.7. • WR110, WN5-6: being analyzed; P = 2.1d & 4.0d + stochastic? • WR124, WN8h: being analyzed; P ~ 6d + stochastic? Fig.8. Fig1: zeta Oph: v sin i ~ 400 km/s, runaway; clear beta Cep radial/NR pulsations driven by Fe opacity bump (Walker et al. 2005). Fig.2: delta Cep: Left: folded lc f1 = 6.2 c/d = 1st radial overtone. Right: Fourier Sp after pre-whiten (f1, 2f1)  multiperiodic (mono before). Models: 10.2 M, 18 Myr  evolved beta Cep star (Aerts et al. 2006). N.B.: MOST’s first target! Fig.4: HD 163830, a new SPB (slowly-pulsating B-star) with largest no. of detected g-mode frequencies; model  4.5 M (Aerts et al. 2006). Fig.3: HD163899, ~35 frequencies: p- & g-mode, latter 1st time in a BSG. Great potential for asteroseismology (Saio et al. 2006). Fig.7: WR111 (top) cf. WR123 (bottom) & WR103 (middle). No P of A > 0.05 mmag (~40 x less cf. SMP models: Glatzel et al. 1993) for f = 10 – 1000 c/d (P = 1.4m – 2.4 h), after removing f = 14.2 c/d MOST orbital + harmonics. Also: no damped oscillations or flares >~1 mmag. Moffat et al. (2007). Fig.8: HST H-alpha image of M1-67 nebula around WR124 (Grosdidier et al. 1998). Fig.6: WR103, similar to WR123, except sl. lower amplitude variations & no P. Both light-curves = superposition of short-lived (5-7d coherency), multiple-frequency pulsations of amplitude 5-20 mmag mostly at freq. <~1c/d. No periodic signal >0.2 mmag in traditional domain freq. >~10 c/d. Moffat et al. (2008). Fig.5: WR123, runaway, no H. P = 10h: 1st ~clear pulsation period in a WR star  SMP driven by normal Fe bump (Dorfi et al. 2006 – but took X(H) = 0.35) OR(?) g-modes driven by Fe bump at log T = 6.25 (Townsend & MacDonald 2006 – but took R = 2R cf. ~15 R observed). Spectral lines ~10% of total broadband flux & vary little  observed variation (P = 10h & other) must be related to pulsations of the stellar core! (supported by sp analysis for WN8 stars by Haeffener & Hamann 2008). Delayed reaction of wind (sp lines) triggered by superposition of pulsation events. Lefevre et al. (2005). Conclusions Despite its modest size, MOST can provide powerful high-precision photometric constraints on the properties of hot luminous stars. The key is contiguous coverage over long time intervals from space.