Dust & Gas around Stars Young & Old, Near & Far

Transcription

1 Dust & Gas around Stars Young & Old, Near & Far Kathleen Kraemer ISR Scientific

2 Collaborators Steve Price (BC) Greg Sloan (Cornell (formerly BC)) Don Mizuno (BC) Tom Kuchar (BC) Charles Engelke (BC) Bev Smith (ETSU) Joe Hora (CfA) Ciska Kemper (Acad. Sinica) Nick Wright (CfA) Paul Ruffle (U. Manchester) Joana Oliveira (Keele U.) Nicola Schneider (U. Paris) Sean Carey (Spitzer SciCtr, formerly BC)

3 Stellar Evolution stellar nursery protostar blue supergiant Supernova (SN) interstellar medium protostar blue supergiant black hole mass protostar blue supergiant Type II SN black hole protostar yellow giant red giant blue giant Type II SN neutron star Type Ia SN protostar yellow dwarf (Sun) red giant planetary nebula white dwarf protostar protostar red dwarf brown dwarf time red dwarf brown dwarf white dwarf Chart Credit: NASA

4 Image credits: NASA, DSS, AFRL, NASA IR Astronomy Surveys η Car luminous blue variable & nebula IRAS 1983 MSX VISIBLE 1996 Spitzer 2005

5 Spitzer Space Telescope Mapping Projects Cygnus-X MIPS 24 & 70 µm IRAC 4-band MIPSGAL MIPS 24 & 70 µm Spectroscopy Projects Small Magellanic Cloud Large Magellanic Cloud Local Group Galaxies Cygnus-X Werner et al. 2004, Rieke et al. 2004, Fazio et al. 2004, Houck et al Infrared Spectrograph (IRS) µm Infrared Array Camera (IRAC) 3.6, 4.5, 5.8, 8.0 µm Multiband Imaging Photometer for Spitzer (MIPS) 24, 70, 160 µm Cryo: Post-cryo:

6 Cygnus-X Massive Star Forming Region <2 kpc >10 3 OB stars > 10 4 protostars M >10 5 M M tot >10 6 M blue=3.6 µm ~stars green=8 µm ~warm gas/dust red=24 µm ~cool dust Hora et al. 2009

7 Infrared Dark Clouds LDN 896 IRDCs discovered by MSX & ISO very dense cold dust lanes youngest, most deeply embedded YSOs near AFGL 2636 near G

8 Cygnus-X Evolved Stars Evolved Object Type # in 24µm Region # Det d at 24µm Det n Rate PNe % WRs % pagbs % C*s % S*s % SNRs 10?? Miras % semi-reg % Cepheids % RR Lyr 1?? cont. bin % Dw. Nov % other V*s % Kraemer et al. 2010

9 Evolved Stars BD HBHA G Carbon star with a bipolar outflow Moving Wolf- Rayet star with shell Luminous blue variable near IRDC

10 Evolved Stars He-shell flashes & dredge-ups create C, N etc. & move it out C/O>1 carbon star molecule & dust formation, wind Adapted from Karakas & Lattanzio 2008 and Habing & Olofsson 2004

11 Evolved Stars: Models HBHA Line through peak: 30 Space motion: 31

12 Evolved Stars: Models HBHA thin shell & model thick shell & model Radiative transfer model with 3 carbon-rich dust shells

13 MIPSGAL 24 µm Survey blue= 3.6 µm ~stars green=8 µm ~warm gas/dust red=24 µm ~cool dust Carey et al. 2009, Benjamin et al. 2003

14 Evolved Stars Catalog of >400 disks & rings in MIPSGAL Little or no emission at other wavelengths ~15% previously ID d as evolved objects Likely planetary nebulae or other evolved objects missing population Mizuno et al. 2010, Flagey et al. 2009

15 Magellanic Clouds Image credit: ESO Visible

16 Magellanic Clouds IRAS 100 µm

17 The Small Magellanic Cloud low metallicity: ~0.2xsolar nearby: ~60 kpc local surrogate for galaxies in the earlier Universe WISE SKY model & LMC to predict object types for brightest MSX objects Spitzer s IRS spectra to verify

18 SMC IRS Project The plan The plan: observe several of each type of evolved star These stars create: dust energy balance C & N planets, life The result: many, many carbon stars! What happened Sloan et al. 2006

19 SMC IRS Project Carbon rich Oxygen rich silicates crystalline silicates silicates C 2 H 2, HCN, CS, C 3, CN oxides Si, Al, Mg, Fe

20 Extended IRS Projects Carbon rich initial study: 36 objects extending to other IRS programs ~250+ SMC ~1000+ LMC ~dozens Local Group C 2 H 2, HCN, CS, C 3, CN Sloan et al. 2012

21 Spectra for Calibration Mid-IR selection, isolated, ~uniform sky coverage Non-variable to <<10% at 12 & 25 µm (IRAS) 600+ calibration stars, 1-35 µm spectral templates Moderate spectral resolution & photometric accuracy Limited actually measured spectra

22 Spectra for Calibration Upgrades current calibration network to improve: absolute accuracy (MSX) spectral resolution (ISO) wavelength coverage (ISO, MSX, DIRBE, Tycho/Hip, Kurucz, Pickles) dynamic range (ISO, MSX, Spitzer) variability assessments (near- IR, visible) Price et al. 2004, Engelke et al. 2006, 2010

23 Variability Assessments Flux (Jy) β UMi 1.25 µm Flux (Jy) T Cep 1.25 µm t (weeks) t (weeks) Lomb-Scargle periodogram Lomb-Scargle periodogram Power Power Period (weeks) Period (weeks) Price et al. 2010

24 IR Periodogram Results Expected Variables 16; 7% 12; 5% IR Standards 17; 3% 1; 0% 199; 88% 589; 97% Control Sample Variables; 266; 15% Candidates; 58; 3% IR Bright 19; 33% Non - variables; 1457; 82% 36; 62% 3; 5% Kraemer et al Visible assessment in-progress

25 IR-Visible Phase Lags Vis-IR Lag (days) Miras C stars S stars SRs Peak Matching T, shocks, molecular formation cause a lag between the visible peak & the IR peaks Vis-IR Lag (days) Co esu ts Miras C stars S stars SRs X-Cor lag = 0.098P IR IR Period (days) IR Period (days) Cross-correlation

26 TODAY: Last transit of Venus til 2117 I: 1 st contact ~6:05pm II: 2 nd contact ~6:23pm Sunset ~8:18pm Boston University & Harvard-Smithsonian observing from rooftops & other locations (incl. indoors if cloudy) NH Astro.Soc & McAuliffe-Shepard Disc.Ctr. nhastro.com/events/transit.php starhop.com/ ($) sunearthday.nasa.gov/2012/transit/webcast.php Thanks!