Hubble Science Briefing: 25 Years of Seeing Stars with the Hubble Space Telescope. March 5, 2015 Dr. Rachel Osten Dr. Alex Fullerton Dr.

Transcription

1 Hubble Science Briefing: 25 Years of Seeing Stars with the Hubble Space Telescope March 5, 2015 Dr. Rachel Osten Dr. Alex Fullerton Dr. Jay Anderson

2 Hubble s Insight into the Lives of Stars Comes From: Better image clarity: no atmosphere, no blurring means higher spatial resolution Access to ultraviolet wavelengths: not possible from the ground 2

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4 Outline Rachel Osten - cool stars Alex Fullerton - massive stars Jay Anderson globular clusters 4

5 The UV spectrum of a Sun-like star Hot gas (>10,000 K) means that many elements are ionized Hotter than the visible surface of the star (Sun=5800 K) Linsky & Wood

6 The UV spectrum of a Sun-like star B r i g h t n e s s Alpha Cen A at higher spectral resolution than UV spectra from the Sun! Pagano et al

7 The UV spectrum of a Sun-like star B r i g h t n e s s Linsky & Wood 1994 Dynamics of the atmosphere 7

8 The UV spectrum of a Sun-like star B r i g h t n e s s Time (seconds) The changing of a star s intensity with time on these short timescales is due to heating from flares occurring in the atmosphere of the star Hawley et al. (2003) 8

9 Stars Blow Bubbles in Space 9

10 Stars Blow Bubbles in Space Wood et al

11 Stars Blow Bubbles in Space Wood et al

12 Stars Blow Bubbles in Space Linsky et al

13 Outline Rachel Osten - cool stars Alex Fullerton - massive stars Jay Anderson globular clusters 13

14 Massive Stars Massive stars are also luminous stars. 1 Solar Mass 1 Solar Radius 1 Solar Luminosity T = 5,800 Kelvin Massive stars can be luminous because they are hot and compact hot and large cool and very large (?) Solar Masses 3,000,000 Solar Luminosities Temperature: 10,000 50,000 Kelvin Radius: 2 15 Solar Radii 30 Solar Radii T = 7,500 3, 600 Kelvin R = 80 8, 000 Solar Radii Blue supergiants Red supergiants Image Source: kids.britannica.com The Kelvin Temperature Scale: K = 5 ( 9 F -32 )

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16 R136 16

17 P Cygni Profiles tell us about mass loss via a stellar wind Space Telescope Imaging Spectrograph (STIS) From a poster paper by A. Bostroem, N. Walborn, et al. 17

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19 The Carinae Region: A Cauldron of Hot, Massive Stars This spectacular montage was created to celebrate the 17 th anniversary of Hubble s deployment. It is composed of many separate exposures with Hubble s Advanced Camera for Surveys (ACS) and ground-based images from the Cerro Tololo Inter-American Observatory (CTIO). For a fuller appreciation of its information content, explore the zoomable version: 19

20 The Carinae Region: A Cauldron of Hot, Massive Stars η Carinae This spectacular montage was created to celebrate the 17 th anniversary of Hubble s deployment. It is composed of many separate exposures with Hubble s Advanced Camera for Surveys (ACS) and ground-based images from the Cerro Tololo Inter-American Observatory (CTIO). For a fuller appreciation of its information content, explore the zoomable version: 20

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23 The Carinae Region: A Cauldron of Hot, Massive Stars η Carinae Trumpler 14 This spectacular montage was created to celebrate the 17 th anniversary of Hubble s deployment. It is composed of many separate exposures with Hubble s Advanced Camera for Surveys (ACS) and ground-based images from the Cerro Tololo Inter-American Observatory (CTIO). For a fuller appreciation of its information content, explore the zoomable version: 23

24 S-Curve from an FGS scan of a point source. ine Guidance Sensors Introduction The unprecedented pointing precision required by the Hubble Space Telescope (HST) motivated the design of the Fine Guidance Sensors (FGS). These are large field of view (FOV) interferometers that are able to track the positions of luminous objects in HST s focal plane with ~1 millisecond of arc (mas) precision. The FGS can also scan an object s interferogram with sub-mas resolution. These capabilities enable the FGS to perform as a high-precision astrometric science instrument and high resolution interferometer which can be applied to a variety of topics and objectives, including: Visual orbits for binary systems with separations as small as 10 mas. Detection of duplicity down to 7 mas. Measuring the angular size of extended objects. Relative astrometry at the 0.2 mas level (m V < 14.5). 40 Hz relative photometry (e.g., flares, occultations) with milli-mag accuracy Transfer Mode Observing In Transfer Mode the FGS scans an object to obtain its interferometric fringes with sub-mas resolution. This is conceptually equivalent to imaging an object with sub-mas pixels. This makes the FGS ideal for studying binary systems and extended objects over a large magnitude range (3.0 < m V < 16.0). Binary Systems Actual WFPC2 and simulated FGS Observations of a 168 mas binary system. Simulated WFPC2 and FGS Observations of a 70 mas binary system. Although the binary in this example is clearly resolved by the WFPC2 Planetary Camera (PC) (Niemela et al. 1999), the FGS could measure the component separation and relative brightness with greater accuracy (± 1 mas v. ± 30 mas). Although a PC detection would be questionable at 70 mas, the FGS clearly isn t challenged in detecting duplicity and measuring separations. Detections of duplicity down to 7 mas are possible with the FGS. From the FGS Instrument Handbook 24

25 HD 93129A Trumpler 14 Component A is also a binary! Palomar Digital Sky Survey HD 93129A HD 93129B ESO VLT: Aperture Mask with Adaptive Optics Sana et al Astrophysical Journal Supplement European Southern Observatory Science Release 0947 Very Large Telescope + Multi-Conjugate Adaptive Optics Demonstrator 25

26 NGC 3603 HST/ACS 26

27 Outline Rachel Osten - cool stars Alex Fullerton - massive stars Jay Anderson globular clusters 27

28 Plan (1) Globular Clusters before HST (2) Globular Clusters with HST (3) Globular Clusters with 25 years of HST 28

29 Globular Clusters Textbook simple stellar populations Formed stars early Single cloud, single metallicity, single age Not large enough to self-enrich Continue orbiting in spheroid of Galaxy Perfect fossil laboratories to evaluate stellar evolution GC GC GC GC GC NGC4013(NOAO) 29

30 Central Field project-nightflight.net ω Centauri Early Release Field 30

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32 What Astronomers see 32

33 What Astronomers see 33

34 What Astronomers see 34

35 What Astronomers see 35

36 What Astronomers see 36

37 What Astronomers see 37

38 What Astronomers see 38

39 What Astronomers see 39

40 What Astronomers see 40

41 What Astronomers see 41

42 What Astronomers see 42

43 What Astronomers see 43

44 What Astronomers see 44

45 What Astronomers see 3) Red Giant Branch 4) Horizontal Branch 5) White Dwarf Sequence 1) Main Sequence 2) SubGiant Branch 45

46 Easy to identify stars RGB HB BSs SGB MSTO WDs Red Dwarfs 46

47 Isochrone More metals Red Giant Branch C Stellar Populations One line means: same age same metallicity same distance Age A B same small cloud More Helium test of good photometry 47

48 Omega N T Omega Cen NGC Tuc Extra sequences 48

49 Plan (1) Globular Clusters before HST (2) Globular Clusters with HST (3) Globular Clusters with 25 years of HST 49

50 Cambridge, UK 2001 Globular Cluster or Dwarf Spheroidal? 50

51 Red Giant Branch metal poor Stellar Populations intermediate More metals metal rich Age More metals More Helium Inversion! Similar to galaxies 51

52 Is Omega Cen a GC? OmCen Could the textbook globular cluster not be one? 47Tuc N2808 N6388 N

53 Is Omega Cen a globular? Are there any globular clusters? NGC6652 Questions to answer: 1) How does the enrichment happen? 2) Why are they all so different? 3) What connection is there between clusters and galaxies? 4) Any relevance for star formation going on today? NGC

54 Plan (1) Globular Clusters before HST (2) Globular Clusters with HST (3) Globular Clusters with 25 years of HST 54

55 GCs with Hubble Over Time Set up new experiments Probe deeper Probe more broadly Use new detectors Better sensitivity, resolution Better filter sets Things move! 55

56 ω Centauri Anderson et al 2002 Initial 2-seq Discovery on Main Sequence (WF/PC2) Bellini 2014 (WFC3/UVIS) Latest results all over the 56 diagram! 10 Seqs!

57 NGC2808 D Antona 2005 (ACS) Initial Discovery Bellini et al in prep (WFC3/UVIS) 57

58 Motions in ω Centauri 2002 ACS H-alpha 58

59 Motions in ω Centauri 2015 WFC3/UVIS F606W 59

60 Motions in ω Centauri MOTIONS OVER 13 YEARS 2015 WFC3/UVIS F606W 60

61 Proper Motions Important Qs Formation hints Are GCs just little galaxies? Do they have mediumsized BHs? How did the big BHs form in big galaxies? 61

62 Plan (1) Globular Clusters before HST (2) Globular Clusters with HST (3) Globular Clusters with 25 years of HST (4) Globular Clusters in the next 25 years 62

63 View to the Future: the James Webb Space Telescope 63

64 View to the Future: the James Webb Space Telescope 64