Presentation is loading. Please wait.

Presentation is loading. Please wait.

Stellar Winds and their Interaction with the Interstellar Medium Brian E. Wood (Naval Research Laboratory) Jeffrey L. Linsky (JILA, University of Colorado)

Similar presentations


Presentation on theme: "Stellar Winds and their Interaction with the Interstellar Medium Brian E. Wood (Naval Research Laboratory) Jeffrey L. Linsky (JILA, University of Colorado)"— Presentation transcript:

1 Stellar Winds and their Interaction with the Interstellar Medium Brian E. Wood (Naval Research Laboratory) Jeffrey L. Linsky (JILA, University of Colorado) OUTLINE I.Astrospheric and Heliospheric Evolution Associated with Solar/Stellar Wind Evolution A.Intro to Basic Heliospheric Structure B.How Can We Detect Stellar Winds and/or Astrospheres? C.Inferring Wind Evolution from Astrospheric Absorption D.Planetary Implications for Wind Evolution II.Astrospheric and Heliospheric Evolution Associated with ISM Variability (Linsky) Neutrals interact through simple charge exchange processes (e.g., H o +H + → H + +H o )

2 Neutral Diagnostics of the Outer Heliosphere Bow Shock? Heliopause Termination Shock V ISM B ISM “Post-TS Neutralized Pick-Up Ions” Tail Solar Wind Schwadron et al. 2011, ApJ, 731, 56

3 Neutral Diagnostics of the Outer Heliosphere Bow Shock? Heliopause Termination Shock V ISM B ISM “Post-TS Neutralized Pick-Up Ions” Tail Solar Wind Schwadron et al. 2011, ApJ, 731, 56 “The Ribbon,” presumably where B ISM  n=0

4 Neutral Diagnostics of the Outer Heliosphere Bow Shock? Heliopause Termination Shock V ISM B ISM  Cen “Hydrogen Wall,” or “Post-BS Neutralized ISM” “Post-TS Neutralized Pick-Up Ions” Tail Solar Wind Schwadron et al. 2011, ApJ, 731, 56 Linsky & Wood 1996, ApJ, 463, 254 Schwadron et al. 2011, ApJ, 731, 56 “The Ribbon,” presumably where B ISM  n=0

5 Neutral Diagnostics of the Outer Heliosphere Bow Shock? Heliopause Termination Shock V ISM B ISM  Cen  1 Ori “Post-TS Neutralized Bulk Solar Wind” “Hydrogen Wall,” or “Post-BS Neutralized ISM” “Post-TS Neutralized Pick-Up Ions” Tail Solar Wind Schwadron et al. 2011, ApJ, 731, 56 Linsky & Wood 1996, ApJ, 463, 254 Wood et al. 2007, ApJ, 657, 609 Schwadron et al. 2011, ApJ, 731, 56 “The Ribbon,” presumably where B ISM  n=0

6 Astrosphere Images Young Star (LL Ori) Red Supergiant (Mira) Red Supergiant (Betelgeuse) Massive Hot Star Pulsar But unfortunately we cannot detect the astrosphere of a Sun-like star like this!

7 Mg II HD (O7 II) C IV Spectroscopic Diagnostics of Stellar Winds

8 ACE (Advanced Composition Explorer) Methods for Detecting and Studying the Solar Wind Aurora Comet tails Direct spacecraft measurement Coronal imaging

9 Evolution of the Solar X-ray and EUV FLux Ribas et al. 2005, ApJ, 622, 680

10 The Case for a Very Strong Wind for the Young Sun 1.The young Sun would have been much more coronally active, with higher coronal densities, so one would intuitively expect a stronger wind. 2.Aside from the quiescent wind, the stronger and more frequent flares of the young Sun should by themselves lead to a massive CME-dominated wind. Example: Due to CMEs alone, Drake et al. (2013) predict Ṁ=150 Ṁ ʘ for the 500 Myr old solar analog  1 UMa. Conclusion: There is every reason to believe the solar wind must have been much stronger in the past. Drake et al. 2013, ApJ, 764, 170

11 The Case for a Relatively Weak Wind for the Young Sun Solar activity varies significantly over the course of its activity cycle, but: 1.Voyager has observed little variation from the canonical solar mass loss rate of Ṁ ʘ =2× M ʘ /yr. 2.There is no strong correlation between solar X-ray flux and mass loss rate. Conclusion: Perhaps the solar wind is relatively constant over time. Cohen 2011, MNRAS, 417, 2592

12 astrospheric absorption heliospheric absorption

13

14 Ṁ=0.2 Ṁ ⊙ Ṁ=0.5 Ṁ ⊙ Ṁ=1.0 Ṁ ⊙ Ṁ=2.0 Ṁ ⊙ Models of the  Cen Astrosphere

15 Wood et al. 2001, ApJ, 547, L49 Astrospheric Absorption Predictions for  Cen

16 Wood et al. 2002, ApJ, 574, 412

17 Astrospheric Models The ε Eri astrosphere is comparable in size to the full moon in the night sky!

18 The New  1 UMa Measurement  1 UMa and 3 other young Sun analogs observed by HST in Only  1 UMa provided an astrospheric detection.  1 UMa (G1.5 V) is a 500 Myr solar analog. The absorption suggests a mass loss rate of only 0.5 Ṁ ʘ (Wood et al. 2014, ApJ, 781, L33).

19 List of Astrospheric Measurements

20 Mass Loss/X-ray Relation Red: Solar-like GK main sequence stars Green: M dwarfs ṀF X 1.340.18 Wood et al. 2014, ApJ, 781, L33

21 Rice & Strassmeier 2001, A&A, 377, 264 Is Magnetic Topology Inhibiting the Winds of Young, Active Stars?

22

23 Ṁt -2.330.55 Wind Evolution for a Sun-like Star

24 Evolution of the Martian Atmosphere Mars Today Mars 4 Gyr ago

25 Lundin 2001, Science, 291, 1909 What Role do Magnetospheres Play in Atmospheric Evolution? Earth is protected by a “magnetosphere,” but Mars is not!

26 Stellar Wind Erosion of a “Hot Jupiter” This is just an artist’s conception of a stellar wind eroding a planetary atmosphere, but Ly  absorption from such an eroding atmosphere may have actually been detected for the transiting exoplanet HD b (Vidal- Madjar et al. 2003, Nature, 422, 143; Linsky et al. 2010, ApJ, 717, 1291).

27 Bahcall et al. 2001, ApJ, 555, 990 The Faint Young Sun Problem (FYSP) (first defined by Sagan & Mullen 1972, Science, 177, 52)

28 Sackmann & Boothroyd 2003, ApJ, 583, 1084 Could the FYSP be Resolved by a More Massive Young Sun?

29 Mass Lost due to Solar Wind Inferred from Astrospheric Measurements

30 Shaviv 2003, JGR, 108, 1437 Could a Stronger Wind for the Young Sun Explain the FYSP Via Cosmic Ray Cooling?

31 SUMMARY Currently the only way to study the astrospheres and winds of solar-like stars is through astrospheric Lyα absorption observed by HST. Analysis of the astrospheric absorption suggests that for solar-like GK dwarfs, mass loss and activity are correlated such that Ṁ F X 1.34  However, this relation does not extend to high activity levels (F X >10 6 ergs cm -2 s -1 ), possibly indicating a fundamental change in magnetic structure for more active stars. The mass-loss/activity relation described above suggests that mass loss decreases with time as Ṁ t  However, the apparent high activity cutoff means that this mass loss evolution law doesn’t extend to times earlier than t~0.7 Gyr. Despite the higher mass loss rates predicted for the young Sun by our mass loss evolution law, the total mass lost by the Sun in its lifetime is still insignificant, so this stronger young wind can’t directly solve the Faint Young Sun problem, though there is speculation that it could indirectly via cosmic ray attenuation. The existence of generally stronger winds at younger stellar ages makes it more likely that solar/stellar wind erosion plays an important role in the evolution of planetary atmospheres.


Download ppt "Stellar Winds and their Interaction with the Interstellar Medium Brian E. Wood (Naval Research Laboratory) Jeffrey L. Linsky (JILA, University of Colorado)"

Similar presentations


Ads by Google