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Solar and stellar chromospheric activity

Solar and stellar chromospheric activity. Katarzyna Mikuła Astronomical Institute , University of Wrocław March 28 th , 2014. 1 st SOLARNET Spring School March 24 th  – April 4 th , 2014, Wrocław , Poland. Outline. Observations in Ca II H & K lines HK Project

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Solar and stellar chromospheric activity

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  1. Solar and stellarchromosphericactivity Katarzyna MikułaAstronomicalInstitute, University of Wrocław March 28th, 2014 1st SOLARNET Spring SchoolMarch 24th – April 4th, 2014, Wrocław, Poland

  2. Outline Observationsin Ca II H & K lines HK Project Stellarchromosphericactivity Mainresults Summary 1st SOLARNET Spring SchoolMarch 24th – April 4th, 2014, Wrocław, Poland Katarzyna Mikuła, AstronomicalInstitute, University of WrocławSolar and stellarchromosphericactivity

  3. Chromosphere and activity Whatisthechromosphere? • Indicators of chromosphericactivity: • UV lines: Lyα, O I (1304 Å), C I (1557 Å, 1561 Å), Si II (1808 Å, 1817 Å), Mg II h & k (2796 Å, 2803 Å) • VIS lines: Ca II H & K (3968 Å, 3934 Å) 1st SOLARNET Spring SchoolMarch 24th – April 4th, 2014, Wrocław, Poland Katarzyna Mikuła, AstronomicalInstitute, University of WrocławSolar and stellarchromosphericactivity

  4. Observationsin Ca II H & K • Eberhard & Schwarzschild (1913) – discoveredemissionin Ca II H & K lines inArcturus and otherstars spectra • Wilson (1963) and Wilson & Skumanich (1964) – fromobservations (Mount Wilson Observatory) theydiscoveredthatchromosphericactivity of main-sequencestarsdecreaseswithage • Result of theobservations was confirmed by Skumanich (1972): t -1/2 1st SOLARNET Spring SchoolMarch 24th – April 4th, 2014, Wrocław, Poland Katarzyna Mikuła, AstronomicalInstitute, University of WrocławSolar and stellarchromosphericactivity

  5. Long-term observationsin Ca II H & K Linearrelationbetweentheabsolutemagnitude and thelogarithm of the K lineemissionwidths (Wilson - Bappueffect): MV = 27.59 – 14.94 log W0(K) Similarrelationshipswerefound for otherresonance lines, such as Mg II k and Lyα. 1st SOLARNET Spring SchoolMarch 24th – April 4th, 2014, Wrocław, Poland Katarzyna Mikuła, AstronomicalInstitute, University of WrocławSolar and stellarchromosphericactivity

  6. HK Project • Systematic program of Ca II H & K observations of main-sequnecestars. • First phase: 1966 – 1977 • Doesthechromosphericactivity of main-sequencestarsvarywith time, and if so, how? ~Olin Wilson • Wilson, O., 1978, ChromosphericVariationsinMain-sequenceStars. 1st SOLARNET Spring SchoolMarch 24th – April 4th, 2014, Wrocław, Poland Katarzyna Mikuła, AstronomicalInstitute, University of WrocławSolar and stellarchromosphericactivity

  7. HK Project • HK Project continued under thedirection of S. Baliunas(1977 – 2003) • Mount Wilson Observatory S index: • SMWO = α[(H+K)/(R+V)] • Another observations: • O. Wilson – observedtheMoon as a solarproxy • National SolarObservatory (1974) • Sacramento Peak(1976) 1st SOLARNET Spring SchoolMarch 24th – April 4th, 2014, Wrocław, Poland Katarzyna Mikuła, AstronomicalInstitute, University of WrocławSolar and stellarchromosphericactivity

  8. Observations of Ca II H & K • From HK Project observations(to 1991): • 60 % of starsexhibitedperiodic, cyclicvariations • 25 % - irregularorperiodicvariability • 15 % - flatactivity Examples of HK Project observations (Hall et al. 2007b). 1st SOLARNET Spring SchoolMarch 24th – April 4th, 2014, Wrocław, Poland Katarzyna Mikuła, AstronomicalInstitute, University of WrocławSolar and stellarchromosphericactivity

  9. HD 114710 • MWO seriescan be used: • Identifyrotationperiods • Diferrentialrotation via drifts • Donahue & Baliunas (1992) – reporteddetection of a driftintheapparentrotation period inβCom = HD 114710. • Solarcycle: 1. activityislow, ARsappearat high latitudes 2. themeanlatitude of ARsmovestowardtheequator (shortestrotation period). • HD 114710 cycle: rotation period increasefromcyclemaximumthroughcycle minimum. 1st SOLARNET Spring SchoolMarch 24th – April 4th, 2014, Wrocław, Poland Katarzyna Mikuła, AstronomicalInstitute, University of WrocławSolar and stellarchromosphericactivity

  10. Observations of Ca II H & K Thedistribution of activityin 815 southern Sun-likestars (Henry et al. 1996). 1st SOLARNET Spring SchoolMarch 24th – April 4th, 2014, Wrocław, Poland Katarzyna Mikuła, AstronomicalInstitute, University of WrocławSolar and stellarchromosphericactivity

  11. Grand minima TheMaunder Minimum: 1645 – 1715. Baliunas& Jastrow(1990) - study of magnetic activity for 70solar-typestars. Twodifferentpopulations: SMWO ~ 0.17 SMWO ~ 0.15 SMWO for the Sun: ~0.17 – 0.18 - active Sun ~0.14 - zero magneticactivity 1st SOLARNET Spring SchoolMarch 24th – April 4th, 2014, Wrocław, Poland Katarzyna Mikuła, AstronomicalInstitute, University of WrocławSolar and stellarchromosphericactivity

  12. Grand minima HK fluxvariations for twostars (HD 10476 and HD 3651) withsimilar mass and rotation. Left: HD14538 appears to have made a transition from a at activitystate to short cycle in 2000 (Hall et al. 2007b). Right: HD 3651 showsevidence of having entered a at activitystate around 1980 (Baliunaset al. 1995). 1st SOLARNET Spring SchoolMarch 24th – April 4th, 2014, Wrocław, Poland Katarzyna Mikuła, AstronomicalInstitute, University of WrocławSolar and stellarchromosphericactivity

  13. Summary • Long-term observations of stellarchromosphericactivity – over 60 years of observationsin Ca II H & K lines • The most of starsrevealactivitycyclessimilar to solaractivitycycle • Thesamples of starsare not large – we cannotunderstandchromosphericactivity to theend • Studying of solar/stellar dynamo 1st SOLARNET Spring SchoolMarch 24th – April 4th, 2014, Wrocław, Poland Katarzyna Mikuła, AstronomicalInstitute, University of WrocławSolar and stellarchromosphericactivity

  14. Bibliography Hall, J.C., 2008, LivingReviewsinSolarPhysics, 5, 2 Wilson, P., 1994, Solar and StellarActivityCycles, CAS Fares, R., 2013, IAU Symp. 302 Fletcher , L., 2012, ASP ConferenceSeries, 448, 1 Bruevich, E.A. & Rozgacheva, I.K., 2012 eprint arXiv:1204.5705 Wilson, O., 1978, ApJ, 226, 379 Donahue, R.A. & Baliunas, S., 1992, ApJ, 393, 63 Baliunas S. et al., 1995, ApJ, 438, 269 1st SOLARNET Spring SchoolMarch 24th – April 4th, 2014, Wrocław, Poland Katarzyna Mikuła, AstronomicalInstitute, University of WrocławSolar and stellarchromosphericactivity

  15. Thankyou for yourattention! 1st SOLARNET Spring SchoolMarch 24th – April 4th, 2014, Wrocław, Poland Katarzyna Mikuła, AstronomicalInstitute, University of WrocławSolar and stellarchromosphericactivity

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