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Travis Metcalfe Monitoring Stellar Magnetic Activity Cycles with SONG

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Monitoring Stellar Magnetic Activity Cycles with SONG. Travis Metcalfe. Solar and stellar activity cycles. Magnetic regions on the Sun are bright in Mg II (UV) and Ca II (optical) Measure ratio of total emission in line cores to flux in the wings - PowerPoint PPT Presentation

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Page 1: Travis Metcalfe

Travis Metcalfe

Monitoring Stellar Magnetic Activity Cycles with SONG

Page 2: Travis Metcalfe

Solar and stellar activity cycles

• Magnetic regions on the Sun are bright in Mg II (UV) and Ca II (optical)

• Measure ratio of total emission in line cores to flux in the wings

• Use disk-integrated time series measurements to track magnetic cycles

http://spacescience.spaceref.com/

Page 3: Travis Metcalfe

Cycle-induced frequency shifts

• Solar p-mode shifts first detected in 1990, depend on frequency and degree

• Even the lowest degree solar p-modes are shifted by the solar cycle

• Unique constraints on the mechanism could come from solar-type stars

Libbrecht & Woodard (1990)

Salabert et al. (2004)

Page 4: Travis Metcalfe

Mount Wilson survey

Baliunas et al. (1995)

• Started by O. Wilson in mid-1960’s with 100-inch telescope on 91 stars

• Continued through 1980’s and 1990’s with 60-inch on hundreds of stars

• Stopped in early 2000’s after more than 30 years of observations

Page 5: Travis Metcalfe

Lowell survey

• 1.1-m telescope close to Flagstaff Arizona, allocate 7 nights/month bright time

• Solar observations 3-6x per week, 50 target stars sampled a few nights/mo.

• Solar/stellar/comparison all fed to spectrograph through a single fiber

Hall & Lockwood (1995)

Page 6: Travis Metcalfe

Solar-Stellar spectrograph

• Built at NCAR, delivered to Lowell in 1988, regular observations since 1995

• Dedicated to long-term observations of the Sun and Sun-like stars

• Example: observations of the “solar twin” 18 Sco show ~7 yr activity cycle

Hall, Lockwood & Henry (2007)

Page 7: Travis Metcalfe

SMARTS survey

Metcalfe et al. (2009, arXiv:0909.5464)

• Small telescopes at CTIO now run by a consortium; NCAR is a minor partner

• Monitor bright southern asteroseismic targets for stellar activity variations

• Example: observations of the exoplanet host star HD 17051 = HR 810

Page 8: Travis Metcalfe

SONG at MLSO