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- Foukal, Peter, et al.
(författare)
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DIMMING OF THE 17TH CENTURY SUN
- 2011
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Ingår i: The Astrophysical Journal Letters. - 2041-8205. ; 733:2, s. L38-
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Tidskriftsartikel (refereegranskat)abstract
- Reconstructions of total solar irradiance (TSI) rely mainly on linear relations between TSI variation and indices of facular area. When these are extrapolated to the prolonged 15th-17th century Sporer and Maunder solar activity minima, the estimated solar dimming is insufficient to explain the mid-millennial climate cooling of the Little Ice Age. We draw attention here to evidence that the relation departs from linearity at the lowest activity levels. Imaging photometry and radiometry indicate an increased TSI contribution per unit area from small network faculae by a factor of 2-4 compared with larger faculae in and around active regions. Even partial removal of this more TSI-effective network at prolonged minima could enable climatically significant solar dimming, yet be consistent with the weakened but persistent 11 yr cycle observed in Be 10 during the Maunder Minimum. The mechanism we suggest would not alter previous findings that increased solar radiative forcing is insufficient to account for 20th century global warming.
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| 2. |
- Hubrig, Swetlana, et al.
(författare)
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Studying the Magnetic Properties of Upper Main-sequence Stars with FORS1
- 2009
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Ingår i: The Messenger (ESO). ; 135, s. 21-25
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We summarise the results of our recent magnetic field studies in upper main-sequence stars, which have exploited the spectropolarimetric capability of FORS1 at the VLT extensively.
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| 3. |
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| 4. |
- Schnerr, Roald
(författare)
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The Total Solar Irradiance and Small Scale Magnetic Fields
- 2011
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Ingår i: Solar Polarization Workshop 6. - San Francisco : Astronomical Society of the Pacific. - 9781583817544 ; , s. 167-
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Konferensbidrag (refereegranskat)abstract
- “What is the contribution of the weak small scale fields in the quiet Sun to the Total Solar Irradiance (TSI)?.” This is the question we try to answer by investigating the relation between magnetic fields and continuum intensity in SST and Hinode quiet Sun observations. We find that the increase in brightness of the quiet Sun due to weak (B < 30 G) fields could be as large as 0.3%, which would make it a major contributor to TSI variations. We also find that most of the magnetic flux appears to be resolved at the 0.16″ resolution of the SST data.
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