The solar corona during the eclipse of August 1, 2008

The Color and Brightness of the F-Corona Inferred from the 2019 July 2 Total Solar Eclipse

“…For example, the streamers have a substantially higher (∼ 10× at 1.5 R ) intensity than the poles, as expected, and the highest and lowest intensities broadly agree with the higher and lower estimates from the literature (i.e., van de Hulst 1950; Koutchmy & Lamy 1985;Morgan & Habbal 2007). Similarly, the MLSO K-Cor observations (see Section 2.2) on the day of the eclipse are consistent with previous work on the polarized brightness (pB) of the K-corona (i.e., Guhathakurta et al 1996;Morgan & Habbal 2007;Skomorovsky et al 2011), which are shown in the right panels of Figure 6. The comparison to Skomorovsky et al (2011) is especially interesting, as they observed the K-corona pB during the 2008 total solar eclipse, close to solar minimum (much like this 2019 eclipse).…”

“…Similarly, the MLSO K-Cor observations (see Section 2.2) on the day of the eclipse are consistent with previous work on the polarized brightness (pB) of the K-corona (i.e., Guhathakurta et al 1996;Morgan & Habbal 2007;Skomorovsky et al 2011), which are shown in the right panels of Figure 6. The comparison to Skomorovsky et al (2011) is especially interesting, as they observed the K-corona pB during the 2008 total solar eclipse, close to solar minimum (much like this 2019 eclipse). Further, the MLSO K-Cor data appear to be rather robust in the equatorial streamers out to about 1.8 R , but they diverge rather quickly in the lower intensity regions near the poles of the Sun (top right panel of Fig.…”

“…Of course, there are a multitude of studies that have observed the K-corona pB and tB intensity, either through direct observation of the F-corona lines (e.g., van de Hulst 1950) or via polarization observations. The polarization observations, in particular, have been repeated many times with both eclipses (e.g., Guhathakurta et al 1996;Skomorovsky et al 2011) and coronagraphic datasets (e.g., Morgan & Habbal 2007;Lamy et al 2020). To compare our K-corona intensity results with other studies, we have chosen a small number for the sake of brevity and clarity, especially given that the decades of work have consistently reproduced the same intensities within a range that is comparable to the real physical variation of the electron density over the solar cycle and across different coronal structures (e.g., streamers vs. coronal holes).…”

“…The spatially dependent scattering of the K-corona -depending both on the plane-of-sky (POS) distance from the Sun, or elongation angle (often referred to as the 'impact parameter'), and the location of structures along the line-of-sight (LOS) -enables the characterization of 3-dimensional (3D) structures like streamers (e.g., Kramar et al 2014) and Coronal Mass Ejections (CMEs; e.g., Moran & Davila 2004;Dere et al 2005;Howard & Tappin 2009), especially if the event is observed from multiple viewing angles around the Sun (e.g., Colaninno & Vourlidas 2009;Moran et al 2010;DeForest et al 2017). Such pB inversion methods have been extensively used to infer the electron density in the corona (e.g., Allen 1947;Guhathakurta et al 1996;Skomorovsky et al 2011;Morgan & Cook 2020). Techniques have been developed to infer the electron density from total brightness (tB) observations as well (Hayes et al 2001), though such methods require an assumed F-corona contribution to the continuum.…”