Latitudinal variation of the solar photospheric intensity

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Rast, Mark P. ; Ortiz, Ada ; Meisner, Randle W. (2007)
  • Related identifiers: doi: 10.1086/524655
  • Subject: Astrophysics
    arxiv: Astrophysics::Galaxy Astrophysics | Astrophysics::Earth and Planetary Astrophysics | Astrophysics::Solar and Stellar Astrophysics | Physics::Space Physics

We have examined images from the Precision Solar Photometric Telescope (PSPT) at the Mauna Loa Solar Observatory (MLSO) in search of latitudinal variation in the solar photospheric intensity. Along with the expected brightening of the solar activity belts, we have found a weak enhancement of the mean continuum intensity at polar latitudes (continuum intensity enhancement $\sim0.1 - 0.2%$ corresponding to a brightness temperature enhancement of $\sim2.5{\rm K}$). This appears to be thermal in origin and not due to a polar accumulation of weak magnetic elements, with both the continuum and CaIIK intensity distributions shifted towards higher values with little change in shape from their mid-latitude distributions. Since the enhancement is of low spatial frequency and of very small amplitude it is difficult to separate from systematic instrumental and processing errors. We provide a thorough discussion of these and conclude that the measurement captures real solar latitudinal intensity variations.
  • References (3)

    Altrock, R.C. & Canfield, R.C. 1972, Sol. Phys., 23, 257 Brun, A.S. & Toomre, J. 2002, ApJ, 570, 865 Caccin, B., Falciani, R., Moschi, G., & Rigutti, M. 1970, Sol. Phys., 13, 33 Coulter, R.L. & Kuhn, J.R. 1994, in ASP Conf. Ser. 68, ed. K.S. Balasubramaniam & G. W. Simon (San Francisco: ASP), 37

    Dicke, R.H. 1964, Nature, 202, 432 Dicke, R.H. & Goldenberg, H.M. 1967, Phys. Rev. Lett., 18, 313 Falciani, R., Rigutti, M., & Roberti, G. 1974, Sol. Phys., 35, 277 Harvey, K.L. & White, O.R. 1999, ApJ, 515, 812 Howard, R. & Labonte, B.J. 1981, Sol. Phys., 74, 131 Knaack, R., Stenflo, J.O., & Berdyugina, S. 2004, A&A, 418, L17 Kitchatinov, L.L. & Ru¨diger, G. 1995, A&A, 299, 446 Koutchmy, S., Koutchmy, O., & Kotov, V. 1977, A&A, 59, 189 Kuhn, J.R., Libbrecht, K.G., & Dicke, R.H. 1985, ApJ, 290, 758 Kuhn, J.R., Libbrecht, K.G., & Dicke, R.H. 1987, ApJ, 319, 1010 Kuhn, J.R., Libbrecht, K.G., & Dicke, R.H. 1988, Science, 242, 908 Kuhn, J.R., Lin, H., & Loranz, D. 1991, PASP, 103, 1097 Kuhn, J.R., Bush, R.I., Scheick, X. & Scherrer, P. 1998, Nature, 392, 155 Miesch, M.S., Brun, A.S., & Toomre, J. 2006, ApJ, 641, 618 Muller, R. & Roudier, Th. 1984, Sol. Phys., 94, 33 Ortiz, A. & Rast, M.P. 2005, Mem SAIt., 76, 1018 Rast, M.P., Meisner, R.W., Lites, B.W., Fox, P.A., & White, O.R. 2001, ApJ, 557, 864 Rast, M.P. 2003, in ESA Special Publication 517, Proceedings of SOHO12/GONG+ 2002. Local and Global Helioseismology: The Present and Future, ed. H. Sawaya-Lacoste (Noordwijk: ESA publications Division), 163

    Schrijver, C.J., Cote, J., Zwaan, C., & Saar, S.H. 1989, ApJ, 337, 964 Sheeley, N.R. & Warren, H.P. 2006, ApJ, 641, 611 Skumanich, A., Smythe, C., & Frazier, E.N. 1975, ApJ, 200, 747 Spruit, H.C. 2003, Sol. Phys., 213, 1 Thompson, M.J., et al. 1996, Science, 272, 1300 Zaatri, A., Komm, R., Gonz´alez Hern´andez, I., Howe, R., & Corbard, T. 2006, Sol. Phys., 236, 227

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