Artículo
Abstract:
Radio-bright regions near the solar poles are frequently observed in Nobeyama Radioheliograph (NoRH) maps at 17 GHz, and often in association with coronal holes. However, the origin of these polar brightenings has not been established yet. We propose that small magnetic loops are the source of these bright patches, and present modeling results that reproduce the main observational characteristics of the polar brightening within coronal holes at 17 GHz. The simulations were carried out by calculating the radio emission of the small loops, with several temperature and density profiles, within a 2D coronal hole atmospheric model. If located at high latitudes, the size of the simulated bright patches are much smaller than that of the beam size and they present the instrument beam size when observed. The larger bright patches can be generated by a great number of small magnetic loops unresolved by the NoRH beam. Loop models that reproduce bright patches contain denser and hotter plasma near the upper chromosphere and lower corona. On the other hand, loops with increased plasma density and temperature only in the corona do not contribute to the emission at 17 GHz. This could explain the absence of a one-to-one association between the 17 GHz bright patches and those observed in extreme ultraviolet. Moreover, the emission arising from small magnetic loops located close to the limb may merge with the usual limb brightening profile, increasing its brightness temperature and width. © 2017. The American Astronomical Society. All rights reserved.
Registro:
| Documento: | Artículo |
| Título: | Association of Radio Polar Cap Brightening with Bright Patches and Coronal Holes |
| Autor: | Selhorst, C.L.; Simões, P.J.A.; Silva, A.J.O.E.; Castro, C.G.G.D.; Costa, J.E.R.; Valio, A. |
| Filiación: | NAT-Núcleo de Astrofísica Teórica, Universidade Cruzeiro Do sul, São Paulo, SP, Brazil SUPA, School of Physics and Astronomy, University of GlasgowG12 8QQ, United Kingdom IPandD, Universidade Do Vale Do Paraba-UNIVAP, São José dos Campos, SP, Brazil CRAAM, Universidade Presbiteriana Mackenzie, São Paulo, SP, 01302-907, Brazil IAFE, Universidad de Buenos Aires, CONICET, Buenos Aires, Argentina CEA, Instituto Nacional de Pesquisas Espaciais, São José dos Campos, SP, Brazil |
| Palabras clave: | Sun: chromosphere; Sun: general; Sun: radio radiation |
| Año: | 2017 |
| Volumen: | 851 |
| Número: | 2 |
| DOI: | http://dx.doi.org/10.3847/1538-4357/aa992b |
| Título revista: | Astrophysical Journal |
| Título revista abreviado: | Astrophys. J. |
| ISSN: | 0004637X |
| Registro: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_0004637X_v851_n2_p_Selhorst |
Referencias:
- Brajša, R., Benz, A.O., Temmer, M., (2007) SoPh, 245, p. 167
- Efanov, V.A., Moiseev, I.G., Nesterov, N.S., Stewart, R.T., (1980) IAU Symp. 86: Radio Physics of the Sun, p. 141. , (Cambridge: Cambridge Univ. Press)
- Gopalswamy, N., Shibasaki, K., Thompson, B.J., Gurman, J., DeForest, C., (1999) JGR, 104, p. 9767
- Lemen, J.R., Title, A.M., Akin, D.J., (2012) SoPh, 275, p. 17
- Maksimov, V.P., Prosovetsky, D.V., Grechnev, V.V., Krissinel, B.B., Shibasaki, K., (2006) PASJ, 58, p. 1
- Martínez-Sykora, J., De Pontieu, B., Carlsson, M., (2017) ApJ, 847 (1), p. 36
- Nakajima, H., Nishio, M., Enome, S., (1994) IEEEP, 82, p. 705
- Nindos, A., Kundu, M.R., White, S.M., (1999) ApJ, 527 (1), p. 415
- Nitta, N.V., Sun, X., Hoeksema, J.T., DeRosa, M.L., (2014) ApJL, 780, p. L23
- Oliveira Silva, E.A.J., Selhorst, C.L., Simões, P.J.A., Giménez De Castro, C.G., (2016) A&A, 592, p. A91
- Pereira, T.M.D., De Pontieu, B., Carlsson, M., (2014) ApJL, 792, p. L15
- Riehokainen, A., Urpo, S., Valtaoja, E., (1998) A&A, 333, p. 741
- Riehokainen, A., Urpo, S., Valtaoja, E., (2001) A&A, 366, p. 676
- Selhorst, C.L., Giménez De Castro, C.G., Varela Saraiva, A.C., Costa, J.E.R., (2010) A&A, 509, p. A51
- Selhorst, C.L., Silva, A.V.R., Costa, J.E.R., (2005) A&A, 433, p. 365
- Selhorst, C.L., Silva, A.V.R., Costa, J.E.R., (2005) A&A, 440, p. 367
- Selhorst, C.L., Silva, A.V.R., Costa, J.E.R., Shibasaki, K., (2003) A&A, 401, p. 1143
- Selhorst, C.L., Silva-Válio, A., Costa, J.E.R., (2008) A&A, 488, p. 1079
- Shibasaki, K., (1998) ASP Conf. Ser. 140, Synoptic Solar Physics, p. 373. , ed K. S. Balasubramaniam, J. Harvey and D. Rabin (San Francisco, CA: ASP)
- Sterling, A.C., (2000) SoPh, 196, p. 79
- Tsiropoula, G., Tziotziou, K., Kontogiannis, I., (2012) SSRv, 169, p. 181
- Wedemeyer, S., Bastian, T., Brajša, R., (2016) SSRv, 200, p. 1
- Wilhelm, K., (2006) A&A, 455, p. 697
Citas:
---------- APA ----------
Selhorst, C.L., Simões, P.J.A., Silva, A.J.O.E., Castro, C.G.G.D., Costa, J.E.R. & Valio, A. (2017) . Association of Radio Polar Cap Brightening with Bright Patches and Coronal Holes. Astrophysical Journal, 851(2).http://dx.doi.org/10.3847/1538-4357/aa992b
---------- CHICAGO ----------
Selhorst, C.L., Simões, P.J.A., Silva, A.J.O.E., Castro, C.G.G.D., Costa, J.E.R., Valio, A. "Association of Radio Polar Cap Brightening with Bright Patches and Coronal Holes" . Astrophysical Journal 851, no. 2 (2017).http://dx.doi.org/10.3847/1538-4357/aa992b
---------- MLA ----------
Selhorst, C.L., Simões, P.J.A., Silva, A.J.O.E., Castro, C.G.G.D., Costa, J.E.R., Valio, A. "Association of Radio Polar Cap Brightening with Bright Patches and Coronal Holes" . Astrophysical Journal, vol. 851, no. 2, 2017.http://dx.doi.org/10.3847/1538-4357/aa992b
---------- VANCOUVER ----------
Selhorst, C.L., Simões, P.J.A., Silva, A.J.O.E., Castro, C.G.G.D., Costa, J.E.R., Valio, A. Association of Radio Polar Cap Brightening with Bright Patches and Coronal Holes. Astrophys. J. 2017;851(2).http://dx.doi.org/10.3847/1538-4357/aa992b
