PERIODIC AND SPORADIC VARIATIONS IN THE SPECTRAL FLUX DENSITY OF THE CAS A SUPERNOVA REMNANT
Purpose: Based on the long-term study data in all radio spectrum ranges, the nature of deviations of spectral flux density of the Cas A supernova remnant from the tendency of its secular decrease is considered. The aim of this work is determining the presence of quasiperiodic variations and sporadic...
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Видавничий дім «Академперіодика»
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Radio physics and radio astronomy| id |
oai:ri.kharkov.ua:article-1346 |
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Radio physics and radio astronomy |
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English |
| topic |
Cas A secular radiation flux decrease supernova remnant ionosphere solar activity Cas A secular radiation flux decrease supernova remnant ionosphere solar activity Cas A вікове зменшення потоку випромінювання залишок наднової іоносфера сонячна активність |
| spellingShingle |
Cas A secular radiation flux decrease supernova remnant ionosphere solar activity Cas A secular radiation flux decrease supernova remnant ionosphere solar activity Cas A вікове зменшення потоку випромінювання залишок наднової іоносфера сонячна активність Gorbunov, A. A. Ryabov, M. I. Sukharev, A. L. Bezrukovs, V. V. PERIODIC AND SPORADIC VARIATIONS IN THE SPECTRAL FLUX DENSITY OF THE CAS A SUPERNOVA REMNANT |
| topic_facet |
Cas A secular radiation flux decrease supernova remnant ionosphere solar activity Cas A secular radiation flux decrease supernova remnant ionosphere solar activity Cas A вікове зменшення потоку випромінювання залишок наднової іоносфера сонячна активність |
| format |
Article |
| author |
Gorbunov, A. A. Ryabov, M. I. Sukharev, A. L. Bezrukovs, V. V. |
| author_facet |
Gorbunov, A. A. Ryabov, M. I. Sukharev, A. L. Bezrukovs, V. V. |
| author_sort |
Gorbunov, A. A. |
| title |
PERIODIC AND SPORADIC VARIATIONS IN THE SPECTRAL FLUX DENSITY OF THE CAS A SUPERNOVA REMNANT |
| title_short |
PERIODIC AND SPORADIC VARIATIONS IN THE SPECTRAL FLUX DENSITY OF THE CAS A SUPERNOVA REMNANT |
| title_full |
PERIODIC AND SPORADIC VARIATIONS IN THE SPECTRAL FLUX DENSITY OF THE CAS A SUPERNOVA REMNANT |
| title_fullStr |
PERIODIC AND SPORADIC VARIATIONS IN THE SPECTRAL FLUX DENSITY OF THE CAS A SUPERNOVA REMNANT |
| title_full_unstemmed |
PERIODIC AND SPORADIC VARIATIONS IN THE SPECTRAL FLUX DENSITY OF THE CAS A SUPERNOVA REMNANT |
| title_sort |
periodic and sporadic variations in the spectral flux density of the cas a supernova remnant |
| title_alt |
PERIODIC AND SPORADIC VARIATIONS IN THE SPECTRAL FLUX DENSITY OF THE CAS A SUPERNOVA REMNANT ПЕРІОДИЧНІ І СПОРАДИЧНІ ПРОЯВИ ВАРІАЦІЙ СПЕКТРАЛЬНОЇ ЩІЛЬНОСТІ ПОТОКУ ВИПРОМІНЮВАННЯ ЗАЛИШКА НАДНОВОЇ CAS A |
| description |
Purpose: Based on the long-term study data in all radio spectrum ranges, the nature of deviations of spectral flux density of the Cas A supernova remnant from the tendency of its secular decrease is considered. The aim of this work is determining the presence of quasiperiodic variations and sporadic changes in the Cas A spectral radiation flux density depending on frequency.Design/methodology/approach: The main database is using the published results obtained with the method of absolute measurements of the Cas A spectral radiation flux density in a wide range from millimeter to decimeter wavelengths, as well as the results obtained with the method of relative measurements of the ratio of the flux densities of the Cas A supernova remnant and radio galaxy Cyg A, this latter being used as a reference source in the meter wavelength range. For making comparison with the aforesaid data obtained with different methods, the results of a long-term monitoring (since 1987) of the variation of the ratio of the spectral flux densities of Cas A and Cyg A made with the URAN-4 radio telescope of the Institute of Radio Astronomy of the National Academy of Sciences of Ukraine at 25 MHz were used.Findings: As a result of the analysis of the observed data for the Cas A radiation flux density in the entire radio wavelength range, the existence of quasiperiodic variations in the range from millimeter to meter wavelengths within 2 to 9 years has been noted. The reason for the detected quasiperiodic variations can be the processes in the Cas A remnant itself. In the decameter wavelength range, according to monitoring data obtained with the URAN-4 radio telescope, the seasonal-diurnal and long-term variations are noted, being associated with changes in the ionosphere state in the solar activity cycle, with some weak appearance of the secular decrease of the Cas A radiation flux. The presence of sporadic variations in the ratio of the spectral flux densities of Cas A and Cyg A is associated with the effect of the increased solar activity. For explaining the lowering of the Cas A spectral flux density to the Cyg A level and maintaining the excess of the Cas A flux at decameter waves, the quasi-simultaneous observations made with radiotelescopes for different wavelength ranges will be required.Conclusions: The evolution of the Cas A supernova remnant remains the focus of interest of current research efforts. An intriguing moment was the discovery of a point X-ray source in the center of radio source Cas A as a possible supernova remnant. The role of this source in the Cas A radio flux secular decrease and in its variations needs to be clarified. A detailed analysis of the long-term data and making quasi-simultaneous observations will allow to reveal the processes occurring in the radio source itself and to determine the influence of the ionosphere state on the results of measurements. A joint program is suggested for observations of Cas A and Cyg A flux variations with the RT-32 and RT-16 radio telescopes, the LOFAR element of the Ventspils International Radio Astronomy Center (Latvia), and the URAN, UTR-2 and GURT radio telescopes of the Institute of Radio Astronomy of the National Academy of Sciences of Ukraine. Key words: Cas A; secular radiation flux decrease; supernova remnant; ionosphere; solar activityManuscript submitted 08.11.2020Radio phys. radio astron. 2020, 25(4): 268-275REFERENCES1. BAARS, J. W. M., GENZEL, R., PAULINY-TOTH, I. I. K. and WITZEL, A., 1977. The Absolute spectrum of Cas A: An Accurate Flux Density Scale and Set of Secondary Calibrators. Astron. Astrophys. vol. 61, is. 1, pp. 99–106.2. STANKEVICH, K. S., IVANOV, V. P. and STOLYAROV, S. P., 1999. Fifty Years of Radio Observations of the Discrete Source Cassiopeia A. Astron. Lett. vol. 25, is. 8, pp. 501–507.3. BARABANOV, A. P., IVANOV, V. P., STANKEVICH, K. S. and STOLYAROV, S. P., 1986. Evolution of the Cassiopeia A radio spectrum: evidence for cyclic variability. Sov. Astron. vol. 30, is. 5, pp. 549–554.4. IVANOV, V. P. and STANKEVICH, K. S., 1989. Periodic variations of the radio emission and evolution of the spectrum of the supernova remnant Cassiopeia A. Sov. Astron. vol. 33, is. 1, pp. 15–20.5. TROTTER, A. S., REICHART, D. E., EGGER, R. E., STÝBLOVÁ, J., PAGGEN, M. L., MARTIN, J. R., DUTTON, D. A., REICHART,J. E.,. KUMAR, N. D, MAPLES, M. P., BARLOW, B. N., BERGER, T. A., FOSTER, A. C., FRANK, N. R., GHIGO, F. D., HAISLIP, J. B., HEATHERLY, S. A., KOUPRIANOV, V. V., LACLUYZÉ, A. P., MOFFETT, D. A., MOORE, J. P., STANLEY, J. L. and WHITE, S., 2017. The fading of Cassiopeia A, and improved models for the absolute spectrum of primary radio calibration sources. Mon. Not. R. Astr. Soc. vol. 469, is. 2, pp. 1299–1313. DOI: 10.1093/mnras/stx8106. VINYAIKIN, E. N., 2007. Evolution of the radio spectrum of Cassiopeia A from long-term observations. Observations at 290 and 927 MHz. Astron. Rep. vol. 51, pp. 87–96. DOI:101134/S10637729070200237. VINYAIKIN, E. N., 2014. Frequency dependence of the evolution of the radio emission of the supernova remnant Cas A. Astron. Rep. vol. 58, pp. 626–639. DOI: 101134/S10637729140900788. MARTIROSSYAN, R. M., GOULYAN, A. G., SANAMYAN, V. A. and MANASELYAN, KH. A., 2020. Flux density variations of Cassiopea A radio source. Astrofizika. vol.45, no. 3, pp. 443–449. (in Russian).9. HELMBOLT, J. F. and KASSIM, N. E., 2009. The Evolution of Cassiopeia A at Low Radio Frequencies. Astron. J. vol. 138, is. 3, pp. 838–844. DOI: 1088/0004-6256/138/3/83810. WALCZOWSKI, L. T. and SMITH, K. L., 1985. A recurrence of the Cassiopeia A flux anomaly. Mon. Not. R. Astron. Soc. vol. 212, is. 1, pp. 27P–31P. DOI: 10.1093/mnras/212.1.27P11. RYABOV, M. I., PANISHKO, S. K. and GUGLYA, L. I., 2011. Space weather impacts on the Earth’s upper atmosphere according to the monitoring of powerful radio sources fluxes at the URAN-4 radio telescope (Institute of Radio Astronomy, NAS of Ukraine). Odessa Astronomical Publications. vol. 24, pp. 159–161. (in Russian).12. GORBYNOV, A. A., RYABOV, M. I. and PANISHKO, S. K. 2015. Secular Decrease the Flux of Supernova Eemnant Cas A on Monitoring Results to Radiotelescope “URAN-4” IRA NASU. Odessa astronomical publications. vol. 28, no. 2, pp. 224–226.13. RYABOV, M. I. and SEROKUROVA, N. G., 1993. On the secular decrease of the radio flux Cas A at low frequencies. Astron. Astrophys. Trans. vol. 4, is. 1, pp. 29–32. DOI: 10.1080/10556799308205353 |
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Видавничий дім «Академперіодика» |
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2020 |
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http://rpra-journal.org.ua/index.php/ra/article/view/1346 |
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oai:ri.kharkov.ua:article-13462020-12-07T14:28:43Z PERIODIC AND SPORADIC VARIATIONS IN THE SPECTRAL FLUX DENSITY OF THE CAS A SUPERNOVA REMNANT PERIODIC AND SPORADIC VARIATIONS IN THE SPECTRAL FLUX DENSITY OF THE CAS A SUPERNOVA REMNANT ПЕРІОДИЧНІ І СПОРАДИЧНІ ПРОЯВИ ВАРІАЦІЙ СПЕКТРАЛЬНОЇ ЩІЛЬНОСТІ ПОТОКУ ВИПРОМІНЮВАННЯ ЗАЛИШКА НАДНОВОЇ CAS A Gorbunov, A. A. Ryabov, M. I. Sukharev, A. L. Bezrukovs, V. V. Cas A; secular radiation flux decrease; supernova remnant; ionosphere; solar activity Cas A; secular radiation flux decrease; supernova remnant; ionosphere; solar activity Cas A; вікове зменшення потоку випромінювання; залишок наднової; іоносфера; сонячна активність Purpose: Based on the long-term study data in all radio spectrum ranges, the nature of deviations of spectral flux density of the Cas A supernova remnant from the tendency of its secular decrease is considered. The aim of this work is determining the presence of quasiperiodic variations and sporadic changes in the Cas A spectral radiation flux density depending on frequency.Design/methodology/approach: The main database is using the published results obtained with the method of absolute measurements of the Cas A spectral radiation flux density in a wide range from millimeter to decimeter wavelengths, as well as the results obtained with the method of relative measurements of the ratio of the flux densities of the Cas A supernova remnant and radio galaxy Cyg A, this latter being used as a reference source in the meter wavelength range. For making comparison with the aforesaid data obtained with different methods, the results of a long-term monitoring (since 1987) of the variation of the ratio of the spectral flux densities of Cas A and Cyg A made with the URAN-4 radio telescope of the Institute of Radio Astronomy of the National Academy of Sciences of Ukraine at 25 MHz were used.Findings: As a result of the analysis of the observed data for the Cas A radiation flux density in the entire radio wavelength range, the existence of quasiperiodic variations in the range from millimeter to meter wavelengths within 2 to 9 years has been noted. The reason for the detected quasiperiodic variations can be the processes in the Cas A remnant itself. In the decameter wavelength range, according to monitoring data obtained with the URAN-4 radio telescope, the seasonal-diurnal and long-term variations are noted, being associated with changes in the ionosphere state in the solar activity cycle, with some weak appearance of the secular decrease of the Cas A radiation flux. The presence of sporadic variations in the ratio of the spectral flux densities of Cas A and Cyg A is associated with the effect of the increased solar activity. For explaining the lowering of the Cas A spectral flux density to the Cyg A level and maintaining the excess of the Cas A flux at decameter waves, the quasi-simultaneous observations made with radiotelescopes for different wavelength ranges will be required.Conclusions: The evolution of the Cas A supernova remnant remains the focus of interest of current research efforts. An intriguing moment was the discovery of a point X-ray source in the center of radio source Cas A as a possible supernova remnant. The role of this source in the Cas A radio flux secular decrease and in its variations needs to be clarified. A detailed analysis of the long-term data and making quasi-simultaneous observations will allow to reveal the processes occurring in the radio source itself and to determine the influence of the ionosphere state on the results of measurements. A joint program is suggested for observations of Cas A and Cyg A flux variations with the RT-32 and RT-16 radio telescopes, the LOFAR element of the Ventspils International Radio Astronomy Center (Latvia), and the URAN, UTR-2 and GURT radio telescopes of the Institute of Radio Astronomy of the National Academy of Sciences of Ukraine. Key words: Cas A; secular radiation flux decrease; supernova remnant; ionosphere; solar activityManuscript submitted 08.11.2020Radio phys. radio astron. 2020, 25(4): 268-275REFERENCES1. BAARS, J. W. M., GENZEL, R., PAULINY-TOTH, I. I. K. and WITZEL, A., 1977. The Absolute spectrum of Cas A: An Accurate Flux Density Scale and Set of Secondary Calibrators. Astron. Astrophys. vol. 61, is. 1, pp. 99–106.2. STANKEVICH, K. S., IVANOV, V. P. and STOLYAROV, S. P., 1999. Fifty Years of Radio Observations of the Discrete Source Cassiopeia A. Astron. Lett. vol. 25, is. 8, pp. 501–507.3. BARABANOV, A. P., IVANOV, V. P., STANKEVICH, K. S. and STOLYAROV, S. P., 1986. Evolution of the Cassiopeia A radio spectrum: evidence for cyclic variability. Sov. Astron. vol. 30, is. 5, pp. 549–554.4. IVANOV, V. P. and STANKEVICH, K. S., 1989. Periodic variations of the radio emission and evolution of the spectrum of the supernova remnant Cassiopeia A. Sov. Astron. vol. 33, is. 1, pp. 15–20.5. TROTTER, A. S., REICHART, D. E., EGGER, R. E., STÝBLOVÁ, J., PAGGEN, M. L., MARTIN, J. R., DUTTON, D. A., REICHART,J. E.,. KUMAR, N. D, MAPLES, M. P., BARLOW, B. N., BERGER, T. A., FOSTER, A. C., FRANK, N. R., GHIGO, F. D., HAISLIP, J. B., HEATHERLY, S. A., KOUPRIANOV, V. V., LACLUYZÉ, A. P., MOFFETT, D. A., MOORE, J. P., STANLEY, J. L. and WHITE, S., 2017. The fading of Cassiopeia A, and improved models for the absolute spectrum of primary radio calibration sources. Mon. Not. R. Astr. Soc. vol. 469, is. 2, pp. 1299–1313. DOI: 10.1093/mnras/stx8106. VINYAIKIN, E. N., 2007. Evolution of the radio spectrum of Cassiopeia A from long-term observations. Observations at 290 and 927 MHz. Astron. Rep. vol. 51, pp. 87–96. DOI:101134/S10637729070200237. VINYAIKIN, E. N., 2014. Frequency dependence of the evolution of the radio emission of the supernova remnant Cas A. Astron. Rep. vol. 58, pp. 626–639. DOI: 101134/S10637729140900788. MARTIROSSYAN, R. M., GOULYAN, A. G., SANAMYAN, V. A. and MANASELYAN, KH. A., 2020. Flux density variations of Cassiopea A radio source. Astrofizika. vol.45, no. 3, pp. 443–449. (in Russian).9. HELMBOLT, J. F. and KASSIM, N. E., 2009. The Evolution of Cassiopeia A at Low Radio Frequencies. Astron. J. vol. 138, is. 3, pp. 838–844. DOI: 1088/0004-6256/138/3/83810. WALCZOWSKI, L. T. and SMITH, K. L., 1985. A recurrence of the Cassiopeia A flux anomaly. Mon. Not. R. Astron. Soc. vol. 212, is. 1, pp. 27P–31P. DOI: 10.1093/mnras/212.1.27P11. RYABOV, M. I., PANISHKO, S. K. and GUGLYA, L. I., 2011. Space weather impacts on the Earth’s upper atmosphere according to the monitoring of powerful radio sources fluxes at the URAN-4 radio telescope (Institute of Radio Astronomy, NAS of Ukraine). Odessa Astronomical Publications. vol. 24, pp. 159–161. (in Russian).12. GORBYNOV, A. A., RYABOV, M. I. and PANISHKO, S. K. 2015. Secular Decrease the Flux of Supernova Eemnant Cas A on Monitoring Results to Radiotelescope “URAN-4” IRA NASU. Odessa astronomical publications. vol. 28, no. 2, pp. 224–226.13. RYABOV, M. I. and SEROKUROVA, N. G., 1993. On the secular decrease of the radio flux Cas A at low frequencies. Astron. Astrophys. Trans. vol. 4, is. 1, pp. 29–32. DOI: 10.1080/10556799308205353 Purpose: Based on the long-term study data in all radio spectrum ranges, the nature of deviations of spectral flux density of the Cas A supernova remnant from the tendency of its secular decrease is considered. The aim of this work is determining the presence of quasiperiodic variations and sporadic changes in the Cas A spectral radiation flux density depending on frequency.Design/methodology/approach: The main database is using the published results obtained with the method of absolute measurements of the Cas A spectral radiation flux density in a wide range from millimeter to decimeter wavelengths, as well as the results obtained with the method of relative measurements of the ratio of the flux densities of the Cas A supernova remnant and radio galaxy Cyg A, this latter being used as a reference source in the meter wavelength range. For making comparison with the aforesaid data obtained with different methods, the results of a long-term monitoring (since 1987) of the variation of the ratio of the spectral flux densities of Cas A and Cyg A made with the URAN-4 radio telescope of the Institute of Radio Astronomy of the National Academy of Sciences of Ukraine at 25 MHz were used.Findings: As a result of the analysis of the observed data for the Cas A radiation flux density in the entire radio wavelength range, the existence of quasiperiodic variations in the range from millimeter to meter wavelengths within 2 to 9 years has been noted. The reason for the detected quasiperiodic variations can be the processes in the Cas A remnant itself. In the decameter wavelength range, according to monitoring data obtained with the URAN-4 radio telescope, the seasonal-diurnal and long-term variations are noted, being associated with changes in the ionosphere state in the solar activity cycle, with some weak appearance of the secular decrease of the Cas A radiation flux. The presence of sporadic variations in the ratio of the spectral flux densities of Cas A and Cyg A is associated with the effect of the increased solar activity. For explaining the lowering of the Cas A spectral flux density to the Cyg A level and maintaining the excess of the Cas A flux at decameter waves, the quasi-simultaneous observations made with radiotelescopes for different wavelength ranges will be required.Conclusions: The evolution of the Cas A supernova remnant remains the focus of interest of current research efforts. An intriguing moment was the discovery of a point X-ray source in the center of radio source Cas A as a possible supernova remnant. The role of this source in the Cas A radio flux secular decrease and in its variations needs to be clarified. A detailed analysis of the long-term data and making quasi-simultaneous observations will allow to reveal the processes occurring in the radio source itself and to determine the influence of the ionosphere state on the results of measurements. A joint program is suggested for observations of Cas A and Cyg A flux variations with the RT-32 and RT-16 radio telescopes, the LOFAR element of the Ventspils International Radio Astronomy Center (Latvia), and the URAN, UTR-2 and GURT radio telescopes of the Institute of Radio Astronomy of the National Academy of Sciences of Ukraine. Key words: Cas A; secular radiation flux decrease; supernova remnant; ionosphere; solar activityManuscript submitted 08.11.2020Radio phys. radio astron. 2020, 25(4): 268-275REFERENCES1. BAARS, J. W. M., GENZEL, R., PAULINY-TOTH, I. I. K. and WITZEL, A., 1977. The Absolute spectrum of Cas A: An Accurate Flux Density Scale and Set of Secondary Calibrators. Astron. Astrophys. vol. 61, is. 1, pp. 99–106.2. STANKEVICH, K. S., IVANOV, V. P. and STOLYAROV, S. P., 1999. Fifty Years of Radio Observations of the Discrete Source Cassiopeia A. Astron. Lett. vol. 25, is. 8, pp. 501–507.3. BARABANOV, A. P., IVANOV, V. P., STANKEVICH, K. S. and STOLYAROV, S. P., 1986. Evolution of the Cassiopeia A radio spectrum: evidence for cyclic variability. Sov. Astron. vol. 30, is. 5, pp. 549–554.4. IVANOV, V. P. and STANKEVICH, K. S., 1989. Periodic variations of the radio emission and evolution of the spectrum of the supernova remnant Cassiopeia A. Sov. Astron. vol. 33, is. 1, pp. 15–20.5. TROTTER, A. S., REICHART, D. E., EGGER, R. E., STÝBLOVÁ, J., PAGGEN, M. L., MARTIN, J. R., DUTTON, D. A., REICHART,J. E.,. KUMAR, N. D, MAPLES, M. P., BARLOW, B. N., BERGER, T. A., FOSTER, A. C., FRANK, N. R., GHIGO, F. D., HAISLIP, J. B., HEATHERLY, S. A., KOUPRIANOV, V. V., LACLUYZÉ, A. P., MOFFETT, D. A., MOORE, J. P., STANLEY, J. L. and WHITE, S., 2017. The fading of Cassiopeia A, and improved models for the absolute spectrum of primary radio calibration sources. Mon. Not. R. Astr. Soc. vol. 469, is. 2, pp. 1299–1313. DOI: https://doi.org/10.1093/mnras/stx8106. VINYAIKIN, E. N., 2007. Evolution of the radio spectrum of Cassiopeia A from long-term observations. Observations at 290 and 927 MHz. Astron. Rep. vol. 51, pp. 87–96. DOI: https://doi.org/10.1134/S10637729070200237. VINYAIKIN, E. N., 2014. Frequency dependence of the evolution of the radio emission of the supernova remnant Cas A. Astron. Rep. vol. 58, pp. 626–639. DOI: https://doi.org/10.1134/S10637729140900788. MARTIROSSYAN, R. M., GOULYAN, A. G., SANAMYAN, V. A. and MANASELYAN, KH. A., 2020. Flux density variations of Cassiopea A radio source. Astrofizika. vol.45, no. 3, pp. 443–449. (in Russian).9. HELMBOLT, J. F. and KASSIM, N. E., 2009. The Evolution of Cassiopeia A at Low Radio Frequencies. Astron. J. vol. 138, is. 3, pp. 838–844. DOI: https://doi.org/10.1088/0004-6256/138/3/83810. WALCZOWSKI, L. T. and SMITH, K. L., 1985. A recurrence of the Cassiopeia A flux anomaly. Mon. Not. R. Astron. Soc. vol. 212, is. 1, pp. 27P–31P. DOI: https://doi.org/10.1093/mnras/212.1.27P11. RYABOV, M. I., PANISHKO, S. K. and GUGLYA, L. I., 2011. Space weather impacts on the Earth’s upper atmosphere according to the monitoring of powerful radio sources fluxes at the URAN-4 radio telescope (Institute of Radio Astronomy, NAS of Ukraine). Odessa Astronomical Publications. vol. 24, pp. 159–161. (in Russian).12. GORBYNOV, A. A., RYABOV, M. I. and PANISHKO, S. K. 2015. Secular Decrease the Flux of Supernova Eemnant Cas A on Monitoring Results to Radiotelescope “URAN-4” IRA NASU. Odessa astronomical publications. vol. 28, no. 2, pp. 224–226. DOI: https://doi.org/10.18524/1810-4215.2015.28.7101313. RYABOV, M. I. and SEROKUROVA, N. G., 1993. On the secular decrease of the radio flux Cas A at low frequencies. Astron. Astrophys. Trans. vol. 4, is. 1, pp. 29–32. DOI: https://doi.org/10.1080/10556799308205353 Предмет і мета роботи: За даними багаторічних досліджень у всіх діапазонах радіоспектра розглядається характер відхилень спектральної щільності потоку випромінювання залишка наднової Cas A від тенденції її вікового зменшення. Метою роботи є визначення наявності квазіперіодичних варіацій та спорадичних змін спектральної щільності потоку випромінювання Cas A залежно від частоти.Методи і методологія: Основною базою даних є опубліковані результати, отримані методом абсолютних вимірювань спектральної густини потоку випромінювання Cas A в діапазоні від міліметрових до дециметрових довжин хвиль, та результати, отримані методом відносних вимірювань співвідношення потоків випромінювання залишка наднової Cas A та радіогалактики Cyg A, що використовується як опорне джерело в діапазоні метрових довжин хвиль. Для співставлення із вказаними даними, знайденими різними методами, використано результати тривалого моніторингу (з 1987 р.варіацій відношення спектральної щільності потоків Cas A та Cyg A на радіотелескопі “УРАН-4” Радіоастрономічного інститута НАН України на частоті 25 МГц.Результати:В результаті аналізу даних спостережень щільності потоку випромінювання Cas A у всьому радіодіапазоні відмічається існування квазіперіодичних варіацій на часовому інтервалі від 2 до 9 років. Причиною виявлених квазіперіодичних варіацій можуть бути процеси в самому залишку Cas A. В діапазоні декаметрових довжин хвиль за даними моніторингу на РТ “УРАН-4” відмічаються сезонно-добові та довготривалі варіації, пов’язані зі зміною стану іоносфери в циклі сонячної активності при слабкому прояві вікового зменшення потоку випромінювання Cas A. Наявність спорадичних варіацій відношення спектральних щільностей потоків Cas A та Cyg A пов’язана з проявами підвищеної сонячної активності. Аби пояснити зниження спектральної щільності потоку Cas A до рівня Cyg A та збереження перевищення потоку Cas A на декаметрових хвилях слід виконувати квазіодночасні спостереження на радіотелескопах різних діапазонів.Висновок: Еволюція залишку наднової Cas A залишається в центрі уваги сучасних досліджень. Інтригуючим моментом стало виявлення в центрі радіоджерела Cas A точкового рентгенівського джерела як можливого залишку наднової. Роль цього джерела у зменшенні вікового радіопотока Cas A та в його варіаціях ще належить з’ясувати. Детальний аналіз багаторічних даних та виконання квазіодночасних спостережень, дозволять виявити процеси, що відбуваються в самому радіоджерелі, та визначити, як на результати вимірювань впливає стан іоносфери. Пропонується спільна програма спостережень варіацій потоків випромінювання Cas A та Cyg A на радіотелескопах РТ-32, РТ-16 і елементі радіоінтерферометра LOFAR Вентспілського Радіоастрономічного центра (Латвія) та радіотелескопах “УРАН”, “УТР-2” і ГУРТ Радіоастрономічного інститута НАН України.Ключові слова: Cas A; вікове зменшення потоку випромінювання; залишок наднової; іоносфера; сонячна активністьСтаття надійшла до редакції 08.11.2020Radio phys. radio astron. 2020, 25(4): 268-275REFERENCES1. BAARS, J. W. M., GENZEL, R., PAULINY-TOTH, I. I. K. and WITZEL, A., 1977. The Absolute spectrum of Cas A: An Accurate Flux Density Scale and Set of Secondary Calibrators. Astron. Astrophys. vol. 61, is. 1, pp. 99–106.2. STANKEVICH, K. S., IVANOV, V. P. and STOLYAROV, S. P., 1999. Fifty Years of Radio Observations of the Discrete Source Cassiopeia A. Astron. Lett. vol. 25, is. 8, pp. 501–507.3. BARABANOV, A. P., IVANOV, V. P., STANKEVICH, K. S. and STOLYAROV, S. P., 1986. Evolution of the Cassiopeia A radio spectrum: evidence for cyclic variability. Sov. Astron. vol. 30, is. 5, pp. 549–554.4. IVANOV, V. P. and STANKEVICH, K. S., 1989. Periodic variations of the radio emission and evolution of the spectrum of the supernova remnant Cassiopeia A. Sov. Astron. vol. 33, is. 1, pp. 15–20.5. TROTTER, A. S., REICHART, D. E., EGGER, R. E., STÝBLOVÁ, J., PAGGEN, M. L., MARTIN, J. R., DUTTON, D. A., REICHART,J. E.,. KUMAR, N. D, MAPLES, M. P., BARLOW, B. N., BERGER, T. A., FOSTER, A. C., FRANK, N. R., GHIGO, F. D., HAISLIP, J. B., HEATHERLY, S. A., KOUPRIANOV, V. V., LACLUYZÉ, A. P., MOFFETT, D. A., MOORE, J. P., STANLEY, J. L. and WHITE, S., 2017. The fading of Cassiopeia A, and improved models for the absolute spectrum of primary radio calibration sources. Mon. Not. R. Astr. Soc. vol. 469, is. 2, pp. 1299–1313. DOI: 10.1093/mnras/stx8106. VINYAIKIN, E. N., 2007. Evolution of the radio spectrum of Cassiopeia A from long-term observations. Observations at 290 and 927 MHz. Astron. Rep. vol. 51, pp. 87–96. DOI:101134/S10637729070200237. VINYAIKIN, E. N., 2014. Frequency dependence of the evolution of the radio emission of the supernova remnant Cas A. Astron. Rep. vol. 58, pp. 626–639. DOI: 101134/S10637729140900788. MARTIROSSYAN, R. M., GOULYAN, A. G., SANAMYAN, V. A. and MANASELYAN, KH. A., 2020. Flux density variations of Cassiopea A radio source. Astrofizika. vol.45, no. 3, pp. 443–449. (in Russian).9. HELMBOLT, J. F. and KASSIM, N. E., 2009. The Evolution of Cassiopeia A at Low Radio Frequencies. Astron. J. vol. 138, is. 3, pp. 838–844. DOI: 1088/0004-6256/138/3/83810. WALCZOWSKI, L. T. and SMITH, K. L., 1985. A recurrence of the Cassiopeia A flux anomaly. Mon. Not. R. Astron. Soc. vol. 212, is. 1, pp. 27P–31P. DOI: 10.1093/mnras/212.1.27P11. RYABOV, M. I., PANISHKO, S. K. and GUGLYA, L. I., 2011. Space weather impacts on the Earth’s upper atmosphere according to the monitoring of powerful radio sources fluxes at the URAN-4 radio telescope (Institute of Radio Astronomy, NAS of Ukraine). Odessa Astronomical Publications. vol. 24, pp. 159–161. (in Russian).12. GORBYNOV, A. A., RYABOV, M. I. and PANISHKO, S. K. 2015. Secular Decrease the Flux of Supernova Eemnant Cas A on Monitoring Results to Radiotelescope “URAN-4” IRA NASU. Odessa astronomical publications. vol. 28, no. 2, pp. 224–226.13. RYABOV, M. I. and SEROKUROVA, N. G., 1993. On the secular decrease of the radio flux Cas A at low frequencies. Astron. Astrophys. Trans. vol. 4, is. 1, pp. 29–32. DOI: 10.1080/10556799308205353 Видавничий дім «Академперіодика» 2020-11-30 Article Article application/pdf http://rpra-journal.org.ua/index.php/ra/article/view/1346 10.15407/rpra25.04.268 РАДИОФИЗИКА И РАДИОАСТРОНОМИЯ; Vol 25, No 4 (2020); 268 RADIO PHYSICS AND RADIO ASTRONOMY; Vol 25, No 4 (2020); 268 РАДІОФІЗИКА І РАДІОАСТРОНОМІЯ; Vol 25, No 4 (2020); 268 2415-7007 1027-9636 10.15407/rpra25.04 en http://rpra-journal.org.ua/index.php/ra/article/view/1346/pdf Copyright (c) 2020 RADIO PHYSICS AND RADIO ASTRONOMY |