On Mode Correlation of Solar Acoustic Oscillations
In helioseismology it is normally assumed that p-mode oscillations are excited in a statistically independent fashion. Unfortunately, however, this issue is not clearly settled down in that two experiments exist, which apparently look in discrepancy. That is, Appourchaux et al.~(2000) looked at bin-...
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| Format: | Article |
| Language: | English |
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The Korean Space Science Society
2009-09-01
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| Series: | Journal of Astronomy and Space Sciences |
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| Online Access: | http://ocean.kisti.re.kr/downfile/volume/kosss/OJOOBS/2009/v26n3/OJOOBS_2009_v26n3_287.pdf |
| _version_ | 1797370418049318912 |
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| author | Heon-Young Chang |
| author_facet | Heon-Young Chang |
| author_sort | Heon-Young Chang |
| collection | DOAJ |
| description | In helioseismology it is normally assumed that p-mode oscillations are excited in a statistically independent fashion. Unfortunately, however, this issue is not clearly settled down in that two experiments exist, which apparently look in discrepancy. That is, Appourchaux et al.~(2000) looked at bin-to-bin correlation and found no evidence that the assumption is invalid. On the other hand, Roth (2001) reported that p-mode pairs with nearby frequencies tend to be anti-correlated, possibly by a mode-coupling effect. This work is motivated by an idea that one may test if there exists an excess of anticorrelated power variations of pairs of solar p-modes. We have analyzed a 72-day MDI spherical-harmonic time series to examine temporal variations of p-mode power and their correlation. The power variation is computed by a running-window method after the previous study by Roth (2001), and then distribution function of power correlation between mode pairs is produced. We have confirmed Roth's result that there is an excess of anti-correlated p-mode pairs with nearby frequencies. On the other hand, the amount of excess was somewhat smaller than the previous study. Moreover, the distribution function does not exhibit significant change when we paired modes with non-nearby frequencies, implying that the excess is not due to mode coupling. We conclude that the origin of this excess of anticorrelations may not be a solar physical process, by pointing out the possibility of statistical bias playing the central role in producing the excess. |
| first_indexed | 2024-03-08T18:02:18Z |
| format | Article |
| id | doaj.art-49167183dd504c9cbef9b275d651e190 |
| institution | Directory Open Access Journal |
| issn | 2093-5587 2093-1409 |
| language | English |
| last_indexed | 2024-03-08T18:02:18Z |
| publishDate | 2009-09-01 |
| publisher | The Korean Space Science Society |
| record_format | Article |
| series | Journal of Astronomy and Space Sciences |
| spelling | doaj.art-49167183dd504c9cbef9b275d651e1902024-01-02T00:41:04ZengThe Korean Space Science SocietyJournal of Astronomy and Space Sciences2093-55872093-14092009-09-0126328729410.5140/JASS.2009.26.3.287On Mode Correlation of Solar Acoustic OscillationsHeon-Young Chang0Department of Astronomy and Atmospheric Sciences, Kyungpook National University 1370 Sankyuk-dong, Buk-gu, Daegu 702-701, KoreaIn helioseismology it is normally assumed that p-mode oscillations are excited in a statistically independent fashion. Unfortunately, however, this issue is not clearly settled down in that two experiments exist, which apparently look in discrepancy. That is, Appourchaux et al.~(2000) looked at bin-to-bin correlation and found no evidence that the assumption is invalid. On the other hand, Roth (2001) reported that p-mode pairs with nearby frequencies tend to be anti-correlated, possibly by a mode-coupling effect. This work is motivated by an idea that one may test if there exists an excess of anticorrelated power variations of pairs of solar p-modes. We have analyzed a 72-day MDI spherical-harmonic time series to examine temporal variations of p-mode power and their correlation. The power variation is computed by a running-window method after the previous study by Roth (2001), and then distribution function of power correlation between mode pairs is produced. We have confirmed Roth's result that there is an excess of anti-correlated p-mode pairs with nearby frequencies. On the other hand, the amount of excess was somewhat smaller than the previous study. Moreover, the distribution function does not exhibit significant change when we paired modes with non-nearby frequencies, implying that the excess is not due to mode coupling. We conclude that the origin of this excess of anticorrelations may not be a solar physical process, by pointing out the possibility of statistical bias playing the central role in producing the excess.http://ocean.kisti.re.kr/downfile/volume/kosss/OJOOBS/2009/v26n3/OJOOBS_2009_v26n3_287.pdfSun: oscillationsSun: interiormethods: data analysis |
| spellingShingle | Heon-Young Chang On Mode Correlation of Solar Acoustic Oscillations Journal of Astronomy and Space Sciences Sun: oscillations Sun: interior methods: data analysis |
| title | On Mode Correlation of Solar Acoustic Oscillations |
| title_full | On Mode Correlation of Solar Acoustic Oscillations |
| title_fullStr | On Mode Correlation of Solar Acoustic Oscillations |
| title_full_unstemmed | On Mode Correlation of Solar Acoustic Oscillations |
| title_short | On Mode Correlation of Solar Acoustic Oscillations |
| title_sort | on mode correlation of solar acoustic oscillations |
| topic | Sun: oscillations Sun: interior methods: data analysis |
| url | http://ocean.kisti.re.kr/downfile/volume/kosss/OJOOBS/2009/v26n3/OJOOBS_2009_v26n3_287.pdf |
| work_keys_str_mv | AT heonyoungchang onmodecorrelationofsolaracousticoscillations |