OBSERVATIONS OF INTERMEDIATE DEGREE SOLAR OSCILLATIONS - 1989 APRIL-JUNE

被引:6
作者
BACHMANN, KT [1 ]
SCHOU, J [1 ]
BROWN, TM [1 ]
机构
[1] AARHUS UNIV,INST FYS,DK-8000 AARHUS,DENMARK
关键词
SUN; OSCILLATIONS;
D O I
10.1086/172969
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We present frequencies, splittings, and line widths from 85 days of full disk Doppler observations of solar p-modes taken between 1989 April 4 and June 30. We include all modes within the frequency range 2200 muHz < v < 3500 muHz and with spherical harmonic degrees l > 10 such that v/L greater-than-or-equal-to 45 muHz, where L = [l(l + 1)]1/2. We describe our analysis systems in moderate detail and give evidence indicating that they are working correctly. Comparison of our mode parameters with published Big Bear Solar Observatory (BBSO) results yields good agreement in general and is thus a confirmation of their work using an independent instrument and set of analysis routines. Small differences between the two experiments are consistent with known short-term characteristics of the Sun and the inherent accuracy of the measurements in general. We explain average differences in p-mode frequencies measured by the two experiments in 1989 spring-summer as a result of differences in the exact periods of data collection during a time of rapidly changing solar activity. The scatter in these frequency differences, within narrow ranges of frequency and degree, yields standard deviations confirming those estimated by the BBSO group from their fitting methods alone. We believe that an almost-equal-to 10% difference in line widths between our results and those from BBSO represents the current precision limit of line width measurements due to systematic uncertainties in calculating spatial crosstalk. We present even splitting coefficients from 1989 and show that their magnitudes are enhanced from 1988 BBSO even splitting coefficients, presumably due to increased solar activity. Our odd splitting coefficients for p-modes with v/L greater-than-or-equal-to 45 muHz match, within calculated uncertainties, those published by BBSO for their 1986 data, indicating that odd splitting coefficients do not vary appreciably with solar activity. We show that our a, splitting coefficients for p-modes with v/L < 45 muHz suffer from a significant systematic error, but we are unable to identify the cause of this error. We present evidence that a detector distortion or alignment problem, not a problem with the power spectra analysis, is the most likely explanation of this a, anomaly.
引用
收藏
页码:870 / 879
页数:10
相关论文
共 23 条
  • [1] MODELING OF SOLAR OSCILLATION POWER SPECTRA
    ANDERSON, ER
    DUVALL, TL
    JEFFERIES, SM
    [J]. ASTROPHYSICAL JOURNAL, 1990, 364 (02) : 699 - 705
  • [2] Brown T. M., 1984, SOLAR SEISMOLOGY SPA, P157
  • [3] SOLAR ROTATION AS A FUNCTION OF DEPTH AND LATITUDE
    BROWN, TM
    [J]. NATURE, 1985, 317 (6038) : 591 - 594
  • [4] DEPTH AND LATITUDE DEPENDENCE OF SOLAR ROTATION
    BROWN, TM
    MORROW, CA
    [J]. ASTROPHYSICAL JOURNAL, 1987, 314 (01) : L21 - L26
  • [5] BROWN TM, 1986, SEISMOLOGY SUN DISTA, P199
  • [6] BROWN TM, 1980, SOLAR INSTRUMENTATIO, P150
  • [7] CHRISTENSENDALS.J, 1992, LECTURES NOTES STELL, P62
  • [8] FREQUENCIES OF SOLAR PARA-MODE OSCILLATIONS
    DUVALL, TL
    HARVEY, JW
    LIBBRECHT, KG
    POPP, BD
    POMERANTZ, MA
    [J]. ASTROPHYSICAL JOURNAL, 1988, 324 (02) : 1158 - 1171
  • [9] ASYMMETRIES OF SOLAR OSCILLATION LINE-PROFILES
    DUVALL, TL
    JEFFERIES, SM
    HARVEY, JW
    OSAKI, Y
    POMERANTZ, MA
    [J]. ASTROPHYSICAL JOURNAL, 1993, 410 (02) : 829 - 836
  • [10] A DISPERSION LAW FOR SOLAR OSCILLATIONS
    DUVALL, TL
    [J]. NATURE, 1982, 300 (5889) : 242 - 243