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1.
We present examples of umbral oscillations observed on Big Bear H filtergram movies and investigate the relation between umbral oscillations and running penumbral waves occurring in the same sunspot. Umbral oscillations near the center of the umbra are probably physically independent of the penumbral waves because the period of these umbral oscillations (150 s) is shorter than the penumbral wave period (270 s) but not a harmonic. We also report dark puffs which emerge from the edge of the umbra and move outward across the penumbra, and which have the same period as the running penumbral waves. We interpret these dark puffs to be the extension of chromospheric umbral oscillations at the edge of the umbra. It is suggested that the dark puffs and the running penumbral waves have a common source: photospheric oscillations just inside the umbra. 相似文献
2.
Reizaburo Kitai 《Solar physics》1986,104(2):287-301
Time-sequenced H filtergrams and narrow-band blue filtergrams (0 = 4308 Å, = 10 Å) of umbral dots in a decaying sunspot were studied. The results are: (a) Photospheric umbral dots have lifetimes of about 40 min. (b) Two types of proper motion were found for photospheric umbral dots. Umbral dots born in the umbra or in the light bridge show virtually no proper motion. On the other hand, umbral dots of penumbral origin move inward to the umbra with speeds of about 0.4 km s –1. (c) Chromospheric umbral dots, which have dimensions of 0.6 × 1.2 in the mean, were more numerously found than photospheric umbral dots. (d) Photospheric umbral dots were observed to be associated with chromospheric umbral dots. Thus umbral dots are not phenomena confined to photospheric levels but also extend to chromospheric levels. (e) Some of the chromospheric umbral dots are unrelated to the photospheric umbral dots. They may be excited by the infalling matter from the umbral corona.Contribution from the Kwasan and Hida Observatories, University of Kyoto, No. 266. 相似文献
3.
R. G. Giovanelli 《Solar physics》1972,27(1):71-79
Observations have been made in H of the vertical velocity distribution in a sunspot. Over the umbra the pattern consists of structures of scale-size 2–3. The velocity distribution undergoes oscillations with a period of about 165 s and typical amplitude ±3 km s–1, but the pattern breaks down after one or two cycles because the period of oscillation varies typically by ±20 s from place to place. Transverse waves develop in the outer 0.1 of the umbral radius and propagate outwards with a velocity of about 20 km s–1, becoming gradually invisible by or before the outer penumbral boundary; the amplitude is about ±1 km s–1 at the umbra-penumbra border.The penumbral waves are believed to be basically of the Alfvén type, with 3 × 10–8 g cm–3. The umbral oscillations presumably represent gravity waves. In both cases the fluxes are inadequate by two orders of magnitude to account for the sunspot energy deficit. 相似文献
4.
H. I. Abdussamatov 《Solar physics》1986,105(1):27-33
Preliminary results of a study of photographic and photometric properties of the large-scale ( 3) structure of a sunspot and its surrounding photosphere are given. Stratospheric direct frames of the solar photosphere were used in the study. Isophotes located immediately beyond the outer edge of the penumbra were of an irregular form and reflected bright and dark regions. No presence of either a sunspot bright outer ring or inner ring was detected. The photospheric structure and its behaviour with time were, in fact, unchanged up to the very boundary of the penumbra.A distribution of the smeared intensity in a sunspot has been derived. The mean brightness of the penumbra is I
PU 0.62 I
and umbra I
U < 0.15 I
. An analysis of the obtained results allowed us to make a conclusion that the area of the dark penumbral regions exceeds that of the bright penumbral regions, and the condition S
BR/S
DR < 1 should be fulfilled in the penumbrae of sunspots. 相似文献
5.
F. Kneer 《Solar physics》1973,28(2):361-367
Photographic spectra of the umbra of a sunspot (1971, August 24, Rome No. 6205) around 6150 Å show fine bright threads which were identified as the spectra of a lightbridge, of the bright end of a penumbral filament and of umbral dots, respectively. It was found, in agreement with the results of other authors, that the magnetic field in bright structures is considerably weaker than in dark umbral material. Analysis of line profiles of Fe ii 6149.2 Å in umbral dots indicates (a) a fieldstrength reduced by a factor 2 compared to the surroundings, (b) an outflow with v3.0 km s–1 relative to the penumbra and (c) possibly photospheric temperatures in umbral dots.Mitteilungen aus dem Fraunhofer Institut Nr. 115. 相似文献
6.
R. S. Bogart S. H. Ferguson P. H. Scherrer T. D. Tarbell A. M. Title 《Solar physics》1988,116(2):205-214
The SOUP experiment demonstrated that photospheric surface flows can be measured by correlation tracking of white-light intensity features at high resolution (November et al., 1987). In order to assess the feasibility of this technique with observations made at lower resolution, we have applied it to the same SOUP data artificially degraded, but still free of seeing distortion. Comparison with the velocity structures inferred from the original data shows generally good agreement when the resolution is better than about 2. The radial outflow from a sunspot penumbra, however, can only be seen with resolution of better than 1. With resolution of worse than 2, the inferred velocity fields rapidly lose coherence, while resolution of better than 1 yields little improvement. We conclude that apertures as small as 10–14 cm on a space-based platform will be useful for the measurement of large-scale horizontal motions. 相似文献
7.
Thomas E. Corbin 《Celestial Mechanics and Dynamical Astronomy》1980,22(1):25-34
Systematic reductions of nineteenth century observations to the system of the FK4 are discussed. Reductions made on a nightly basis are described and compared with the results obtained through the use of conventional tables. The series of observations made at the Paris Observatory from 1837 to 1881 was used to compare the two methods, and a combined system of 24 000 FK4, FK4 Sup and AGK 3R positions and proper motions provided the reference stars. The results show that for Uranus the mean error of a single observation in right ascension is ±1..33 when tables are used for the reductions, and ±1.12 when nightly reductions are made, while in declination the corresponding mean errors are ±0.88 and ±0.80. The observations of Neptune show an even greater difference between the two methods; the mean errors for the tabular and nightly reductions are ±1.57 and ±1.09 in right ascension and ±0.88 and ±0.75 in declination. Secular rates in the (0–C)'s of Uranus of –0.029/year in right ascension and ±0.030/year in declination are present when the observations are reduced with tables. These rates are reduced to –0.007/year and +0.015/year, respectively, when nightly reductions are made.Presented at the Symposium Star Catalogues, Positional Astronomy and Celestial Mechanics, held in honor of Paul Herget at the U.S. Naval Observatory, Washington, November 30, 1978. 相似文献
8.
R. Muller 《Solar physics》1977,52(2):249-262
From time series of high resolution photographs, morphological properties of the photospheric facular granules were derived. The facular granules are cells of the common granular pattern, brighter than the normal granules when seen between cos = 0.6 and the limb. Their apparent diameter, which decreases towards the limb, is smaller than that of the normal granules: 0.65 and 1.25 respectively at cos = 0.55; their lifetime is 25 min but their bright stage lifetime is only 15 min; they are visible closer to the limb than the normal granules: 1.2 compared to 2–5; the brightening of the facular granules occurs at a faster rate than their fading. From the great similitude of both morphological properties and temperature models of facular and normal granules, it appears possible that the photospheric facular granules are convective cells modified by the presence of a magnetic field of some hundreds Gauss. 相似文献
9.
CASPIR is a near-infrared spectrometer/imager being built for the Mount Stromlo and Siding Spring Observatories' 2.3 m telescope. The instrument is based on a SBRC 256×256 InSb detector array and uses AR-coated Sapphire, MgO, CaF2, and BaF2 optics to produce two imaging focal plane scales with 0.5/pixel and 0.25/pixel. Spectral resolving powers of 500 will be achieved through a 1×128 slit with three grisms designed for the J, H, and K bands. IJ, JH, and HK cross-dispersed échelle grisms will achieve resolving powers of 1100 through a 1×15 slit. Coronograph and imaging polarimetry modes will also be available. The various observing configurations are selected via five remotely controlled wheels. The instrument design and system architecture are discussed, and preliminary detector performance figures reported. 相似文献
10.
A prime objective of this experiment was to determine whether type I or IV sources at 333 MHz contain features of small (arc sec) scale. With the VLA, our resolution was better than 4. However, we never observed any structure of size smaller than about 30, with the typical source sizes being between about 40 and 90.Many observations were simultaneous with the Trieste Astronomical Observatory records at 327 MHz. The observations were made on two days in November 1988. On 8 November the observations were of a type I storm about two hours after a major flare. On 14 November they were mostly of the main phase of a type IV event, including pulsations of a kind rarely seen, strongly circularly polarized, and having a well-defined period of about 12 s. The size of the pulsating source was about 40 by 60, and the brightness temperature was about 109 K. We compare these pulsations with those observed earlier. 相似文献
11.
Spectro-polarimetric observations at 2231 nm were made of NOAA 10008 near the west solar limb on 29 June 2002 using the National Solar Observatory McMath–Pierce Telescope at Kitt Peak and the California State University Northridge – National Solar Observatory infrared camera. Scans of spectra in both Stokes I and Stokes V were collected; the intensity spectra were processed to remove strong telluric absorption lines, and the Stokes V umbral spectra were corrected for instrumental polarization. The sunspot temperature is computed using the continuum contrast and umbral temperatures down to about 3700 K are observed. A strong Tii line at 2231.0 nm is used to probe the magnetic and velocity fields in the spot umbra and penumbra. Measurements of the Tii equivalent width versus plasma temperature in the sunspot agree with model predictions. Zeeman splitting measurements of the Stokes I and Stokes V profiles show magnetic fields up to 3300 G in the umbra, and a dependence of the magnetic field on the plasma temperature similar to that which was seen using Fei 1565 nm observations of the same spot two days earlier. The umbral Doppler velocity measurements are averaged in 16 azimuthal bins, and no radial flows are revealed to a limit of ±200 m s–1. A Stokes V magnetogram shows a reversal of the line-of-sight magnetic component between the limb and disk center sides of the penumbra. Because the Tii line is weak in the penumbra, individual spectra are averaged in azimuthal bins over the entire penumbral radial extent. The averaged Stokes V spectra show a magnetic reversal as a function of sunspot azimuthal angle. The mean penumbral magnetic field as measured with the Stokes V Zeeman component splitting is 1400 G. Several weak spectral lines are observed in the sunspot and the variation of the equivalent width versus temperature for four lines is examined. If these lines are from molecules, it is possible that lines at 2230.67, 2230.77, and 2231.70 nm originate from OH, while the line at 2232.21 nm may originate from CN. 相似文献
12.
D. C. Murphy 《Experimental Astronomy》1994,3(1-4):141-142
Tracing results for two designs based on the Offner reimager are given: a practical 256×256 NICMOS-3 IR/CCD I-K camera designed for use on a f/13.5 1-m telescope yielding a 154×154 field, and a hypothetical 1024×1024 pixel nextgeneration IR camera for a f/7.5 2.5-m telescope yielding a 244×244 field. Both designs produce near-diffration limited results. 相似文献
13.
The synthetic Voigt profile of the following transitions (v=0,v=0), (v=0,v=1), (v=1,v=1), (v=1,v=0) have been computed for different concentrations and temperatures of CO and compaed to the measured intensities of the UV sunspot spectrum by a high resolution spectrograph. From this comparison the solar minimum temperature has been determined. 相似文献
14.
A new photographic method suitable for digital processing of a two-dimensional density distribution of lunar eclipse shadow has been developed and it has been applied to the observation of the eclipse of December 30, 1982. The principle of this method is to extract the terrestrial shadow by utilizing immediate post- or pre-eclipse full Moon image as a reference template. The uncertainties of the obtained shadow maps in density and position are mostly 0.03–0.05 and 10–15 respectively. Iso-density contours of the penumbra have revealed unknown systematic deviations from a geometrical (concentric) shadow model in terms of their directions of center and radii of curvature. A density map of the umbra has shown very irregular shapes of isophotoes and density variation in the outer umbra has been proved to be consistent with the optical depth measurement of the stratosphere performed in the same period of time with lidars and aircrafts. Geographic consideration of the shadow terminator on the Earth suggests that the remnant aerosols above the northern Pacific and northern Europe flown up by a Mexican volcano 8 months ago prior to this eclipse will be mainly responsible for the formation of such variation of density in the outer penumbra.On leave from Tokyo Astronomical Observatory as Visiting Scientist (from 28 Aug. 1984 to 27 Aug. 1985). 相似文献
15.
Using optically identical telescopes at different sites, we have measured the solar diameter with a drift-scan technique. In order to investigate the cause of the observed fluctuations, we not only compare observations made simultaneously by different observers at the same telescope, but also observations made simultaneously at two different sites. Our main results are: (a) The mean error of a single drift time measurement is ±0.08s(or ± 1.1) at Izaña and ±0.11 s (or ± 1.7) at Locarno; this closely corresponds to the angular resolution at those two sites under normal seeing conditions, (b) We find no correlation between observations at different sites; a significant correlation exists, however, between observations made simultaneously by different observers at the same site: This indicates that most of the observed fluctuations are due to atmospheric effects (image motion) rather than personality effects, (c) The mean solar semi-diameter derived from a total of 1122 observations made in 1990 (472 at Izaña, 650 at Locarno) is R = (960.56 ± 0.03) (Izaña: 960.51, Locarno: 960.59); this may be compared with R = (960.32 ± 0.02) which is obtained from a re-analysis of 1773 observations made in 1981 (Izaña: 960.16, Locarno: 960.38). Although a small residual increase of the solar diameter during the last ten years seems to be indicated, we conclude that most - if not all - of the observed variations are due to variable seeing conditions, and that there is still no conclusive evidence for a genuine solar variation with amplitudes in excess of about ±0.3. 相似文献
16.
W. Mattig 《Solar physics》1971,18(3):434-442
In order to test the usual method for correcting sunspot intensity measurements for stray light, we have measured, during the Mercury transit of 1970 May 9, the intensities of Mercury, a sunspot umbra, and the aureole. The direct observations result in Mercury intensities < 0.06 I
and aureole intensities <0.01 I
. The stray light correction to the spot intensities has been <(0.03 ± 0.01) I
. The main contribution to the stray light on the solar disc is shown to be produced by a spread-function with a half width of 10 arc sec. Consequently, for stray light corrections the range R R
+ + 20 in the aureole has to be measured very precisely; furthermore, a remarkable fraction of the stray light in the center of an umbra originates from the surrounding penumbra.Mitteilungen aus dem Fraunhofer Institut, Nr. 102. 相似文献
17.
High resolution photographs of the solar chromosphere have been obtained with the 40-cm refractor of the Athens Observatory and a 0.5 Å Halle H filter. Our best photographs show a resolution of 0.6, which is comparable with the theoretical resolving limit of 0.4, at H. The achieved resolution permitted us to secure some excellent observations of the fine structure of the chromosphere on the disk as well as on the limb. The study of these observations leads to the following results: (a) the bright filaments of the disturbed chromosphere as well as the penumbral ones appear to consist of knots, (b) inside the cells of the chromospheric network of the quiet chromosphere, bright roundish granule-like formations are present, their mean size being of the order of 2500 km. (c) the bright fine mottles seem to lie at the root of the elongated dark ones, each pair of them giving rise to a spicule. 相似文献
18.
The HXIS, a joint instrument of the Space Research Laboratory at Utrecht, The Netherlands, and the Department of Space Research of the University of Birmingham, U.K., images the Sun in hard X-rays: Six energy bands in energy range 3.5–30 keV, spatial resolution 8 over Ø 240 and 32 over Ø 624 field of view, and time resolution of 0.5–7 s depending on the mode of operation. By means of a flare flag it alerts all the other SMM instruments when a flare sets in and informs them about the location of the X-ray emission. The experiment should yield information about the position, extension and spectrum of the hard X-ray bursts in flares, their relation to the magnetic field structure and to the quasi-thermal soft X-rays, and about the characteristics and development of type IV electron clouds above flare regions. 相似文献
19.
Two novel methods of measuring umbral and penumbral areas of sunspots and of complex sunspot groups are described. Both methods comprise the digitization of photoheliograms by a frame grabber and the computation of intensity histograms of selected areas of activity. The first method, called cumulative histogram method, in principle determines the intensity boundaries umbra–penumbra and penumbra–photosphere from the intersections of linear fits into the corresponding parts of the cumulative histograms of sunspots. The second method, called maximum gradient method, marks image pixels of a given intensity level ±2 units wide as a white isophote on a display. Interactive variation of this level makes it easy to visually select the contour line fitting the boundary penumbra–photosphere (or umbra–penumbra) best. At the same level usually the width of the contour line is smallest. In both cases the summation of the pixel numbers above the corresponding intensity levels yields the umbral and the total sunspot areas, respectively. Some limitations of the two methods are discussed. 相似文献
20.
Correlations between continuum intensity, velocity, and equivalent widths of two Mn i lines as observed with two different entrance apertures tend to deteriorate with improvement in spatial resolution. The KPNO multichannel magnetograph was used to make area scans at the center of the disk with entrance apertures 3.5×2.5 arc and 1×1 arc. A coherence analysis shows that this effect is caused by marked differences of fluctuations in temperature and temperature gradients as well as in the velocity structure of photospheric elements of various sizes. 相似文献