共查询到20条相似文献，搜索用时 78 毫秒
1.
B.N. Handy M.E. Bruner T.D. Tarbell A.M. Title C.J. Wolfson M.J. Laforge J.J. Oliver 《Solar physics》1998,183(1):29-43
The Transition Region and Coronal Explorer is a space-borne solar telescope featuring high spatial and temporal resolution. TRACE images emission from solar plasmas in three extreme-ultraviolet (EUV) wavelengths and several ultraviolet (UV) wavelengths, covering selected ion temperatures from 6000 K to 1 MK. The TRACE UV channel employs special optics to collect high-resolution solar images of the H i L line at 1216 Å, the C iv resonance doublet at 1548 and 1550 Å, the UV continuum near 1550 Å, and also a white-light image covering the spectrum from 2000–8000 Å.We present an analytical technique for creating photometrically accurate images of the C iv resonance lines from the data products collected by the TRACE UV channel. We use solar spectra from several space-borne instruments to represent a variety of solar conditions ranging from quiet Sun to active regions to derive a method, using a linear combination of filtered UV images, to generate an image of solar C iv 1550 Å emission. Systematic and statistical error estimates are also presented. This work indicates that C iv measurements will be reliable for intensities greater than 1014 photons s–1 cm–2 sr–1. This suggests that C iv 1550 Å images will be feasible with statistical error below 20% in the magnetic network, bright points, active regions, flares and other features bright in C iv. Below this intensity the derived image is dominated by systematic error and read noise from the CCD. 相似文献
2.
This study is based on a set of ten solar rocket spectra well exposed for photometry photographed on July 27, 1966 by Purcell, Snider, and Tousey.The photometry of the far UV continuum illustrates the transition of the solar temperature minimum at 1700 Å in the solar spectrum - (a) the continuum intensity decreases by 30–50% between 1700 Å and the1
D limit of silicon at 1682 Å, and (b) the equivalent brightness temperature shows minimum values throughout the spectral range 1540–1682 Å, which average just under 4700 ± 100K.The minimum UV brightness temperature is 300K higher than the far infrared measurement of the solar minimum temperature, and possible reasons for this are discussed.Brightness temperatures measured in prominent CO band heads and in the aluminum 1937 Å auto-ionization line also are given. 相似文献
3.
Wilhelm K. Lemaire P. Curdt W. Schühle U. Marsch E. Poland A. I. Jordan S. D. Thomas R. J. Hassler D. M. Huber M. C. E. Vial J.-C. Kühne M. Siegmund O. H. W. Gabriel A. Timothy J. G. Grewing M. Feldman U. Hollandt J. Brekke P. 《Solar physics》1997,170(1):75-104
SUMER – the Solar Ultraviolet Measurements of the Emitted Radiation instrument on the Solar and Heliospheric Observatory (SOHO) – observed its first light on January 24, 1996, and subsequently obtained a detailed spectrum with detector B in the wavelength range from 660 to 1490 Å (in first order) inside and above the limb in the north polar coronal hole. Using detector A of the instrument, this range was later extended to 1610 Å. The second-order spectra of detectors A and B cover 330 to 805 Å and are superimposed on the first-order spectra. Many more features and areas of the Sun and their spectra have been observed since, including coronal holes, polar plumes and active regions. The atoms and ions emitting this radiation exist at temperatures below 2 × 106 K and are thus ideally suited to investigate the solar transition region where the temperature increases from chromospheric to coronal values. SUMER can also be operated in a manner such that it makes images or spectroheliograms of different sizes in selected spectral lines. A detailed line profile with spectral resolution elements between 22 and 45 mÅ is produced for each line at each spatial location along the slit. From the line width, intensity and wavelength position we are able to deduce temperature, density, and velocity of the emitting atoms and ions for each emission line and spatial element in the spectroheliogram. Because of the high spectral resolution and low noise of SUMER, we have been able to detect faint lines not previously observed and, in addition, to determine their spectral profiles. SUMER has already recorded over 2000 extreme ultraviolet emission lines and many identifications have been made on the disk and in the corona. 相似文献
4.
Measurements of the solar X-ray spectrum between 3 Å and 15 Å are reported. They were made with two slitless Bragg crystal spectrometers flown on a Sun-pointed Skylark rocket on 8 August, 1967.The use of a beryl crystal has provided higher spectral resolution than hitherto in the spectral range 12 Å and 15 Å leading, in particular, to a revised identification of the strong line at 13.71 Å. Separate components of the stronger emission lines are clearly seen from each of three coronal active regions which may be identified on radio and X-ray spectroheliograms.The absolute line fluxes are used to determine a model for each active region in terms of the differential emission measure as a function of electron temperature. Emission lines due to the transition 1s
2
1
S
0 – 1s2s
3
S
1 in several helium-like ions are identified and values of the local electron density derived from measurement of the line flux in these ions. 相似文献
5.
Further observations of the ultraviolet spectrum (550–2000 Å) of the solar limb and disc were obtained during a Skylark rocket flight on 5 August 1971. These observations have enabled several new spectral lines to be identified and classified. 相似文献
6.
Some results of observations of the spectrum of the spectroscopic-binary Ap star CrB in the region of the lithium line Li I 6708Å are presented. The observations were made at the Crimean Astrophysical Observatory over the period 1993–1995 with the coudé spectrograph equipped with a CCD camera on the 2.6-m telescope. Several factors which can affect the behavior of the lithium blend are examined: stellar rotation, magnetic field, isotopic shift, the binary system, and blending by unidentified elements. The principal result of this work is the detection of variability of the lithium blend Li I 6708Å over the period of rotation of the star. The variations of the radial velocity Vr, and the FWHM of the lithium blend are reported here for the first time. They indicate either a nonuniform distribution of lithium or a nonuniform distribution of conditions for excitation of the lithium resonance doublet in the complex structure of the strong surface magnetic field. Similar variations are also shown by the lines of the rare-earth elements Gd II 6702.10 Å, Gd II + Ce II 6704.3Å, and Ce II + Fe I 6706.0 Å.Translated fromAstrofizika, Vol. 39, No. 1, pp. 19–30, January–March, 1996. 相似文献
7.
Analysis of bright features in 3840 Å and H shows that forevery Ellerman bomb (H-0.9 Å) there is a cospatial brightening in the 3840 Å network. We give properties of these bright points in both wavelengths as well as describe: (1) the appearance, and subsequent separation, of new elements in the 3840 Å network and (2) the direct transition from a 3840 Å bright point to a new sunspot. 相似文献
8.
Rawi Bhavilai 《Solar physics》1968,5(4):471-488
Evidence is presented demonstrating the existence of a type of chromospheric structure in the form of bright streaks. These are extensions across the solar disk of elongated bright mottles which originate in the central regions of clusters of mottles. They are best observed on good filtergrams at H ± 0.5 Å through comparison with filtergrams at other positions on the line profile. Their length can be as much as 200 sec of arc. The bright streaks appear to be predominantly horizontal loop structures, while the well-known spicules are mainly vertical structures. A bright streak may be well defined or rather diffuse along its length, and many of them are accompanied by darker boundaries or envelopes. It is usual to find a loop of bright streak bridging the central areas of two mottle clusters. It seems that the observed pattern in the space between the chromospheric network at H ± 0.5 Å results partly from the interactions of the bright streaks of different stages of evolution traversing the area in different directions. 相似文献
9.
Carmen Morales Joaquín Trapero José F. Gómez Verónica Orozco Alvaro Gimenez Stuart Bowyer Jerry Edelstein Eric Korpela Michael Lampton Jeff Cobb 《Astrophysics and Space Science》2001,276(1):141-150
We present here stellar spectra of B stars obtained with the EURD spectrograph, one of the three instruments on board MINISAT-01. EURD is a spectrograph specially designed to detect diffuse radiation in thewavelength range between 350 and 1100 Å with 5 Å spectral resolution. EURD main scientific targets are: the spectrum of interstellar medium,atmospheric airglow, decaying neutrinos, Moon and early type stars. 相似文献
10.
A bright fireball (TN920729) of minus-ninth absolute magnitude flew above Dushanbe (Tajikistan) at 22:12 UT on the night of July 29/30, 1992, and was photographed at two observatories (Gissar and Sanglok) of the Academy of Sciences of Tajikistan. The length of the photographed portion of the fireball trajectory and the luminous duration were equal to 40.4 km and 1.98 s, respectively. The coordinates of the radiant, velocity, and orbital elements of the fireball were determined. The fireball was found to belong to the -Capricornids shower. The mass and density of the fireball progenitor were inferred from photometric measurements of the plates and found to be equal to 0.574 kg and 2 g/cm3, respectively. 相似文献
11.
Vladimir A. KrasnopolskyPaul D. Feldman 《Icarus》2002,160(1):86-94
A spectrum of Mars of unprecedented quality was obtained in the range of 904-1183 Å with a spectral resolution of 0.2 Å using the Far Ultraviolet Spectroscopic Explorer. Besides marking the first detection of molecular hydrogen on Mars (Krasnopolsky and Feldman, Science 2001 294, 1914-1917), the spectrum also revealed many emission lines of H, O, N, C, Ar, He, N+, C+, and Ar+ and the bands of N2 and CO. The spectrum makes it possible to study the emission multiplet structures and the component ratios and to separate many of the blended lines. From the argon lines, we retrieved Ar mixing ratios of 1.5 and 1.3% at 150 and 130 km, respectively, in excellent agreement with the Viking mass spectrometric measurements of 1.6% in the lower atmosphere. The He 584-Å emission observed in second order also agrees with the Extreme Ultraviolet Explorer detection of He on Mars. The observed spectrum may be used as a database to study specific problems such as the dayglow excitation, radiative transfer, and composition in Mars' upper atmosphere. 相似文献
12.
A photographic Fabry-Perot interferometer was used to measure the breadth and wavelength of the Fexiv spectral line at 5303 Å in the solar corona, during the eclipse of 7 March, 1970, in Mexico. The observations were consistent with a possible large-scale vortex structure in a bright streamer, in which cooler gases revolved about a hotter core.Work supported by the United States National Science Foundation and by the Air Force Office of Scientific Research, Office of Aerospace Research, United States Air Force, under Grant AF-AFOSR-68-1496. 相似文献
13.
Wavelengths and identifications of the near ultraviolet solar spectrum are presented. The data were obtained during the rocket flight of an interferometer spectrograph with a spectral resolution of 0.03 Å.SRC Astrophysics Research Unit, Culham Laboratory, Abingdon, Berks, now at Max-Planck Institut fur Radioastronomie, Bonn, Germany.Now at Kevin Street College of Technology, Dublin, Eire. 相似文献
14.
The uncertainty about a possible correlation between magnetic field strength, inclination, and the continuum intensity of sunspot penumbral fine-structure has been removed from detailed analysis of a spatially very well-resolved spectrum: the darker, long penumbral lanes host a 10% stronger and 30° flatter magnetic field as compared to the field in bright penumbral locations. This finding is not only based on the high spatial resolution but also on the use of a spectral line, here Fe 6842.7 Å, obtaining its essential contribution from those deep layers where the penumbral structure is seen, i.e. the continuum intensity level. The almost perfect correlation establishes that the penumbral structure is formed by the two magnetic components mainly differing by the field inclination. The different results from other Zeeman lines, as, e.g., Fe 6302.5 Å, indicate a different field structure above the white-light penumbral layers. 相似文献
15.
A recently observed broad 3.4 μm spectral ‘fingerprint’ in a persistent Leonid meteor train at a height of 83km is likely
to be due to emission of surrounding mesospheric bacteria heated by the passage of an incandescent fireball.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
16.
P. S. Murty 《Astrophysics and Space Science》1980,68(2):513-518
The unidentified absorption feature at 9730±5 Å observed in the spectra of pure S stars is provisionally identified with the predicted 9732 Å (0,0) band of thee
1II-c
1 transition of ZrO molecule. Relative band strengths and band head positions ofthis transition in the 8300–12 500 Å region are presented to assist both laboratory and stellar spectral studies. The insistent need for the laboratory study of gas phase infrared spectrum of ZrO is accentuated. 相似文献
17.
J.-C. Gérard J. Gustin B. Hubert G.R. Gladstone L.W. Esposito 《Planetary and Space Science》2011,59(13):1524-1528
The helium resonance line at 584 Å has been observed with the UltraViolet Imaging Spectrograph (UVIS) Extreme Ultraviolet channel during the flyby of Venus by Cassini at a period of high solar activity. The brightness was measured along the disk from the morning terminator up to the bright limb near local noon. The mean disk intensity was ∼320 R, reaching ∼700 R at the bright limb. These values are slightly higher than those determined from previous observations. The sensitivity of the 584 Å intensity to the helium abundance is analyzed using recent cross-sections and solar irradiance measurements at 584 Å. The intensity distribution along the UVIS footprint on the disk is best reproduced using the EUVAC solar flux model and the helium density distribution from the VTS3 empirical model. It corresponds to a helium density of 8×106 cm−3 at the level of where the CO2 is 2×1010 cm−3. 相似文献
18.
Natalia A. Konovalova Jose M. Madiedo Josep M. Trigo‐Rodríguez 《Meteoritics & planetary science》2013,48(12):2469-2479
The results of the atmospheric trajectory, radiant, heliocentric orbit, and preliminary strewn field calculations for an extremely bright slow‐moving fireball are presented. In the evening hours of July 23, 2008, a bright object entered Earth's atmosphere over Tajikistan. The fireball had a ?20.3 maximum absolute magnitude and a spectacularly long persistent dust trail remained visible over a widespread region of Tajikistan for about 28 minutes after sunset. The fireball was also recorded by a visible‐light satellite system at 14 h 45 min 25 s UT, and the dust trail was imaged by video and photocameras. A unique aspect of this event is that it was detected by two infrasound and five seismic stations too. The bolide was first recorded at a height of 38.2 km, reached its maximum brightness at a height of 35.0 km, and finished at a height of 19.6 km. The first breakup occurred under an aerodynamic pressure of approximately 1.6 MPa, similar to the values derived for breakups of the scarcely reported meteorite‐dropping bolides. The fireball's trajectory and dynamic results suggest that meteorite survival is likely. The meteoroid followed an Apollo‐like asteroid orbit comparable to those derived for previously recovered meteorites with accurately known orbits. 相似文献
19.
Keizo Nishi 《Solar physics》1973,33(1):23-31
The absolute intensities and the centre-to-limb variations of the Sun at three wavelengths of 1629 Å, 1684 Å, and 1739 Å were measured by a rocket-borne spectrometer flown from the Kagoshima Space Centre on 1 September 1971. The spectrometer was a double-dispersive trichrometer, whose spectral and spatial resolutions were 8.3 Å and 1.3 respectively. The results concerning the absolute intensities were similar to those measured by the Harvard College Observatory group. The results for the centre-to-limb variation at 1629 Å and 1684 Å seem to support the HSRA model but not those at 1739 Å. 相似文献
20.
In this paper, we give a detailed list and analysis of line identifications of the UV spectrum of the Be star 88 Her in the wavelength range 1958–3002 Å recorded in 1984, 23 May with the International Ultraviolet Explorer (IUE). The spectrum is crowded by shell absorptions lines, mostly those of singly ionized iron peak elements.The detailed analysis of the radial velocities measured in the whole spectral range 1100–3002 Å is also given. 相似文献