共查询到20条相似文献，搜索用时 31 毫秒
1.
S. O. Mejidova B. N. Rustamov Kh. M. Mikayilov I. A. Alekberov 《Kinematics and Physics of Celestial Bodies》2014,30(2):85-91
Investigations in the line Hα of the spectrum of UX Ori WW Vul are presented. Comparison with the data of other researchers has shown that the regime of variable matter ejection of the star WW Vul is retained for a long time. The spectra of two nights (July 18 and 23, 2006) showed an increased intensity of red emission component without noticeable change in the radial velocity. On the other hand, radial velocity of the central absorption considerably changed to negative values with decreasing V/R. During the night on July 8, 2006, we found doubling of the blue emission component for these two spectra. 相似文献
2.
《天文和天体物理学研究(英文版)》2017,(4)
Variations of the Hα line in the spectra of the star HD14134 are investigated using observations carried out in 2013–2014 and in 2016 with the 2-m telescope at Shamakhy Astrophysical Observatory.In the spectra of this star,the absorption and emission components of Hα are found to disappear and an inverse P Cyg profile of Hα is seen on some observational epochs.Our observations showed that when the Hα line disappeared or an inversion of the P-Cyg-type profile is observed in the spectra,the Hβ line is redshifted.When these events appeared,no synchronous variabilities were observed in the spectral parameters of other spectral lines formed in deeper atmospheric layers.In addition,the structures of Hα,CII(6578.05 ,6582.88 ),SiII(6347.1 ,6371.36 ) and Hβ lines are variable on a timescale of hours,but we did not detect significant variations in the other photospheric lines,as well as in the HeI(5875.72 ) line.It is suggested that observational evidence for the non-stationary atmosphere of HD14134 can be associated in part with non-spherical stellar wind. 相似文献
3.
Two examples of sudden brightenings in local regions of active prominences as observed at the center of the H line are described. The origin of the brightenings is discussed in terms of Doppler shifts along the line of sight, Doppler brightenings and intrinsic changes of physical conditions. It is shown that the two examples presented here have common characteristics and the origin may probably be attributed to intrinsic changes of physical conditions.Contributions from the Kwasan and Hida Observatories, University of Kyoto, No. 257. 相似文献
4.
The eruptive prominence observed on 27 May 1999 in H at Ondejov Observatory is analyzed using image-processing techniques. To understand the physical processes behind the prominence eruption, heated structures inside the cold H prominence material are sought. Two local minima of intensity (holes), the first above and the second below the erupting H prominence, have been found in the processed H images. A comparison of H images with the SOHO/EIT and Yohkoh/SXT images showed: (a) the cold H prominence is visible as a dark feature in the EIT images, (b) the upper local minimum of intensity in the H image corresponds to a hot structure seen in EIT, (c) the lower minimum corresponds to a hot loop observed by SXT. The physical significance of the H intensity minima and their relation to the hot structures observed by EIT and SXT is discussed. The time sequence of observed processes is in favor of the prominence eruption model with the destabilization of the loop spanning the prominence. For comparison with other events the velocities of selected parts of the eruptive prominence are determined. 相似文献
5.
Horacio A. Dottori 《Astrophysics and Space Science》1981,80(2):267-280
The synthetic equivalent width (W
H) of the line H in emission is obtained for Hii regions opaque to the Lyman photon flux, with embedded OB associations with different initial chemical compositions and initial mass functions. The variation ofW
H as a function of the evolution of the ionizing stars is analysed. The observations ofW
H for M33, M101, and M51 by Searle (1971) are discussed. 相似文献
6.
Sergiy Silich Guillermo Tenorio-Tagle Casiana Muñoz-Tuñón 《Astrophysics and Space Science》2009,324(2-4):215-217
The existence of compact H?ii regions around massive stellar clusters with ages exceeding several Myr challenges our understanding of the physical processes occurring inside such clusters, and their impact on the interstellar medium of the host galaxy. Here, we summarize our recent results dealing with the hydrodynamics of matter ejected by massive stars inside the cluster and show that compact H?ii regions found around some massive clusters may indicate that these are evolving in a bimodal hydrodynamic regime. The latter is characterized by the accumulation of the injected matter in the central, thermally unstable zone, and by the ejection of mass supplied by massive stars in the outer regions of the cluster. 相似文献
7.
Results are presented from a study of 31 new H
-emission objects in the Cepheus region. The observations were performed with the 40 Schmidt telescope of the Byurakan Astrophysical Observatory in 1979, 1985, and 1989. Spectral plates were obtained with a 4° objective prism (-1100 Å/mm near H
on Kodak 103-aE, 103-aF, III-aF and ORWO ZP-3 emulsions. Type RG1 and RG2 light filters were used during the observations.Translated from Astrofizika, Vol. 37, No. 2, pp. 219–228, April–June, 1994. 相似文献
8.
High dispersion CCD spectra are used to study the profiles of the Hα and Hβ lines of 48 stars in early spectral classes in
the young diffuse binary cluster h/χ Per. In addition, moderate resolution spectra of 15 B and Be stars were taken over the
interval 4400–4960 Å. One or, possibly, two new Be stars are discovered. The major parameters of the Hα line are measured
for the observed B and Be stars. The spectra over 4400–4960 Å are used to estimate Teff, logg, and υsin i. No traces of emission are detected in the Hα line profiles for 28 of the stars and emission is observed in the Hα line
for 20. During our observations an absorption profile of the Hα line was observed for some of the stars, such as Oo146, Oo566,
Oo922, and Oo1268, although they have previously been identified as Be stars. A significant long-term variability of the Hα
line is discovered for the Be stars Oo1161 and Oo2242. Oo2371 manifests a variability in its faint emission spectrum which
is typical of close binary systems that include a Be star.
__________
Translated from Astrofizika, Vol. 51, No. 2, pp. 305–319 (May 2008). 相似文献
9.
The time dependence of Doppler shift and line-center intensity is simultaneously observed for the H emission of three solar prominences, each one during about two hours. Doppler oscillations with periods near one hour and amplitudes between 1 and 2 km s–1 are conspicuously visible in the recordings of all three prominences. Fourier analysis yields periods of 50, 60, and 64 min, as well as slight indications of short periods near 3 and 5 min. No oscillations are found in the line-center brightness. 相似文献
10.
High-speed jets of solar quiet regions have been observed at Big Bear Solar Observatory in H–1.0 Ú, and compared with high-resolution magnetograms. Over the whole Sun, the birthrate of the H–1.0 Ú jets is about 19±3 events s–1, which is much lower than the birthrate of spicules. The average lifetime of these jets is 2±1 min. H–1.0 Ú jets are very different from spicules, in the sense of birthrate, lifetime, and shape. Jets tend to recur in the same sites, always located in boundaries of supergranules. Under the best observing conditions, we found that 80% of the major jet sites are associated with converging magnetic dipoles – mainly the sites where intranetwork elements are canceling with opposite polarity network elements. In order to establish a possible relationship between the disk H jets and limb macrospicules, we have also obtained time sequences of H center-line images at the limb. These images are enhanced by median filtering so that jet structures over the limb are easily studied. We found that these limb H jets (above the spicule forest) repeatedly occur in the same sites, which is the property shared by the disk H–1.0 Ú jets. However, their mean lifetime is 10 min, substantially longer than that of disk jets. Comparison with simultaneous SOHO/EIT Heii 304 Ú images shows that every Heii 304 Ú jet over the limb coincides with an H jet, although Heii 304 Ú jets extend much farther out. Some H jets do not have associated He jets, probably due to the difference in image resolutions. H spectra of selected jets are analyzed, and we found that jets are not simply blue-shifted; instead, the line profiles are broadened with significantly larger broadening on the blue side. Two-component fitting finds that the velocity of the blue-shifted component (an optically-thin component) is around 20 to 40 km s–1. 相似文献
11.
P. S. Goraya 《Astrophysics and Space Science》1984,107(2):323-325
Photoelectric spectrum scans of the Be shell star Per in the H region have been taken to investigate the variations of H emission lines. Definite variations with time-scales of a few minutes have been detected. It is hoped that hydromagnetic instability within the envelope is responsible for such variations. 相似文献
12.
Full-disk synoptic observations of the chromosphere using Hα telescope at the Kodaikanal Observatory
《天文和天体物理学研究(英文版)》2016,(8)
This paper reports on the installation and observations of a new solar telescope installed on 2014 October 7 at the Kodaikanal Observatory. The telescope is a refractive type equipped with a tunable Lyot Hα filter. A CCD camera with size 2k×2k acquires images of the Sun and has a pixel size of 1.21′′pixel-1and a full field-of-view of 41′. The telescope is equipped with a guiding system which keeps the image of the Sun within a few pixels throughout the observations. The FWHM of the Lyot filter is 0.4 A? and the filter is motorized, capable of scanning the Hα line profile at a smaller step size of 0.01 A?. Partial-disk imaging covering about 10′is also possible with the help of a relay lens kept in front of the CCD camera. In this paper, we report the detailed specifications of the telescope, filter unit, the installation, observations and the procedures we have followed to calibrate and align the data. We also present preliminary results with this new full-disk telescope. 相似文献
13.
Evolutions of the cool component of the inner solar corona have animportant part in the equilibria and energy transport processes in thesun atmosphere. Since 1994, a numerical daily survey of the entirelimb in the Hydrogen H line is performed with the HACOcoronagraph at Pic-du-Midi observatory. This experiment is includedin the general ground based support programs for the SOHO mission.Real and differed time data are available within the solar data baseBASS2000. A statistical study using the data set obtained during thefirst four years of this program shows some important properties ofthe distribution of the polar ejection and surge events. An asymmetrybetween North and South polar regions is well established. Its signreverseal near the time of the apparition of the new solar magneticactivity cycle is discussed. 相似文献
15.
Hassan M. Basurah 《Astrophysics and Space Science》1992,192(1):21-33
When spectra of the daytime sky are compared with those directly from the Sun, it is found that the depths of the Fraunhofer lines are reduced. This indicates the presence of an added light, the Ring effect. Most previous research on the Ring effect has been performed spectroscopically, with the notion that the added component is always unpolarized. Here we presented spectropolarimetric observations using the principle of the line depth method (compression between the line centre and its continuum) to investigate this effect. The general scattered light of the blue sky is polarized and as the additional component may or may not also be polarized, the filling-in effect should be detectable by performing spectropolarimetry, which indeed has been achieved. The observations have involved the use of high precision polarimetry with spectral resolution 2 Å at the H Fraunhofer spectral line. The data indicate a variation of the linear polarization in the H line centre as a function of the solar zenith angle. One possible advantage of the polarimetric technique is that the Ring effect detections can be made without recourse to solar measurements directly or indirectly using an attenuator. Finally, a model without knowledge of the filling-in mechanism, has yielded a good qualitative agreement with the observational behaviours and it can be taken as a first step to explain the variation of the linear polarization across the spectral line. 相似文献
16.
Monochromatic photographs of the Orion Nebula taken through narrow bandpass interference filters (Δλ=10 Å) centred on Hα, Hβ and [NII] lines are presented. Ratio contours of Hα/[NII] and Hα/Hβ are derived. They enable a detailed study of the point-to-point variation in ionization structure and temperature throughout the nebula. Dust located within the ionized gas is studied from the Hα/Hβ ratio which varies from point to point over the nebula. Its strongest concentration, apart in the obvious ‘dark bay’, occurs in a shell surrounding the exciting stars, with about 2′ of diameter. Close to Θ1 Ori the Hα/Hβ ratio, corrected for interstellar reddening, is about 3.0 in good agreement with the predicted value (Brocklehurst, 1971). To account for these measures, the following arguments are proposed:
- Dust grains are completely or partially destroyed in region close to the exciting stars.
- Radiation pressure and stellar wind push the remaining dust up to some equilibrium distance outwards. The consequence of this action is obviously the formation of a ‘dust mantle’ which is seen as a ring in projection.
17.
In an active region, several points were observed to brighten progressively on the monochromatic image of H - 1.2 Å formed by the Domeless Solar Telescope installed recently at Hida Observatory. The phenomena were interpreted as small flares or subflares. The propagation velocity was measured in two cases and discussed in terms of the multiple loop activation observed in EUV radiation.Contributions from the Kwasan and Hida Observatories, University of Kyoto, No. 249. 相似文献
18.
H emission objects were searched for, using the objective-prismSchmidt plates in a 36 deg2 sky area covering the Cepheus OB3 association.Hundred and eight emission stars have been found, 68 of which are newfindings to our knowledge. The properties of the IRAS point sourcesidentified with H emission stars indicate that most of theH emission stars are T Tauri stars or related objects. Hemission stars associated with IRAS sources and those unassociated havedifferent distributions, suggesting an age sequence among them.Altogether, they show a ring- or shell-like surface distribution, whichalmost coincides with that of heated dusts, and these distributionsappear to be encompassed by an HI shell. 相似文献
19.
A Fabry-Perot spectrometer was used to map the H II region around the O star ξ Per in the Hβ emission line. The angular size of the region is \(9_.^ \circ 1 \times 6_.^ \circ 0\). The region-boundary contour drawn at the double background level is centered on the star. The accuracy of our emission intensity measurements is 0.2 rayleigh. The proximity of the nebula NGC 1499 has virtually no effect on the measured emission measure toward the star. The star excitation parameter derived from observations corresponds to the spectral type O7.5 III and is U(Sp)=56.0±8.4 pc cm?2; the mean electron density in the region is ne=3.1±0.4 cm?3. 相似文献
20.
Ming-Guo Sun~ 《中国天文和天体物理学报》2006,6(1):87-95
A technique for obtaining a three-dimensional distribution of received pho- tons in Hα flares in the solar atmosphere is presented.It is well known that during flares hydrogen atoms in the chromosphere and photosphere are excited(even ion- ized)by the downward heating of non-thermal particles and then emit Hα photons. We trace back these Ha photons to their original layers by use of the contribution func- tion in the theory of spectral line formation,and so acquire their three-dimensional (3D)distribution.This technique is applied to the two-ribbon flare of 2002 January 20.The atmospheric models are obtained by fitting the“quasi-profiles”with the help of the generally used model atmospheres.Since the variety of the 3D images reflects the response of the atmospheric layers to the impact of energy transport,an analysis of the development of the flare is given through a comparison of the 3D images with the 2D temperature distribution. 相似文献