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1.
The equivalent widths of the oxygen lines at 7774 and 8446 and of H (and some H) have been measured for 22 early-type, emission-line stars. A strong correlation between H and 8446 intensities has been found, although there is no such correlation between H and 7774. This confirms the probability that Bowen's mechanism is operative (the neutral oxygen 33 D state is overpopulated because the excitation energy of Ly- nearly coincides with that of theOi 1025 line). The possibility of using 8446 and H equivalent widths for a comparison of oxygen to hydrogen abundances in these stars is discussed.  相似文献   

2.
A detailed list of line identifications of the far UV spectrum of the O4I(n)f star Puppis (HD 66811) in the wavelength range 1168–1984 Å recorded on 16 April, 1981 with the International Ultraviolet Explorer (IUE) is presented. The detailed analysis of the radial velocities measured in the same wavelength range is also presented.  相似文献   

3.
Kiselev  N. N.  Jockers  K.  Rosenbush  V. K.  Korsun  P. P. 《Solar System Research》2001,35(6):480-495
We present the imaging polarimetry and photometry of Comet C/1996 Q1 (Tabur) obtained on October 10, 1996, with a two-channel focal reducer attached to the 2-m Pik Terskol Observatory telescope through blue (4430/44 Å) and red (6420/26 Å) continuum filters and through a 6620/59 Å filter that isolated the NH2(0.7.0) band. We analyze the 3600–9300 Å long-slit spectrograms of the comet taken on October 5–6, 1996, with the 2.6-m Crimean Astrophysical Observatory telescope. The NH2(0.8.0) 6408 Å emission and an unidentified 6428 Å emission were found to fall within the pass band of the red filter. The blue filter transmits weak unidentified emissions at 4424–4444 Å and partially C2(4360 Å). Correction for the depolarizing effect of molecular emissions resulted in an increase of the dust polarization by 2–4% in the near-nucleus region and by almost a factor of 2 in the outer coma regions. However, the polarization and color differences between different coma regions remained even after correction for the contribution of emissions. We found no dust polarization difference between the gas comet Tabur and the dust comet C/1988 A1 (Liller), which are believed to be fragments of a common parent comet. The NH2coma was found to be elongated perpendicular to the comet radius vector. The causes of the spatial asymmetry in the NH2molecular distribution are yet to be established. We study the evolution of activity and the spatial distribution of dust brightness, polarization, and color in the comet. We consider a taxonomic classification of gas and dust comets according to dust polarization properties. The polarization differences between dust and gas comets at large phase angles are most likely related both to the actual differences in dust and to the effect of molecular emissions, nuclear gas- and dust-production rates and to the evolution of grain properties with distance from the nucleus.  相似文献   

4.
Extinction measurements were made for some silicate and iron-oxide mineral grains in mid- and far-infrared region. For far-infrared region, high temperature magnesium silicates such as olivine and pyroxenes show the absorption spectra of steep dependence as –3 ( being the wavelength) with some peak structure, but the spectrum of magnetite shows –1 dependence.  相似文献   

5.
A coronal condensation was observed simultaneously with Fexiv 5303, Fex 6374, Fe xi 7892, and H filtergraphs. The size and shape of the condensation in 5303 are different from those in other filtergrams. H filtergrams taken around the eclipse time show that a small transient prominence exists in close proximity to the condensation core and behaves like a post-flare loop system, though the appearance is quite different and no flare-report exists. A small-scale energetic phenomenon seems to have occurred at the top of magnetic loops.Contributions from the Kwasan and Hida Observatories, University of Kyoto, No. 285.  相似文献   

6.
Slitless flash spectrograms in heights below 8000 km above the solar limb were obtained by the University of Kyoto Expedition at Atar, Mauritania. The integrated intensities of Fexiv 5303, Fex 6374, Fexi 7892, and the continuum are measured as a function of height above the solar limb at eleven points (P.A. = 284–300°) around the third contact point. It is found that a significant amount of the emission in Fex 6374 originates in chromospheric levels well below 8000 km. This implies that the interspicular region of the chromosphere is occupied by coronal material. The average values of the electron temperature and the electron density in the interspicular region are derived from the Fex 6374 and the Fexi 7892 intensities on the assumption of spherical symmetry: T e = 0.9–1.1 × 106 K and N e = 9–10 × 108 cm–3. The intensity variations of the coronal lines and the continuum with position angle are also studied. Strong correlations between Fexiv 5303 and the continuum and between Fex 6374 and Fexi 7892 are found. From the Fex 6374 intensities it is inferred that there is a density fluctuation in the innermost corona by at least a factor of two.Contributions from the Kwasan and Hida Observatories, University of Kyoto, No. 271.  相似文献   

7.
The Mees CCD (MCCD) instrument is an imaging spectroscopy device which uses the 25 cm coronagraph telescope and the 3.0 m Coudé spectrograph at Mees Solar Observatory (MSO) on Haleakala, Maui. The instrument works with resolving power up to R 200 000 with significant throughput from 3934 Å (Caii K) to 10 000 Å. A fast guiding active mirror stabilizes the image during observations. A rapidly writing magnetic tape storage system allows observations to be recorded at 256 kbytes s–1. Currently, the MCCD is used for imaging spectroscopy of solar flares at 6563 Å (H), and velocity measurements of umbral oscillations; future plans include emission line studies of active region coronae, and photospheric studies of solar oscillations.  相似文献   

8.
Resume On étudie la stabilité des solutions périodiques d'un couplage de systèmes linéaires au voisinage de résonances. Les valeurs propres distinctes k de la matrice du système linéaire non perturbé sont telles que k–j=iq pour tout couple [k, j]; i=–1, q est un nombre entier, la fréquence de la solution. Une application est faite pour un système à trois degrés de liberté au voisinage de la résonance 221.
Hamiltonian systems in the neighbourhood of an equilibrium solution. II:The stability of periodic solutions
The stability of the periodic solutions for an Hamiltonian system is investigated. Here the distinct eigen values k of the matrix of the unperturbated linear system are such that k–j=iq for any [k, j]; i=–1, q is an integer, is the frequency of the periodic solution. An application is made for a system with three degrees of freedom, near the resonance 221.
  相似文献   

9.
Time resolved spectroscopy of the dwarf nova IP Pegasi in the range 7670–8320Å shows absorption lines originating from the cool secondary. A radial velocity curve for this component has been derived by cross-correlation with a normal M star. The curve has semi-amplitude K2=288.3±4 km s–1, and is slightly distorted. This distortion is equivalent to an orbit with an apparent eccentricity of 0.075±0.024. The mass function of the primary is 0.394±0.016M. From this we derive constraints on the component masses of 0.621<1.14M and 0.172<0.71M. The red star has a radius in the range 0.322<0.51R and is probably on the main sequence.Paper presented at the IAU Colloquium No. 93 on Cataclysmic Variables. Recent Multi-Frequency Observations and Theoretical Developments, held at Dr. Remeis-Sternwarte Bamberg, F.R.G., 16–19 June, 1986  相似文献   

10.
Wheatland  M.S.  Litvinenko  Y.E. 《Solar physics》2002,211(1-2):255-274
The observed distribution of waiting times t between X-ray solar flares of greater than C1 class listed in the Geostationary Operational Environmental Satellite (GOES) catalog exhibits a power-law tail (t) for large waiting times (t>10hours). It is shown that the power-law index varies with the solar cycle. For the minimum phase of the cycle the index is =–1.4±0.1, and for the maximum phase of the cycle the index is –3.2±0.2. For all years 1975–2001, the index is –2.2±0.1. We present a simple theory to account for the observed waiting-time distributions in terms of a Poisson process with a time-varying rate (t). A common approximation of slow variation of the rate with respect to a waiting time is examined, and found to be valid for the GOES catalog events. Subject to this approximation the observed waiting-time distribution is determined by f(), the time distribution of the rate . If f() has a power-law form for low rates, the waiting time-distribution is predicted to have a power-law tail (t)–(3+) (>–3). Distributions f() are constructed from the GOES data. For the entire catalog a power-law index =–0.9±0.1 is found in the time distribution of rates for low rates (<0.1hours –1). For the maximum and minimum phases power-law indices =–0.1±0.5 and =–1.7±0.2, respectively, are observed. Hence, the Poisson theory together with the observed time distributions of the rate predict power-law tails in the waiting-time distributions with indices –2.2±0.1 (1975–2001), –2.9±0.5 (maximum phase) and –1.3±0.2 (minimum phase), consistent with the observations. These results suggest that the flaring rate varies in an intrinsically different way at solar maximum by comparison with solar minimum. The implications of these results for a recent model for flare statistics (Craig, 2001) and more generally for our understanding of the flare process are discussed.  相似文献   

11.
The diffuse far UV radiation ( 1350–1480 Å) observed in the sky region ofl II180°, 0°b II40° is analyzed in connection with the distributions of stars and dust grains as well as with optical properties of grains. Its intensity (starlight+scattered light) is about 6×10–7 erg cm–2 sec–1 sr–1 Å–1 in the direction ofb II0° andl II180°. The latitude dependence of the intensity is in approximate agreement with the plane parallel slab model of the galaxy with a reasonable set of parameters. The interstellar scattering gives an albedo close to unity and forward phase function of about 0.6, which are not inconsistent with the model of interstellar grains of Wickramasinghe. The upper limit of the extragalactic UV is 2×10–8 erg cm–2 sec–1 sr–1 Å–1 in the same region of wave-length.  相似文献   

12.
In this paper we study the far-UV as well as the UV spectrum of the spectroscopic binary system SZ Psc in the wavelength ranges 1235–1950 Å and 2710–3090 Å, respectively, from spectra obtained with the International Ultraviolet Explorer (IUE). The UV spectrum of SZ Psc is mainly an emission spectrum. The short wavelength region includes emission lines formed from the low chromosphere to the transition region (e.g., Siiv,Civ, andNv) and also a deep and broad absorption line of Feii.The Mgii[1] resonance doublet at about 2800 Å presents a P Cygni profile and a multiple structure with two emission and two absorption satellite components. We also present the emission measure diagram in the temperature region 4.4T e <53.  相似文献   

13.
We report on a new ESB source, as defined by Allenet al. (1991), with Wolf-Rayet (WR) bands in its optical spectrum. The WR bump at 4605-4686 is detected. The bump consists of broad HeII 4686, NV4605-4619, NIII4634-41, and possibly, CIII4647-52 emission. The narrow nebular lines are clearly discernable on our spectrum. The number of WR stars derived from the luminosity of HeII4686 is about 8100. The oxygen abundance is about 9.06×10–4, greater than the solar value.  相似文献   

14.
Measurements of radial velocities from the SiII 6347A and 6371Alines and the HeI 6678A line based on observations of 1989–1994 are examined. The variability of the line shapes over the 96.6-day orbital period is analyzed. Evidence for a second component is found from lines in the spectrum of And which correspond to the silicon lines 6347 and 6371A. The preliminary value for the rotational velocity of the secondary component is 100–120 km/sec. Analysis of the variability of the radial velocities of the HeI 6678A line during the night has given the rotational period of the star of Prot=Id.012344 and indicates an inhomogeneous distribution either of the helium abundance or of the physical conditions over the surface. Thus, we have the first evidence for the existence of spots on the surface of an HgMn star.Translated fromAstrofizika, Vol. 39, No. 3, pp. 375–384, July–September, 1996.  相似文献   

15.
The continuum energy distributions of a totally eclipsing binary system GG Cas at phases 0 . P 903 and 0 . P 003 in the wavelenght range 3200–7600 Å have been presented and discussed. The flux of continuum of the secondary star seems to dominate longward of 4500 Å. The spectral types of the systemic components are found to be as B4+K0.  相似文献   

16.
Time succession of 25 H spicules has been studied. The spectra are obtained at a height of 6 arc sec during 21 min (38 pictures) with the 53 cm Lyot coronagraph. Total intensities W, widths and radial velocities V r are determined (about 650 H line profiles). For 14 spicules the sign of V r varies, for the rest the sign variation is absent or it is doubtful. Characterized period of V r variation is 3–7 min with a mean amplitude of ± 4km s–1. W and also vary with a similar period and mean amplitudes equal to 50% and 30% respectively. dependence of W (Figure 1) points to the existence of two spicules groups: group I (70%) characterized by relatively small W and (mean values are 0.08 Å and 1.3 Å respectively); group II comprising brighter (W 0.13 Å) spicules with wider profiles ( 1.6 Å). Group II may consist of the unresolved, superimposed group I spicules. We believe, that H spicules involve formations consisting of separate elements having the temperature of 6000 K and non-thermal velocities of 25 km s–1.  相似文献   

17.
The four diffuse interstellar absorption bands at 4430, 4760, 4890, and 6180 and the two diffuse lines at 5780 and 5797 are interpreted as belonging to pre-ionization transitions in H– and O–, respectively. In both cases the identifications are supported by extrapolations of wave numbers of resonance lines along isoelectronic sequences.In the H– case the hypothesis as to the origin of the bands is supported by quantum-mechanical results byHerzenberg andMandl (1963) as to the positions of resonances in collisions between neutral hydrogen atoms and free electrons. The relatively large intensities of the forbidden transitions indicate that the extent of the ion in its excited states may be very large as compared to ordinary atomic dimensions. In the O– case the relative doublet separation, as extrapolated along the isoelectronic sequence, is used for the identification of the doublet.  相似文献   

18.
We show that a 3 extinction feature in galactic infrared sources cannot be due to water-ice grains. Infrared spectra with a resolution of /=0.015 are in remarkably close agreement with the 2.5–4 extinction properties calculated for bacterial grains.  相似文献   

19.
The intensity of the He+ 304 coronal line relative to the H0 1216 line, including the dominant contribution due to resonance scattering, is presented. All physical processes important in the corona are included. It is found that He+ 304 is a major contributor to the XUV corona, and that the sensitivity of the He+ 304/H0 1216 intensity ratio to coronal temperature is very weak, supporting the belief that this ratio is a good indicator of the coronal helium abundance.  相似文献   

20.
M. P. Nakada 《Solar physics》1979,62(2):343-346
An attempt is made to specify coronal hole boundaries in the brightness of 284 of Fe xv. This is done by evaluating brightnesses of 284 at boundaries selected by various groups. These results are in quite good agreement and suggest a brightness value of (0.8±0.4)×1012 photons cm–2 s–1 sr–1 for coronal hole boundaries in 284. The examination of a number of isophote maps near this boundary brightness shows no consistent brightness gradient.  相似文献   

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