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1.
Preliminary results of observations of a region containing known H stars are presented. The observations were made on the 2.6-m telescope of the V. A. Ambartsumian Byurakan Astrophysical Observatory in August 2000. A VAGR integral field spectrograph was used in the observations. The size of the region studied is about 6×11 arcmin. Besides the two already known, five new H stars and five HHL objects were discovered in this region. One of these stars coincides with the well-known object RNO 127. One infrared and one cometary nebula were discovered. The presence of so many peculiar objects in a region of such size suggests that it is one of the youngest star-forming regions. 相似文献
2.
About 15 areas were observed in the equatorial regions of Mars by the infrared spectrometers IRS (Mariner 6 and 7) and ISM (Phobos-2). The comparison between the spectra shows a remarkable consistency between two data sets acquired 20 years apart and calibrated independently. This similarity demonstrates the accuracy of ISM calibration above 2 μm, except for a possible stray light contribution above 2.6 μm, on the order of ∼1–2% of the solar flux at 2.7 μm. Most differences in spectral shapes are related to differences in spectral/spatial resolution and viewing geometries. No important variation in surface properties is detected, except for a spot in southern Arabia Terra which has a much deeper hydration feature in IRS spectra; differences in viewing geometries and spatial resolutions do not seem to account for this difference that could result from shifting or dehydration of surface materials. Composite spectra of several types of bright and dark materials are computed by modeling the thermal emission and are completed with telescopic spectra in the visible range. Modeled reflectance in the 3.0–5.7 μm range is consistent with basalts and palagonites. The bright regions and analog palagonite spectra are different from hematite in this range, but resemble several phyllosilicates. We infer that (1) although hematite dominates the spectra in the 0.4- to 2.5-μm range, the silicate-clay host is spectrally active beyond 3 μm and can be identified from this domain; (2) phyllosilicates such as montmorillonite or smectite may be abundant components of the martian soils, although the domain below 3 μm lacks the characteristic features of the most usual terrestrial clay minerals. 相似文献
3.
A new CCD (V) light curve is presented for'the semi-detached binary system FU Ara. The light curve, obtained in 2007, is the first one since the last 50 years. With our data we were able to determine six new times of minimum light and refined the period of the system to 0.8645049 days. A Wilson-Devinney analysis leads to a solution of a semi-detached configuration, composed of a main-sequence primary component of spectral type F5, fractionally smaller than its Roche lobe, and an evolved secondary component of spectral type K I which fills its Roche lobe, and which is overluminous and oversized as compared with the main-sequence. The two components of FU Ara differ considerably in effective temperature. It is classified as an FO Virginis type of near-contact binary system. Assuming a reasonable value for the mass of the primary component, an estimate of the absolute elements of FU Ara has been made, on the assumption that the primary has a mass corresponding to its spectral type according to Svechnikov & Taidakova. 相似文献
4.
A new method of determination of distances to stellar associations is proposed. This method is based on the measurements of
mean thicknesses of globules of the systems of dark globules connected with that association. It is shown that the method
is in good agreement with other known methods. A new grouping of OB stars in Pup-CMa is found. It is shown that this grouping
has properties characteristic for OB-associations: the stars of that grouping have similar distances, similar radial velocities,
the grouping is connected with molecular clouds, with Herbig-Haro objects, and cometary nebulae. All these results are in
favour of this grouping to be a new OB-association. We named that association OB-association Pup-CMa. The preliminary results
of12CO observations of molecular clouds connected with that association are also given. The radial velocities of these clouds
are in good agreement with the mean radial velocity of stars in the association in Pup-CMa.
Translated from Astrofizika, Vol. 42, No. 2, pp. 179–188, April–June, 1999. 相似文献
5.
We have reported the discovery of a population of the normal extragalactic field galaxies with the clear presence of strong
FHIL (forbidden high by ionized lines) and HeII 4686 emission. In this paper we present a dozen of them extracted from the
SDSS dr7. The high resolution spectra 0.86 ? /px obtained with the 6-m telescope of the Special Astrophysical observatory
of Russia are introduced for one of them, SDSS J093801.63 + 135317.0 confirming the presence of strong and wide FHIL and HeII
4686 emission. These objects show typical narrow (FWHM ~ 120 - 250 km s-1) emission lines both of HI and forbidden emission lines of [NII] 6548/84, [SII] 6717/31, [OI] 6300, [OII] 3727, and [OIII]
5007/4959 with underlying stellar absorption lines, coupled with the strong FHIL emission of [FeVII] 5721, 6087, [FeX] 6375,
[FeXI] 7892, [FeXIV] 5303, and HeII 4686, sometimes very broad up to 1500 km s-1. Following the direct images, all morphological types are introduced, spherical, elliptical, spiral, barred spiral, etc.,
without morphological or other peculiarity and any signs of "standard" AGN activity. None of them are X-ray source. The appearance
of the FHIL emission in normal galaxies (the objects of SBN/HII/ELG spectral types) might be one of the important sign of
the beginning of the AGN activity. The existence of the numerous normal extragalactic objects with FHIL and HeII 4686 emission
tell us that the link between the AGNs and the normal galaxies perhaps might be realized with the FHIL flare in normal galaxies.
For all of them, the existence of the nonthermal source in normal galaxies should be proposed. 相似文献
6.
A new intrinsic-colour calibration is presented for the uvby-β photometric system, making use of re-calibrated Hipparcos parallaxes and published reddening maps. This new calibration for , our Eq. (1), has been based upon stars with in the photometric catalogues of Schuster and Nissen (1988), Schuster et al., 2004, Schuster et al., 2006, provides a small dispersion, , and has a positive “standard” coefficient, which is not too different from the coefficients of Crawford (1975a, +1.11) and of Olsen (1988, +1.34). For 61 stars with spectra from CASPEC, UVES/VLT, and FIES/NOT databases, without detectable Na I lines, the average reddening value shows that any zero-point correction to our intrinsic-colour equation must be minuscule. 相似文献
7.
Xuefu Liu Aigen Li He Huang Fangjun Lu Guangwei Cha 《Astrophysics and Space Science》1993,205(2):359-380
We had observed the high-resolution H profiles of fourteen chromospherically active binaries which are And, 3 Cam, 4 UMi,
2 Sgr, Sgr, HR 7333, 33 Psc, UMi, And, UMa, 12 Cam, And, Aur and Dra from August 1990 to August 1991. The H emission and absorption equivalent widths, and the half widths and the radial velocities of these systems were determined. These data have a good supply for the information of the catalog of chromospherically active binary stars. The H profiles of HR 7333, 12 Cam, 4 UMi, UMi and And show marked emission filling in core, but 33 Psc, Sgr, Sgr and And systems show the H as the stronger absorption lines. The observed fourteen binaries presented very different activity levels. 相似文献
8.
9.
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
10.
A new radio spectrometer, CALLISTO, is presented. It is a dual-channel frequency-agile receiver based on commercially available consumer electronics. Its major characteristic is the low price for hardware and software, and the short assembly time, both two or more orders of magnitude below existing spectrometers. The instrument is sensitive at the physical limit and extremely stable. The total bandwidth is 825 MHz, and the width of individual channel is 300 kHz. A total of 1000 measurements can be made per second. The spectrometer is well suited for solar low-frequency radio observations pertinent to space weather research. Five instruments of the type were constructed until now and put into operation at several sites, including Bleien (Zurich) and NRAO (USA). First results in the 45–870 MHz range are presented. Some of them were recorded in a preliminary setup during the time of high solar activity in October and November 2003. 相似文献
11.
12.
Results of a search for new H objects in the Cepheus region are presented. The observations on which the search was based were made in 1979 and 1985 at the 40 Schmidt telescope of the Byurakan Astrophysical Observatory with a 4° objective prism. Of the 80 emission stars detected, 68 are new. Most of them are fainter than the sun in absolute magnitude. A large fraction of the emission stars discovered may be flare stars as well as T Tau and Herbig Ae/Be stars.Translated fromAstrofizika, Vol. 39, No. 1, pp. 57–65, January–March, 1996. 相似文献
13.
A New Method to Determine Epochs of Solar Cycle Extrema 总被引：1，自引：0，他引：1
Zhan-Le Du Hua-Ning Wang Xiang-Tao He Department of Astronomy Beijing Normal University Beijing National Astronomical Observatories Chinese Academy of Sciences Beijing 《中国天文和天体物理学报》2006,6(3):338-344
A weighted average method is proposed to determine the epochs of solar cycle extrema and hence the solar cycle lengths. Comparing to the previous methods, this method has the advantage that the extremum epochs are easily and uniquely determined. 相似文献
14.
Christopher A.Tout 《中国天文和天体物理学报》2007,(2)
Based on previous works of OPAL, we construct a series of opacity tables for various metallicities Z=0, 0.000 01, 0.000 03, 0.000 1, 0.000 3, 0.001, 0.004, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.08 and 0.1. These tables can be easily used in Eggleton's stellar evolution code in place of the old tables without changing the code. The OPAL tables are used for log10(T/K) > 3.95 and Alexander's for log10(T/K) < 3.95. At log10(T/K) = 3.95, the two groups' data fit well for all hydrogen mass fractions. Conductive opacities are included by reciprocal addition according to the formulae of Yakovlev and Urpin. A comparison of 1 and 5 M models constructed with the older OPAL tables of Iglesias and Rogers shows that the new opacities have most effect in the late stages of evolution, the extension of the blue loop during helium burning for intermediate-mass and massive stars. 相似文献
15.
Zhi-Bin Zhang Jia-Gan Deng Rui-Jing Lu Hai-Feng GaoNational Astronomical Observatories/Yunnan Observatory Chinese Academy of Sciences Kunming Physics Department Guangxi University Nanning Sishui No. Middle School Shandong Graduate School of Chinese Academy of Sciences Beijing 《中国天文和天体物理学报》2006,6(3):312-322
Using 64 ms count data of long gamma-ray bursts (T_(90) > 2.6 s), we analyze the quantity named relative spectral lag (RSL), T31/FWHM(1). We investigated in detail all the correlations between the RSL and other parameters for a sample of nine long bursts, using the general cross-correlation technique that includes the lag between two different energy bands. We conclude that the distribution of RSLs is normal and has a mean value of 0.1; that the RSLs are weakly correlated with the FWHM, the asymmetry, peak flux (Fp), peak energy (Ep) and spectral indexes (α and β), while they are uncorrelated with T31, the hardness-ratio (HR31) and the peak time (tm). Our important discovery is that redshift (z) and peak luminosity (Lp) are strongly correlated with the RSL, which can be measured easily and directly, making the RSL a good redshift and peak luminosity indicator. 相似文献
16.
17.
N. D. Melikian V. S. Tamazian A. A. Karapetian A. L. Samsonian G. R. Kostandian 《Astrophysics》2011,54(2):203-213
A search for Hα objects in four fields with an overall area of about 0.14 square degrees in the region of NGC 6910 (the core
of the known Cyg OB9 association) has led to the discovery of 64 emission stars, of which 49 are newly detected. The high
surface density is indicative of a very rich T association or, possibly, of the projection of several T associations onto
one another in this direction. The latter possibility is also indicated by the range of the R photometric stellar magnitudes
of the emission stars, 9m.68-19m.42. A comparison with earlier observations shows that for many of the stars, the emission line intensity is variable. A P
Cyg Hα line profile is recorded for the star V 1515 Cyg with an emission component equivalent width that greatly exceeds the
equivalent absorption width. 相似文献
18.
Cong Yu National Astronomical Observatories/Yunnan Observatory Chinese Academy of Sciences Kunming 《中国天文和天体物理学报》2007,7(6):743-756
We formulate the general relativistic force-free electrodynamics in a new 3 1 language. In this formulation,when we have properly defined electric and magnetic fields,the covariant Maxwell equations could be cast in the traditional form with new vacuum con-stitutive constraint equations. The fundamental equation governing a stationary,axisymmet-ric force-free black hole magnetosphere is derived using this formulation which recasts the Grad-Shafranov equation in a simpler way. Compared to the classic 3 1 system of Thorne and MacDonald,the new system of 3 1 equations is more suitable for numerical use for it keeps the hyperbolic structure of the electrodynamics and avoids the singularity at the event horizon. This formulation could be readily extended to non-relativistic limit and find applica-tions in flat spacetime. We investigate its application to disk wind,black hole magnetosphere and solar physics in both flat and curved spacetime. 相似文献
19.
We formulate the general relativistic force-free electrodynamics in a new 3 ＋ 1 language. In this formulation, when we have properly defined electric and magnetic fields, the covariant Maxwell equations could be cast in the traditional form with new vacuum constitutive constraint equations. The fundamental equation governing a stationary, axisymmetric force-free black hole magnetosphere is derived using this formulation which recasts the Grad-Shafranov equation in a simpler way. Compared to the classic 3＋1 system of Thorne and MacDonald, the new system of 3＋1 equations is more suitable for numerical use for it keeps the hyperbolic structure of the electrodynamics and avoids the singularity at the event horizon. This formulation could be readily extended to non-relativistic limit and find applications in fiat spacetime. We investigate its application to disk wind, black hole magnetosphere and solar physics in both fiat and curved spacetime. 相似文献
20.
A.L.Tadross 《中国天文和天体物理学报》2004,4(1):67-74
The present study of the open cluster Collinder 223 (Cr 223) depended greatly on the photoelectric data of Claria and Lapasset. We use the data in conjunction with the AAO/DSS^1 image of the cluster in a re-investigation to improve the main parameters of Cr 223, including the stellar density, the position of the cluster‘s center, the cluster‘s diameter. Its luminosity function, mass function, and total mass are also estimated. 相似文献