排序方式： 共有43条查询结果，搜索用时 15 毫秒
1.
The eighth list of late-type stars of spectral classes M and C detected on the plates of the First Byurakan Spectral Sky Survey (FBS) in the zone +80 +90° is presented. Of the 79 objects detected, 67 are new discoveries (66 M stars and one carbon star); 16 objects are unidentified IRAS sources. The equatorial coordinates, spectral classes, and magnitudes are given.Translated fromAstrofizika, Vol. 39, No. 4, pp. 523–529, November, 1996. 相似文献
2.
The X-ray emission properties of T Tau type stars and the basic results from the ROSAT X-ray mission are presented. The results
of optical follow-up observations of ROSAT sources unidentified with known T Tau type stars are given. Surprisingly, some
of them are located outside the classical borders of starforming regions, i.e. outside the dark clouds. Their kinematics and
formation are discussed.
Translated from Astrofizika, Vol. 42, No. 2, pp. 311–326, April–June, 1999. 相似文献
3.
The properties of OH megamaser galaxies in the x-ray region are discussed. Observational data from the XMM-Newton x-ray satellite
are presented for three megamasers, IRAS 01418+1651, IRAS 11010+4107, and IRAS 13218+0552. Based on a sample of OH megamaser
galaxies it is shown that the x-ray and OH emission are closely coupled. Megamaser emission also correlates with the column
density of the medium and the OH emissivity increases as the square of the column density. The results of this study indicate
that in OH megamaser galaxies an active nucleus, x-ray heating of molecules, and saturation of the maser emission can play
an important role. In some megamasers, active star formation may be the dominant source.
__________
Translated from Astrofizika, Vol. 50, No. 2, pp. 171–182 (May 2007). 相似文献
4.
Axel D. Schwope Valeri Hambaryan Frank Haberl Christian Motch 《Astrophysics and Space Science》2007,308(1-4):619-623
We present a first analysis of a deep X-ray spectrum of the isolated neutron star RBS1223 obtained with XMM-Newton. Spectral
data from four new monitoring observations in 2005/2006 were combined with archival observations obtained in 2003 and 2004
to form a spin-phase averaged spectrum containing 290 000 EPIC-pn photons. This spectrum shows higher complexity than its
predecessors, and can be parameterised with two Gaussian absorption lines superimposed on a blackbody. The line centers, E
2≃2E
1, could be regarded as supporting the cyclotron interpretation of the absorption features in a field B∼4×1013 G. The flux ratio of those lines does not support this interpretation. Hence, either feature might be of truly atomic origin.
相似文献
5.
V. Hambaryan D. Wagner J.G. Schmidt M. M. Hohle R. Neuhuser 《Astronomische Nachrichten》2015,336(6):545-565
We performed an X‐ray timing and spectral analysis of the variable source 3XMM J185246.6+003317 to investigate its physical nature. The data from all observations of 3XMMJ185246.6+003317 conducted by XMM‐Newton EPIC MOS1 and MOS2 with the same instrumental setup in 2004–2009 were reprocessed to form a homogenous data set of solar barycenter corrected photon arrival times and high S/N spectra of 3XMM J185246.6+003317. A Bayesian method for the search, detection, and estimation of the parameters of a periodic signal of unknown shape was employed, as developed by Gregory & Loredo (1992, 1993). The results show that 3XMM J185246.6+003317 is a transient neutron star with the genuine spin‐period of 23.11722 (23.11711–23.11727) s and its derivative of 5.3(0.3–5.5)×10–11 s s–1, implying a characteristic age of 7 (6–104) kyr, if the period derivative can be ascribed to the genuine spin‐down rate of the neutron star. The rotational‐phase averaged X‐ray spectra at the different brightness periods can be fitted with a highly absorbed blackbody model with different temperatures. The phase‐folded light curves in different energy bands with high S/N ratio show a double‐peaked profile; the variations depend on time and energy, indicating that radiation emerges from at least two emitting areas. The spectra at the phases corresponding to the maxima in the phase‐folded light curve show different spectral parameters of absorbed blackbody radiation, i.e. the hotter one has a smaller size. The source is detected only from September 2008 to April 2009 with persistently decreasing brightness, but not before, even though it was observed by XMM. Hence, it is a transient neutron star or a binary system hosting it. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
6.
Philip H. Scherrer John M. Wilcox Valeri Kotov A. B. Severny Robert Howard 《Solar physics》1977,52(1):vi-12
The mean solar magnetic field as measured in integrated light has been observed since 1968. Since 1970 it has been observed both at Hale Observatories and at the Crimean Astrophysical Observatory. The observing procedures at both observatories and their implications for mean field measurements are discussed. A comparison of the two sets of daily observations shows that similar results are obtained at both observatories. A comparison of the mean field with the interplanetary magnetic polarity shows that the IMF sector structure has the same pattern as the mean field polarity. 相似文献
7.
Gerhard Drolshagen Valeri Dikarev Markus Landgraf Holger Krag Wim Kuiper 《Earth, Moon, and Planets》2008,102(1-4):191-197
Over the last decade several new models for the sporadic interplanetary meteoroid flux have been developed. These include
the Divine-Staubach and the Dikarev model. They typically cover mass ranges from 10−18 g to 1 g and are applicable for model specific Sun distance ranges between 0.1 AU and 20 AU Near 1 AU averaged fluxes (over
direction and velocities) for all these models are tuned to the well established interplanetary model by Grün et al. However,
in many respects these models differ considerably. Examples are the velocity and directional distributions and the assumed
meteoroid sources. In this paper flux predictions by the various models to Earth orbiting spacecraft are compared. Main differences
are presented and analysed. The persisting differences even for near Earth space can be seen as surprising in view of the
numerous ground based (optical and radar) and in situ (captured Inter Stellar Dust Particles, in situ detectors and analysis
of retrieved hardware) measurements and simulations. 相似文献
8.
9.
The ROSAT source 1RXS J181333.7+453118 is a Seyfert Sy1 galaxy with a red shift of z=0.093. A ROSAT spectrum and a spectrum over wavelengths of λ4500-7250? taken with the 2.6-m telescope at the Byurakan Astrophysical
Observatory are shown. The x-ray spectrum has characteristics similar to an AGN with a soft x-ray excess. 相似文献
10.
Trapezium type multiple stars are centers of star formation in stellar associations. Theoretical and observational studies
show that they are dynamically instable. Due to the special space configurations of the components, Trapezium type multiple
stars disintegrate completely or partly after several rotations around their centers. These stars have a main role in the
origin and evolution of stars on OB- and T-associations. According to observations of 15 Trapezium type multiple stars having
the brightest star of OB-class 14 are in expansion. The age of the Trapezium type multiple stars is of the order of 21(P years.
There are weighty arguments to assume that the majority of them are in a state of expansion with positive total energy.
Translated from Abastumani Astrophysical Observatory, Academy of Sciences, Georgia. Published in Astrofizika, Vol. 41, No.
1, pp. 91–100, January-March, 1998. 相似文献