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Magnitudes of comets P/Giacobini-Zinner (1984e), P/Halley (1982i), P/Hartley-Good (1985 1), and Thiele (1985 m) in the bandpasses of the standard IHW comet filters are presented. For comet P/Halley production rates for CN, C3, C2, and solids were derived. For the gaseous components these show a strong dependence on heliocentric distance. The dependence is less steep for the solids which may be due to relatively pronounced backscattering properties in case of comet P/Halley. During one night (1985 Dec. 22/23) intensity profiles along three sections through the coma of comet P/Halley were measured. Compared with theoretical profiles they show a global anisotropy of the coma and possibly local structure. 相似文献
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B. Stecklum 《Astronomische Nachrichten》1989,310(5):375-379
Using analytical approximations of the mass spectra of molecular clouds and stellar systems including open clusters and associations a relation between the final star formation efficiency (final SFE) and the initial cloud mass is derived. The dependence of the SFE on cloud mass is estimated for two cases of molecular cloud destruction by stellar winds in spherical geometry. The result of growing SFE with rising cloud mass does not agree with current observations and the above relation. A decrease of the SFE is expected if the fraction of high-mass stars grows with increasing mass of the cloud. 相似文献
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Bringfried Stecklum Helmut Meusinger Dirk Froebrich 《Astrophysics and Space Science》2007,311(1-3):63-67
Herbig-Haro objects (HHOs) are caused by outflows from young objects. Since the outflow relies on mass accretion from a circumstellar
disk, it indicates ongoing growth. Recent results of infrared observations yielded evidence for disks around brown dwarfs.
This suggests that at least a certain fraction of brown dwarfs forms like stars. Thus, young sub-stellar objects might cause
HHOs as well. We present selected results of a general survey for HHOs based on DSS-II plates and CCD images taken with the
Tautenburg Schmidt telescope. Numerous young objects could be identified due to their association with newly detected HHOs.
In some cases the luminosity is consistent with very low-mass stars or close to sub-stellar values. This holds for L1415-IRS
and a few infrared sources embedded in other dark clouds (e.g., GF9, BHR111). The question on the minimum mass for outflow
activity is addressed. 相似文献
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S. Minardi A. Chipouline S. Krmer T. Pertsch R. Follert B. Stecklum R. Neuhuser 《Astronomische Nachrichten》2009,330(5):518-522
We present a fiber sensor based on an active integrated component which could be effectively used to measure the longitudinal vibration modes of telescope mirrors in an interferometric array. We demonstrate the possibility to measure vibrations with frequencies up to ⋍100 Hz with a precision better than 10 nm (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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Ch. Leinert U. Graser F. Przygodda L.B.F.M. Waters G. Perrin W. Jaffe B. Lopez E.J. Bakker A. Böhm O. Chesneau W.D. Cotton S. Damstra J. de Jong A.W. Glazenborg-Kluttig B. Grimm H. Hanenburg W. Laun R. Lenzen S. Ligori R.J. Mathar J. Meisner S. Morel W. Morr U. Neumann J.-W. Pel P. Schuller R.-R. Rohloff B. Stecklum C. Storz O. von der Lühe K. Wagner 《Astrophysics and Space Science》2003,286(1-2):73-83
After more than five years of preparation, the mid-infrared interferometric instrument MIDI has been transported to Paranal
where it will undergo testing and commissioning on theVery Large Telescope Interferometer VLTI from the end of 2002through
large part of this year 2003. Thereafter it will be available as a user instrument to perform interferometric observations
over the8 μm–13 μm wavelength range, with a spatial resolution of typically 20 milliarcsec, a spectral resolution of up to
250, and an anticipated point source sensitivity of N = 3–4 mag or 1–2.5 Jy for self –fringe tracking, which will be the only
observing mode during the first months of operation. We describe the layout of the instrument, laboratory tests, and expected
performance, both for broadband and spectrally resolved observing modes. We also briefly outline the planned guaranteed time
observations.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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For stars to be used as flux standards and solar type analogues magnitudes in the system of the International Halley Watch (IHW) filters are given. 相似文献
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使用德国Th(u|¨)ringer Landessternwarte Tautenburg(TLS)的2 m望远镜对Aquila Rift的16个区域进行了Hα、R和I共3个波段的成像观测.这些观测区域大约覆盖了Aquila Rift 7平方度的天区.除去3个数据质量不高的天区,对其余的13个区域进行了测光分析,从中证认出点源,并利用双色图的方法最终证认出7颗Hα发射线星候选体.这7个候选体是从5个观测区域中选出的,其中3颗位于银道面区域,4颗位于银纬高于4°的区域.对于这5个天区,证认了其中点源的2MASS对应体,并利用双色图的方法进一步分析了7个Hα发射线星候选体的性质.这些Hα发射线星候选体的近红外辐射并没有明显的红外超现象,有一颗还落在了主序分支上.这也说明有Hα发射的年轻星并不都伴随有红外超现象.Hα发射线观测和红外超观测的结果是相互补充的.如果将这7颗Hα发射线星候选体作为年轻星候选体,则Aquila Rift区域的年轻星数目是较少的.对于这些候选体的进一步证认还需要后续的光谱观测. 相似文献