Erratum to: Nanoscale zero-valent iron flakes for groundwater treatment     

R. Köber  H. Hollert  G. Hornbruch  M. Jekel  A. Kamptner  N. Klaas  H. Maes  K.-M. Mangold  E. Martac  A. Matheis  H. Paar  A. Schäffer  H. Schell  A. Schiwy  K. R. Schmidt  T. J. Strutz  S. Thümmler  A. Tiehm  J. Braun 《Environmental Earth Sciences》2016,75(6):532

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Spectroscopy of planetary atmospheres in our Galaxy     

Giovanna?TinettiEmail author  Thérèse?Encrenaz  Athena?Coustenis 《Astronomy and Astrophysics Review》2013,21(1):63

About 20 years after the discovery of the first extrasolar planet, the number of planets known has grown by three orders of magnitude, and continues to increase at neck breaking pace. For most of these planets we have little information, except for the fact that they exist and possess an address in our Galaxy. For about one third of them, we know how much they weigh, their size and their orbital parameters. For less than 20, we start to have some clues about their atmospheric temperature and composition. How do we make progress from here?We are still far from the completion of a hypothetical Hertzsprung–Russell diagram for planets comparable to what we have for stars, and today we do not even know whether such classification will ever be possible or even meaningful for planetary objects. But one thing is clear: planetary parameters such as mass, radius and temperature alone do not explain the diversity revealed by current observations. The chemical composition of these planets is needed to trace back their formation history and evolution, as happened for the planets in our Solar System. As in situ measurements are and will remain off-limits for exoplanets, to study their chemical composition we will have to rely on remote sensing spectroscopic observations of their gaseous envelopes.In this paper, we critically review the key achievements accomplished in the study of exoplanet atmospheres in the past ten years. We discuss possible hurdles and the way to overcome those. Finally, we review the prospects for the future. The knowledge and the experience gained with the planets in our solar system will guide our journey among those faraway worlds.  相似文献   

Ejnar Hertzsprung: 8. 10. 1873–21. 10. 1967     

P. Th. Oosterhoff 《Astronomische Nachrichten》1969,291(2):85-87

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Spectral indices in quantitative spectral classification from stellar libraries     

V. Malyuto  Th. Schmidt-Kaler 《Astronomische Nachrichten》1999,320(2):71-76

With the use of modern detectors stellar spectral classification libraries have been extended from the photographic regime to the near ℝ at 11000 Å. We have defined new spectral indices within this extended wavelength-range that can be used to determine the luminosity classification for G-K-M stars. An advantage of the new indices, which sample the stellar flux in and out of selected spectral features, is that they are insensitive to catalog differences. This facilitates the use of many catalogs, with varying resolution, different reddening corrections, and calibrations, hence extending the total number of stellar standards available. Furthermore, we demonstrate that the indices can be used to infer absolute magnitudes with good accuracy. The indices should prove useful for analysis of spectra from distant clusters, galaxies, and in particular for problems involving spectral synthesis of stellar populations of galaxies.  相似文献   

An infrared imaging search for low‐mass companions to members of the young nearby β Pic and Tucana/Horologium associations     

R. Neuhuser  E.W. Guenther  J. Alves  N. Hulamo  Th. Ott  A. Eckart 《Astronomische Nachrichten》2003,324(6):535-542

We present deep high dynamic range infrared images of young nearby stars in the Tucana/Horologium and β Pic associations, all ∼10 to 35 Myrs young and at ∼10 to 60 pc distance. Such young nearby stars are well‐suited for direct imaging searches for brown dwarf and even planetary companions, because young sub‐stellar objects are still self‐luminous due to contraction and accretion. We performed our observations at the ESO 3.5m NTT with the normal infrared imaging detector SofI and the MPE speckle camera Sharp‐I. Three arc sec north of GSC 8047‐0232 in Horologium a promising brown dwarf companion candidate is detected, which needs to be confirmed by proper motion and/or spectroscopy. Several other faint companion candidates are already rejected by second epoch imaging. Among 21 stars observed in Tucana/Horologium, there are not more than one to five brown dwarf companions outside of 75 AU (1.5″ at 50 pc); most certainly only ≤5% of the Tuc/HorA stars have brown dwarf companions (13 to 78 Jupiter masses) outside of 75 AU. For the first time, we can report an upper limit for the frequency of massive planets (∼10 M_jup) at wide separations (∼100 AU) using a meaningfull and homogeneous sample: Of 11 stars observed sufficiently deep in β Pic (12 Myrs), not more than one has a massive planet outside of ∼100 AU, i.e. massive planets at large separations are rare (≤9%). (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

Narrow‐Line Seyfert 1 Galaxies with high‐energy sharp spectral drops: reflection‐versus absorption models     

Th. Boller 《Astronomische Nachrichten》2006,327(10):1071-1075

With the launch of XMM‐Newton in 1999, two Narrow‐Line Seyfert 1 Galaxies (NLS1s) have been detected (IRAS 13224–3809 and 1H 0707–495) showing sharp spectral drops at energies equal or above the neutral Fe K edge at 7.1 keV without any narrow Fe K reemission. In this paper I summarize our present knowledge on the observed properties of sharp high‐energy spectral drops. I list the problems presently arising from the reflection dominated and the optically thick disc models. Finally, I present an alternative solution which consists of a combination of the accretion disc model and the reflection dominated model. This might solve the problems of the standard accretion disc model. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献