Astronomische Nachrichten

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ISSN / EISSN : 00046337 / 15213994
Current Publisher: Wiley (10.1002)
Total articles ≅ 48,035
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Fernando J. Selman, Fuyan Bian, Israel Blanchard, Stephane Brillant, Lodovico Coccato, Stefano Cristiani, Pascale Hibon, Darshan Kakkad, Andrea Mehner, Sabine Moehler, et al.
Published: 16 February 2020
by Wiley
Astronomische Nachrichten; doi:10.1002/asna.202013637

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Susanne M. Hoffmann, Nikolaus Vogt, Philipp Protte
Published: 11 February 2020
by Wiley
Astronomische Nachrichten; doi:10.1002/asna.202013682

Abstract:Ancient Chinese, Korean, and Vietnamese observers left us records of celestial sightings, the so‐called “guest stars” dated up to ∼2500 years ago. Their identification with modern observable targets could open interesting insights into the long‐term behavior of astronomical objects, as shown by the successful identification of eight galactic supernovae. Here, we evaluate the possibility to identify ancient classical novae with presently known cataclysmic variables (CVs). For this purpose, we have developed a method which reconsiders in detail positions and sizes of ancient asterisms, in order to define areas on the sky that should be used for a search of modern counterparts. These areas range from a few to several 100 square degrees, depending on the details given in ancient texts; they should replace the single coordinate values given by previous authors. Any appropriate target (CVs, X‐ray binaries etc.) within these areas can be considered as a valid candidate for identification with the corresponding ancient event. Based on the original descriptions of several 100 old events, we selected those without movement and without a tail (to exclude comets) and which was not only visible within a certain hour (to exclude meteors). This way, we present a shortlist of 24 most promising events which could refer to classical nova eruptions. Our method is checked by applying it to the known SN identifications, leading to a margin of error between 0 and 4.5 degrees, meaning that some SN remnants lay exactly inside the areas given by the historical reports while in some other cases they are laying at considerable distances.
Charles R. Cowley, Kutluay Yüce, Donald J. Bord
Published: 11 February 2020
by Wiley
Astronomische Nachrichten; doi:10.1002/asna.202013694

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Irham Taufik Andika, Mochamad Ikbal Arifyanto, Wolfram Kollatschny
Published: 6 February 2020
by Wiley
Astronomische Nachrichten; doi:10.1002/asna.202013697

Abstract:We analyze emission line properties and their correlations for 18,043 type 1 active galactic nucleus (AGN) in the range of 0.02 ≤ z ≤ 0.8, based on Sloan Digital Sky Survey Data Release 14 data. We complement the data with photometric measurements from ROSAT, GALEX, 2MASS, and FIRST. We find the following: (a) The average correlation between luminosity of [O III] and AGN luminosity is stronger than those for [O II] line. This is consistent with the stratified model of narrow line region (NLR). Furthermore, we also find a weak dependence of ionization degree with AGN luminosity. (b) The narrow lines luminosity and radio luminosity correlation is stronger for radio quiet AGN and weaker for radio loud (RL) AGN, most likely due to radio jets. A possible explanation is as the jets penetrate the NLR, the shock will ionize its gas, increase the narrow lines emission, and cause a bigger dispersion in the correlation for RL AGN. (c) The investigated narrow lines, [O II], [O III], Hβ, Hα, [N II], and [S II], show a significant trend of decreasing luminosity ratio relative to the broad Hβ luminosity where the slopes in the range of −0.26 to −0.50. We did not find any correlation of the trend slopes with ionization potential or critical density of the lines. We suggest that this correlation is due to decrease in covering factor of NLR as AGN luminosity increases. (d) The EV1 correlation is found in our data and represents change in Eddington ratio. By using L[O III]/L[O II] ratio, we found that the ionization degree decreases as Eddington ratio increases. We also confirm that objects with higher Eddington ratio tend to have narrower Hβ, stronger Fe II emission, and weaker [O III] strength. In contrast to that, objects with lower Eddington ratio tend to have broader Hβ, weaker Fe II emission, and higher [O III] strength.
Juha Kallunki, Merja Tornikoski, Petri Kirves, Erkki Oinaskallio, Juha Aatrokoski, Ari Mujunen, Joni Tammi
Published: 5 February 2020
by Wiley
Astronomische Nachrichten; doi:10.1002/asna.202013684

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Jacek Krełowski, Gazinur A. Galazutdinov, Arkadii Bondar
Published: 5 February 2020
by Wiley
Astronomische Nachrichten; doi:10.1002/asna.202013650

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Bhavneet Kaur, Dinesh Kumar, Shipra Chauhan
Published: 25 November 2019
by Wiley
Astronomische Nachrichten; doi:10.1002/asna.201913645

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Roberto Rampazzo, Michela Uslenghi, Iskren Y. Georgiev, Arianna Cattapan, Lourdes Verdes‐Montenegro, Marco Bonaglia, Jose Luis Borelli, Lorenzo Busoni, Wolfgang Gäessler, Demetrio Magrin, et al.
Published: 24 November 2019
by Wiley
Astronomische Nachrichten; doi:10.1002/asna.201913633

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Lien Rodríguez‐López, Rolando Cárdenas, Lisdelys González‐Rodríguez, Liuba Peñate, Oscar Parra, Roberto Urrutia
Published: 1 November 2019
by Wiley
Astronomische Nachrichten, Volume 340, pp 828-833; doi:10.1002/asna.201913753

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Fabio Köpp, César A. Zen Vasconcellos, Magno Machado
Published: 1 November 2019
by Wiley
Astronomische Nachrichten, Volume 340, pp 892-897; doi:10.1002/asna.201913747

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