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RE: NGC 4013
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NGC 4013



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Supernova 1989Z
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Title: Star near NGC 4013 = Supernova 1989Z?
Authors: Kushida, R.; Nakano, S.; Kushida, Y.; Aoki, M.

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PGC 37691
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NGC 4013 (also IRAS 11559+4413, MCG 7-25-9, UGC 6963 and PGC 37691)is a magnitude +12.1 edge-on barred spiral galaxy located 60.6 8.1 million light-years away in the constellation Ursa Major.

The galaxy was discovered by German-British astronomer William Herschel using a 47.5 cm (18.7 inch) f/13 speculum reflector at Windsor Road, Slough, on the 6th February 1788

Supernova SN 1989Z was discovered on December 30, 1989 at apparent magnitude 12.
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Right ascension 11h 58m 31.13s, Declination +43 56' 50.1"



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Title: The NGC 4013 tale: a pseudo-bulged, late-type spiral shaped by a major merger
Author: Jianling Wang (1), Francois Hammer (2), Mathieu Puech (2), Yanbin Yang (2), Hector Flores (2) ((1) National Astronomical Observatories, Chinese Academy of Sciences (NAOC) (2) GEPI, Observatoire de Paris)

Many spiral galaxy haloes show stellar streams with various morphologies when observed with deep images. The origin of these tidal features is discussed, either coming from a satellite infall or caused by residuals of an ancient, gas-rich major merger. By modelling the formation of the peculiar features observed in the NGC 4013 halo, we investigate their origin. By using GADGET -2 with implemented gas cooling, star formation, and feedback, we have modelled the overall NGC 4013 galaxy and its associated halo features. A gas-rich major merger occurring 2.7-4.6 Gyr ago succeeds in reproducing the NGC 4013 galaxy properties, including all the faint stellar features, strong gas warp, boxy-shaped halo and vertical 3.6 mum luminosity distribution. High gas fractions in the progenitors are sufficient to reproduce the observed thin and thick discs, with a small bulge fraction, as observed. A major merger is able to reproduce the overall NGC 4013 system, including the warp strength, the red colour and the high stellar mass density of the loop, while a minor merger model cannot. Because the gas-rich model suffices to create a pseudo-bulge with a small fraction of the light, NGC 4013 is perhaps the archetype of a late-type galaxy formed by a relatively recent merger. Then late type, pseudo-bulge spirals are not mandatorily made through secular evolution, and the NGC 4013 properties also illustrate that strong warps in isolated galaxies may well occur at a late phase of a gas-rich major merger.

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Title: Discovery of a Giant Stellar Tidal Stream Around the Disk Galaxy NGC 4013
Authors: David Martinez-Delgado (1,2), Michael Pohlen (3), R. Jay Gabany (4), Steven R. Majewski (5), Jorge Penarrubia (6), Chris Palma (7) ((1) Instituto de Astrofisica de Canarias E, (2) Max-Planck Institut fuer Astronomie D, (3) Cardiff University UK, (4) BlackBird Observatory USA, (5) University of Virginia USA, (6) University of Victoria CDN, (7) Penn State University USA)

We report the discovery of a giant, low surface-brightness loop-like stellar structure around the edge-on spiral galaxy NGC 4013. This arcing feature extends 6 arcmin (~26 kpc in projected distance) northeast from the centre; likely related features are also apparent on the southwest side of the disk, extending to 4 arcmin (~17 kpc). The detection of this loop-like structure is independently confirmed in three separate datasets from three different telescopes. We estimate a surface brightness of muB = 28.6+0.6-0.4 magsqarcsec and muR = 27.0+0.3-0.2 magsqarcsec. The significantly redder colour of the stream material compared to the outer parts of the disk of NGC 4013 suggests that this loop did not originate from the disk itself, but rather is the tidal stream of a dwarf galaxy being destroyed in NGC 4013's gravitational potential. Although its true three-dimensional geometry is unknown, the projected tidal loop displays a very good overall match with the external edge-on perspective of the Monoceros tidal stream in the Milky Way predicted by recent N-body simulations. Our results demonstrate that NGC 4013, previously considered a prototypical isolated disk galaxy, is in fact undergoing a tidal encounter with a low-mass satellite. In this sense NGC 4013, with one of the most prominent HI warped disks known but showing no previously obvious indication of tidal activity, could be a Rosetta Stone for understanding disks that appear almost pristine in the optical but warped in HI maps and may provide key insights into the formation of warps in general.

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