اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدEuropean Historical Evidence of the Supernova of AD 1054 Balkan Medieval Tombstones
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In a previous work, we establish that the acclaimed Arabic records of SN 1054 from ibn Butlan originate from Europe. Also, we reconstructed the European sky at the time of the event and find that the new star (SN 1054) was in the west while the planet Venus was on the opposite side of the sky (in the east) with the Sun sited directly between these two equally bright objects, as documented in East-Asian records. Here, we investigate the engravings on tombstones (stecci) from several necropolises in present-day Bosnia and Herzegovina (far from the influence of the Church) as a possible European record of SN 1054. Certainly, knowledge and understanding of celestial events (such as supernovae) were somewhat poor in the mid-XI century.
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We investigate possible reasons for the absence of historical records of the supernova of 1054 in Europe. At the same time, we search for the new evidences as well. We establish that the previously acclaimed Arabic records from ibn Butlan originate f
rom Europe. As one of the most prominent scientists of the era, he was in Constantinople at the time of the supernova and actively participated in the medieval Church feud known as the Great Schism. Next, we reconstruct the European sky at the time of the event and find that the new star (SN 1054) was in the west while the planet Venus was on the opposite side of the sky (in the east) with the Sun sited directly between these two equally bright objects, as documented in East-Asian records.
As new classes of transients and variable stars are discovered, and theoretical models are established to work or not to work for a few members of the class, it is often the case that some researchers will make arguments on the basis of Occams razor
that all members of the class must be produced by whichever mechanism first successfully explained one of the objects. It is also frequent that this assumption will be more more implicitly. Retrospective analysis shows rather clearly that this argument fails a large fraction of the time, and in many cases, this search for false consistency has led to more fundamental astrophysical errors, a few of which are quite prominent in the history of astronomy. A corollary of this is that on numerous occasions, theoretical models to explain transients have turned out to be models that describe real (but often not yet discovered) phenomenona other than the ones to which they have first been applied, albeit with minor errors that caused the model to appear to fit to a known phenomenon it did not describe. A set of examples of such events is presented here (some of which will be quite familiar to most astronomers), along with a discussion of why this phenomenon occurs, how it may be manifesting itself at the present time. Some discussion will also be made of why and when survey designs have led to immediate separation of various transient mechanisms, generally by being overpowered in some way relative to what is needed to {it detect} a new class of objects.
We study an interstellar signaling scheme which was originally proposed by Seto (2019) and efficiently links intentional transmitters to ETI searchers through a conspicuous astronomical burst, without prior communication. Based on the geometrical and
game theoretic viewpoints, the scheme can be refined so that intentional signals can be sent and received after observing a reference burst, in contrast to the original proposal (before observing a burst). Given this inverted temporal structure, Galactic supernovae recorded in the past 2000 years can be regarded as interesting guideposts for an ETI search. While the best use period of SN 393 has presumably passed $sim$100 years ago, some of the historical supernovae might allow us to compactify the ETI survey regions down to less than one present of $4pi$, around two rings in the sky.
Supernova (SN) 2006gy was a hydrogen-rich core-collapse SN that remains one of the most luminous optical supernovae ever observed. The total energy budget (> 2 x 10^51 erg radiated in the optical alone) poses many challenges for standard SN theory. W
e present new ground-based near-infrared (NIR) observations of SN 2006gy, as well as a single epoch of Hubble Space Telescope (HST) imaging obtained more than two years after the explosion. Our NIR data taken around peak optical emission show an evolution that is largely consistent with a cooling blackbody, with tentative evidence for a growing NIR excess starting at day ~100. Our late-time Keck adaptive optics (AO) NIR image, taken on day 723, shows little change from previous NIR observations taken around day 400. Furthermore, the optical HST observations show a reduced decline rate after day 400, and the SN is bluer on day 810 than it was at peak. This late-time decline is inconsistent with Co56 decay, and thus is problematic for the various pair-instability SN models used to explain the nature of SN 2006gy. The slow decline of the NIR emission can be explained with a light echo, and we confirm that the late-time NIR excess is the result of a massive (>10 Msun) dusty shell heated by the SN peak luminosity. The late-time optical observations require the existence of a scattered light echo, which may be generated by the same dust that contributes to the NIR echo. Both the NIR and optical echoes originate in the proximity of the progenitor, ~10^18 cm for the NIR echo and <~10-40 pc for the optical echo, which provides further evidence that the progenitor of SN 2006gy was a very massive star.
The guest star of AD 1181 is the only historical supernova of the last millennium that is without a definite counterpart. The previously proposed association with supernova remnant 3C58 is in strong doubt because of the inferred age of this remnant.
Here we report a new identification of SN 1181 with our codiscovery of the hottest known Wolf Rayet star of the Oxygen sequence (dubbed Parkers star) and its surrounding nebula Pa 30. Our spectroscopy of the nebula shows a fast shock with extreme velocities of approx. 1,100kms. The derived expansion age of the nebula implies an explosive event approx 1,000 years ago which agrees with the 1181 AD event. The on sky location also fits the historical Chinese and Japanese reports of SN 1181 to 3.5degrees. Pa 30 and Parkers star have previously been proposed to be the result of a double-degenerate merger, leading to a rare Type Iax supernova. The likely historical magnitude and the distance suggest the event was subluminous for normal supernova. This agrees with the proposed Type Iax association which would also be the first of its kind in the Galaxy. Taken together, the age, location, event magnitude and duration elevate Pa 30 to prime position as the counterpart of SN 1181. This source is the only Type Iax supernova where detailed studies of the remnant star and nebula are possible. It provides strong observational support for the double degenerate merger scenario for Type Iax supernovae.
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