麻豆淫院

It's great to see old astronomical observations come to light. Not only can these confirm or refute what's known about historic astronomical events, but they can describe what early observers actually saw.

A posted to the arXiv preprint server cites two Arabic texts that may refer to accounts of two well-known supernovae seen in our galaxy: one in 1006 AD and another in 1181 AD.

Like Far Eastern observers, Arab astronomers were astute observers of the night sky, and patiently noted what they saw, including changes in the familiar constellation patterns such as novae and supernovae.

While we often see supernovae out across the universe in distant galaxies, galactic supernovae are a rarity. The last prominent one, Kepler's Star in 1604 occurred just before the telescope came into general use. Here we are, more than four centuries later, still waiting for the next one.

The two historic supernovae in 1006 and 1181 were prominent in the sky, and noted by observers across the Near and Far East.

Arab astronomers noted the Supernova of 1181 (SN 1181) in the constellation they referred to as "The Henna Painted Hand," in the modern-day W-shaped constellation of Cassiopeia. The text found in the study was written by Ibn San膩' al-Mulk praising Saladin, known for his defeat of Crusader armies and conquest of Jerusalem. The crucial line in the text translates:

"I see how everything on the surface of Earth has increased in number thanks to your justice; now even the stars (anjum) in the sky have increased in number. (The sky) adorned itself with a star (najm); nay, it smiled through it, because whoever is delighted by a delightful thing smiles."

The study notes that the poem would have probably been written to be read in the presence of both Saladin and his brother, both of whom were last present in Cairo in 1181鈥�1182, right around the time the supernova would have been visible.

The other supernova referenced in the study (SN 1006) occurred deep in the southern hemisphere and was only visible to viewers from latitude 40 southward. Rome, Italy is located at northern latitude 41 degrees. SN 1006 was seen on what is the modern-day border of the constellations Lupus and Hydra.

The account of the Supernova of 1006 comes from historian Ahmad ibn 'Al墨 al-Maqr墨z墨 who lived and wrote some centuries later from 1364 to 1442. He writes that:

"When Ab奴 Rakwah rose in revolt, a star (kawkab) with a tail appeared. It shone like the moon with brightness and gleam and its light strengthened and increased so long as Ab奴 Rakwah's cause got on well and became ominous. This star remained some months; then its light dwindled and its gleam faded away."

Certainly, a comet would've also fit the description, though it's rare that a bright comet lingers in the sky for several months. Other contemporary Arab texts use the term "kawkab" interchangeably for comets, stars and planets, and notably for the prominent SN 1006. Certainly, its low southern declination would have been subject to distortion and scintillation, low in the murk of the horizon.

"For SN 1181, there were only Chinese and Japanese records known before, so that any new reports with astronomical details are important," Ralph Neuh盲user (University of Jena, Germany) told Universe Today. This is essential, as the potential source remnant as seen today and its location in the sky is still a matter of dispute.

"The Arabic poem gives information on the position of the star and maybe its brightness (brighter than the stars in Cassiopeia)." This would've pegged it at magnitude 0, easily naked-eye. "SN 1181 is also important to astrophysics, because it was previously suggested to be an unusual type Iax supernova (a rare type of supernova which leaves behind a 'zombie' star remnant). This would be the first found in our galaxy."

"For SN 1006, it is just one more Arabic text without new astronomical information, but consistent with previous ones," says Neuh盲user. "It was very bright and reported often."

Indeed, SN 1006 may have topped out at an amazing magnitude -7, and been bright enough to be seen in the daytime sky. European observers missed this one for the most part, due to its deep southern declination.

"The poem on SN 1181 was discovered by Jens Fischer of the University of M眉nster in Germany, who re-dated the poem and then noticed the supernova," says Neuh盲user. "The new text on SN 1006 was found by Heinz Halm of the University of T眉bingen, Germany. Both discoveries were serendipitous."

It's fascinating that only Arab and Oriental observers seemed to have made mention of these two supernovae, although they must have been fairly prominent in the sky.

"SN 1006 was brighter than all the planets and reported in East Asia and Arabia, but was too far south in the sky for most of Europe," says Neuh盲user. "It was reported by a Swiss monk, and some people in Italy. SN 1181 was not very bright, maybe 0 to +1st magnitude (comparable to Saturn). It may still be possible to expect and find more reports from Arabia and Europe."

Certainly, there's more left to discover, in terms of ancient texts and astronomical research.

"I am currently working on the reconstruction of light curves and color evolution of the supernovae of 1572 and 1604 with many new records found in Europe," says Neuh盲user.

The study of supernovae is important to modern astronomy and astrophysics. Supernovae are crucial recyclers of material, shedding heavy elements back into the cosmos. And though a nearby "kilonova" would spell a bad day for Earth, none exist with the potential to go supernova within the 25 light-year kill radius. The most famous supernova-in-waiting of all is Betelgeuse, located approximately 500 light-years distant. An ancient supernova event near our solar system may even be the reason we walk upright.

For now, though, we'll still have to just read about these supernovae of yore, while we wait until the next brilliant galactic supernova graces our night skies, hopefully, in our lifetimes.