A supernova host galaxy hides an impostor: one explosion may have been a star that survived

the gist

UGC 5460 is a spiral galaxy about 60 million light-years away in Ursa Major, with a central bar and bright blue star clusters. It has hosted two supernovae, SN 2011ht and SN 2015as. SN 2015as was a core-collapse supernova, which happens when a massive star runs out of fuel and its core collapses, triggering an explosion. SN 2011ht might also have been one, but it could instead have been a luminous blue variable, a rare star that erupts so violently it mimics a supernova. The key difference is that such a star survives its eruption, while a true supernova destroys it. Hubble is searching for a surviving star at the SN 2011ht location to settle which it was.

how it works

When a massive star's core runs out of fuel, it collapses and its outer layers are blasted outward. A luminous blue variable can also eject material violently, but it keeps its core and survives.

so what

Finding out whether a supernova was really a survivor would sharpen how astronomers classify stellar explosions. It also helps show how massive stars end their lives.

the bigger pattern

Astronomers have long debated the nature of some unusual supernovae, and similar questions appear with other stars that erupt without dying. Finding a surviving star after an event is one of the cleanest ways to tell them apart.

ESA/Hubble · CC BY 4.0

Image: ESA/Hubble & NASA, W. Jacobson-Galán, A. Filippenko, J. Mauerhan

source: ESA/Hubble ↗

historyWikipediaclassic1336–1565 · Karnataka, India

Hampi was once one of the world's largest cities, until its Vijayanagara capital was destroyed in 1565

the gist

Hampi is a UNESCO World Heritage Site in Karnataka, India, with more than 1,600 surviving remains spread over 4,100 hectares. It was the capital of the Vijayanagara Empire from 1336 to 1565. Travellers from Persia and Portugal described it as a prosperous, wealthy and grand city with temples, markets and farms along the Tungabhadra River. By 1500 it was estimated to be the world's second-largest city after Beijing, and probably India's richest at the time. In 1565 a coalition of Muslim sultanates defeated the Vijayanagara Empire, its capital was conquered and destroyed, and the city was left in ruins. Hampi remains a religious centre, with the active Virupaksha Temple at its heart.

how it works

The city was built around a fortified core with temples, markets and water structures along the river, supplied by an extensive network of roads and waterworks. When the empire fell, the city was not rebuilt, so its stone monuments were left standing.

so what

Hampi shows how quickly a great city can vanish after a military defeat, and how a ruined capital can remain sacred. Its ruins give historians a view of medieval South Asia that few other sites can match.

fun fact

The name Hampi comes from Pampa, an old name for the Tungabhadra River.

From Wikipedia, the free encyclopedia · text CC BY-SA 4.0

Image: Wikimedia Commons

source: Wikipedia ↗

2 min

politicsshortCNA2:01

False allegations about Singapore’s hand in Indonesia’s markets and a made-up meeting

from CNA

CNA Verify has found close to 400 posts pushing falsehoods tying Singapore to Indonesia’s stock market rout and to a secret meeting that never took place. Together, they drew nearly 12 million views, and some were circulated by accounts that appeared to be working in concert, across multiple social media platforms.

Here’s how the disinformation campaign targeting Singapore was uncovered.

on YouTube: CNA ↗