Astronomers rediscover ancient ‘lost’ nova first spotted six centuries ago

A team of astronomers have pinpointed the location of a nova that was last seen almost 600 years ago.

In 1437, Korean astrologers spotted a bright new star in the tail of the constellation Scorpius and observed it for 14 days before it faded from view. Studying the ancient record made by the Royal Imperial Astrologers, modern astronomers determined that what they had seen was a nova explosion but, until now, they were unable to find the binary system that caused it.

“This is the first nova that’s ever been recovered with certainty based on the Chinese, Korean, and Japanese records of almost 2,500 years,” said the study’s lead author Michael Shara, a curator in the American Museum of Natural History’s Department of Astrophysics.

An image of the nova, which was first identified in 1437, taken with the Carnegie SWOPE 1-meter telescope in Chile. Image© K. Ilkiewicz and J. Mikolajewska. Above: a Korean star chart (rotated) first created in 1395, and reproduced in 1687. Image courtesy of Seoul National University / National Geographic Information Resource Map Museum

A nova is essentially a hydrogen bomb on a gigantic scale, produced in a binary system where a star is being devoured by a white dwarf (a dead star). Over roughly 100,000 years, the white dwarf builds up a critical layer of hydrogen that it then blows off, producing a burst of light that can make the star up to 300,000 times brighter than the sun for any period from a few days to a few months.

Shara has tried to locate the Korean nova for several years, teaming up with Durham University’s Richard Stephenson, a historian of ancient Asian astronomical records, and Liverpool John Moores University astrophysicist Mike Bode.  Their recent success came after expanding the search field and discovering the ejected shell of the classical nova. The finding was confirmed with a photographic plate from 1923 taken at the Harvard Observatory station in Peru.

“With this plate, we could figure out how much the star has moved in the century since the photo was taken,” Shara said. “Then we traced it back six centuries, and bingo, there it was, right at the centre of our shell. That’s the clock, that’s what convinced us that it had to be right.”

Photographic plates of the nova taken over six weeks in 1942. Image ©Harvard DASCH

The Peru plate is available online as part of the Digitizing a Sky Century at Harvard (DASCH) project and it was other such DASCH plates that helped reveal the system has now become a dwarf nova. The discovery supports the idea that novae go through an incredibly long-term life cycle, fading for thousands of years after eruption before slowly building back up to full-fledged nova once more.

It was previously believed that “cataclysmic binaries” – novae, novae-like variables and dwarf novae—were separate entities, but the rediscovery of this ancient nova as a dwarf suggests instead that they are one and the same, but at different stages in their lives. Following an eruption, a nova becomes nova-like, before taking the form of a dwarf nova.  Then there may be a period of hibernation, after which it becomes nova-like again and then a fully fledged nova. This cycle repeats, potentially up to 100,000 times over the course of billions of years.

The study, which is published in the journal Nature, was based on observations from the Southern African Large Telescope (SALT), and the Las Campanas Observatories’ Swope and Dupont telescopes.

Soviet report detailing lunar rover Lunokhod-2 released for first time

Russian space agency Roskosmos has released an unprecedented scientific report into the lunar rover Lunokhod-2 for the first time, revealing previously unknown details about the rover and how it was controlled back on Earth.

The report, written entirely in Russian, was originally penned in 1973 following the Lunokhod-2 mission, which was embarked upon in January of the same year. It had remained accessible to only a handful of experts at the space agency prior to its release today, to mark the 45th anniversary of the mission.

Bearing the names of some 55 engineers and scientists, the report details the systems that were used to both remotely control the lunar rover from a base on Earth, and capture images and data about the Moon’s surface and Lunokhod-2’s place on it. This information, and in particularly the carefully documented issues and solutions that the report carries, went on to be used in many later unmanned missions to other parts of the solar system.

As a result, it provides a unique insight into this era of space exploration and the technical challenges that scientists faced, such as the low-frame television system that functioned as the ‘eyes’ of the Earth-based rover operators.

A NASA depiction of the Lunokhod mission. Above: an image of the rover, courtesy of NASA, overlaid onto a panorama of the Moon taken by Lunokhod-2, courtesy of Ruslan Kasmin.

One detail that main be of particular interest to space enthusiasts and experts is the operation of a unique system called Seismas, which was tested for the first time in the world during the mission.

Designed to determine the precise location of the rover at any given time, the system involved transmitting information over lasers from ground-based telescopes, which was received by a photodetector onboard the lunar rover. When the laser was detected, this triggered the emission of a radio signal back to the Earth, which provided the rover’s coordinates.

Other details, while technical, also give some insight into the culture of the mission, such as the careful work to eliminate issues in the long-range radio communication system. One issue, for example, was worked on with such thoroughness that it resulted in one of the devices using more resources than it was allocated, a problem that was outlined in the report.

The document also provides insight into on-Earth technological capabilities of the time. While it is mostly typed, certain mathematical symbols have had to be written in by hand, and the report also features a number of diagrams and graphs that have been painstakingly hand-drawn.

A hand-drawn graph from the report, showing temperature changes during one of the monitoring sessions during the mission

Lunokhod-2 was the second of two unmanned lunar rovers to be landed on the Moon by the Soviet Union within the Lunokhod programme, having been delivered via a soft landing by the unmanned Luna 21 spacecraft in January 1973.

In operation between January and June of that year, the robot covered a distance of 39km, meaning it still holds the lunar distance record to this day.

One of only four rovers to be deployed on the lunar surface, Lunokhod-2 was the last rover to visit the Moon until December 2013, when Chinese lunar rover Yutu made its maiden visit.

Robot takes first steps towards building artificial lifeforms

A robot equipped with sophisticated AI has successfully simulated the creation of artificial lifeforms, in a key first step towards the eventual goal of creating true artificial life.

The robot, which was developed by scientists at the University of Glasgow, was able to model the creation of artificial lifeforms using unstable oil-in-water droplets. These droplets effectively played the role of living cells, demonstrating the potential of future research to develop living cells based on building blocks that cannot be found in nature.

Significantly, the robot also successfully predicted their properties before they were created, even though this could not be achieved using conventional physical models.

The robot, which was designed by Glasgow University’s Regius Chair of Chemistry, Professor Lee Cronin, is driven by machine learning and the principles of evolution.

It has been developed to autonomously create oil-in-water droplets with a host of different chemical makeups and then use image recognition to assess their behaviour.

Using this information, the robot was able to engineer droplets to have different properties­. Those which were found to be desirable could then be recreated at any time, using a specific digital code.

“This work is exciting as it shows that we are able to use machine learning and a novel robotic platform to understand the system in ways that cannot be done using conventional laboratory methods, including the discovery of ‘swarm’ like group behaviour of the droplets, akin to flocking birds,” said Cronin.

“Achieving lifelike behaviours such as this are important in our mission to make new lifeforms, and these droplets may be considered ‘protocells’ – simplified models of living cells.”

One of the oil droplets created by the robot

The research, which is published today in the journal PNAS, is one of several research projects being undertaken by Cronin and his team within the field of artificial lifeforms.

While the overarching goal is moving towards the creation of lifeforms using new and unprecedented building blocks, the research may also have more immediate potential applications.

The team believes that their work could also have applications in several practical areas, including the development of new methods for drug delivery or even innovative materials with functional properties.