The spectacular Hubble image showed three different moments of a supernova
By looking at one of the old Hubble images and using the gravitational lens, researchers managed to identify three different times of a supernova explosion event.
During the past few decades, human ability to observe supernovae when they occur has improved greatly. Today, space telescopes can pick up the high-energy photons emitted by such events and identify their source so that other telescopes can look toward the supernova very quickly.
Even some automatic sky-mapping telescopes, several They imaged the same areas at night so that image processing software could identify new light sources that indicate a supernova. However, luck still plays a decisive role in the detection of supernovae.
The same is true of the Hubble image recorded in 2010, which accidentally captured a supernova. But this was not an ordinary image, and due to the phenomenon of gravitational lensing, this single event appeared in three different places in Hubble's field of view.
The interesting thing is that, thanks to the strange characteristics of the performance of this special lens, every The three sites also recorded different times after the star exploded, allowing researchers to piece together the time course of the supernova event, even though it had been observed for more than a decade.
3 Space, three times
Now in a new study, researchers have scoured the Hubble archive for transient events, specifically those observed by gravitational lensing. That is, when a huge foreground mass distorts the space and like a lens, bends the path of light that originates behind it.
Because gravitational lenses do not have a regular structure like man-made optical lenses, often They create strange distortions in the background objects and in many cases, magnify the image of the same object in different places. Its light, taking into account the redshift, shows that we are looking at more than 11 billion years ago.
The complete Hubble image is on the left and the image of the distant galaxy distorted by gravitational lensing at various times is seen on the right.
Credit: NASA, ESA, STScI, Wenlei Chen, Patrick Kelly
The relative brightness of the observed light, its sudden appearance and its location in a galaxy, strongly suggest that this event is a supernova and at this distance , many photos The high-energy rays produced in the supernova are shifted to the lower end of the visible spectrum, so Hubble is able to image them.
To understand more about the background supernova, the research team investigated the function of gravitational lensing provided by the Abell 370 galaxy cluster. Created, checked. The resulting lens model showed that there are actually four images of the galaxy, but one of them is not magnified enough and cannot be seen. The three observed ones were magnified by 4, 6, and 8 times.
Gravitational lensing has affected not only the location of the image, but also the arrival time of the light. Gravitational lenses cause light to travel paths of different lengths between the source and the observer, and since light travels at a constant speed, different lengths mean different times for light to arrive, which makes a significant difference on a cosmic scale.
Using modeling, scientists estimated the possible delays and found that compared to the first image, the second image is delayed by 2.4 days and the third image by 7.7 days with an error factor of one day. Thus, a single photo of this region shows several images of the galaxy at different times.
By examining the Hubble data and comparing with different classifications of supernovae, it was found that This event was probably produced by the explosion of a red or blue supergiant star, and its characteristics were more consistent with a red supergiant that was approximately 500 times the size of the Sun at the time of its explosion.
Light intensity in wavelengths different indicates the explosion temperature. In the first image, the temperature was almost 100,000 Kelvin, which means that Hubble looked at it only 6 hours after the explosion. The latest lensed image also shows that the remnants of the explosion have cooled to 10,000 Kelvin over eight days between two different images.
Obviously, there are newer and closer supernovae that are important for understanding the process of exploding a star. We can study them in much more detail. But while this is the second one discovered, if we can find more of these supernova images past gravitational lensing, we could learn more about stars in the early universe.
Cover photo: Gravitational lensing Taken by the galaxy cluster Abell 370
Credit: NASA, ESA/Hubble, HST Frontier Fields
Source: Arst Technica