On 16th April 2024, a team of astronomers led by Pasquale Panuzzo announced the presence of a previously undetected blackhole 1,926 lightyears from Earth in the constellation Aquila. This exciting announcement came via a press release from the European Southern Observatory and a publication in the Astronomy and Astrophysics journal.
At Space India, through “Space Explorers Workshop’s, capturing celestial objects”, Students will be exposed to a variety of astrophotography methods and styles. Students will click on the planets, moon, and rising constellations that are visible in the sky, and they will learn how to handle the data using a variety of tools and methods.
Gaia BH3, or BH3, is the second closest black hole to Earth after Gaia BH1. Despite its, relatively, close distance to us, BH3 has evaded detection for decades, hiding within the cosmic matrix. BH3 avoided detection as it is a dormant black hole, a stellar remnant that does not emit electromagnetic waves. The reason for this can vary. In BH3’s case, its companion star is so far away that the dead star cannot cannibalize its companion star.
A black hole is an astronomical object with the strongest gravitational pull in the universe. All black holes have an outer boundary called the event horizon, where the escape velocity is higher than the speed of light. Thus, no object, not even light, is able to leave once it passes the event horizon. Due to this, black holes do not emit or reflect any light, making them hard to detect. However, the gravitational influence of the stellar remnant on the material it consumes results in intense tidal forces that make the material glow brightly and emit X-rays. Due to this emission, we can detect active black holes.
The discovery of Gaia BH3 was accidental. Astronomers were reviewing data from Gaia’s observation when they noticed an odd wobbling motion of a metal-poor star. Utilizing astrometric calculations, they investigated the unusual motion. Through this investigation, astronomers discovered that the metal-poor star was locked in an 11.6-year elliptical orbit, with the distance varying from 4.95 AU to 30.33 AU, with the black hole we now know as Gaia BH3.
Gaia BH3 is the third black hole found by the Gaia mission. The first black hole discovered is, currently, the closest black hole to us. It is approximately 1500 lightyears in the constellation Ophiuchus.
Gaia BH3 is also the largest stellar black hole in our home galaxy. After analysing Gaia’s data, and verifying it with the data from ground-based observatories, astronomers calculated BH3’s to weigh 33 solar mass. With this, BH3 has dethroned Cygnus X-1, 21 solar masses, which previously held the record. Even though this is not the first time a massive stellar black hole has been discovered, this is the first time a massive stellar black hole has been discovered within the Milky Way.
While BH3 is the largest stellar black hole in the galaxy, it is not the largest black hole in the galaxy. That title belongs to Sagittarius A*. Sagittarius A* mass, which is a comfortable 4 million solar mass, makes Gaia BH3 seem tiny. Sagittarius A* is the supermassive black hole in the centre of the Milky Way. Origins of black holes such as Sagittarius A* are unknown but they are known to exist from the earliest days of a galaxy’s life.
The origins of stellar black holes, on the other hand, are known. Stellar black holes are stellar remnants that form after a single star collapse at the end of its life after its fuel runs out. Not every star becomes a black hole. To become a black hole, a star needs to have a solar mass that is greater than 20 solar masses and a stellar core whose solar mass is larger than 3 solar masses.
Gaia BH3’s massive size proves that massive stellar black holes exist. Its presence also confirms that ancient stars, which only had hydrogen and helium as their heaviest elements, could lead to a high-mass black hole upon their death. Due to these stars being metal-poor, it is believed that they lost less mass over their lifetime which meant that the star had more material to produce high-mass black holes. Additionally, since Gaia BH3’s companion is metal poor and stars in pairs tend to have similar chemical composition, it is highly likely that Gaia BH3, when it was living, was also a metal poor star.
In association with the International Astronomical Search Collaboration (IASC), headed by Dr. Patrick Miller of Hardin Simmons University in the United States, SPACE conducts this campaign throughout India as part of an educational outreach program. Over the course of 14 fruitful years, SPACE gave more than 7000 participants in India this chance, which has led to various accomplishments and the first-ever asteroid discoveries by Indian schoolchildren. We have accomplished an amazing number of 2 Numbered Asteroid Discovery, 80 Provisional Discoveries of Asteroids, 2 Special Discoveries, 11,560 Preliminary Discoveries of Asteroids, 62 Near-Earth Object Confirmations, and 1636 Near-Earth Object Observations thanks to the training that SPACE has given Indian students.
The Global Astrometric Interferometer for the Astrophysics mission, or Gaia mission, is a European Space Agency astronomical observatory mission that is the successor to the Hipparcos mission. Launched in 2013, Gaia is an ambitious mission which aims to create the largest and most detailed map of the Milky Way Galaxy while also cataloguing a billion astronomical objects.
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