ការបង្កើតផ្ទះរបស់យើង។ កាឡាក់ស៊ី Milky Way began 12 billion years ago. Since then, it has undergone a sequence of mergers with other galaxies and grew in mass and size. The remnants of building blocks (i.e., galaxies that merged with the Miky Way in the past) can be identified through their unusual values for energy and angular momentum and low metallicity. The two earliest building blocks of our home កាឡាក់ស៊ី have recently been identified using Gaia dataset and have been named Shiva and Shakti after Hindu deities. Gaia អវកាស telescope which is dedicated to the study of our home galaxy has revolutionised the study of Milky Way. Gaia Enceladus/ Sausage stream, the Pontus stream and the “poor old heart” of the Milky Way were identified earlier using Gaia dataset. The history of Milky Way is replete with mergers. Hubble អវកាស Telescope images suggest that six billion years from now, our home galaxy will merge with the neighbouring Andromeda galaxy.
កាឡាក់ស៊ី និងរចនាសម្ព័ន្ធធំ ៗ ផ្សេងទៀតដែលបង្កើតឡើងនៅក្នុង សាកល ប្រហែល 500 លានឆ្នាំបន្ទាប់ពី Big Bang ។
ការបង្កើតផ្ទះរបស់យើង។ កាឡាក់ស៊ី Milky Way បានចាប់ផ្តើមប្រហែល 12 ពាន់លានឆ្នាំមុន។ ចាប់តាំងពីពេលនោះមក វាបានឆ្លងកាត់លំដាប់នៃការរួមបញ្ចូលគ្នាជាមួយកាឡាក់ស៊ីផ្សេងទៀត ដែលបានរួមចំណែកដល់ការលូតលាស់របស់វាទាំងក្នុងបរិមាណ និងទំហំ។ ប្រវត្តិនៃមីលគីវេយ៍ គឺជាប្រវត្តិសាស្រ្តនៃការរួមបញ្ចូលគ្នានៃកាឡាក់ស៊ីផ្សេងទៀតជាមួយនឹងកាឡាក់ស៊ីផ្ទះរបស់យើង។
The basic properties of the ផ្កាយទាំងឡាយ like energy and angular momentum are directly linked to the speed and direction of the កាឡាក់ស៊ី of origin and are shared between the stars of the same galaxy. When galaxies merge, energy and angular momentum remain conserved over time. This serves as a key tool in identification of a merger remnant. A large group of ផ្កាយទាំងឡាយ with similar unusual values of energy and angular momentum are likely to be a merger remnant of a galaxy. Also, the older stars have low metallicity, i.e., stars that formed earlier have low metal contents. Based on these two criteria, it is possible to trace merger history of the Milky Way however it would not have been possible without the Gaia datasets.
Launched by ESA on 19 December 2013, Gaia អវកាស telescope is dedicated to the study of Milky Way including its origin, structure and evolutionary history. Parked in Lissajous គន្លង around L2 Lagrange point (located approximately 1.5 million km from Earth in the direction opposite the Sun) along JWST and Euclid spacecrafts, Gaia probe is conducting a huge stellar census covering about 1.5 billion stars in the Milky Way recording their motions, luminosity, temperature and composition and creating a precise 3D map of the home កាឡាក់ស៊ី. Hence, Gaia is also referred as billion-star surveyor. The datasets generated by Gaia has revolutionized study of history Milky Way.
In 2021, using Gaia datasets, astronomers learnt of a major merger and identified Gaia Enceladus/Sausage stream, the remnant of Gaia-Sausage-Enceladus (GSE) កាឡាក់ស៊ី that merged with the Milky Way between 8 and 11 billion years ago. Subsequently, Pontus stream and “poor old heart” of the Milky Way were identified the following year. The Pontus stream is the remnant of Pontus merger while “poor old heart” is តារា group that formed during the initial mergers that created the proto-Milky Way and continue to reside in the central region of Milky Way.
Now, astronomers report discovery of two streams of ផ្កាយទាំងឡាយ that formed and merged with an early version of our Milky Way between 12 and 13 billion years ago, around the time when galaxies were forming in the early សាកល. សម្រាប់ការនេះ អ្នកស្រាវជ្រាវបានរួមបញ្ចូលគ្នានូវទិន្នន័យ Gaia ជាមួយនឹងវិសាលគមផ្កាយលម្អិតពី ការស្ទង់មតិ Sky Slo ឌីជីថលមេឃ (DR17) and observed that stars were crowded around two specific combinations of energy and angular momentum for a certain range of low-metal stars. The two groups had angular momentum similar to the stars that had been part of separate galaxies which merged with the Milky Way. Perhaps, the earliest building blocks of the Milky Way, the researchers have named them Shiva and Shakti after the Hindu deities. It is possible that the newly discovered star groups were first to merge with the ‘poor old heart’ of our Milky Way and the story towards a large កាឡាក់ស៊ី began. Future studies should confirm if Shiva and Shakti are indeed part of prehistory of Milky Way.
តើនឹងមានអ្វីកើតឡើងចំពោះកាឡាក់ស៊ីផ្ទះរបស់យើងនាពេលអនាគត?
Evolutionary history of Milky Way is replete with mergers. Hubble អវកាស Telescope images suggests that six billion years from now, our home galaxy will merge with the neighbouring Andromeda galaxy situated at 2.5 million light-years away to give rise to a new galaxy. Andromeda will collide with the Milky Way at 250,000 mph about 4 billion years from now. The clash between the two galaxies will last for 2 billion years giving rise to a combined elliptical galaxy.
The solar system and the Earth will survive but will have new coordinates in អវកាស.
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ឯកសារយោង:
- Naidu RP, et al 2021. ការកសាងឡើងវិញនូវការរួមបញ្ចូលគ្នាដ៏សំខាន់ចុងក្រោយនៃ Milky Way ជាមួយនឹងការស្ទង់មតិ H3 ។ ទិនានុប្បវត្តិ Astrophysical លេខ 923 លេខ 1. DOI: https://doi.org/10.3847/1538-4357/ac2d2d
- ម៉ាល់ហាន ខេ. et al 2022. អាត្លាសថាមវន្តសកលនៃការរួមបញ្ចូលគ្នានៃមីលគីវ៉េ៖ ឧបសគ្គពីគន្លងដែលមានមូលដ្ឋានលើ Gaia EDR3 នៃចង្កោមសកល ស្ទ្រីមផ្កាយ និងកាឡាក់ស៊ីផ្កាយរណប។ ចេញផ្សាយ ថ្ងៃទី 17 ខែកុម្ភៈ ឆ្នាំ 2022។ ទិនានុប្បវត្តិតារាសាស្ត្រ លេខ 926 លេខ 2. DOI: https://doi.org/10.3847/1538-4357/ac4d2a
- Malhan K. និង Rix H.-W., 2024. 'Shiva and Shakti: សន្មត់ថា Proto-Galactic Fragments in the Inner Milky Way។ ទិនានុប្បវត្តិ Astrophysical ។ ចេញផ្សាយ ថ្ងៃទី 21 ខែ មីនា ឆ្នាំ 2024 ។ DOI: https://doi.org/10.3847/1538-4357/ad1885
- វិទ្យាស្ថាន Max Planck សម្រាប់តារាសាស្ត្រ (MPIA) ។ ព័ត៌មាន – ក្រុមអ្នកស្រាវជ្រាវកំណត់អត្តសញ្ញាណអគារពីរដំបូងបំផុតរបស់ Milky Way ។ មាននៅ https://www.mpia.de/news/science/2024-05-shakti-shiva?c=5313826
- Schiavi R. et al 2021. ការបញ្ចូលគ្នានាពេលអនាគតនៃ Milky Way ជាមួយកាឡាក់ស៊ី Andromeda និងជោគវាសនានៃប្រហោងខ្មៅដ៏ធំសម្បើមរបស់ពួកគេ។ បោះពុម្ពជាមុននៅ arXiv ។ DOI៖ https://doi.org/10.48550/arXiv.2102.10938
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