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Here are 50 facts from a new research paper titled “Shiva and Shakti: Presumed Proto-Galactic Fragments in the Inner Milky Way” published 2024 March 21 by
Khyati Malhan and Hans-Walter Rix in “The Astrophysical Journal, Volume 964, Number 2”.

1. Astronomers have identified potential early building blocks of the Milky Way, named “Shakti” and “Shiva.”
2. These structures are believed to be remnants of galaxies that merged with the Milky Way around 12 to 13 billion years ago.
3. The merging of Shakti and Shiva contributed to the initial growth of the Milky Way.
4. The process required combining data from ESA’s Gaia mission with measurements from the SDSS survey.
5. The findings have been published in the Astrophysical Journal.
6. The Milky Way’s early history involves the merging of smaller galaxies.
7. The merging process results in large building blocks for the Milky Way.
8. Shakti and Shiva are proto-galactic fragments that merged with the early Milky Way.
9. They were identified by combining Gaia and SDSS data.
10. This discovery is akin to finding traces of an initial settlement that grew into a large city.
11. When galaxies merge, hydrogen gas clouds are destabilized, leading to the formation of new stars.
12. Stars from merging galaxies mingle, contributing to the stellar population of the merged galaxy.
13. Basic physics principles aid in tracing the origins of stars from merging galaxies.
14. Stars retain properties linked to their original galaxies’ speed and direction.
15. Stars with similar values for energy and angular momentum likely originated from the same galaxy.
16. Accreted stars contribute to the newly-formed galaxy’s stellar population.
17. New stars contain more heavy elements than older stars.
18. Metallicity helps identify stars formed billions of years ago.
19. Gaia provides a large, high-quality dataset for galactic archaeology.
20. Gaia’s dataset includes positions and distances for nearly 1.5 billion stars.
21. Gaia data revolutionized studies of stellar dynamics in the Milky Way.
22. Gaia helped discover structures like the Gaia Enceladus/Sausage stream and the Pontus stream.
23. The “poor old heart” of the Milky Way consists of newly formed stars during initial mergers.
24. Malhan and Rix used Gaia data combined with stellar spectra from the Sloan Digital Sky Survey.
25. The detailed spectra provide information about stars’ chemical composition.
26. Metal-poor stars were observed to cluster around specific combinations of energy and angular momentum.
27. Shakti and Shiva exhibit large angular momentum, suggesting they were part of separate merging galaxies.
28. The structures are named after Hindu deities symbolizing cosmic forces.
29. Shakti and Shiva have low metallicity similar to the “poor old heart” of the Milky Way.
30. They are considered potential early ancestors of the Milky Way.
31. Shakti and Shiva may have initiated the growth of the Milky Way towards a large galaxy.
32. Ongoing and upcoming surveys promise additional relevant data for further study.
33. These surveys include SDSS-V, 4MOST, and LSST/Rubin Observatory.
34. Spectra data from these surveys will provide additional insights into stellar composition.
35. Precise distance measurements will aid in confirming the nature of Shakti and Shiva.
36. The research involved analyzing data from Gaia and the Sloan Digital Sky Survey.
37. Gaia’s dataset includes information on positions, changes in position, and distances for stars.
38. The Gaia dataset has become increasingly accurate over the past decade.
39. Gaia data have led to the discovery of previously unknown galactic structures.
40. The merging of galaxies leads to the formation of new stars.
41. New stars have higher metal content compared to older stars.
42. Metallicity is a key factor in identifying stars formed billions of years ago.
43. The merging process results in the mingling of stars from different galaxies.
44. Stars retain properties linked to their original galaxies’ speed and direction.
45. Gaia’s dataset includes information on nearly 1.5 billion stars within the Milky Way.
46. Gaia data have revolutionized studies of stellar dynamics in our galaxy.
47. The identification of structures like Shakti and Shiva provides insights into the Milky Way’s early history.
48. Ongoing and upcoming surveys promise to provide additional data for further study.
49. Spectra data from these surveys will help understand the chemical composition of stars.
50. Precise distance measurements will aid in confirming the origins of structures like Shakti and Shiva.