Astronomers Discovered Unexpected Formations in the Heart of Our Galaxy

Astronomers Discovered Unexpected Formations in the Heart of Our Galaxy

In the heart of the Milky Way, a team of astronomers has made a fascinating discovery: the existence of long, slim, and dust-free filamentary structures primarily composed of gas in the central molecular zone (CMZ) [1]. This region, which surrounds the Galaxy’s supermassive black hole, presents unique conditions that differ significantly from other star-forming regions.

The formation process of these structures is a step-by-step sequence that begins with molecular clouds rich in dust and gas, similar to other star-forming regions in the Milky Way [1]. Powerful shockwaves, likely generated by energetic events near the Galactic center, pass through these molecular clouds. These shocks are energetic enough to destroy dust grains, releasing their constituent molecules into the gas phase and effectively “sweeping” the dust away [1].

As the dust is destroyed, the remaining gas is compressed and stretched, forming long, slender filaments. These structures are observed to have much higher internal pressure than their surroundings, indicating a dynamic, transient state [1]. The high internal pressure and harsh environment lead to the filaments dispersing over time. The molecules, now spread widely across the CMZ, eventually cool and recondense into dust, restarting the cycle [1].

This sequence — dust-rich cloud → shock-induced dust destruction → gas-phase filament formation → filament dissipation and molecular dispersal → eventual dust re-formation — creates a material “life cycle” unique to the CMZ [1]. The distinctive “tornado”-like shapes observed in some of these filamentary structures may be a result of the repeated action of shockwaves and the strong gravitational field near the Galactic center [1].

Unlike most galactic filaments, which are rich in dust and are sites of star formation, these CMZ filaments are dust-free and dominated by molecular gas [1]. The formation is driven not by gravitational collapse but by mechanical processes (shockwaves) associated with the extreme environment near the Galactic center [1]. The filaments are transient, with a relatively short lifetime compared to more stable structures in less extreme environments [1].

These conclusions are based on high-resolution observations using the Atacama Large Millimeter/submillimeter Array (ALMA), which can resolve the gas dynamics and chemistry in the CMZ. The presence of molecules like silicon monoxide (SiO) is of particular interest, as it is a known tracer of shock activity in interstellar gas [1].

The following table summarizes the key steps in the formation process:

| Step | Process Description | |-----------------------------|---------------------------------------------------------| | Initial Cloud | Dust and gas-rich molecular cloud | | Shock Passage | Shockwave destroys dust, releasing molecules into gas | | Filament Formation | Gas compressed into slim, high-pressure filaments | | Filament Dissipation | Filaments disperse, molecules spread in CMZ | | Dust Re-formation | Molecules eventually cool and re-form dust |

The understanding of these processes provides insight into how material cycles through the Galaxy’s most extreme environments, influencing both star formation and the evolution of the Galactic center [1]. The unique conditions near the Milky Way’s black hole — intense radiation, strong magnetic fields, and frequent energetic events — make this region a natural laboratory for studying astrophysical processes under conditions not found elsewhere in the Galaxy [1].

[1] Kai Yang, et al., "Dust-free filamentary structures in the central molecular zone of the Milky Way," _J. Astrophys. Astron._, vol. 76, no. 7, pp. 59–68, Jul. 2025. (Accessed 15 Aug. 2025)

1. The formation of these long, slim, and dust-free filaments in the central molecular zone (CMZ) of the Milky Way is a unique sequence driven by energetic events near the Galactic center, resulting in molecular gas dominance instead of dust.
2. The process begins with molecular clouds rich in dust and gas, similar to other star-forming regions in the Milky Way, which are then affected by powerful shockwaves.
3. As dust is destroyed, the remaining gas is compressed and stretched, forming long, slender filaments that have much higher internal pressure than their surroundings.
4. These filaments dissipate over time, with the molecules spreading widely across the CMZ before eventually cooling and re-forming dust, thus starting the cycle anew.
5. High-resolution observations using the Atacama Large Millimeter/submillimeter Array (ALMA) have revealed the presence of molecules like silicon monoxide (SiO), a known tracer of shock activity in interstellar gas, supporting this sequence of events in the heart of our galaxy.

Read also: