A population of dust-enshrouded objects orbiting the Galactic black hole

• Published in: Nature (London) Vol. 577; no. 7790; pp. 337 - 340
• Main Authors: Ciurlo, Anna, Campbell, Randall D., Morris, Mark R., Do, Tuan, Ghez, Andrea M., Hees, Aurélien, Sitarski, Breann N., Kosmo O’Neil, Kelly, Chu, Devin S., Martinez, Gregory D., Naoz, Smadar, Stephan, Alexander P.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 16-01-2020; Nature Publishing Group
• Subjects: 639/33/34/4118; 639/33/34/863; Astrophysics; Celestial bodies; Cosmic dust; Deposition; Dust; Dust clouds; Dust emission; Emission; Emissions; Galactic Astrophysics; Humanities and Social Sciences; Infrared sources (astronomy); Massive stars; Milky Way; Molecular clouds; multidisciplinary; Observations; Orbits; Properties; S stars; Science; Science (multidisciplinary); Sciences of the Universe; Supermassive black holes; Tidal interaction; Velocity; United States
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/s41586-019-1883-y

The central 0.1 parsecs of the Milky Way host a supermassive black hole identified with the position of the radio and infrared source Sagittarius A* (refs.
1
,
2
), a cluster of young, massive stars (the S stars
3
) and various gaseous features
4
,
5
. Recently, two unusual objects have been found to be closely orbiting Sagittarius A*: the so-called G sources, G1 and G2. These objects are unresolved (having a size of the order of 100 astronomical units, except at periapse, where the tidal interaction with the black hole stretches them along the orbit) and they show both thermal dust emission and line emission from ionized gas
6
–
10
. G1 and G2 have generated attention because they appear to be tidally interacting with the supermassive Galactic black hole, possibly enhancing its accretion activity. No broad consensus has yet been reached concerning their nature: the G objects show the characteristics of gas and dust clouds but display the dynamical properties of stellar-mass objects. Here we report observations of four additional G objects, all lying within 0.04 parsecs of the black hole and forming a class that is probably unique to this environment. The widely varying orbits derived for the six G objects demonstrate that they were commonly but separately formed.
The Galactic Centre is orbited by two objects that look like gas and dust clouds but behave more like stars, and now four additional similar objects are reported.