Letter to the Editor

Spectroscopic evidence of a possible young stellar cluster at the Galactic Center

¹ Instituto de Astrofísica de Andalucía (CSIC), University of Granada, Glorieta de la astronomía s/n, 18008 Granada, Spain
e-mail: amartinez@iaa.es
² European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, Germany
³ Centro de Astrobiología (CSIC/INTA), ctra. de Ajalvir km. 4, 28850 Torrejón de Ardoz, Madrid, Spain

Received: 6 March 2024
Accepted: 22 April 2024

Abstract

Context. The nuclear stellar disk has been the most prolific star-forming region in the Milky Way over the past ∼30 million years. Notably, the cumulative mass of the three clusters currently found in the nuclear stellar disk, the Quintuplet, the Arches, and the Nuclear clusters, amounts to just 10% of the total anticipated mass of young stars that formed in this period. This discrepancy, known as the missing cluster problem, is attributed to factors such as high stellar density and tidal forces. Traces of dissolving clusters may exist as comoving groups of stars, providing insights into the star formation history of the region. Recently, a new cluster candidate associated with an HII region was reported through the analysis of kinematic data

Aims. Our aim is to determine whether the young and massive stellar objects in the region share proper motion, positions in the plane of the sky, and line-of-sight distances. We use reddening as a proxy for the distances.

Methods. We reduced and analyzed integral field spectroscopy data from the KMOS instrument at the ESO VLT to locate possible massive young stellar objects in the field. Then, we identified young massive stars with astrophotometric data from the two different catalogs to analyze their extinction and kinematics.

Results. We present a group of young stellar objects that share velocities, are close together in the plane of the sky, and are located at a similar depth in the nuclear stellar disk.

Conclusions. The results presented here offer valuable insights into the missing clusters problem. They indicate that not all young massive stars in the Galactic center form in isolation; some of them seem to be the remnants of dissolved clusters or stellar associations.