Differential reddening in 48 globular clusters
- Author(s)
- E. Pancino, A. Zocchi, M. Rainer, M. Monaci, D. Massari, M. Monelli, L. K. Hunt, L. Monaco, C. E. Martínez-Vázquez, N. Sanna, S. Bianchi, P. B. Stetson
- Abstract
For decades, it has been theorized that a tenuous but detectable intracluster medium should be present in globular clusters, which is continuously replenished by the gas and dust ejected by bright giants and periodically cleared by interactions with the Galactic disk. However, dedicated searches, especially in infrared and radio wavelengths, have returned mostly upper limits, which are lower than theoretical expectations by several orders of magnitude. We profited from recent wide-field photometry for 48 Galactic globular clusters to compute high-resolution maps of differential reddening, which can be used to correct any photometric catalog in these areas for reddening variations. Using 3D reddening maps from the literature, we evaluated the amount of foreground extinction. This allowed us to estimate the masses of the intracluster medium in our sample clusters, with an accuracy of one order of magnitude. Our estimates agree with the few available literature detections and with theoretical expectations. Because the discrepancy between observations and expectations only concerns literature upper limits, we explored possible reasons why they could be underestimated and we show that two recent discoveries can explain the discrepancy. The first is the recent discovery that the intracluster medium in 47 Tuc is not centrally concentrated. This is also supported by our maps, which in the majority of cases do not show a central reddening concentration. The second is the discovery that the dust in metal-poor ([Fe/H] ≲ -1 dex) globular clusters is dominated by iron grains rather than silicates, which undermines previous dust mass estimates from observed upper limits. We conclude that current evidence, including our maps, does not contradict theoretical expectations and the problem of the missing intracluster medium is no longer an issue.
- Organisation(s)
- Department of Astrophysics
- External organisation(s)
- INAF - Osservatorio Astrofisico di Arcetri, INAF Osservatorio Astronomico di Brera, University of Pisa, Instituto Nazionale die Astrofisica (INAF), Institute of Astrophysics of the Canary Islands, Andrés Bello National University , Gemini Observatory Northern Operations Center, National Research Council Canada (NRC-CNRC)
- Journal
- Astronomy and Astrophysics
- Volume
- 686
- ISSN
- 0004-6361
- DOI
- https://doi.org/10.1051/0004-6361/202449462
- Publication date
- 06-2024
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 103003 Astronomy, 103004 Astrophysics
- Keywords
- ASJC Scopus subject areas
- Astronomy and Astrophysics, Space and Planetary Science
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/2a7f8466-4158-4fd6-8106-8cea87441142