In order to fully understand the gravitational collapse of molecular clouds, the star formation process, and the evolution of circumstellar disks, these phenomena must be studied in different Galactic environments with a range of stellar contents and positions in the Galaxy. The young massive association Cygnus OB2, in the Cygnus-X region, is a unique target to study how star formation and the evolution of circumstellar disks proceed in the presence of a large number of massive stars. We present a catalog obtained with recent optical observations in the r, i, z filters with OSIRIS, mounted on the 10.4 m Gran Telescopio CANARIAS telescope, which is the deepest optical catalog of Cyg OB2 to date. The catalog consists of 64,157 sources down to M = 0.15 M ☉ at the adopted distance and age of Cyg OB2. A total of 38,300 sources have good photometry in all three bands. We combined the optical catalog with existing X-ray data of this region, in order to define the cluster locus in the optical diagrams. The cluster locus in the r – i versus i – z diagram is compatible with an extinction of the optically selected cluster members in the 2.64 m < AV < 5.57 m range. We derive an extinction map of the region, finding a median value of AV = 4.33 m in the center of the association, decreasing toward the northwest. In the color-magnitude diagrams, the shape of the distribution of main-sequence stars is compatible with the presence of an obscuring cloud in the foreground ~850 ± 25 pc from the Sun.
Advertised on
References
2012 ApJS, 202, 19
It may interest you
-
Understanding the magnetic field in the corona is key for explaining the fascinating physical processes occurring there. However, the extreme conditions in the outer solar atmosphere hamper the possibility of acquiring observations with enough quality to infer the coronal magnetic field. Analyzing observations of overdensities of cold plasma supported by coronal magnetic fields, including filaments and prominences, allows us to understand such magnetic fields and their interaction with plasma. In this study, we have analyzed an active region prominence, a type of prominence that has barelyAdvertised on
-
The solar corona—the outermost layer of the Sun’s atmosphere—is extremely hot and very low in density. One of the main challenges in solar physics is understanding why the corona reaches temperatures of over a million degrees. This heating is believed to be closely related to the Sun’s magnetic field. However, quantifying the coronal magnetic field is difficult because the light emitted by the corona is extremely faint, and its polarization signals, which encode the information on the magnetic field, are subtle. Thanks to recent advances in technology, telescopes like the Daniel K. InouyeAdvertised on
-
WISEA J181006.18-101000.5 (WISE1810) is the nearest metal-poor ultracool dwarf to the Sun. It has a low effective temperature and has been classified as an extreme early-T subdwarf. However, methane--the characteristic molecule of the spectral class T--was not detected in the previous low-resolution spectrum. Constraining the metallicity--the abundance of elements heavier than helium-- of these cold objects has been a challenge. Using the 10.4 m Gran Telescopio Canarias, the largest optical-infrared telescope in the world, we collected a high-quality near-infrared intermediate-resolutionAdvertised on