分类： 天文学 >> 天文学 提交时间： 2023-02-19
Jiaming Pan
Eric F. Bell
Adam Smercina
Paul Price
Colin T. Slater
Jeremy Bailin
Roelof S. de Jong
Richard D'Souza
In Sung Jang
Antonela Monachesi
摘要： The study of outer halo globular cluster (GC) populations can give insight into galaxy merging, globular cluster accretion and the origin of GCs. We use archival Subaru Hyper Suprime-Cam (HSC) data in concert with space-based GALEX, IRAC and Gaia EDR3 data to select candidate Globular clusters (GCs) in the outer halo of the M81 group for confirmation and future study. We use a small sample of previously-discovered GCs to tune our selection criteria, finding that bright already-known GCs in the M81 group have sizes that are typically slightly larger than the Subaru PSF in our fields. In the optical bands, GCs appear to have colours that are only slightly different from stars. The inclusion of archival IRAC data yields dramatic improvements in colour separation, as the long wavelength baseline aids somewhat in the separation from stars and clearly separates GCs from many compact background galaxies. We show that some previously spectroscopically-identified GCs in the M81 group are instead foreground stars or background galaxies. GCs close to M82 have radial velocities suggesting that they fell into the M81 group along with M82. The overall M81 GC luminosity function is similar to the Milky Way and M31. M81's outer halo GCs are similar to the Milky Way in their metallicities and numbers, and much less numerous than M31's more metal-rich outer halo GC population. These properties reflect differences in the three galaxies' merger histories, highlighting the possibility of using outer halo GCs to trace merger history in larger samples of galaxies.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
DES Collobration
Jiaming Pan
Hsing Wen Lin
David W. Gerdes
Kevin J. Napier
Jichi Wang
T. M. C. Abbott
M. Aguena
S. Allam
O. Alves
D. Bacon
P. H. Bernardinelli
G. M. Bernstein
E. Bertin
D. Brooks
D. L. Burke
A. Carnero Rosell
M. Carrasco Kind
J. Carretero
M. Costanzi
摘要： The Jupiter Trojans are a large group of asteroids that are co-orbiting with Jupiter near its L4 and L5 Lagrange points. The study of Jupiter Trojans is crucial for testing different models of planet formation that are directly related to our understanding of solar system evolution. In this work, we select known Jupiter Trojans listed by the Minor Planet Center (MPC) from the full six years dataset (Y6) of the Dark Energy Survey (DES) to analyze their photometric properties. The DES data allow us to study Jupiter Trojans with a fainter magnitude limit than previous studies in a homogeneous survey with $griz$ band measurements. We extract a final catalog of 573 unique Jupiter Trojans. Our sample include 547 asteroids belonging to L5. This is one of the largest analyzed samples for this group. By comparing with the data reported by other surveys we found that the color distribution of L5 Trojans is similar to that of L4 Trojans. We find that L5 Trojans' $g - i$ and $g - r$ colors become less red with fainter absolute magnitudes, a trend also seen in L4 Trojans. Both the L4 and L5 clouds consistently show such a color-size correlation over an absolute magnitude range $11 < H < 18$. We also use DES colors to perform taxonomic classifications. C and P-type asteroids outnumber D-type asteroids in the L5 Trojans DES sample, which have diameters in the 5 - 20 km range. This is consistent with the color-size correlation.
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