An Optical and Infrared Photometric Study of the Young Open Cluster IC 1805 in the Giant H ii Region W4{sup †}
- Department of Astronomy and Space Science, Sejong University, 209 Neungdong-ro, Kwangjin-gu, Seoul 05006 (Korea, Republic of)
- Research School of Astronomy and Astrophysics, The Australian National University, Canberra, ACT 2611 (Australia)
- Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro, Yuseong-gu, Daejeon 34055 (Korea, Republic of)
- SELab, Inc., 8 Nonhyeon-ro 150-gil, Gangnam-gu, Seoul 06049 (Korea, Republic of)
- Groupe d’Astrophysique des Hautes Energies, Institut d’Astrophysique et de Géophysique, Université de Liège, Allée du 6 Août, 19c, Bât B5c, B-4000 Liège (Belgium)
- Ulugh Beg Astronomical Institute, Uzbek Academy of Sciences, 33 Astronomical Street, Tashkent 700052 (Uzbekistan)
- Daegu National Science Museum, 20, Techno-daero-6-gil, Yuga-myeon, Dalseong-gun, Daegu 43023 (Korea, Republic of)
We present deep wide-field optical CCD photometry and mid-infrared Spitzer/IRAC and MIPS 24 μm data for about 100,000 stars in the young open cluster IC 1805. The members of IC 1805 were selected from their location in the various color–color and color–magnitude diagrams, and the presence of Hα emission, mid-infrared excess emission, and X-ray emission. The reddening law toward IC 1805 is nearly normal (R {sub V} = 3.05 ± 0.06). However, the distance modulus of the cluster is estimated to be 11.9 ± 0.2 mag (d=2.4±0.2 kpc) from the reddening-free color–magnitude diagrams, which is larger than the distance to the nearby massive star-forming region W3(OH) measured from the radio VLBA astrometry. We also determined the age of IC 1805 (τ{sub MSTO}=3.5 Myr). In addition, we critically compared the age and mass scale from two pre-main-sequence evolution models. The initial mass function with a Salpeter-type slope of Γ = −1.3 ± 0.2 was obtained and the total mass of IC 1805 was estimated to be about 2700 ± 200 M{sub ⊙}. Finally, we found our distance determination to be statistically consistent with the Tycho-Gaia Astrometric Solution Data Release 1, within the errors. The proper motion of the B-type stars shows an elongated distribution along the Galactic plane, which could be explained by some of the B-type stars being formed in small clouds dispersed by previous episodes of star formation or supernova explosions.
- OSTI ID:
- 22872733
- Journal Information:
- Astrophysical Journal, Supplement Series, Vol. 230, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0067-0049
- Country of Publication:
- United States
- Language:
- English
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