Rotation Curve and Metallicity of the Outer Disc from Cepheids
نویسندگان
چکیده
منابع مشابه
Rotation of the outer disc from classical cepheids
Radial velocities and distances have been measured for a sample of 48 remote classical cepheids located in the outer disc of the Galaxy (1180 < l < 2740). The distances are determined from BVI photometry, with semi-empirical metallicity corrections calibrated on the Magellanic Clouds. Using these cepheids as tracers, the rotation curve of the disc is determined between R0 and 2R0. The result is...
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Using an outer rotation curve of the Galaxy, we explore the galactic constants and the mass of the Galaxy. We show that Θ0 of 200 km s −1 is more favorable than the IAU standard value of 220 km s, and also show that if Θ0 is smaller than 207 km s −1 the rotation curve beyond 2R0 is declining in Keplerian fashion. In the case of Θ0= 200 km s −1 and R0= 7.6 kpc, the total mass and the extent of t...
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The 87 new 0 determinations were added to the existing sample of cepheids with known radial velocities, forming an extended sample of 278 galactic classical cepheids with reliable radial velocity and photometry. We then calculated distances for these objects through a Period-Luminosity-Colour relation due to Feast & Walker (1987). The position of the cepheids in the galactic disk as given by th...
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پس ازفروپاشی شوروی،رشد منابع نفت و گاز، آسیای میانه و قفقاز را در یک بازی ژئوپلتیکی انرژی قرار داده است. با در نظر گرفتن این منابع هیدروکربنی، این منطقه به یک میدانجنگ و رقابت تجاری برای بازی های ژئوپلتیکی قدرت های بزرگ جهانی تبدیل شده است. روسیه منطقه را به عنوان حیات خلوت خود تلقی نموده و علاقمند به حفظ حضورش می باشد تا همانند گذشته گاز طبیعی را به وسیله خط لوله مرکزی دریافت و به عنوان یک واس...
15 صفحه اولBeat Cepheids as Probes of Stellar and Galactic Metallicity
The mere location of a Beat Cepheid model in a Period Ratio vs. Period diagram (Petersen diagram) puts very tight constraints on its metallicity Z. The Beat Cepheid Peterson diagrams are revisited with linear nonadiabatic turbulent convective models, and their accuracy as a probe for stellar metallicity is evaluated. They are shown to be largely independent of the helium content Y , and they ar...
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ژورنال
عنوان ژورنال: International Astronomical Union Colloquium
سال: 1995
ISSN: 0252-9211
DOI: 10.1017/s0252921100036964