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The Subaru Seminar is usually held in Room 104 of the Hilo Base Facility, adjacent to the main lobby. Everyone is welcome to attend. If you are interested in giving a seminar, please contact Subaru seminar organizers (Tae-Soo Pyo, Sherry Yeh, Nagayoshi Ohashi) by email : (please change"_at" to @).

November 06, Friday, 11:00 am in 104

" The Structure of Class 0 Protostars: BHR71 in Herschel View "

Yao-Lun Yang

(UT Austin)

We performed a comprehensive analysis of the Herschel spectra of BHR71, an embedded Class 0 protostar. We recover 66 lines in the central spaxel, and more than 700 lines are detected in all spaxels in PACS, and SPIRE. This line fitting result is part of our CDF (COPS-DIGIT-FOOSH) Archive, which is publicly available in Herschel Science Archive. The CO rotational diagram analysis shows four excitation temperature components, 51 K, 153 K, 408 K, and 1053 K. Low-J CO lines trace the outflow while the high-J CO lines are centered on the infrared source. The low-excitation emission lines of water trace the large-scale outflow, while the high-excitation emission lines trace small scale distribution around the equatorial plane. We model the structure of the envelope using dust radiative transfer by Hyperion to fit the spectral energy distribution (SED) observed by Spitzer and Herschel. The model incorporates rotational collapse and an outer static envelope as well as outflow cavity and disk. Our exploration of parameter space shows that the evolution of a collapsing envelope can be constrained by the Herschel SED and that the structure of outflow cavity plays a critical role in the shorter wavelength. We found the density profile of a cavity with a power law with a constant-density inner region can reproduce the observations. The high central luminosity in the best-fit model shows a hint of a higher accretion rate than the rate derived from the collapse model. Our model shows that BHR71 has an envelope with an age ranging from 1.0x10^4 to 1.75x10^4 years and a total dust mass of 0.22 solar mass.

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