NOAO >   Observing Info >   Approved Programs >   2013B-0465

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Proposal Information for 2013B-0465


PI: Ren-Shiang Sung, National Tsing Hua University, kings1023@hotmail.com
Address: Astronomy Department, No. 101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan

CoI: Shih-Ping Lai, National Tsing Hua University
CoI: Tien-Hao Hsieh, National Tsing Hua University

Title: Mass Accretion Rate of Very Low Luminosity Objects

Abstract: We propose to measure the mass accretion rate of six Very Low Luminosity Objects (VeLLOs) using Near-infrared Integral Spectrometer (NIFS). The extremely low luminosity of VeLLOs, L_int \le 0.1 L_\odot, was previously thought not existing in the nature because the typical accretion rate gives much larger accretion luminosity even for the lowest mass star (``Luminosity Problem''). The commonly accepted solution is that the accretion rate is not constant but episodic. Thus, VeLLOs could be interpreted as protostars being in the quiescent phase of accretion activities. However, there is no observational data directly measuring the mass accretion rate of VeLLOs. The main goal of this proposal is to examine such theory and directly measure the mass accretion rate of VeLLOs for the first time. We propose to measure the blue continuum excess (veiling) of the stellar spectrum, which is the most reliable method for measuring the accretion rate. The measurements have to be made in infrared due to the very high extinction for highly embedded protostars. Our proposal provide a first opportunity to explain the long time ``Luminosity Problem'' through the observational aspects, and Gemini is the only instrument that can provide accurate and high sensitivity infrared spectroscopy measurements within reasonably short time scale.


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