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تسجيل مستخدم جديدDetection of Vibrationally Excited CO in IRC+10216
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Using the Submillimeter Array we have detected the J=3-2 and 2-1 rotational transitions from within the first vibrationally excited state of CO toward the extreme carbon star IRC+10216 (CW Leo). The emission remains spatially unresolved with an angular resolution of ~2 and, given that the lines originate from energy levels that are ~3100 K above the ground state, almost certainly originates from a much smaller (~10^{14} cm) sized region close to the stellar photosphere. Thermal excitation of the lines requires a gas density of ~10^{9} cm^{-3}, about an order of magnitude higher than the expected gas density based previous infrared observations and models of the inner dust shell of IRC+10216.
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The J,K = 1,0-0,0 rotational transition of phosphine (PH3) at 267 GHz has been tentatively identified with a T_MB = 40 mK spectral line observed with the IRAM 30-m telescope in the C-star envelope IRC+10216. A radiative transfer model has been used t
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We present the detection of C4H2 for first time in the envelope of the C-rich AGB star IRC+10216 based on high spectral resolution mid-IR observations carried out with the Texas Echelon-cross-Echelle Spectrograph (TEXES) mounted on the Infrared Teles
cope Facility (IRTF). The obtained spectrum contains 24 narrow absorption features above the detection limit identified as lines of the ro-vibrational C4H2 band nu6+nu8(sigma_u^+). The analysis of these lines through a ro-vibrational diagram indicates that the column density of C4H2 is 2.4(1.5)E+16 cm^(-2). Diacetylene is distributed in two excitation populations accounting for 20 and 80% of the total column density and with rotational temperatures of 47(7) and 420(120) K, respectively. This two-folded rotational temperature suggests that the absorbing gas is located beyond ~0.4~20R* from the star with a noticeable cold contribution outwards from ~10~500R*. This outer shell matches up with the place where cyanoacetylenes and carbon chains are known to form due to the action of the Galactic dissociating radiation field on the neutral gas coming from the inner layers of the envelope.
Methyl formate in its first torsionally excited state (vt=1 at 131 cm-1) is detected for the first time toward W51 e2. All transitions from excited methyl formate within the observed spectral range are actually detected (82 transitions) and no strong
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