اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدFundamental Vibrational Transitions of HCl Detected in CRL 2136
335
0
0.0
(
0
)
تأليف
Miwa Goto
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
We would like to understand the chemistry of dense clouds and their hot cores more quantitatively by obtaining more complete knowledge of the chemical species present in them. We have obtained high-resolution infrared absorption spectroscopy at 3-4 um toward the bright infrared source CRL 2136. The fundamental vibration-rotation band of HCl has been detected within a dense cloud for the first time. The HCl is probably located in the warm compact circumstellar envelope or disk of CRL 2136. The fractional abundance of HCl is (4.9-8.7)e-8, indicating that approximately 20 % of the elemental chlorine is in gaseous HCl. The kinetic temperature of the absorbing gas is 250 K, half the value determined from infrared spectroscopy of 13CO and water. The percentage of chlorine in HCl is approximately that expected for gas at this temperature. The reason for the difference in temperatures between the various molecular species is unknown.
قيم البحث
اقرأ أيضاً
Deuterated interstellar molecules frequently have abundances relative to their main isotopologues much higher than the overall elemental D-to-H ratio in the cold dense interstellar medium. The H$_3^+$ and its isotopologues play a key role in the deut
erium fractionation; however, the abundances of these isotopologues have not been measured empirically with respect to H$_3^+$ to date. Our aim was to constrain the relative abundances of H$_2$D$^+$ and D$_3^+$ in the cold outer envelope of the hot core CRL 2136 IRS 1. We carried out three observations targeting H$_3^+$ and its isotopologues using the spectrographs CRIRES at the VLT, iSHELL at IRTF, and EXES on board SOFIA. In addition, the CO overtone band at 2.3 $mu$m was observed by iSHELL to characterize the gas on the line of sight. The H$_3^+$ ion was detected toward CRL 2136 IRS 1 as in previous observations. Spectroscopy of lines of H$_2$D$^+$ and D$_3^+$ resulted in non-detections. The 3$sigma$ upper limits of $N({rm H_2D^+})/N({rm H_3^+})$ and $N({rm D_3^+})/N({rm H_3^+})$ are 0.24 and 0.13, respectively. The population diagram for CO is reproduced by two components of warm gas with the temperatures 58 K and 530 K, assuming a local thermodynamic equilibrium (LTE) distribution of the rotational levels. Cold gas ($<$20 K) makes only a minor contribution to the CO molecular column toward CRL 2136 IRS 1. The critical conditions for deuterium fractionation in a dense cloud are low temperature and CO depletion. Given the revised cloud properties, it is no surprise that H$_3^+$ isotopologues are not detected toward CRL 2136 IRS 1. The result is consistent with our current understanding of how deuterium fractionation proceeds.
The simplest molecules in nature, molecular hydrogen ions in the form of H2+ and HD+, provide an important benchmark system for tests of quantum electrodynamics in complex forms of matter. Here, we report on such a test based on a frequency measureme
nt of a vibrational overtone transition in HD+ by laser spectroscopy. We find that the theoretical and experimental frequencies are equal to within 0.6(1.1) parts per billion, which represents the most stringent test of molecular theory so far. Our measurement not only confirms the validity of high-order quantum electrodynamics in molecules, but also enables the long predicted determination of the proton-to-electron mass ratio from a molecular system, as well as improved constraints on hypothetical fifth forces and compactified higher dimensions at the molecular scale. With the perspective of comparisons between theory and experiment at the 0.01 part-per-billion level, our work demonstrates the potential of molecular hydrogen ions as a probe of fundamental physical constants and laws.
We report monitoring observations of the T Tauri star EX Lupi during its outburst in 2008 in the CO fundamental band at 4.6-5.0 um. The observations were carried out at the VLT and the Subaru Telescope at six epochs from April to August 2008, coverin
g the plateau of the outburst and the fading phase to a quiescent state. The line flux of CO emission declines with the visual brightness of the star and the continuum flux at 5 um, but composed of two subcomponents that decay with different rates. The narrow line emission (50 km s-1 in FWHM) is near the systemic velocity of EX Lupi. These emission lines appear exclusively in v=1-0. The line widths translate to a characteristic orbiting radius of 0.4 AU. The broad line component (FWZI ~ 150 km s-1) is highly excited upto v<=6. The line flux of the component decreases faster than the narrow line emission. Simple modeling of the line profiles implies that the broad-line emitting gas is orbiting around the star at 0.04-0.4 AU. The excitation state, the decay speed of the line flux, and the line profile, indicate that the broad-line emission component is physically distinct from the narrow-line emission component, and more tightly related to the outburst event.
We present the results of near-infrared (2.5--5.4um) long-slit spectroscopy of the extended green object (EGO) G318.05+0.09 with AKARI. Two distinct sources are found in the slit. The brighter source has strong red continuum emission with H2O ice, CO
2 ice, and CO gas and ice absorption features at 3.0, 4.25um, 4.67um, respectively, while the other greenish object shows peculiar emission that has double peaks at around 4.5 and 4.7um. The former source is located close to the ultra compact HII region IRAS 14498-5856 and is identified as an embedded massive young stellar object. The spectrum of the latter source can be interpreted by blue-shifted (-3000 ~ -6000km/s) optically-thin emission of the fundamental ro-vibrational transitions (v=1-0) of CO molecules with temperatures of 12000--3700K without noticeable H2 and HI emission. We discuss the nature of this source in terms of outflow associated with the young stellar object and supernova ejecta associated with a supernova remnant.
We report on the detection of anhydrous hydrochloric acid (hydrogen chlorine, HCl) in the carbon-rich star IRC+10216 using the spectroscopic facilities onboard the Herschel satellite. Lines from J=1-0 up to J=7-6 have been detected. From the observed
intensities, we conclude that HCl is produced in the innermost layers of the circumstellar envelope with an abundance relative to H2 of 5x10^-8 and extends until the molecules reach its photodissociation zone. Upper limits to the column densities of AlH, MgH, CaH, CuH, KH, NaH, FeH, and other diatomic hydrides have also been obtained.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
