Fundamental Vibrational Transitions of HCl Detected in CRL 2136

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.Comment: 6 pages, 3 figures, A&A in pres

Absorption Line Survey of H3+ toward the Galactic Center Sources III. Extent of the Warm and Diffuse Clouds

We present follow-up observations to those of Geballe & Oka (2010), who found high column densities of H3+ ~100 pc off of the Galactic center (GC) on the lines of sight to 2MASS J17432173-2951430 (J1743) and 2MASS J17470898-2829561 (J1747). The wavelength coverages on these sightlines have been extended in order to observe two key transitions of H3+, R(3,3)l and R(2,2)l, that constrain the temperatures and densities of the environments. The profiles of the H3+ R(3,3)l line, which is due only to gas in the GC, closely matches the differences between the H3+ R(1,1)l and CO line profiles, just as it does for previously studied sightlines in the GC. Absorption in the R(2,2)l line of H3+ is present in J1747 at velocities between -60 and +100 km/s. This is the second clear detection of this line in the interstellar medium after GCIRS 3 in the Central Cluster. The temperature of the absorbing gas in this velocity range is 350 K, significantly warmer than in the diffuse clouds in other parts of the Central Molecular Zone. This indicates that the absorbing gas is local to Sgr B molecular cloud complex. The warm and diffuse gas revealed by Oka et al. (2005) apparently extends to ~100 pc, but there is a hint that its temperature is somewhat lower in the line of sight to J1743 than elsewhere in the GC. The observation of H3+ toward J1747 is compared with the recent Herschel observation of H2O+ toward Sgr B2 and their chemical relationship and remarkably similar velocity profiles are discussed.Comment: 6 pages, 3 figures, 2 tables, Accepted for publication in Publications of the Astronomical Society of Japa

Supergiant Barocaloric Effects in Acetoxy Silicone Rubber over a Wide Temperature Range: Great Potential for Solid-state Cooling

Solid-state cooling based on caloric effects is considered a viable alternative to replace the conventional vapor-compression refrigeration systems. Regarding barocaloric materials, recent results show that elastomers are promising candidates for cooling applications around room-temperature. In the present paper, we report supergiant barocaloric effects observed in acetoxy silicone rubber - a very popular, low-cost and environmentally friendly elastomer. Huge values of adiabatic temperature change and reversible isothermal entropy change were obtained upon moderate applied pressures and relatively low strains. These huge barocaloric changes are associated both to the polymer chains rearrangements induced by confined compression and to the first-order structural transition. The results are comparable to the best barocaloric materials reported so far, opening encouraging prospects for the application of elastomers in near future solid-state cooling devices.Comment: 19 pages, 7 figures, 2 table

Constraints on core-collapse supernova progenitors from explosion site integral field spectroscopy

Observationally, supernovae (SNe) are divided into subclasses pertaining to their distinct characteristics. This diversity reflects the diversity in the progenitor stars. It is not entirely clear how different evolutionary paths leading massive stars to become a SN are governed by fundamental parameters such as progenitor initial mass and metallicity. This paper places constraints on progenitor initial mass and metallicity in distinct core-collapse SN subclasses, through a study of the parent stellar populations at the explosion sites. Integral field spectroscopy (IFS) of 83 nearby SN explosion sites with a median distance of 18 Mpc has been collected and analysed, enabling detection and spectral extraction of the parent stellar population of SN progenitors. From the parent stellar population spectrum, the initial mass and metallicity of the coeval progenitor are derived by means of comparison to simple stellar population models and strong-line methods. Additionally, near-infrared IFS was employed to characterise the star formation history at the explosion sites. No significant metallicity differences are observed among distinct SN types. The typical progenitor mass is found to be highest for SN Ic, followed by type Ib, then types IIb and II. SN IIn is the least associated with young stellar populations and thus massive progenitors. However, statistically significant differences in progenitor initial mass are observed only when comparing SNe IIn with other subclasses. Stripped-envelope SN progenitors with initial mass estimate lower than 25~$M_\odot$ are found; these are thought to be the result of binary progenitors. Confirming previous studies, these results support the notion that core-collapse SN progenitors cannot arise from single-star channel only, and both single and binary channels are at play in the production of core-collapse SNe. [ABRIDGED]Comment: 18 pages, 10 figures, accepted to A&

Carcinogen-induced Thyroid Proliferative Lesions in Wistar Hannover GALAS Rats with Thyroid Dysplasia

Incidences and morphological features of thyroid proliferative lesions induced by carcinogens in Wistar Hannover GALAS rats (GALAS rats) showing normal growth with or without thyroid dysplasia were examined. All thyroid tissue samples were obtained from our recently conducted study using male GALAS rats treated with 5 carcinogens according to the medium-term multiorgan carcinogenicity bioassay protocol (called DMBDD treatment). In the DMBDD-treated rats, thyroid dysplasia was found in 9 out of 114 rats. Follicular cell adenomas were found in 5 out of 9 rats with thyroid dysplasia and in 7 out of 105 rats without thyroid dysplasia. The incidence of adenoma was significantly increased in rats with thyroid dysplasia (55.6%) compared with that in rats without thyroid dysplasia (6.7%). Adenomas in rats with thyroid dysplasia were observed as single or multiple nodules, well demarcated and composed of variously sized vacuolated cells or unvacuolated cells. These histopathological features and staining profiles of luminal colloid for PAS and thyroglobulin, together with PCNA-positive cells, were fundamentally similar to those of rats without thyroid dysplasia. On the other hand, the luminal colloid in adenomas of rats with thyroid dysplasia had a tendency to be poorly stained for T4 compared with that of rats without thyroid dysplasia. From these findings, it appears that dysplastic thyroids of rats showing normal growth are more sensitive to carcinogens than normal thyroids. In addition, the morphological features of carcinogen-induced thyroid proliferative lesions in GALAS rats with thyroid dysplasia were fundamentally similar to those of rats without thyroid dysplasia, except for the vacuoles and T4 staining profile

Absorption Line Survey of H3+ toward the Galactic Center Sources I. GCS 3-2 and GC IRS3

We present high-resolution (R = 20000) spectroscopy of H3+ absorption toward the luminous Galactic center sources GCS 3-2 and GC IRS 3. With the efficient wavelength coverage afforded by Subaru IRCS, six absorption lines of H3+ have been detected in each source from 3.5 to 4.0 um, three of which are new. In particular the 3.543 um absorption line of the R(3, 3)^l transition arising from the metastable (J, K) = (3, 3) state has been tentatively detected for the first time in the interstellar medium, where previous observations of H3+ had been limited to absorption lines from the lowest levels: (J, K) = (1, 0) of ortho-H3+ and (1, 1) of para-H3+. The H3+ absorption toward the Galactic center takes place in dense and diffuse clouds along the line of sight as well as the molecular complex close to the Galactic nucleus. At least four kinematic components are found in the H3+ absorption lines. We suggest identifications of the velocity components with those of HI, CO, and H2CO previously reported from radio and infrared observations. H3+ components with velocities that match those of weak and sharp CO and H2CO lines are attributed to diffuse clouds. Our observation has revealed a striking difference between the absorption profiles of H3+ and CO, demonstrating that the spectroscopy of H3+ provides information complementary to that obtained from CO spectroscopy. The tentative detection of the R(3, 3)^l line and the non-detection of spectral lines from other J > 1 levels provide observational evidence for the metastability of the (3, 3) level, which is theoretically expected. This suggests that other metastable J = K levels with higher J may also be populated.Comment: 18 pages, 7 figures, To appear in Publications of the Astronomical Society of Japan vol. 54 no.