Scientific news

We measure for the first time the overall extent within which stars in distant galaxies were born. At all cosmic epochs, star formation in massive galaxies preferentially takes place in their central region, indicating that we are witnessing the final assembly of their stellar bulges. Few galaxies have a more compact star-forming extent, and all of them produce stars at a much higher rate than the average. This suggests a different mechanism triggering their star formation activities, such as the merger of two gas-rich disks.

https://doi.org/10.1051/0004-6361/201935178

The IRAM/GISMO 2 millimeter survey in the COSMOS field provides a unique view on star formation at the time when the Universe was only two billion years old. It reveals a significant population of extreme galaxies. Compared to the Milky-Way, they are about three times more massive, and form about 1000 times more stars per year. The sheer existence of these galaxies, soon after the Big-Bang, challenges current galaxy formation models.

https://iopscience.iop.org/article/10.3847/1538-4357/ab1912

This article reports the interstellar detection of urea. The detection was made possible thanks to a new, sensitive spectral line survey carried out with ALMA toward the high-mass star-forming region Sgr B2(N).

https://arxiv.org/abs/1906.04614

This article analyzes the chemical composition of a sample of hot molecular cores detected with ALMA in the high-mass star forming region Sgr B2(N). It shows that a cosmic-ray ionization rate enhanced by a factor 50 best reproduces the observed abundance ratios of various complex organic molecules.

https://arxiv.org/abs/1906.04695

The low-frequency stretching and bending vibrations of the isotopologues  and  have been recorded at low temperature and low resolution. For this, a cryogenic 22-pole trapping machine coupled to an IR beamline of the FELIX free electron laser facility has been used. To record the overview spectra, the laser induced reactions have been applied for these species. As this scheme is not applicable to , the latter has been tagged with He and subsequently dissociated by the IR beam. For the resulting - spectrum, broad features are observed below 1000 possibly related to vibrational motions involving the He atom. The extracted vibrational band positions for all species are compared to results from high-level quantum-chemical calculations.

https://doi.org/10.1016/j.jms.2018.02.006

C–H stretches of the fundamental ions CH⁺ and ¹³CH⁺, which have long been searched for, have been observed for the first time in the laboratory. The state-dependent attachment of He atoms to these ions at cryogenic temperatures has been exploited to obtain high-resolution rovibrational data. In addition, the lowest rotational transitions of CH⁺, ¹³CH⁺ and CD⁺ have been revisited and their rest frequency values have improved substantially.

https://doi.org/10.3847/1538-4357/aab36a

We report rest frequencies for rotational transitions of the deuterated ammonium isotopologues NH₃D⁺, NH₂D₂⁺, and NHD₃⁺, measured in a cryogenic ion trap machine. For the symmetric tops NH₃D⁺ and NHD₃⁺, one and three transitions are detected, respectively, and five transitions are detected for the asymmetric top NH₂D₂⁺. While the lowest frequency transition of NH₃D⁺ was already known in the laboratory and space, this work enables the future radio astronomical detection of the two other isotopologues.

https://doi.org/10.3847/1538-4357/aadf83

Geometry of S235 resolved from SOFIA observations of ionized carbon

Velocity-resolved observations of ionized carbon in the HII-region S235 show that, although most of the radiation comes from the direction of ionized hydrogen, it has a different velocity than the ionized hydrogen. Practically the emission does not come from the same gas, but from photon-dominated dense gas behind the HII region.

https://arxiv.org/pdf/1904.12029.pdf (accepted by ApJ)

We report the first velocity-resolved observations of atomic oxygen in the Large Magellanic Cloud (LMC) seen in emission lines at a wavelength of 63 and 145 micrometers. The line profiles neither match those from ionized carbon nor from carbon monoxide. This confirms that clouds in very different physical conditions co-exist within the observing beam.

https://doi.org/10.1051/0004-6361/201833398

Laboratory spectroscopic data of large and complex molecules are of upmost importance for the astronomy community to detect new molecular species in space and to achieve a greater understanding of the chemistry involved in star forming regions and processes. In our publication we present high-resolution rotational spectroscopy of the two higher energy conformers of 2- cyanobutane (C4H9CN), a a member of a larger family of cyanides.

https://doi.org/10.1016/j.jms.2018.11.009