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Supernova remnants (SNRs) contribute to regulate the star formation efficiency and evolution of galaxies. As they expand into the interstellar medium (ISM), they transfer vast amounts of energy and momentum that displace, compress, and heat the surrounding material. Despite the extensive work in galaxy evolution models, it remains to be observationally validated to what extent the molecular ISM is affected by the interaction with SNRs. We use the first results of the ESO–ARO Public Spectroscopic Survey SHREC to investigate the shock interaction between the SNR IC443 and the nearby molecular clump G. We use high-sensitivity SiO(2-1) and H13CO+(1-0) maps obtained by SHREC together with SiO(1-0) observations obtained with the 40-m telescope at the Yebes Observatory. We find that the bulk of the SiO emission is arising from the ongoing shock interaction between IC443 and clump G. The shocked gas shows a well-ordered kinematic structure, with velocities blue-shifted with respect to the central velocity of the SNR, similar to what observed towards other SNR–cloud interaction sites. The shock compression enhances the molecular gas density, n(H2), up to >105 cm−3, a factor of >10 higher than the ambient gas density and similar to values required to ignite star formation. Finally, we estimate that up to 50 per cent of the momentum injected by IC443 is transferred to the interacting molecular material. Therefore, the molecular ISM may represent an important momentum carrier in sites of SNR–cloud interactions. [ABSTRACT FROM AUTHOR]

Infrared dark clouds (IRDCs) are potential hosts of the elusive early phases of high mass star formation (HMSF). Here, we conduct an in-depth analysis of the fragmentation properties of a sample of 10 IRDCs, which have been highlighted as some of the best candidates to study HMSF within the Milky Way. To do so, we have obtained a set of large mosaics covering these IRDCs with Atacama Large Millimeter/submillimeter Array (ALMA) at Band 3 (or 3 mm). These observations have a high angular resolution (∼3 arcsec; ∼0.05 pc), and high continuum and spectral line sensitivity (∼0.15 mJy beam−1 and ∼0.2 K per 0.1 km s−1 channel at the N2H+ (1 − 0) transition). From the dust continuum emission, we identify 96 cores ranging from low to high mass (M  = 3.4−50.9 M⊙) that are gravitationally bound (αvir = 0.3−1.3) and which would require magnetic field strengths of B  = 0.3−1.0 mG to be in virial equilibrium. We combine these results with a homogenized catalogue of literature cores to recover the hierarchical structure within these clouds over four orders of magnitude in spatial scale (0.01–10 pc). Using supplementary observations at an even higher angular resolution, we find that the smallest fragments (<0.02 pc) within this hierarchy do not currently have the mass and/or the density required to form high-mass stars. None the less, the new ALMA observations presented in this paper have facilitated the identification of 19 (6 quiescent and 13 star-forming) cores that retain >16 M⊙ without further fragmentation. These high-mass cores contain trans-sonic non-thermal motions, are kinematically sub-virial, and require moderate magnetic field strengths for support against collapse. The identification of these potential sites of HMSF represents a key step in allowing us to test the predictions from high-mass star and cluster formation theories. [ABSTRACT FROM AUTHOR]

The 14N/15N ratio in molecules exhibits a large variation in star-forming regions, especially when measured from N2H+ isotopologues. However, there are only a few studies performed at high-angular resolution. We present the first interferometric survey of the 14N/15N ratio in N2H+ obtained with Atacama Large Millimeter Array observations towards four infrared-dark clouds harbouring 3 mm continuum cores associated with different physical properties. We detect N15NH+ (1–0) in |$\sim 20\!-\!40{{\ \rm per\ cent}}$| of the cores, depending on the host cloud. The 14N/15N values measured towards the millimetre continuum cores range from a minimum of ∼80 up to a maximum of ∼400. The spread of values is narrower than that found in any previous single-dish survey of high-mass star-forming regions and than that obtained using the total power data only. This suggests that the 14N/15N ratio is on average higher in the diffuse gaseous envelope of the cores and stresses the need for high-angular resolution maps to measure correctly the 14N/15N ratio in dense cores embedded in IRDCs. The average 14N/15N ratio of ∼210 is also lower than the interstellar value at the Galactocentric distance of the clouds (∼300–330), although the sensitivity of our observations does not allow us to unveil 14N/15N ratios higher than ∼400. No clear trend is found between the 14N/15N ratio and the core physical properties. We find only a tentative positive trend between 14N/15N and H2 column density. However, firmer conclusions can be drawn only with higher sensitivity measurements. [ABSTRACT FROM AUTHOR]

During the past decade, the dynamical importance of magnetic fields in molecular clouds has been increasingly recognized, as observational evidence has accumulated. However, how a magnetic field affects star formation is still unclear. Typical star formation models still treat a magnetic fields as an isotropic pressure, ignoring the fundamental property of dynamically important magnetic fields: their direction. This study builds on our previous work, which demonstrated how the mean magnetic field orientation relative to the global cloud elongation can affect cloud fragmentation. After the linear mass distribution reported earlier, we show here that the mass cumulative function (MCF) of a cloud is also regulated by the field orientation. A cloud elongated closer to the field direction tends to have a shallower MCF: in other words, a higher portion of the gas is at high density. The evidence is consistent with our understanding of the bimodal star formation efficiency discovered earlier, which is also correlated with the field orientation. [ABSTRACT FROM AUTHOR]

By comparing cumulative linear mass profiles of 12 Gould Belt molecular clouds within |$500\,\,{\rm {\rm pc}}$|⁠, we study how the linear mass distributions of molecular clouds vary with the angles between the molecular cloud long axes and the directions of the local magnetic fields (cloud-field direction offsets). We find that molecular clouds with the long axes perpendicular to the magnetic field directions show more even distributions of the linear mass. The result supports that magnetic field orientations can affect the fragmentation of molecular clouds (Li et al. 2017). [ABSTRACT FROM AUTHOR]

Objectives: Classical inborn errors of metabolism (IEM) affect about 1 in 4000 in Hong Kong. Despite the widespread implementation of expanded newborn screening in most countries, Hong Kong only screen for three conditions and the awareness of public has not been evaluated. This is the first study to examine the parental knowledge and attitudes towards expanded newborn screening in Hong Kong. Methods: A cross-sectional survey was conducted in the Princess Margaret Hospital. Parents with babies bom from 1st July to 31st October 2010 were randomly recruited. Fifteen questions relating to the knowledge of newborn screening and biochemical genetic disorders, preferences about the features of newborn screening, the economic values, and attitudes toward false positive results were asked. Results: In total, 172 subjects were interviewed by phone (overall response rate 97.2%). There were 87.8% parents who had never heard of expanded newborn screening; 99.4% demanded more parental education; 83.5% thought the programme should be implemented immediately; 97.7% supported population screening, even though the diseases are incurable; 93.9% accepted the possibility of false positive and false negative results; 70.4% preferred a voluntary basis; 83.2% believed that the programme should be fully government funded as basic primary care; 98.8% agreed that Hong Kong should follow mainland China's policy on expanded newborn screening; 98.2% required pre-test counseling; and 96.4% required an explicit parental consent before blood sampling. Conclusions: The response from parents overwhelmingly favoured having expanded newborn screening in Hong Kong. Parental tolerance was high. Parents valued the parental autonomy with informed consent and pre-test counseling the most. The success of any screening programme requires the public participation and this study is the first to prove the parental call for an expanded newborn screening in Hong Kong. [ABSTRACT FROM AUTHOR]