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Studies of young planets help us understand planet evolution and investigate important evolutionary processes such as atmospheric escape. We monitored IRAS 04125+2902, a 3 Myr-old T Tauri star with a transiting planet and a transitional disk, with the SPIRou infrared spectropolarimeter on the Canada-France-Hawaii Telescope. Using these data, we constrained the mass and density of the Jupiter-size companion to < 0.16 M_♃and < 0.23 g cm⁻³, respectively (90% upper limits). These rule out a Jovian-like object and support the hypothesis that it is an ancestor to the numerous sub-Neptunes found around mature stars. We unambiguously detected magnetic fields at the stellar surface, small-scale fields reaching 1.5 kG and the large-scale field mostly consisting of a 0.80−0.95 kG dipole inclined by 5−15° to the rotation axis. Accretion onto the star is low and/or episodic at a maximum rate of ≃10⁻¹¹M_⊙yr⁻¹, indicating that IRAS 04125+2902 is most likely in a magnetic “propeller” regime, presumably explaining the star’s slow rotation (11.3 d). We discovered persistent Doppler-shifted absorption in a metastable He I line, clear evidence for a magnetized wind from a gaseous inner disk. Variability in absorption suggests structure in the disk wind that could reflect disk-planet interactions. 

Abstract High Salinity Shelf Water (HSSW) formed in the Ross Sea of Antarctica is a precursor to Antarctic Bottom Water (AABW), a water mass that constitutes the bottom limb of the global overturning circulation. HSSW production rates are poorly constrained, as in-situ observations are scarce. Here, we present high-vertical-and-temporal-resolution salinity time series collected in austral winter 2017 from a mooring in Terra Nova Bay (TNB), one of two major sites of HSSW production in the Ross Sea. We calculate an annual-average HSSW production rate of ~0.4Sv(10⁶m³s⁻¹), which we use to ground truth additional estimates across 2012–2021 made from parametrized net surface heat fluxes. We find sub-seasonal and interannual variability on the order of$$0.1$$ $0.1$$${Sv}$$ $Sv$, with a strong dependence on variability in open-water area that suggests a sensitivity of TNB HSSW production rates to changes in the local wind regime and offshore sea ice pack. 

ortho‐Phosphinophenol (oPP) is an unusual example of an air‐stable primary phosphine and a valuable precursor to a variety of useful organophosphorus compounds.  The presence of PH2 and OH functionalities offers the possibility of intermolecular and intramolecular P•••HO hydrogen bonding (HB).  The close proximity of these two groups also offers the opportunity for intramolecular PH2•••HO dihydrogen bonding (DHB).  This work provides experimental and computational evidence for these various types of interactions.  In the solid state, oPP is associated by significant intermolecular P•••HO hydrogen bonds as revealed by a single crystal X‐ray structural determination.  Multinuclear NMR and IR spectroscopic studies, coupled with DFT computational studies, suggest that oPP adopts multiple conformations in solution whose nature varies with the identity of the solvent.  In the gas phase or non‐polar solvents (such as cyclohexane) an equilibrium between four conformations of oPP is proposed.  Interestingly, in silico, an isomer having bifurcated intramolecular PH2•••HO DHB (PP4) is found to be more stable than an isomer having intramolecular P•••HO HB (PP1).  In polar solvents (S), NMR studies indicate intermolecular OH•••HB play a dominant role on the 31P NMR chemical shifts. 

There is considerable interest in MnOH x moieties, particularly in the stepwise changes in those O–H bonds in tandem with Mn oxidation state changes. The reactivity of aquo-derived ligands, {MOH x }, is also heavily influenced by the electronic character of the other ligands. Despite the prevalence of oxygen coordination in biological systems, preparation of mononuclear Mn complexes of this type with all O-donors is rare. Herein, we report several Mn complexes with perfluoropinacolate (pin F ) 2− including the first example of a crystallographically characterized mononuclear {Mn( iii )OH} with all O-donors, K 2 [Mn(OH)(pin F ) 2 ], 3. Complex 3 is prepared via deprotonation of K[Mn(OH 2 )(pin F ) 2 ], 1, the p K a of which is estimated to be 18.3 ± 0.3. Cyclic voltammetry reveals quasi-reversible redox behavior for both 1 and 3 with an unusually large Δ E p , assigned to the Mn( iii / ii ) couple. Using the Bordwell method, the bond dissociation free energy (BDFE) of the O–H bond in {Mn( ii )–OH 2 } is estimated to be 67–70 kcal mol −1 . Complex 3 abstracts H-atoms from 1,2-diphenylhydrazine, 2,4,6-TTBP, and TEMPOH, the latter of which supports a PCET mechanism. Under basic conditions in air, the synthesis of 1 results in K 2 [Mn(OAc)(pin F ) 2 ], 2, proposed to result from the oxidation of Et 2 O to EtOAc by a reactive Mn species, followed by ester hydrolysis. Complex 3 alone does not react with Et 2 O, but addition of O 2 at low temperature effects the formation of a new chromophore proposed to be a Mn( iv ) species. The related complexes K(18C6)[Mn( iii )(pin F ) 2 ], 4, and (Me 4 N) 2 [Mn( ii )(pin F ) 2 ], 5, have also been prepared and their properties discussed in relation to complexes 1–3.