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Since the hypervelocity stars were discovered in the Milky Way, various mechanisms have been proposed to explain these runaway stars. Up to now, however, the dominant ejected mechanism of hypervelocity stars is still unclear. As the largest and closest face-on satellite galaxy of the Milky Way, the Large Magellanic Cloud (LMC) serves as a good target, allowing us to study this issue. Based on the high-precision astrometric parameters provided by Gaia Data Release 3, we researched the proper motions of 3119 massive O–B2-type stars in the LMC and identified 98 (∼3%) as having the ability to escape from the LMC, with more than 50% confidence. Furthermore, by investigating the characteristics of the identified massive stars and adopting a regression analysis, we find that the dynamic ejection scenario might be the dominant mechanism of the massive hypervelocity runaway stars in the LMC. [ABSTRACT FROM AUTHOR]

We report a measurement of the trigonometric parallax of 22 GHz water masers in the massive star-forming region G034.43+0.24 as part of the Bar and Spiral Structure Legacy Survey using the Very Long Baseline Array. The parallax is 0.330 ± 0.018 mas, corresponding to a distance of 3.03 − 0.16 + 0.17 kpc. This locates G034.43+0.24 near the inner edge of the Sagittarius spiral arm and at one end of a linear distribution of massive young stars that cross nearly the full width of the arm. The measured three-dimensional motion of G034.43+0.24 indicates a near-circular Galactic orbit. The water masers display arc-like distributions, possibly bow shocks, associated with winds from one or more massive young stars. [ABSTRACT FROM AUTHOR]

We measured the relative positions between two pairs of compact extragalactic sources (CESs), J1925-2219 and J1923-2104 (C1â€"C2) and J1925-2219 and J1928-2035 (C1â€"C3), on 2020 October 23â€"25 and 2021 February 5 (totaling four epochs), respectively, using the Very Long Baseline Array at 15 GHz. Accounting for the deflection angle dominated by Jupiter, as well as the contributions from the Sun and planets other than Earth, the Moon, and Ganymede (the most massive of the solar system’s moons), our theoretical calculations predict that the dynamical ranges of the relative positions across four epochs in R.A. of the C1â€"C2 pair and C1â€"C3 pair are 841.2 and 1127.9 ÎĽ as, respectively. The formal accuracy in R.A. is about 20 ÎĽ as, but the error in decl. is poor. The measured standard deviations of the relative positions across the four epochs are 51.0 and 29.7 ÎĽ as in R.A. for C1â€"C2 and C1â€"C3, respectively. These values indicate that the accuracy of the post-Newtonian relativistic parameter, Îł, is ∼0.061 for C1â€"C2 and ∼0.026 for C1â€"C3. Combining the two CES pairs, the measured value of Îł is 0.984 ± 0.037, which is comparable to the latest published results for Jupiter as a gravitational lens, reported by Fomalont & Kopeikin, i.e., 1.01 ± 0.03. [ABSTRACT FROM AUTHOR]

The principle of the background-eliminated extinction-parallax (BEEP) method is examining the extinction difference between on- and off-cloud regions to reveal the extinction jump caused by molecular clouds, thereby revealing the distance in complex dust environments. The BEEP method requires high-quality images of molecular clouds and high-precision stellar parallaxes and extinction data, which can be provided by the Milky Way Imaging Scroll Painting (MWISP) CO survey and the Gaia DR2 catalog, as well as supplementary A V extinction data. In this work, the BEEP method is further improved (BEEP-II) to measure molecular cloud distances in a global search manner. Applying the BEEP-II method to three regions mapped by the MWISP CO survey, we collectively measured 238 distances for 234 molecular clouds. Compared with previous BEEP results, the BEEP-II method measures distances efficiently, particularly for those molecular clouds with large angular size or in complicated environments, making it suitable for distance measurements of molecular clouds in large samples. [ABSTRACT FROM AUTHOR]

Tin oxide (SnO2) was considered as a promising alternative to commonly used graphite anode in energy storage devices thanks to its superior specific capacity. However, its electrochemical property was severely limited due to the inherent poor conductivity and drastic volume variation during the charging/discharging process. To overcome this disadvantage, we grew Sn-MOF directly on graphene oxide (GO) layers to synthesize a double carbon conductive network-encapsulated SnO2 nanoparticles (SnO2/C/rGO) via a facile solvothermal method. During the process, Sn-MOF skeleton transformed into porous carbon shells, in which nanosized SnO2 particles (~8nm) were embedded, while GO template was reduced to highly conductive rGO layer tightly wrapping the SnO2/C particles. This double-carbon structure endowed SnO2/C/rGO anode with enhanced specific capacity and rate property both in lithium ion batteries (LIB) and sodium ion batteries (SIB). The SnO2/C/rGO anode showed a highly reversible specific capacity of 1038.3 mAh g−1 at 100 mA g−1, and maintained a stable capacity of 720.2 mAh g−1 (70.1%) under 500 mA g−1 after 150 cycles in LIBs. Similarly, highly reversible capacity of 350.7 mAh g−1 (81.1%) under 100 mA g−1 after 150 cycles was also achieved in SIBs. This work provided a promising strategy in improving the electrochemical properties of SnO2 nanoparticles (NPs), as well as other potential anode materials suffering from huge volume change and poor conductivity. [ABSTRACT FROM AUTHOR]

We presented a multiwavelength study of the AFGL 333-Ridge. The molecular line data reveals that the AFGL 333-Ridge has two independent velocity components at −50.5 and −48.0 km s−1. In the position–velocity diagram, the bridge feature connects with two parts that are spatially correlated but separated in velocity. This observational evidence supports the scenario that the two velocity components have collided and merged into one molecular cloud. The majority of Class I young stellar objects (YSOs) are distributed within the collision region, suggesting that the cloud–cloud collision has induced the YSOs' formation in the ridge. Using the radio recombination line (RRL) data obtained by the Five-hundred-meter Aperture Spherical radio Telescope, the RRL velocities of three H ii regions are consistent with that of the AFGL 333-Ridge. By comparing the three H ii regions' dynamical ages with the collision timescale of the two components, we conclude that the influence of the three H ii regions may not drive the two clouds to merge. The formation of the AFGL 333-Ridge is probably due to the expansion of the giant H ii region W4. [ABSTRACT FROM AUTHOR]