arXiv subjects

Qianru He

Publications and source records attributed to Qianru He.

7 recordsLinked to original sources

arXiv2026

ALOHA IRDCs Molecular Line Follow-up: I. Gas properties and kinematics

Infrared Dark Clouds are ideal sites for investigating the initial conditions of massive star and cluster formation. The A Lei Of the Habitat and Assembly of Infrared Dark Clouds (ALOHA IRDCs), a James Clerk Maxwell Telescope (JCMT) Large Program, has mapped nearby IRDCs with SCUBA-2. Complementary molecular line observations are needed to characterise the physical, kinematic, and chemical properties of the dense gas. We aim to determine the thermal, kinematic, and chemical properties of clumps identified in the ALOHA IRDCs, and to assess their evolutionary status and level of star-forming activity. We performed single-pointing K-band and W-band observations towards 56 ALOHA IRDCs clumps using the Effelsberg 100-m and Yebes 40-m telescopes, respectively. We derived NH3 kinetic temperatures using the hyperfine group ratio (HFGR) method and identified infall and shock signatures from HCO+, H13CO+, SiO, and HNCO profiles. Water masers and NH2D emission were used as complementary tracers of chemical evolution and star formation. The clumps exhibit kinetic temperatures of 15-29 K. We detect NH2D emission towards 18 sources, with NH2D centroid velocities consistent with NH3, indicating both species trace the same dense gas component. More than half of the clumps display blue-asymmetric HCO+ profiles, identifying them as infall candidates. Water masers are detected in 22 sources, with prominent velocity ranges and variability. Broad SiO emission (>~20 km/s) indicates strong shocks, while narrower extents (<~6km/s) likely trace large-scale interactions or low-velocity shocks. The widespread infall signatures, shock tracers, masers, and NH2D emission suggest that relatively quiescent, chemically young material can coexist with dynamically active gas affected by early protostellar feedback, providing insight into the coupled physical and chemical evolution of massive IRDC clumps.

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arXiv2026

B-field Orion Protostellar Survey (BOPS). IV: The Relative Orientation Between Magnetic Fields and Density Structures in Young Protostellar Envelopes

We investigate the relative alignment between density structures and magnetic fields in eight young protostars from the ALMA B-field Orion Protostellar Survey. Column density maps are derived from 870 $\mu$m dust continuum emission, and the Histogram of Relative Orientations (HRO) method is applied to quantify the correlation between magnetic field orientations and density structures on envelope scales ($\sim$10$^{3}$~au). We find that the relative alignment shows overall weak evidence of systematic evolution with column density, suggesting that column density alone does not fully determine the alignment. The magnetization level also plays a crucial role, with weakly magnetized envelopes exhibiting predominantly parallel or random alignment, whereas strongly magnetized ones show perpendicular configurations even at moderate densities. These results reveal that density and magnetization jointly shape the morphology of protostellar envelopes and the coupling between gravity and magnetic fields during early stages of star formation.

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arXiv2025

Large-field CO(1-0) observations toward the Galactic historical supernova remnants: shocked molecular clouds toward the Crab Nebula

Using the PMO 13.7m telescope, we present large-field and high-sensitivity CO(1-0) line observations toward the Crab Nebula, in order to better understand the interstellar gas environment of this well-known historical supernova remnant. The CO observations show molecular clouds toward the Crab Nebula at a velocity range from about 0 to 16 km/s. After checking the CO spectra, we find shocked signatures in the clouds extending at a velocity of roughly [5, 11] km/s. These shocked molecular clouds, with an angular distance of about 0.4-0.5 degree toward the Crab Nebula, are located at the shell of a bubble discovered in the GALFA-HI (and HI4PI) images at the same velocity range. The dimension of the bubble is roughly 2.3$\times$2.6 degree and the expansion velocity is about 5 km/s. The kinetic energy referred from the shocked molecular clouds (roughly 3.5$\times$10$^{51}$ erg), together with the HI bubble, support the picture that the Crab Nebula belongs to a typical core-collapse supernova remnant. Nevertheless, due to the large uncertainty in the distance measurement, further observations are needed to verify the physical association between the shocked molecular clouds and the Crab Nebula.

astro-ph.GA↗

arXiv2025

Bullet shooting cloud-cloud collision in MIR bubble N65

We report that the formation of the twin-bubble system N65 and N65bis may be caused by the cloud-cloud collision (CCC) from the Bullet Nebula. The blue-shifted $^{13}$CO gas component (N65a [47, 55] km s$^{-1}$) is associated with the twin-bubble system, while the red-shifted $^{13}$CO gas component (N65b [55, 62] km s$^{-1}$) is linked to the Bullet Nebula. The distinct signatures of CCC, such as the bridge feature, the U-shape cavity and the complementary distribution with displacement, are found between N65a and N65b. The collision timescale is estimated to be 1.15 to 2.0 Myr, which is consistent with the dynamical ages of the two \HII regions in N65a (0.73 Myr for N65bis and 1.19 Myr for N65, respectively), indicating their CCC-related origin. A total of 354 young stellar objects (YSOs) are founded, which are clustered into eight MST (Minimum Spinning Tree) groups. The distribution of M1 (at the post-frontal edge) and M2, M3, M4 (at the pre-frontal edge) suggests that the CCC triggers star formation along the collision path of $b=0^{\circ}.35$, with younger YSOs present at the pre-frontal edge. Therefore, the bipolar morphology of the twin-bubble system can be interpreted by the collision of N65a and N65b along $b=0^{\circ}.35$ about 2 Myr ago.

astro-ph.GA↗

arXiv2024

Multiple collisions in N59 bubble: Sequential cloud-cloud collisions

We report that the gas components in the N59 bubble suffered from sequential multiple cloud-cloud collision (CCC) processes. The molecular gas in the N59 bubble can be decomposed into four velocity components, namely Cloud A [95, 108] km s$^{-1}$, Cloud B [86, 95] km s$^{-1}$, Cloud C [79, 86] km s$^{-1}$ and Cloud D [65, 79] km s$^{-1}$. Four CCC processes occurred among these four velocity components, i.e., Cloud A vs. Cloud B, Cloud A vs. Cloud C, Cloud C vs. Cloud D, and Cloud A vs. Cloud D. Using Spitzer MIR and UKIDSS NIR photometric point source catalogs, we identified 514 YSO candidates clustered in 13 YSO groups, and most of them (~60$\%$) were located at the colliding interfaces, indicating that they were mainly triggered by these four CCC processes. We also found that these four collisions occurred in a time sequential order: the earliest and most violent collision occurred between Cloud A and Cloud D about 2 Myr ago, then Cloud B collided with Cloud A about 1 Myr ago, and finally, Cloud C collided with Clouds A and D simultaneously about 0.4 Myr ago.

astro-ph.GA↗

arXiv2023

Cloud-cloud collision in S235: triggered the formation of high-mass stars and young star clusters

We present the analysis of cloud-cloud collision (CCC) process in the Galactic molecular complex S235. Our new CO observations performed with the PMO-13.7m telescope reveal two molecular clouds, namely the S235-Main and the S235-ABC, with $\sim$ 4 km s$^{-1}$ velocity separation. The bridge feature, the possible colliding interface and the complementary distribution of the two clouds are significant observational signatures of cloud-cloud collision in S235. The most direct evidence of cloud-cloud collision process in S235 is that the S235-Main (in a distance of 1547$^{+44}_{-43}$ pc) and S235-ABC (1567$^{+33}_{-39}$ pc) meet at almost the same position (within 1$σ$ error range) at a supersonic relative speed. We identified ten $^{13}$CO clumps from PMO-13.7m observations, 22 dust cores from the archival SCUBA-2 data, and 550 YSOs from NIR-MIR data. 63$\%$ of total YSOs are clustering in seven MST groups (M1$-$M7). The tight association between the YSO groups (M1 $\&$ M7) and the bridge feature suggests that the CCC process triggers star formation there. The collisional impact subregion (the South) shows $3\sim5$ times higher CFE and SFE (average value of 12.3$\%$ and 10.6$\%$, respectively) than the non-collisional impact subregion (2.4$\%$ and 2.6$\%$, respectively), suggesting that the CCC process may have enhanced the CFE and SFE of the clouds compared to those without collision influence.

astro-ph.GA↗

arXiv2023

High-Mass Starless Clumps: Dynamical State and Correlation Between Physical Parameters

In order to study the initial conditions of massive star formation, we have previously built a sample of 463 high-mass starless clumps (HMSCs) across the inner Galactic plane covered by multiple continuum surveys. Here, we use $^{13}$ CO(2-1) line data from the SEDIGISM survey, which covers 78$^{\circ}$ in longitude ($-60^{\circ}<l<18^{\circ}$, $\vert b\vert<0.5^{\circ}$) with 30$^{\prime \prime}$ resolution, to investigate the global dynamical state of these parsec-scale HMSCs (207 sources with good quality data, mass $10^{2}\sim 10^{5}\ \rm M_{\odot}$, size $0.1\sim3.6$ pc). We find that most HMSCs are highly turbulent with a median Mach number $\mathcal{M_{S}}\sim$ 8.2, and 44\%$\sim$55\% of them are gravitationally bound (with virial parameter $α_{\rm vir} \lesssim 2$) if no magnetic fields were present. A median magnetic field strength of 0.33$\sim$0.37 mG would be needed to support these bound clumps against collapse, in agreement with previous observations of magnetic fields in massive star formation regions. Luminosity-to-mass ratio, an important tracer for evolutionary stage, is strongly correlated with dust temperature. Magnetic field strength is also correlated with density. The Larson linewidth-size scaling does not hold in HMSCs. This study advances our understanding of global properties of HMSCs, and our high-resolution ALMA observations are on the way to study the resolved properties.

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