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Arxiv_Daily_Notice/2026-01-19-Arxiv-Daily-Paper.md

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+# Showing new listings for Monday, 19 January 2026
+Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.
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+
+阅读 `Usage.md`了解如何使用此repo实现个性化的Arxiv论文推送
+
+See `Usage.md` for instructions on how to personalize the repo. 
+
+
+Keyword list: ['star formation', 'star-forming', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']
+
+
+Excluded: ['galaxies', 'galaxy cluster', ' AGN ', 'standard candle', 'X-ray binar', 'solar corona']
+
+
+### Today: 8papers 
+#### Checking It Twice: Using [C/N]-Masses and Asteroseismic Masses as a Diagnostic of Mass Loss and Transfer on the RGB
+ - **Authors:** John D. Roberts, Marc H. Pinsonneault, Jennifer A. Johnson, Madeline Howell
+ - **Subjects:** Subjects:
+Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
+ - **Arxiv link:** https://arxiv.org/abs/2601.10800
+
+ - **Pdf link:** https://arxiv.org/pdf/2601.10800
+
+ - **Abstract**
+ The surface [C/N] of red giants is correlated with birth mass, but not directly impacted by mass loss. Exploiting this, we compare asteroseismic masses of red giants with the same [C/N] and but different evolutionary states. We find bulk differences between stars at the beginning of the red giant branch and in the subsequent evolutionary phase, the red clump, providing a direct constraint on the strength of net RGB mass loss in field stars. We find that net mass loss decreases with metallicity and mass, matching recent studies for field giants, but contradicting expectations from the widely used Reimers' mass loss formula. We propose a mass- and metallicity-dependent Reimers' $\eta$ calibration that reproduces the empirical trends that we see. In addition, we identify 207 stars (3.33% of our sample) that are clear outliers from their population in these birth mass bins, which we believe are likely candidates for mass transfer events. These stars do not show any obvious discrepancies in abundances or binary properties from their counterparts. This population should be accounted for in Galactic archaeological studies. Further follow-up is required to quantify their occurrence rate and origin.
+#### Optimal and Unbiased Fluxes from Up-the-Ramp Detectors under Variable Illumination
+ - **Authors:** Bowen Li, Kevin A. McKinnon, Andrew K. Saydjari, Conor Sayres, Gwendolyn M. Eadie, Andrew R. Casey, Jon A. Holtzman, Timothy D. Brandt, Jose G. Fernandez-Trincado
+ - **Subjects:** Subjects:
+Instrumentation and Methods for Astrophysics (astro-ph.IM); Applications (stat.AP)
+ - **Arxiv link:** https://arxiv.org/abs/2601.10878
+
+ - **Pdf link:** https://arxiv.org/pdf/2601.10878
+
+ - **Abstract**
+ Near-infrared (NIR) detectors -- which use non-destructive readouts to measure time-series counts-per-pixel -- play a crucial role in modern astrophysics. Standard NIR flux extraction techniques were developed for space-based observations and assume that source fluxes are constant over an observation. However, ground-based telescopes often see short-timescale atmospheric variations that can dramatically change the number of photons arriving at a pixel. This work presents a new statistical model that shares information between neighboring spectral pixels to characterize time-variable observations and extract unbiased fluxes with optimal uncertainties. We generate realistic synthetic data using a variety of flux and amplitude-of-time-variability conditions to confirm that our model recovers unbiased and optimal estimates of both the true flux and the time-variable signal. We find that the time-variable model should be favored over a constant-flux model when the observed count rates change by more than 3.5%. Ignoring time variability in the data can result in flux-dependent, unknown-sign biases that are as large as ~120% of the flux uncertainty. Using real APOGEE spectra, we find empirical evidence for approximately wavelength-independent, time-dependent variations in count rates with amplitudes much greater than the 3.5% threshold. Our model can robustly measure and remove the time-dependence in real data, improving the quality of data-model comparison. We show several examples where the observed time-dependence quantitatively agrees with independent measurements of observing conditions, such as variable cloud cover and seeing.
+#### Pink Dwarfs and the Paths to Stardom: How Brown Dwarfs Pushed Above the Hydrogen Burning Limit Evolve
+ - **Authors:** Jaime Luisi, John C. Forbes, Heather V. Rusk, Benjamin Gullick
+ - **Subjects:** Subjects:
+Solar and Stellar Astrophysics (astro-ph.SR)
+ - **Arxiv link:** https://arxiv.org/abs/2601.10908
+
+ - **Pdf link:** https://arxiv.org/pdf/2601.10908
+
+ - **Abstract**
+ Brown dwarfs that gain mass through binary interactions may be pushed above the boundary that divides brown dwarfs from low-mass stars: the hydrogen burning limit (HBL). Some of these objects will make their way to the main sequence and may eventually be indistinguishable from ordinary low-mass stars, while others will remain brown dwarf-like, unable to burn hydrogen at a high enough rate to power their surface luminosity. We study the evolution of both types of object to provide a taxonomy and testable observational predictions for these objects depending on their evolutionary path. Using MESA simulations, we find that a subset of the objects that will eventually become stars experience an extended luminosity plateau, where their surface luminosity remains nearly constant on 100 Myr - Gyr timescales. We find that the plateau timescale is set by the amount of energy required to re-heat the cores of these objects to a level sufficient to sustain convection. The timescales required for the cores of these objects to "unfreeze" and arrive at the main sequence is long enough that surveys may be able to find objects in this evolutionary stage. These objects, along with those that never reach the main sequence, occupy a unique space in a mass-luminosity diagram, and would provide a unique constraint on binary mass transfer physics.
+#### How To Use Thermal Dust Continuum Emission To Measure The Physical Properties Of Dusty Astrophysical Objects
+ - **Authors:** Yancy L. Shirley (1 and 2), Jeffrey G. Mangum (3), Desika Narayanan (4), James Di Francesco (2) ((1) University of Arizona, (2) Herzberg Astronomy and Astrophysics Research Centre, (3) National Radio Astronomy Observatory, (4) University of Florida)
+ - **Subjects:** Subjects:
+Astrophysics of Galaxies (astro-ph.GA)
+ - **Arxiv link:** https://arxiv.org/abs/2601.10989
+
+ - **Pdf link:** https://arxiv.org/pdf/2601.10989
+
+ - **Abstract**
+ Dust grains in the interstellar medium interact with photons across the electromagnetic spectrum. They are generally photon energy converters, absorbing short wavelength radiation and emitting long wavelength radiation. Sixty years ago in 1965, thermal emission from dust grains in the interstellar medium was discovered. This tutorial is a summary of the physics of thermal dust continuum emission and how to use observations of the intensity and flux density of dusty objects to calculate physical properties such as mass, column density, luminosity, dust temperature, and dust opacity spectral index. Equations are derived, when feasible, from first principles with all limits and assumptions explicitly stated. Properties of dust opacities appropriate for different astrophysical environments (e.g. diffuse ISM, dense cores, protoplanetary disks) are discussed and tabulated for the wavelengths of past, current, and future bolometer cameras. Corrections for observations at high redshift as well as the effects of telescope measurement limitations are derived. We also update the calculation of the mean molecular weight in different ISM environments and find that it is 1.404 per H atom, 2.809 per H2 molecule, and 2.351 per gas particle assuming protosolar metallicity and the latest values of the ISM gas phase abundances of metals.
+#### ALMA Polarization Study of the Magnetic Fields in Two Massive Clumps in the 20 km s$^{-1}$ Cloud of the Central Molecular Zone
+ - **Authors:** Yuhua Liu, Xing Lu, Junhao Liu, Xing Pan, Qizhou Zhang, Hauyu Baobab Liu, Meng-Zhe Yang, Shih-Ping Lai, Tao-Chung Ching, Wenyu Jiao, Yankun Zhang, Pak Shing Li, Zhiqiang Shen, Tie Liu, Adam Ginsburg, Qi-Lao Gu, Mengke Zhao
+ - **Subjects:** Subjects:
+Astrophysics of Galaxies (astro-ph.GA)
+ - **Arxiv link:** https://arxiv.org/abs/2601.11098
+
+ - **Pdf link:** https://arxiv.org/pdf/2601.11098
+
+ - **Abstract**
+ We present the Atacama Large Millimeter/submillimeter Array (ALMA) observations of linearly polarized 870 $\mu$m continuum emission at a resolution of $\sim$0.2$^{\prime\prime}$ (2000 au) toward the two massive clumps, Clump 1 and Clump 4, in the 20 km s$^{-1}$ cloud. The derived magnetic field strengths for both clumps range from $\sim$0.3 to 3.1 mG using the Angular Dispersion Function (ADF) method. The magnetic field orientations across multiple scales suggests that the magnetic field dominates at the cloud scale, whereas gravity likely governs the structures at the core (0.01$-$0.1 pc) and condensation ($\le$ 0.01 pc) scales. Furthermore, the study on the angular difference between the orientations of the local gravity gradient and the magnetic field suggests that the magnetic field predominantly governs the dynamics in the diffuse regions, while gravity and star formation feedback become increasingly significant within the dense regions. The ratio of the magnetic field tension force $F_\textrm{B}$ to the gravitational force $F_\textrm{G}$ suggests that the magnetic field may provide some support against gravity, but it is insufficient to prevent gas from infalling toward the dense cores.
+#### Unveiling Ionized Jet Morphologies: Sub-arcsecond VLA Observations of Compact Radio Sources
+ - **Authors:** Tatiana M. Rodriguez (1), Peter Hofner (2 and 3), Emmanuel Momjian (4), Esteban D. Araya (5 and 2), Ananay Sethi (2), Viviana Rosero (6) ((1) University of Cologne, (2) New Mexico Institute of Mining and Technology, (3) Adjunct Astronomer at the National Radio Astronomy Observatory, (4) National Radio Astronomy Observatory, (5) Western Illinois University, (6) California Institute of Technology)
+ - **Subjects:** Subjects:
+Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
+ - **Arxiv link:** https://arxiv.org/abs/2601.11130
+
+ - **Pdf link:** https://arxiv.org/pdf/2601.11130
+
+ - **Abstract**
+ We present sub-arcsecond ($\theta\sim0.1^{\prime\prime}$) resolution VLA 1.3 cm continuum and 22.2 GHz H$_2$O maser observations toward 15 compact radio continuum sources with rising spectral index and 8 string-like radio continuum structures in the Rosero et al. (2016, 2019) survey. Three different morphologies are observed: elongated or double-peak string-like structure (6 out of 23 cases), a collection of distinct continuum peaks (4 out of 23 cases), and single compact sources (13 out of 23 cases). The majority of H$_2$O maser spots detected are within a sky-projected distance of $\sim5,000$ au from the radio continuum peaks and tend to be well aligned and distributed in an elongated structure when more than three spots are observed. We generally recover less emission than Rosero et al. (2016, 2019), which together with the fact that more than half of the jet candidates in our survey appear mostly compact, suggest core/halo shock structures even on small scales. We also detected proper motion in 10 cases and measured an average projected velocity of approximately 120 km s$^{-1}$. Radio brightness variability is detected in at least two cases, possibly due to weak accretion bursts. This work, together with our previous molecular jet study, provides further evidence that support the main source of ionization in the studied sources is shocks, yet collimation is only observed in 4 cases. We conclude that the available data supports the thermal jet classification of 7 sources, and the ionized jet interpretation is further supported in 16 sources.
+#### Rescaling Transforms for Local Models of Spherical Flows
+ - **Authors:** Elliot M. Lynch, Guillaume Laibe
+ - **Subjects:** Subjects:
+Solar and Stellar Astrophysics (astro-ph.SR); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)
+ - **Arxiv link:** https://arxiv.org/abs/2601.11337
+
+ - **Pdf link:** https://arxiv.org/pdf/2601.11337
+
+ - **Abstract**
+ Previously we developed a local model for a spherically contracting/expanding gas cloud that can be used to study turbulence and small scale instabilities in such flows. In this work we generalise the super-comoving variables used in studies of cosmological structure formation to our local spherical flow model, which make it significantly easier to derive analytical solutions and analyse the interactions of more complex flows with the background. We show that a wide class of solutions to the local spherical flow model can be obtained via a mapping from the corresponding solutions in regular Cartesian flows. The rescaling of time in the transformation results in a modification of the linear instabilities that can occur in spherical flows, causing them to have a time dependent growth rate in the physical time coordinate, and can prevent slower instabilities from operating. Finally, we show that the small scale flows in isotropic contraction/expansion can be mapped directly to Cartesian, inviscid, incompressible hydrodynamics, meaning that one expects a form of rescaled Kolmogorov-turbulence at the small scale of isotropically contracting/expanding flows.
+#### Galactic core-tail structure in BEC dark matter with Kapitza potential
+ - **Authors:** Itauany do Nascimento Barroso, Hermano Velten
+ - **Subjects:** Subjects:
+Astrophysics of Galaxies (astro-ph.GA)
+ - **Arxiv link:** https://arxiv.org/abs/2601.11477
+
+ - **Pdf link:** https://arxiv.org/pdf/2601.11477
+
+ - **Abstract**
+ Recently, the experimental realization of a Kapitza potential in a Bose-Einstein Condensate (BEC) has been reported for the first time in literature, motivating further theoretical investigations of such system. At the same time, in the astrophysical context, BEC dark matter models have been widely studied as a possible phenomenological explanation for the dark matter phenomena. We model the galactic structure with an inner cored profile obtained from the ground state equilibrium solution of the Schroedinger-Poisson together with a Kapitza-BEC like interaction for the tail region. We find reasonable agreement of the model with representative galaxy rotation curves available in the SPARC catalogue.
+
+
+by olozhika (Xing Yuchen). 
+
+
+2026-01-19