Showing new listings for Friday, 26 September 2025

[olozhika]

Showing new listings for Friday, 26 September 2025

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

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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: 13papers

Revising the Giant Planet Mass-Metallicity Relation: Deciphering the Formation Sequence of Giant Planets

• Authors: Yayaati Chachan, Jonathan J. Fortney, Kazumasa Ohno, Daniel Thorngren, Ruth Murray-Clay

• Subjects: Subjects:
  Earth and Planetary Astrophysics (astro-ph.EP)

• Arxiv link: https://arxiv.org/abs/2509.20428

• Pdf link: https://arxiv.org/pdf/2509.20428

• Abstract
  The rate at which giant planets accumulate solids and gas is a critical component of planet formation models, yet it is extremely challenging to predict from first principles. Characterizing the heavy element (everything other than hydrogen and helium) content of giant planets provides important clues about their provenance. Using thermal evolution models with updated H-He EOS and atmospheric boundary condition that varies with envelope metallicity, we quantify the bulk heavy element content of 147 warm ($&lt; 1000$ K) giant planets with well-measured masses and radii, more than tripling the sample size studied in Thorngren et al. 2016. These measurements reveal that the population's heavy element mass follows the relation $M_{\rm Z} = M_{\rm core} + f_Z (M_{\rm p} - M_{\rm core})$, with $M_{\rm core} = 14.7^{+1.8}{-1.6}$ Earth masses (M$\oplus$), $f_Z = 0.09 \pm 0.01$, and an astrophysical scatter of $0.66 \pm 0.08 \times M_Z$. The classical core-accretion scenario ($Z_{\rm p} = 1$ at 10 M$\oplus$ and $Z{\rm p} = 0.5$ at 20 M$\oplus$) is inconsistent with the population. At low planet masses ($<< 150$ M$\oplus$), $M_{\rm Z} \sim M_{\rm core}$ and as a result, $Z_{\rm p} = M_{\rm Z} / M_{\rm p}$ declines linearly with $M_{\rm p}$. However, bulk metallicity does not continue to decline with planet mass and instead flattens out at $f_Z \sim 0.09$ ($\sim 7 \times$ solar metallicity). When normalized by stellar metallicity, $Z_{\rm p} / Z_\star$ flattens out at $3.3 \pm 0.5$ at high planet masses. This explicitly shows that giant planets continue to accrete material enriched in heavy elements during the gas accretion phase.

Massive Star Formation at Supersolar Metallicities: Constraints on the Initial Mass Function

• Authors: Eda Gjergo, Zhiyu Zhang, Pavel Kroupa, Aleksei Sorokin, Zhiqiang Yan, Ziyi Guo, Tereza Jerabkova, Akram Hasani Zoonozi, Hosein Haghi

• Subjects: Subjects:
  Astrophysics of Galaxies (astro-ph.GA)

• Arxiv link: https://arxiv.org/abs/2509.20440

• Pdf link: https://arxiv.org/pdf/2509.20440

• Abstract
  Metals enhance the cooling efficiency of molecular clouds, promoting fragmentation. Consequently, increasing the metallicity may boost the formation of low-mass stars. Within the integrated galaxy initial mass function (IGIMF) theory, this effect is empirically captured by a linear relation between the slope of the low-mass stellar IMF, $\alpha_1$, and the metal mass fraction, $Z$. This linear $\alpha_1$-$Z$ relation has been calibrated up to $\approx 2 , Z_{\odot}$, though higher metallicity environments are known to exist. We show that if the linear $\alpha_1$-$Z$ relation extends to higher metallicities ($[Z] \gtrsim 0.5$), massive star formation is suppressed entirely. Alternatively, fragmentation efficiency may saturate beyond some metallicity threshold if gravitational collapse cascades rapidly enough. To model this behavior, we propose a logistic function describing the transition from metallicity-sensitive to metallicity-insensitive fragmentation regimes. We provide a user-friendly public code, pyIGIMF, which enables the instantaneous computation of the IGIMF theory with the logistic $\alpha_1$-$Z$ relation.

The interstellar heritage of comets

• Authors: Karen Willacy, Liton Majumdar, Boncho Bonev, Erika Gibb, Neil Dello Russo, Michael DiSanti, Ronald J. Vervack Jr, Nathan X Roth

• Subjects: Subjects:
  Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA)

• Arxiv link: https://arxiv.org/abs/2509.20530

• Pdf link: https://arxiv.org/pdf/2509.20530

• Abstract
  Comets have similar compositions to interstellar medium ices, suggesting at least some of their molecules maybe inherited from an earlier stage of evolution. To investigate the degree to which this might have occurred we compare the composition of individual comets to that of the well-studied protostellar region IRAS 16293-2422B. We show that the observed molecular abundance ratios in several comets correlate well with those observed in the protostellar source. However, this does not necessarily mean that the cometary abundances are identical to protostellar. We find the abundance ratios of many molecules present in comets are enhanced compared to their protostellar counterparts. For COH-molecules, the data suggest higher abundances relative to methanol of more complex species, e.g. HCOOH, CH3CHO, and HCOOCH3, are found in comets. For N-bearing molecules, the ratio of nitriles relative to CH3CN -- HC3N/CH3CN and HCN/CH3CN -- tend to be enhanced. The abundances of cometary SO and SO2 relative to H2S are enhanced, whereas OCS/H2S is reduced. Using a subset of comets with a common set of observed molecules we suggest a possible means of determining the relative degree to which they retain interstellar ices. This analysis suggests that over 84% of COH-bearing molecules can be explained by the protostellar composition. The possible fraction inherited from the protostellar region is lower for N-molecules at only 26--74%. While this is still speculative, especially since few comets have large numbers of observed molecules, it provides a possible route for determining the relative degree to which comets contain disk-processed material.

The SOMA Atomic Outflow Survey. I. An Atomic OI and Highly Ionized OIII Outflow from Massive Protostar G11.94-00.62

• Authors: Phillip Oakey, Yao-Lun Yang, Jonathan C. Tan, Thomas G. Bisbas, Rubén Fedriani, Kei Tanaka, Zoie Telkamp, Yichen Zhang, Christian Fischer, Lianis Reyes Rosa

• Subjects: Subjects:
  Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)

• Arxiv link: https://arxiv.org/abs/2509.20551

• Pdf link: https://arxiv.org/pdf/2509.20551

• Abstract
  Massive stars regulate galaxy evolution and star formation through their powerful physical and chemical feedback, but their formation remains poorly understood. Accretion powered outflows can provide important diagnostics of massive star formation. We present first results from the SOMA Atomic Outflow Survey, a far-infrared massive star formation survey using the FIFI-LS spectrometer on SOFIA. We report detection of [OIII] $^3P_2\rightarrow^3P_1$ emission at 52 $\mu$m from the massive protostar G11.94-0.62, tracing highly ionized gas. We also detect [OI] $^3P_2\rightarrow^3P_1$ and $^3P_1\rightarrow^3P_0$ at 63 and 145 $\mu$m tracing atomic gas, as well as CO $J=14\rightarrow13$ at 186 $\mu$m from highly excited molecular gas. The [OIII] and [OI] lines exhibit large line widths ($\sim400$ and $\sim40-80$ km s$^{-1}$, respectively) and their morphologies are consistent with a wide-angle bipolar outflow. Molecular tracers ($^{12}$CO, $^{13}$CO, C$^{18}$O, H$2$CO, and CH$3$OH) observed with ALMA also suggest a self-consistent outflow morphology. Ionized nebula/PDR modeling imply an ionized outflow mass flux of $\sim8\times10^{-5}:M\odot$ yr$^{-1}$ and an atomic outflow mass flux of $\sim5\times10^{-6}:M\odot$ yr$^{-1}$, while the molecular outflow traced by CO has an implied mass flux of $\sim3\times10^{-4}:M_\odot$ yr$^{-1}$. The mass and momentum flux in the ionized outflow is consistent with the main component of the primary disk wind, while the molecular component is mainly swept-up, secondary outflow gas. We also observe G11.94-0.62 with the LBT in the near-infrared, potentially tracing the base of wide-angle outflow cavities. SED modeling implies $m_\star = 22.4^{+21}{-11}:M\odot$, while the [OIII] emission implies $m_*\gtrsim30:M_\odot$ and that the protostar is in the final stages of its accretion.

Discovery of Two Highly Scattered Pulsars from Image-Based Circular Polarization Searches with the Australian SKA Pathfinder

• Authors: Rahul Sengar, David L. Kaplan, Emil Lenc, Akash Anumarlapudi, Natasha Hurley-Walker, Ziteng Wang, Laura Driessen, Dougal Dobie, Tara Murphy

• Subjects: Subjects:
  High Energy Astrophysical Phenomena (astro-ph.HE)

• Arxiv link: https://arxiv.org/abs/2509.20611

• Pdf link: https://arxiv.org/pdf/2509.20611

• Abstract
  We report the discovery and timing of two pulsars from a sample of four circularly polarized sources identified in radio continuum images taken as part of the Australian SKA Pathfinder (ASKAP) Variables and Slow Transients (VAST) survey. Observations with the Parkes (Murriyang) radio telescope confirmed both sources as normal pulsars with high dispersion measures. PSR J1646$-$4451 has a spin period of 217 ms and a dispersion measure (DM) of 928 $\rm cm^{-3} , pc$, while PSR J1837$-$0616 exhibits a spin period of 118 ms and a DM of 793 $\rm cm^{-3} , pc$. These pulsars show extreme pulse broadening due to scattering, with measured scattering timescales of 290 ms and 343 ms at observing frequencies of 1.8 GHz and 1.9 GHz, respectively. These measurements imply extrapolated scattering timescales at 1 GHz of 2479 ms and 2154 ms, placing them among the most heavily scattered pulsars known to date. Our findings underscore the potential of using circular polarization in radio continuum images as a tool for identifying highly scattered pulsars. Future wide-field radio continuum surveys are poised to uncover a broader population of extreme pulsars particularly those that are heavily scattered at 1.4 GHz, intrinsically faint, or residing in binaries$-$offering valuable insights into both pulsar demographics and the complex structure of the interstellar medium.

Millisecond Pulsar Discoveries in an Image-based MeerKAT Survey of the Galactic Bulge

• Authors: Rahul Sengar, Akash Anumarlapudi, David L. Kaplan, Dale A. Frail, Scott D. Hyman, Emil Polisensky

• Subjects: Subjects:
  High Energy Astrophysical Phenomena (astro-ph.HE)

• Arxiv link: https://arxiv.org/abs/2509.20614

• Pdf link: https://arxiv.org/pdf/2509.20614

• Abstract
  We report on the follow-up observations of circularly polarized sources identified in the MeerKAT image-based survey of the Galactic bulge. Using the Parkes radio telescope, we observed sixteen circularly polarized sources with the UWL receiver and detected nine pulsars among which six of them are new discoveries. All pulsars are fast rotators with spin periods under 100,ms. Among the new discoveries five are millisecond pulsars (MSPs) and one has a spin period of 55,ms. At least four new MSPs exhibit clear signs of binary motion in their discovery observations. The dispersion measures (DMs) of these pulsars fall between 18 and 330,pc,cm$^{-3}$, which is lower than expected for Galactic bulge members and indicates that these pulsars lie in the foreground along the line of sight rather than within the bulge itself. This is the first time such a large number of pulsars have been confirmed via an image-based survey. These discoveries underscore the exceptional efficacy of circular polarization selection in image-based pulsar surveys, and demonstrate the powerful synergy between high-sensitivity imaging and targeted time-domain follow-up using wide-band receivers and strengthen prospects for future deep pulsation searches$-$e.g., with MeerKAT or the forthcoming SKA or DSA-2000$-$to uncover the true millisecond pulsar population in the Galactic bulge.

Constraints on the Orbit of the Young Substellar Companion GQ Lup B from High-Resolution Spectroscopy and VLTI/GRAVITY Astrometry

• Authors: Vidya Venkatesan, S. Blunt, J. J. Wang, S. Lacour, G.-D. Marleau, G.A.L. Coleman, L. Guerrero, W. O. Balmer, L. Pueyo, T. Stolker, J. Kammerer, N. Pourré, M. Nowak, E. Rickman, A. Sivaramakrishnan, D. Sing, K. Wagner, A.-M. Lagrange, R. Abuter, A. Amorim, R. Asensio-Torres, J.-P. Berger, H. Beust, A. Boccaletti, M. Bonnefoy, H. Bonnet, M. S. Bordoni, G. Bourdarot, W. Brandner, F. Cantalloube, P. Caselli, B. Charnay, G. Chauvin, A. Chavez, A. Chomez, E. Choquet, V. Christiaens, Y. Clénet, V. Coudé du Foresto, A. Cridland, R. Davies, R. Dembet, J. Dexter, A. Drescher, G. Duvert, A. Eckart, F. Eisenhauer, N. M. Förster Schreiber, P. Garcia, R. Garcia Lopez, E. Gendron, R. Genzel, S. Gillessen, J. H. Girard, S. Grant, X. Haubois, G. Heißel, Th. Henning, S. Hinkley, S. Hippler, M. Houllé, Z. Hubert, L. Jocou, M. Keppler, P. Kervella, L. Kreidberg, N. T. Kurtovic, V. Lapeyrère, J.-B. Le Bouquin, D. Lutz, A.-L. Maire, F. Mang, A. Mérand, C. Mordasini, D. Mouillet, E. Nasedkin, T. Ott, G. P. P. L. Otten, C. Paladini, T. Paumard, K. Perraut, G. Perrin, S. Petrus, O. Pfuhl, D. C. Ribeiro, Z. Rustamkulov, J. Shangguan, T. Shimizu, A. Shields, J. Stadler, O. Straub, C. Straubmeier, E. Sturm, L. J. Tacconi, A. Vigan, F. Vincent, S. D. von Fellenberg, F. Widmann, T. O. Winterhalder, J. Woillez

• Subjects: Subjects:
  Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)

• Arxiv link: https://arxiv.org/abs/2509.20621

• Pdf link: https://arxiv.org/pdf/2509.20621

• Abstract
  Understanding the orbits of giant planets is critical for testing planet formation models, particularly at wide separations greater than 10 au where traditional core accretion becomes inefficient. However, constraining orbits at these separations has been challenging because of sparse orbital coverage and degeneracies in the orbital parameters. We use existing high-resolution spectroscopic measurements from CRIRES+ (R ~ 100000), astrometric data from SPHERE, NACO, and ALMA, and new high-precision GRAVITY astrometry to refine the orbit of GQ Lup B, a ~30 M_J companion at ~100 au, in a system that also hosts a circumstellar disk and a wide companion, GQ Lup C. Including radial velocity data significantly improves orbital constraints by breaking the degeneracy between inclination and eccentricity that affects astrometry-only fits for long-period companions. This work is among the first to combine high-precision astrometry with the companion's relative radial velocity to achieve improved orbital constraints. The eccentricity is refined from e = 0.47 (+0.14, -0.16) with GRAVITY alone to e = 0.35 (+0.10, -0.09) when RVs and GRAVITY data are combined. The orbit is misaligned by 63 (+6, -14) deg relative to the circumstellar disk and 52 (+19, -24) deg relative to the host star spin axis, and is more consistent (34 (+6, -13) deg) with the inclination of the wide tertiary companion GQ Lup C disk. These results support a formation scenario for GQ Lup B consistent with cloud fragmentation and highlight the power of combining companion RV constraints with interferometric astrometry to probe the dynamics and formation of wide-orbit substellar companions.

Reconciling the Tension Between Light Curve Modeling of Type II Supernovae and Neutrino-Driven Core-Collapse Supernovae Models with Late-Phase Spectroscopy

• Authors: Qiliang Fang, Hiroki Nagakura, Takashi J. Moriya

• Subjects: Subjects:
  High Energy Astrophysical Phenomena (astro-ph.HE)

• Arxiv link: https://arxiv.org/abs/2509.20675

• Pdf link: https://arxiv.org/pdf/2509.20675

• Abstract
  Type II supernovae (SNe II) are the most frequently observed outcome of core-collapse explosions and provide a valuable window into the physical mechanisms governing the deaths of massive stars. However, estimates of explosion properties based on optical light curve modeling often show tension with the predictions of modern neutrino-driven explosion models. In particular, when based on light curves from the explosions of red supergiant (RSG) tied to specific stellar wind models, many SNe II are found to originate from low-mass progenitors yet exhibit unusually high explosion energies ($E_{\rm K}$), far exceeding theoretical predictions. In this study, we incorporate late-phase (nebular) spectroscopy to estimate the helium core mass of the progenitor ($M_{\rm He,core}$), which serves as an additional constraint to break degeneracies in light curve modeling. This approach is applied to a sample of 32 well-observed SNe II, using a light curve model grid constructed from RSGs with arbitrarily stripped hydrogen-rich envelopes, rather than assuming a fixed wind model. Examining the resulting correlations among the physical parameters, we find that the tension between the observed $M_{\rm He,core}$-$E_{\rm K}$ and $E_{\rm K}$-$M_{\rm Ni}$ relations and those predicted by neutrino-driven explosion models has significantly lessened by incorporating nebular spectroscopy in light curve modeling. This study highlights the crucial role of nebular spectroscopy in interpreting SNe II observations and provides support to the neutrino-driven explosion mechanism as the dominant engine powering these events.

Galactic chemical evolution of short-lived radioactive isotopes produced by explosive nucleosynthesis: $^{60}$Fe and $^{53}$Mn

• Authors: Thomas C. L. Truemam, Andrés Yagüe López, Maria Lugaro, Marco Pignatari

• Subjects: Subjects:
  Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE)

• Arxiv link: https://arxiv.org/abs/2509.20956

• Pdf link: https://arxiv.org/pdf/2509.20956

• Abstract
  Several short-lived radionuclides (SLRs) are know to have existed in the early Solar System (ESS). These species, which typically decay with half-lives of the order of a few million years, can be used to probe the timescale of events preceding the birth of the Sun. We investigate the ESS origin of $^{53}$Mn, produced by core-collapse (CCSNe) and Type Ia supernovae (SNe Ia), and $^{60}$Fe, produced exclusively by CCSNe. We model the evolution of the radioactive-to-stable abundance ratios of these SLRs with a galactic chemical evolution (GCE) framework accounting for different supernova yields, SN Ia delay times, and other galactic features $(K)$. A further set of models are calculated assuming that SN Ia did not contribute any $^{53}$Mn to the ESS. The predicted ratios are compared to meteoritic ratios to derive a distribution of solar isolation times that includes uncertainties due to stochastic chemical enrichment and precision of the ESS values. The isolation times are then compared to those of $^{107}$Pd and $^{182}$Hf calculated in previous work. A self-consistent solution can be found within the current uncertainties, especially when using the GCE setups with $K = 1.6$ and 2.3, although the maximum likelihood for the \iso{60}Fe distribution is typically $\sim 4-5$ Myr shorter than for \iso{53}Mn. The predicted \iso{60}Fe/\iso{53}Mn ratio, instead, is completely inconsistent with the ESS value; this could be resolved using a larger fraction of faint CCSNe than usually considered in GCE models.

High energy gammas and neutrinos from the Sun, Jupiter and Earth

• Authors: Pablo de la Torre, Miguel Gutiérrez, Manuel Masip, Alejandro Oliver

• Subjects: Subjects:
  High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph)

• Arxiv link: https://arxiv.org/abs/2509.20970

• Pdf link: https://arxiv.org/pdf/2509.20970

• Abstract
  Cosmic rays reaching the atmosphere of an astrophysical object produce showers of secondary particles that may then scape into space. Here we obtain the flux of gammas and neutrinos of energy $E&gt;10$ GeV emited by the Sun, Jupiter and Earth. We show that, while the solar magnetic field induces an albedo flux of gammas from all the points in the Sun's surface, the dipolar magnetic field in the planets implies gammas only from the very peripheral region. Neutrinos, in contrast, can cross these objects and emerge from any point in their surface. The emission from these astrophysical objects is above the diffuse flux from cosmic ray interactions with the interstellar medium and has a distinct spectrum and gamma to neutrino ratio.

PENELLOPE VIII: Revisiting empirical relations to measure accretion luminosity

• Authors: E. Fiorellino, J. M. Alcalá, C. F. Manara, C. Pittman, P. Ábrahám, L. Venuti, S. Cabrit, R. Claes, M. Fang, Á. Kospál, G. Lodato, K. Mauco, Ł. Tychoniec

• Subjects: Subjects:
  Solar and Stellar Astrophysics (astro-ph.SR)

• Arxiv link: https://arxiv.org/abs/2509.21078

• Pdf link: https://arxiv.org/pdf/2509.21078

• Abstract
  The accretion luminosity (Lacc) in young, low-mass stars is crucial for understanding stellar formation, but direct measurements are often hindered by limited spectral coverage and challenges in UV-excess modeling. Empirical relations linking Lacc to various accretion tracers are widely used to overcome these limitations. This work revisits these empirical relations using the PENELLOPE dataset, evaluating their applicability across different star-forming regions and to accreting young objects other than Classical T Tauri Stars (CTTSs). We analyzed the PENELLOPE VLT/X-Shooter dataset of 64 CTTSs, measuring fluxes of several accretion tracers and adopting the stellar and accretion parameters derived from PENELLOPE works. We supplemented our analysis with the ODYSSEUS HST data set, which covers a wider spectral range in NUV bands. We compared the Lacc values obtained in the PENELLOPE and ODYSSEUS surveys finding statistically consistent results. Our analysis confirms that existing empirical relations, previously derived for the Lupus sample, provide reliable Lacc estimates for CTTSs in several other star-forming regions. We revisit empirical relations for accretion tracers in our dataset, based on HST-fit, with coefficients which are consistent within 1sigma with XS-fit results for most lines. We also propose a method to estimate extinction using these relations and investigate the empirical relations for Brackett lines (Br8 to Br21). The Lacc vs Lline empirical relations can be successfully used for statistical studies of accretion on young forming objects in different star-forming regions. These relations also offer a promising approach to independently estimate extinction in CTTSs. We confirm that near-infrared lines (PaB and BrG) reliably trace Lacc in high accretors, making them valuable tools for probing accretion properties of high accreting young stars not accessible in the UVB.

Unveiling Central ortho-H2D+ Depletion at Sub-kau Scales in Prestellar Core G205.46-14.56M3: The First Interferometric Evidence and Implications for Deuterium Chemistry

• Authors: Sheng-Jun Lin, Sheng-Yuan Liu, Dipen Sahu, Laurent Pagani, Tien-Hao Hsieh, Naomi Hirano, Shih-Ping Lai, Tie Liu, Shih-Ying Hsu, Shanghuo Li, Kee-Tae Kim

• Subjects: Subjects:
  Astrophysics of Galaxies (astro-ph.GA)

• Arxiv link: https://arxiv.org/abs/2509.21158

• Pdf link: https://arxiv.org/pdf/2509.21158

• Abstract
  Prestellar cores represent the initial conditions of star formation, but heavy molecules such as CO are strongly depleted in their cold, dense interiors, limiting the ability to probe core centers. Deuterated molecular ions therefore emerge as key tracers because deuterium fractionation is enhanced at low temperatures. We present the first direct observation of ortho-H2D+ depletion in the prestellar core G205.46-14.56M3 using ALMA 820um continuum and ortho-H2D+(110-111) data at ~300-au resolution. We confirm the previously reported two substructures, B1 and B2, and identify a central ortho-H2D+ depletion zone toward B1 with ~6$\sigma$ contrast and an inferred diameter $\lesssim$600au, together with a peak $x$(N2D+)/$x$(N2H+)=$1.03^{+0.07}_{-0.56}$. The observationally inferred profiles of $x$(ortho-H2D+) and $x$(N2D+)/$x$(N2H+) are reproduced by a deuteration-focused chemo-dynamical model; however, the central ortho-H2D+ depletion is only marginally matched within the $2\sigma$ upper limit, likely suggesting additional deuteration in the depletion zone. From these models we infer a core age of ~0.42Ma, comparable to the free-fall time, suggesting that the substructures formed via rapid, turbulence-dominated fragmentation rather than slow, quasi-static contraction. Our observations also reveal that ortho-H2D+ velocity dispersions are largely subsonic in the core and nearly thermal between B1 and B2, consistent with turbulence dissipating within a few free-fall times. These results highlight the critical role of deuterated ions for both chemical evolution and dynamics in dense cores.

The depletion of the asteroid belt and the impact history of the Earth

• Authors: Julio A. Fernandez

• Subjects: Subjects:
  Earth and Planetary Astrophysics (astro-ph.EP)

• Arxiv link: https://arxiv.org/abs/2509.21194

• Pdf link: https://arxiv.org/pdf/2509.21194

• Abstract
  We have evaluated the rate at which the asteroid belt is losing material, and how it splits between macroscopic bodies and meteoritic dust. The mass loss process is due to the injection of asteroid fragments into unstable dynamical regions, associated to mean-motion resonances with Jupiter, Saturn and Mars or secular resonances, from where they are scattered either to the region of the terrestrial planets or to the vicinity of Jupiter's orbit. Asteroid fragments that do not escape from the belt are ground down by mutual collisions to meteoritic dust. Under the assumption that 25% of the zodiacal dust mass is of asteroidal origin, we find that the asteroid belt is currently losing a fraction of about $\mu_o \simeq 8.8 \times 10^{-5}$ Ma$^{-1}$ of its collisionally-active mass (without the primordial objects Ceres, Vesta and Pallas), about 20% as macroscopic bodies, and 80% as dust particles that feed the zodiacal dust cloud. Extrapolation of the current mass loss rate to the past suggests only a moderate increase of the asteroid belt mass and the mass loss rate around 3.0 - 3.5 Ga ago (by about 50% and a factor of two respectively). Yet, should the computed $\mu_o$ be somewhat underestimated owing to the different uncertainties associated to its computation, the extrapolation to the past would lead to quite different results. For instance, a moderate increase in the computed $\mu_o$, say by a factor of three, would lead to an exponential increase of the asteroid mass and mass loss rate about 3.5 Ga ago. A greater asteroid mass loss rate in the past should be correlated with a more intense impact rate of the Earth, Moon and the other terrestrial planets, which is indeed what suggests the geologic record (Hartmann 2007).

by olozhika (Xing Yuchen).

2025-09-26