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1. The ALMA Survey of Gas Evolution of PROtoplanetary Disks (AGE-PRO). V. Protoplanetary Gas Disk Masses

   https://doi.org/10.3847/1538-4357/adcd6e  

   Trapman, Leon; Zhang, Ke; Rosotti, Giovanni P; Pinilla, Paola; Tabone, Benoît; Pascucci, Ilaria; Agurto-Gangas, Carolina; Anania, Rossella; Carpenter, John; Cieza, Lucas A; et al (July 2025, The Astrophysical Journal)

   Abstract The evolution of the gas mass of planet-forming disks around young stars is crucial for our understanding of planet formation, yet it has proven hard to constrain observationally, due both to the difficulties of measuring gas masses and the lack of a homogeneous sample. Here we present a large grid of thermochemical models that we use to measure protoplanetary gas disk masses of AGE-PRO, the Atacama Large Millimeter/submillimeter Array survey of Gas Evolution in PROtoplanetary disks. AGE-PRO covers a sample of 30 disks around similar spectral type (M3-K6) stars with ages between 0.1 and 10 Myr. Our approach is to simultaneously fit observations of CO isotopologues and N₂H⁺, a complementary molecule produced when CO freezes out. We find that the median gas mass of the three regions decreases over time, from $7.0_{-2.6}^{+4.4}\times 10^{-3}{M}_{\odot }$in Ophiuchus (≲1 Myr) to $9.4_{-3.4}^{+5.4}\times 10^{-4}{M}_{\odot }$for Lupus (∼1–3 Myr) and $6.8_{-2.8}^{+5.1}\times 10^{-4}{M}_{\odot }$for Upper Sco (∼2–6 Myr), with ∼1 dex scatter in gas mass in each region. We note that the gas mass distributions for Lupus and Upper Sco look very similar, which could be due to survivorship bias for the latter. The median bulk CO abundance in the CO emitting layer is found to be a factor ∼10 lower than the interstellar medium value but does not significantly change between Lupus and Upper Sco. From Lupus to Upper Sco, the median gas-to-dust mass ratio increases by a factor ∼3 from ∼40 to ∼120, suggesting efficient inward pebble drift and/or the formation of planetesimals. 

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2. The metastable Q ³ Δ ₂ state of ThO: a new resource for the ACME electron EDM search

   https://doi.org/10.1088/1367-2630/ab6a3a  

   Wu, X.; Han, Z.; Chow, J.; Ang, D. G.; Meisenhelder, C.; Panda, C. D.; West, E. P.; Gabrielse, G.; Doyle, J. M.; DeMille, D. (February 2020, New Journal of Physics)

   Abstract The best upper limit for the electron electric dipole moment was recently set by the ACME collaboration. This experiment measures an electron spin-precession in a cold beam of ThO molecules in their metastable $H{(}^3{\mathrm{\Delta }}_1)$state. Improvement in the statistical and systematic uncertainties is possible with more efficient use of molecules from the source and better magnetometry in the experiment, respectively. Here, we report measurements of several relevant properties of the long-lived $Q{(}^3{\mathrm{\Delta }}_2)$state of ThO, and show that this state is a very useful resource for both these purposes. TheQstate lifetime is long enough that its decay during the time of flight in the ACME beam experiment is negligible. The large electric dipole moment measured for theQstate, giving rise to a large linear Stark shift, is ideal for an electrostatic lens that increases the fraction of molecules detected downstream. The measured magnetic moment of theQstate is also large enough to be used as a sensitive co-magnetometer in ACME. Finally, we show that theQstate has a large transition dipole moment to the $C{(}^1{\mathrm{\Pi }}_1)$state, which allows for efficient population transfer between the ground state $X{(}^1{\mathrm{\Sigma }}^{+})$and theQstate via $X-C-Q$Stimulated Raman Adiabatic Passage (STIRAP). We demonstrate 90 % STIRAP transfer efficiency. In the course of these measurements, we also determine the magnetic moment ofCstate, the $X\to C$transition dipole moment, and branching ratios of decays from theCstate. 

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3. The ALMA Survey of Gas Evolution of PROtoplanetary Disks (AGE-PRO). XI. Beam-corrected Gas Disk Sizes from Fitting ¹² CO Moment Zero Maps

   https://doi.org/10.3847/1538-4357/adc7af  

   Trapman, Leon; Vioque, Miguel; Kurtovic, Nicolás T; Zhang, Ke; Rosotti, Giovanni P; Pinilla, Paola; Carpenter, John; Cieza, Lucas A; Pascucci, Ilaria; Anania, Rossella; et al (July 2025, The Astrophysical Journal)

   Abstract The inward drift of millimeter–centimeter sized pebbles in protoplanetary disks has become an important part of our current theories of planet formation and, more recently, planet composition as well. The gas-to-dust size ratio of protoplanetary disks can provide an important constraint on how pebbles have drifted inward, provided that observational effects, especially resolution, can be accounted for. Here we present a method for fitting beam-convolved models to integrated intensity maps of line emission using theastropyPython package and use it to fit¹²CO moment zero maps of 10 Lupus and 10 Upper Scorpius protoplanetary disks from the ALMA Survey of Gas Evolution of PROtoplanetary Disks (AGE-PRO) Program, a sample of disks around M3-K6 stars that cover the  ∼1–6 Myr of gas disk evolution. From the unconvolved best fit models, we measure the gas disk size ( $R_{\mathrm{CO},90\%}^{\mathrm{model}}$), which we combine with the dust disk size ( $R_{\mathrm{dust},90\%}^{\mathrm{FRANK}}$) from continuum visibility fits from M. Vioque et al. to compute beam-corrected gas-to-dust size ratios. In our sample, we find gas-to-dust size ratios between  ∼1 and  ∼5.5, with a median value of $2.78_{-0.32}^{+0.37}$. Contrary to models of dust evolution that predict an increasing size ratio with time, we find that the younger disks in Lupus have similar (or even larger) median ratios $\left(3.02_{-0.33}^{+0.33}\right)$than the older disks in Upper Sco $\left(2.46_{-0.38}^{+0.53}\right)$. A possible explanation for this discrepancy is that pebble drift is halted in dust traps combined with truncation of the gas disk by external photoevaporation in Upper Sco, although survivorship bias could also play a role. 

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4. The CO-to-H ₂ Conversion Factor in the Barred Spiral Galaxy M83

   https://doi.org/10.3847/1538-4357/ad40a0  

   Lee, Amanda_M; Koda, Jin; Hirota, Akihiko; Egusa, Fumi; Heyer, Mark (June 2024, The Astrophysical Journal)

   Abstract We analyze the CO-to-H₂conversion factor (α_CO) in the nearby barred spiral galaxy M83. We present new Hiobservations from the VLA and single-dish GBT in the disk of the galaxy, and combine them with maps of CO(1-0) integrated intensity and dust surface density from the literature.α_COand the gas-to-dust ratio (δ_GDR) are simultaneously derived in annuli of 2 kpc width fromR= 1–7 kpc. We find thatα_COandδ_GDRboth increase radially, by a factor of ∼2–3 from the center to the outskirts of the disk. The luminosity-weighted averages over the disk areα_CO= 3.14 (2.06, 4.96) $M_{\odot }{\mathrm{pc}}^{-2}{\left[\mathrm{K}\mathrm{km}{\mathrm{s}}^{-1}\right]}^{-1}$andδ_GDR= 137 (111, 182) at the 68% (1σ) confidence level. These are consistent with theα_COandδ_GDRvalues measured in the Milky Way. In addition to possible variations ofα_COdue to the radial metallicity gradient, we test the possibility of variations inα_COdue to changes in the underlying cloud populations, as a function of galactic radius. Using a truncated power-law molecular cloud CO luminosity function and an empirical power-law relation for cloud mass and luminosity, we show that the changes in the underlying cloud population may account for a factor of ∼1.5–2.0 radial change inα_CO. 

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5. Analytical Model of Disk Evaporation and State Transitions in Accreting Black Holes

   https://doi.org/10.3847/1538-4357/ac6d5c  

   Cho 조, Hyerin 혜린; Narayan, Ramesh (June 2022, The Astrophysical Journal)

   Abstract State transitions in black hole X-ray binaries are likely caused by gas evaporation from a thin accretion disk into a hot corona. We present a height-integrated version of this process, which is suitable for analytical and numerical studies. With radiusrscaled to Schwarzschild units and coronal mass accretion rate ${\dot{m}}_c$to Eddington units, the results of the model are independent of black hole mass. State transitions should thus be similar in X-ray binaries and an active galactic nucleus. The corona solution consists of two power-law segments separated at a break radiusr_b∼ 10³(α/0.3)⁻², whereαis the viscosity parameter. Gas evaporates from the disk to the corona forr>r_b, and condenses back forr<r_b. Atr_b, ${\dot{m}}_c$reaches its maximum, ${\dot{m}}_{c,\max }\approx 0.02{\left(\alpha /0.3\right)}^3$. If atr≫r_bthe thin disk accretes with ${\dot{m}}_d<{\dot{m}}_{c,\max }$, then the disk evaporates fully before reachingr_b, giving the hard state. Otherwise, the disk survives at all radii, giving the thermal state. While the basic model considers only bremsstrahlung cooling and viscous heating, we also discuss a more realistic model that includes Compton cooling and direct coronal heating by energy transport from the disk. Solutions are again independent of black hole mass, andr_bremains unchanged. This model predicts strong coronal winds forr>r_b, and aT∼ 5 × 10⁸K Compton-cooled corona forr<r_b. Two-temperature effects are ignored, but may be important at small radii. 

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