arXiv subjects

P. C. Cortés

Publications and source records attributed to P. C. Cortés.

6 recordsLinked to original sources

arXiv2026

Magnetic fields in Massive Star-Forming Regions (MagMaR). VIII. Magnetic field overrun by gravity in GGD 27's accretion streamers

Context. Accretion streamers connected to protostellar disks and/or envelopes are thought to transport material across several thousand of au. Whether the motions of the gas comprising these streamers are dominated by gravity, large scale external turbulence or the action of magnetic fields is still under scrutiny. Aims. The aim of this work is to understand the role of the magnetic fields in the star-formation processes, in particular the role that magnetic forces have in potentially leading flows of gas and the accretion onto the envelopes and disks orbiting protostars. Methods. First, we try to identify the large-scale accretion streamers toward the high-mass Young Stellar Object GGD 27-MM1 and fit their trajectories using the so-called Mendoza's model, a modification of the classical model of pure gravitational infalling motion of fluid particles in a potential well. Second, we estimate the strength of the magnetic field associated with the streamers. Then, we determine if the streamers are dominated by magnetic or centrifugal forces. Results. Inspecting the Atacama Large Millimeter/submillimeter Array (ALMA) H$_2$CO cube we were able to identify four accretion streamers spreading up to $\sim$7,000 au and fit their trajectories in the position-position-velocity space. The polarized continuum emission reveals a good alignment of the magnetic field and the trajectory of the streamers. Using the Davis-Chandrasekhar-Fermi method, we derive estimates for the magnetic field strength, find that the streamers are sub-alfvénic, and discuss (after estimating energy terms for turbulence, ordered motions, magnetic forces and gravity) a possible qualitative scenario in which, the gravitational well of the GGD 27-MM1 protostar dominates streamer gas motions over turbulence and magnetic forces at distances of $\sim 3,000$ au.

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arXiv2026

Challenges in probing turbulent and magnetic support in cores: the W43-MM1 protocluster case study

Estimating the level of non-thermal support in cores is both challenging and crucial for constraining the earliest stages of star formation. We quantify the kinetic and magnetic support operating within the cores of the high-mass protocluster W43-MM1, and test the assumptions behind the virial theorem used to interpret observations. We used ALMA 12m molecular line observations of DCN (3-2), 13CS (5-4), and CH3CN (5_3-4_3) to estimate kinetic support. The plane-of-sky magnetic field strength (B_POS) was derived from dust-polarization observations using the Davis-Chandrasekhar-Fermi method, obtained at the three-beam scale (~12500 au) and extrapolated to core scales (~2500 au) using the density-field strength relation. We derive kinetic support estimates for 45 cores (21 prestellar and 24 protostellar), of which 21 also have magnetic field estimates. Velocity dispersions range from 0.34 to 4.48 km/s, and B_POS values span 1.1-49.3 mG at core scales. Using the virial theorem, ~70% of cores appear stable against collapse when considering turbulence alone, and ~85% when combining both kinetic and magnetic support (alpha_vir,B > 1). These are unexpectedly high values, particularly for protostellar cores expected to be undergoing collapse. We conclude that contamination of linewidths by organized motions (1-3 km/s, consistent with previous observational studies), together with the omission of surface terms in the observational virial theorem, prevents accurate measurement of non-thermal support in cores. This highlights that simplified virial analyses can introduce significant biases when assessing physical support mechanisms within cores.

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arXiv2026

Magnetic Fields in Massive Star-forming Regions (MagMaR). VII. On the dynamical importance of B-fields in massive protocluster W33 A

Magnetic fields (B-fields) are likely important in massive protocluster formation, but their role remains poorly constrained. We present 1.2 mm ALMA full-polarization observations of W33 A, a massive star-forming region at 2.4 kpc, with an angular resolution of 0.3 arcsec (730 au). The region is resolved into 20 dense cores and 9 filaments. The plane-of-sky B-field, inferred from linearly polarized dust emission, shows diverse structures: two nearly perpendicular large-scale components oriented northwest-southeast (NW-SE) and northeast-southwest (NE-SW), and two localized features toward the millimeter peaks MM1 and MM2. The NW-SE component could be shaped by a molecular outflow. The NE-SW component is coherent along the main filaments F1, F-Main, and Tail, all of which show trans-Alfvenic turbulence. In F-Main, the line mass exceeds the turbulent critical value, implying that magnetic support is required to prevent radial collapse and suppress fragmentation. In F1 and Tail, turbulence alone can support the gas against gravity, although B-fields may provide additional support. Toward MM1, the B-field follows a spiral-like infalling streamer traced by CH3CN. The trans-Alfvenic state of the accreting gas suggests efficient magnetic damping of turbulence and a magnetically regulated, laminar accretion flow feeding the core. Toward MM2, the B-field shows an hourglass morphology fitted by parabolic curves. Two independent methods give a consistent field strength of about 8.1(1.9) mG, and virial analysis indicates that the B-field is dynamically important in delaying collapse of MM2. Within a single protocluster, B-fields can stabilize filaments, regulate accretion, and delay core collapse, highlighting their diverse dynamic role in high-mass star formation.

astro-ph.GA↗

arXiv2026

JOYS$+$: A JWST/MIRI survey of the evolution of H$_2$ winds and jets from low-mass protostars

Protostellar outflows display wide-angle winds and collimated jets, the magnetocentrifugal launching of which enables accretion onto the protostar. The majority of the outflow mass is likely ejected or entrained molecular H$_2$, which can now be studied in unprecedented detail with JWST. Using JWST MIRI/MRS observations towards 13 single and 20 multiple Class 0 and I protostars, we investigate the nature and evolution of the H$_2$ wind and jet morphology, mass outflow rate, and velocity and temperature structure. We construct line flux and velocity maps of the H$_2$ S(1) and S(7) lines as well as the sub-mm CO traced by ALMA. Low-$J$ ($J\le4$) H$_2$ transitions trace extended wide-angle, low-velocity (0-20 km s$^{-1}$) winds within the contours of the low-velocity ($< 30$ km s$^{-1}$) sub-mm CO emission, while high-$J$ ($J >5$) transitions are associated with shocks and knots. In Class 0 sources with a known high-velocity ($> 30$ km s$^{-1}$) molecular CO or SiO jet, higher H$_2$ velocities are found along the jet axis. The opening angle of the wind traced by the H$_2$ S(1) line broadens from $\sim20^\circ$ to $\sim90^\circ$ through the Class 0 to Class I stage. Near the base of each blue-shifted outflow lobe, we extract representative spectra, where rotation diagram fitting of the H$_2$ lines is combined with the outflow width and H$_2$ line velocity to measure the mass-loss rates. The rotation diagrams show a warm $\sim 600$ K, component with two orders of magnitude more mass than the hot, 1500-3000 K component. The H$_2$ outflow mass-loss rates decline by two orders of magnitude from the Class 0 to Class II stage and are correlated with bolometric luminosity. The declining warm H$_2$ mass loss rates and increasing opening angles from the Class 0 to I stages, and the absence of H$_2$ jets in the Class I sources, are consistent with the predictions of MHD disk wind models.

astro-ph.SR↗

arXiv2026

PRODIGE - envelope to disk with NOEMA: VII. (Complex) organic molecules in the NGC1333 IRAS4B1 outflow: A new laboratory for shock chemistry

Shock chemistry is an excellent tool to shed light on the formation and destruction mechanisms of complex organic molecules (COMs). The L1157-mm outflow is the only low-mass protostellar outflow that has extensively been studied in this regard. Using the data taken as part of the PRODIGE (PROtostars & DIsks: Global Evolution) large program, we aim to map COM emission and derive the molecular composition of the protostellar outflow driven by the Class 0 protostar NGC1333 IRAS4B1 to introduce it as a new laboratory to study the impact of shocks on COM chemistry. In addition to typical outflow tracers such as SiO and CO, outflow emission is seen from H2CO, HNCO, and HC3N, as well as from the COMs CH3OH, CH3CN, and CH3CHO, and even from deuterated species such as DCN, D2CO, and CH2DOH. Maps of integrated intensity ratios between CH3OH and DCN, D2CO, and CH3CHO reveal gradients with distance from the protostar. Intensity ratio maps of HC3N and CH3CN with respect to CH3OH peak in the southern lobe where temperatures are highest. Rotational temperatures derived towards two positions, one in each lobe, are found in the range ~50-100 K. Abundances with respect to CH3OH are higher by factors of a few than for the L1157-B1. In conclusion, for the first time, we securely detected the COMs CH3CN, CH3CHO, and CH2DOH in the IRAS 4B1 outflow, serendipitously with limited sensitivity and bandwidth. Targeted observations will enable the discovery of new COMs and a more detailed analysis of their emission. Morphological differences between molecules in the IRAS 4B1 outflow lobes and their relative abundances provide first proof that this outflow is a promising new laboratory for shock chemistry, which will offer crucial information on COM formation and destruction as well as outflow structure and kinematics.

astro-ph.GA↗

arXiv2025

ANTIHEROES-PRODIGE: Quantifying the connection from envelope to disk with the IRAM 30m telescope and NOEMA I. Attack of the streamers: L1448N's fight for order in the chaos

Star formation is a hierarchical process ranging from molecular clouds down to individual protostars. In particular how infalling asymmetric structures, called streamers, delivering new material onto protostellar systems, are connected to the surrounding envelope is not understood. We investigate the connection between the cloud material at 10000 au scales down to 300 au scales towards L1448N in the Perseus star-forming region hosting three young Class 0/I protostellar systems. Sensitive molecular line observations taken with the IRAM 30m telescope and NOEMA at 1.4 mm are used to study the kinematic properties in the region traced by the molecular lines. Several infalling streamers are associated with the protostellar systems, some of them traced by C18O and DCN, while one of them is bright in SO and SO2. The kinematic properties of the former streamers are consistent with the velocities observed at large envelope scales of 10000 au, while the latter case show different kinematics. The masses and infall rates of the streamers are 0.01 Msun and 0.01-0.1 Msun and 10^-6 Msun/yr and 5-18x10^-6 Msun/yr for IRS3A and IRS3C, respectively. The envelope mass in the L1448N region is ~16Msun, thus the mass of a single streamer is low compared to the envelope mass (<1%). However, compared to the estimated mass of the protostellar systems a single streamer could deliver up to 1% and 8-17% of mass towards IRS3A (M*~1.2 Msun) and IRS3C (M*~1 Msun), respectively. The rotational signatures of structures in L1448N are all connected - from the large-scale envelope, infalling streamers, down to the rotation of all three disks. Two of the three Class 0/I protostellar systems are still fed by this surrounding material, which can be associated to the remnant envelope. However, we also find a streamer that is bright in SO and SO2 towards IRS3C that could be connected to a nearby sulfur reservoir.

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