Early phases in the stellar and substellar formation and evolution

Barrado, D.; Gregorio-Monsalvo, I. de; Huélamo, N.; Morales-Calderón, M.; Bayo, A.; Palau, Aina; Ruíz, M. T.; Rivière-Marichalar, P.; Bouy, H.; Morata, Ó.; Stauffer, J. R.; Eiroa, C.; Noriega-Crespo, A.

doi:10.1051/0004-6361/201527938

Cited by 5 publications

(3 citation statements)

References 80 publications

(113 reference statements)

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“…On the other hand, it is more likely that the stars in the periphery were formed in the already expanding shell. Indeed, the ages of the B30 and B35 regions are about ∼2-3 Myr (Mathieu 2008;Barrado et al 2018), and thus, these stars could be formed when the shell was half of the size, and thus the stars will inherit the velocity of their parent clump.…”

Section: 𝞴-Orimentioning

confidence: 99%

Flipping-up the field: gravitational feedback as a mechanism for young clusters dispersal

Zamora-Avilés

Ballesteros-Paredes

Hernández

et al. 2019

Monthly Notices of the Royal Astronomical Society

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Recent analyses of Gaia data have provided direct evidence that most young stellar clusters are in a state of expansion, with velocities of the order of ∼ 0.5 km s −1 . Traditionally, expanding young clusters have been pictured as entities that became unbound due to the lack of gravitational binding once the gas from the parental cloud that formed the cluster has been expelled by the stellar radiation of the massive stars in the cluster. In the present contribution we used radiation-magnetohydrodynamic numerical simulations of molecular cloud formation and evolution to understand how stellar clusters form and disperse. We found that the ionising feedback from the newborn massive stars expels the gas from the collapse centre, flipping-up the gravitational potential as a consequence of the mass removal from the inside-out. Since neither the parental clouds, nor the formed shells are distributed symmetrically around the H II region, net forces pulling out the stars are present, accelerating them towards the edges of the cavity. We call this mechanism "gravitational feedback", in which the gravity from the expelled gas appears to be the crucial mechanism producing unbound clusters that expand away from their formation centre in an accelerated way in young stellar clusters. This mechanism naturally explains the "Hubble flow-like" expansion observed in several young clusters.

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Section: 𝞴-Orimentioning

confidence: 99%

Flipping-up the field: gravitational feedback as a mechanism for young clusters dispersal

Zamora-Avilés

Ballesteros-Paredes

Hernández

et al. 2019

Monthly Notices of the Royal Astronomical Society

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“…The Soul of Lupus with ALMA Consortium (SOLA, Saito et al 2015) is focused on the study of the Lupus clouds. The Lupus molecular complex (Barnard 1927) is composed of nine molecular clouds. In this work, we focus on the Lupus 1 and 3 clouds.…”

Section: Introductionmentioning

confidence: 99%

ALMA observations of the early stages of substellar formation in the Lupus 1 and 3 molecular clouds

Santamaría-Miranda

Gregorio-Monsalvo

Plunkett

et al. 2021

A&A

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Context. The dominant mechanism leading to the formation of brown dwarfs (BDs) remains uncertain. While the census of Class II analogs in the substellar domain continues to grow, the most direct keys to formation, which are obtained from younger objects (pre-BD cores and proto-BDs), are limited by the very low number statistics available. Aims. We aim to identify and characterize a set of pre-and proto-BDs as well as Class II BDs in the Lupus 1 and 3 molecular clouds to test their formation mechanism. Methods. We performed ALMA band 6 (1.3 mm) continuum observations of a selection of 64 cores previously identified from AzTEC/ASTE data (1.1 mm), along with previously known Class II BDs in the Lupus 1 and 3 molecular clouds. Surveyed archival data in the optical and infrared were used to complement these observations. We expect these ALMA observations prove efficient in detecting the youngest sources in these regions, since they probe the frequency domain at which these sources emit most of their radiation. Results. We detected 19 sources from 15 ALMA fields. Considering all the pointings in our observing setup, the ALMA detection rate was ∼23 % and the derived masses of the detected sources were between ∼0.18 and 124 M Jup. We classified these sources according to their spectral energy distribution as 5 Class II sources, 2 new Class I/0 candidates, and 12 new possible pre-BD or deeply embedded protostellar candidates. We detected a promising candidate for a Class 0/I proto-BD source (ALMA J154229.778-334241.86) and inferred the disk dust mass of a bona fide Class II BD. The pre-BD cores might be the byproduct of an ongoing process of large-scale collapse. The Class II BD disks follow the correlation between disk mass and the mass of the central object that is observed at the low-mass stellar regime. Conclusions. We conclude that it is highly probable that the sources in the sample are formed as a scaled-down version of low-mass star formation, although disk fragmentation may be responsible for a considerable fraction of BDs.

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“…The OB stars formed approximately 5 Myr ago, whereas the ring formation is less certain, occurring between 1 and 6 Myr ago due to a supernova explosion (Dolan & Mathieu 1999Kounkel 2020). The presence of strong stellar winds from the massive stars and ionization fronts in the region has shaped and ionized the neighboring ring of gas leading to the formation of dense molecular clouds (e.g., B35A, B30; Barrado et al 2018) and photodissociation regions (PDRs; Wolfire et al 1989;De Vries et al 2002;Lee et al 2005). For instance, the stellar wind from λ Orionis, the most massive star of the Collinder 69 cluster (an O8III star; Conti & Leep 1974), hits the western side of B35A compressing the cloud and forming a PDR between the molecular cloud edge and the extended HII region S264 (De Vries et al 2002;Craigon 2015).…”

Section: Introductionmentioning

confidence: 99%

Linking ice and gas in the λ Orionis Barnard 35A cloud

Perotti

Jørgensen

Fraser

et al. 2021

A&A

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Context. Dust grains play an important role in the synthesis of molecules in the interstellar medium, from the simplest species, such as H2, to complex organic molecules. How some of these solid-state molecules are converted into gas-phase species is still a matter of debate. Aims. Our aim is to directly compare ice and gas abundances of methanol (CH3OH) and carbon monoxide (CO) obtained from near-infrared (2.5−5 μm) and millimetre (1.3 mm) observations and to investigate the relationship between ice, dust, and gas in low-mass protostellar envelopes. Methods. We present Submillimeter Array (SMA) and Atacama Pathfinder EXperiment (APEX) observations of gas-phase CH3OH (JK = 5K−4K), 13CO, and C18O (J = 2−1) towards the multiple protostellar system IRAS 05417+0907, which is located in the B35A cloud, λ Orionis region. We use archival IRAM 30 m data and AKARI H2O, CO, and CH3OH ice observations towards the same target to compare ice and gas abundances and directly calculate CH3OH and CO gas-to-ice ratios. Results. The CO isotopologue emissions are extended, whereas the CH3OH emission is compact and traces the giant molecular outflow emanating from IRAS 05417+0907. A discrepancy between sub-millimetre dust emission and H2O ice column density is found for B35A−4 and B35A−5, similar to what has previously been reported. B35A−2 and B35A−3 are located where the sub-millimetre dust emission peaks and show H2O column densities lower than that of B35A−4. Conclusions. The difference between the sub-millimetre continuum emission and the infrared H2O ice observations suggests that the distributions of dust and H2O ice differ around the young stellar objects in this dense cloud. The reason for this may be that the four sources are located in different environments resolved by the interferometric observations: B35A−2, B35A−3, and, in particular, B35A−5 are situated in a shocked region that is plausibly affected by sputtering and heating, which in turn impacts the sub-millimetre dust emission pattern, while B35A−4 is situated in a more quiescent part of the cloud. Gas and ice maps are essential for connecting small-scale variations in the ice composition with the large-scale astrophysical phenomena probed by gas observations.

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Early phases in the stellar and substellar formation and evolution

Cited by 5 publications

References 80 publications

Flipping-up the field: gravitational feedback as a mechanism for young clusters dispersal

Flipping-up the field: gravitational feedback as a mechanism for young clusters dispersal

ALMA observations of the early stages of substellar formation in the Lupus 1 and 3 molecular clouds

Linking ice and gas in the λ Orionis Barnard 35A cloud

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