What is the physics behind the Larson mass–size relation?

Ballesteros-Paredes, Javier; Román-Zúñiga, C.; Salomé, Quentin; Zamora-Avilés, Manuel; Jiménez-Donaire, María J.

doi:10.1093/mnras/stz2575

Cited by 17 publications

(17 citation statements)

References 53 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…While we see a good correlation between these two quantities, the slopes for the relation derived under the two temperature assumptions varies significantly. The mass-size relation in the T H2CO approach follows M ∝ r 2.0±0.3 , close to the lines of constant column densities as would be expected from Larson's relations (e.g., Heyer et al 2009;Lombardi et al 2010;Ballesteros-Paredes et al 2019. In contrast to this, the mass-size relation in the T 20K approach follows a steeper relation of M ∝ r 3.0±0.2 , which is close to the line of constant density at 10 6 cm −3 .…”

Section: Fragmentation and Continuum Emissionsupporting

confidence: 80%

“…In the literature, mass-size relations with various exponents can be found. While some studies report relations close to the classical r −2.0 (e.g., Heyer et al 2009;Lombardi et al 2010;Ballesteros-Paredes et al 2019), steeper relations have been found as well. For example, Kainulainen et al (2011) found a mass-size relation with exponent 2.7 when sampling only the highest column density parts of their studied molecular clouds (those regions where the column density probability density functions leave the lognormal shape and rather flatten out).…”

Section: Fragmentationmentioning

confidence: 91%

See 1 more Smart Citation

Fragmentation and kinematics in high-mass star formation

Beuther

Gieser

Suri

et al. 2021

A&A

View full text Add to dashboard Cite

Context. The formation of high-mass star-forming regions from their parental gas cloud and the subsequent fragmentation processes lie at the heart of star formation research. Aims. We aim to study the dynamical and fragmentation properties at very early evolutionary stages of high-mass star formation. Methods. Employing the NOrthern Extended Millimeter Array and the IRAM 30 m telescope, we observed two young high-mass star-forming regions, ISOSS22478 and ISOSS23053, in the 1.3 mm continuum and spectral line emission at a high angular resolution (~0.8″). Results. We resolved 29 cores that are mostly located along filament-like structures. Depending on the temperature assumption, these cores follow a mass-size relation of approximately M ∝ r2.0 ± 0.3, corresponding to constant mean column densities. However, with different temperature assumptions, a steeper mass-size relation up to M ∝ r3.0 ± 0.2, which would be more likely to correspond to constant mean volume densities, cannot be ruled out. The correlation of the core masses with their nearest neighbor separations is consistent with thermal Jeans fragmentation. We found hardly any core separations at the spatial resolution limit, indicating that the data resolve the large-scale fragmentation well. Although the kinematics of the two regions appear very different at first sight – multiple velocity components along filaments in ISOSS22478 versus a steep velocity gradient of more than 50 km s−1 pc−1 in ISOSS23053 – the findings can all be explained within the framework of a dynamical cloud collapse scenario. Conclusions. While our data are consistent with a dynamical cloud collapse scenario and subsequent thermal Jeans fragmentation, the importance of additional environmental properties, such as the magnetization of the gas or external shocks triggering converging gas flows, is nonetheless not as well constrained and would require future investigation.

show abstract

Section: Fragmentation and Continuum Emissionsupporting

confidence: 80%

Section: Fragmentationmentioning

confidence: 91%

Fragmentation and kinematics in high-mass star formation

Beuther

Gieser

Suri

et al. 2021

A&A

View full text Add to dashboard Cite

show abstract

“…In the literature, mass-size relations with various exponents can be found. While some studies report relations close to the classical r −2.0 (e.g., Heyer et al 2009;Lombardi et al 2010;Ballesteros-Paredes et al 2019), steeper relations have been found as well. For example, Kainulainen et al ( 2011) found a mass-size relation with exponent 2.7 when sampling only the highest column density parts of their studied molecular clouds (those regions where the column density probability density functions leave the lognormal shape and rather flatten out).…”

Section: Fragmentationmentioning

confidence: 91%

Fragmentation and kinematics in high-mass star formation: CORE-extension targeting two very young high-mass star-forming regions

Beuther,

Gieser,

Suri

et al. 2021

Preprint

View full text Add to dashboard Cite

Context. The formation of high-mass star-forming regions from their parental gas cloud and the subsequent fragmentation processes lie at the heart of star formation research. Aims. We aim to study the dynamical and fragmentation properties at very early evolutionary stages of high-mass star formation. Methods. Employing the NOrthern Extended Millimeter Array (NOEMA) and the IRAM 30 m telescope, we observed two young high-mass star-forming regions, ISOSS22478 and ISOSS23053, in the 1.3 mm continuum and spectral line emission at a high angular resolution (∼0.8 ).Results. We resolved 29 cores that are mostly located along filament-like structures. Depending on the temperature assumption, these cores follow a mass-size relation of approximately M ∝ r 2.0±0.3 , corresponding to constant mean column densities. However, with different temperature assumptions, a steeper mass-size relation up to M ∝ r 3.0±0.2 , which would be more likely to correspond to constant mean volume densities, cannot be ruled out. The correlation of the core masses with their nearest neighbor separations is consistent with thermal Jeans fragmentation. We found hardly any core separations at the spatial resolution limit, indicating that the data resolve the large-scale fragmentation well. Although the kinematics of the two regions appear very different at first sight -multiple velocity components along filaments in ISOSS22478 versus a steep velocity gradient of more than 50 km s −1 pc −1 in ISOSS23053 -the findings can all be explained within the framework of a dynamical cloud collapse scenario. Conclusions. While our data are consistent with a dynamical cloud collapse scenario and subsequent thermal Jeans fragmentation, the importance of additional environmental properties, such as the magnetization of the gas or external shocks triggering converging gas flows, is nonetheless not as well constrained and would require future investigation.

show abstract

“…Third, the average scatter in the calculated mean surface density in the molecular ring GMCs (42 M pc −2 ) is found to be 4.5 times higher than that (9 M pc −2 ) in the outer Galaxy GMCs. Random variations in the degree of cloud overlap could account for the larger dispersions measured for Σ GM C in the molecular ring compared to other regions of the Galaxy (e.g., Ballesteros-Paredes et al 2019). These considerations add to the surmise that surface density measurements made toward the molecular ring are much more susceptible to systematic biases that both increase the scatter in and the measured values of Σ GM C compared to other regions of the Galaxy.…”

Section: Nature Of the Radial Variation: A Metallicity Dependent Co X...mentioning

confidence: 99%

The Mass-Size Relation and the Constancy of GMC Surface Densities in the Milky Way

Lada,

Dame

2020

Preprint

View full text Add to dashboard Cite

We use two existing molecular cloud catalogs derived from the same CO survey and two catalogs derived from local dust extinction surveys to investigate the nature of the GMC mass-size relation in the Galaxy. We find that the four surveys are well described by M GM C ∼ R 2 implying a constant mean surface density, Σ GM C , for the cataloged clouds. However, the scaling coefficients and scatter differ significantly between the CO and extinction derived relations. We find that the additional scatter seen in the CO relations is due to a systematic variation in Σ GM C with Galactic radius that is unobservable in the local extinction data. We decompose this radial variation of Σ GM C into two components, a linear negative gradient with Galactic radius and a broad peak coincident with the molecular ring and superposed on the linear gradient. We show that the former may be due to a radial dependence of X CO on metallicity while the latter likely results from a combination of increased surface densities of individual GMCs and a systematic upward bias in the measurements of Σ GM C due to cloud blending in the molecular ring. We attribute the difference in scaling coefficients between the CO and extinction data to an underestimate of X CO . We recalibrate the CO observations of nearby GMCs using extinction measurements to find that locally X CO = 3.6±0.3 × 10 20 cm −2 (K-km/s) −1 . We conclude that outside the molecular ring the GMC population of the Galaxy can be described to relatively good precision by a constant Σ GM C of 35 M pc −2 .

show abstract

What is the physics behind the Larson mass–size relation?

Cited by 17 publications

References 53 publications

Fragmentation and kinematics in high-mass star formation

Fragmentation and kinematics in high-mass star formation

Fragmentation and kinematics in high-mass star formation: CORE-extension targeting two very young high-mass star-forming regions

The Mass-Size Relation and the Constancy of GMC Surface Densities in the Milky Way

Contact Info

Product

Resources

About