Carina’s pillars of destruction: the view from ALMA

Klaassen, Pamela; Reiter, Megan; McLeod, Anna F.; Mottram, J. C.; Dale, James E.; Gritschneder, Matthias

doi:10.1093/mnras/stz3012

Cited by 12 publications

(32 citation statements)

References 66 publications

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“…The pillar regions are considerably smaller (∼ 0.4 pc) and thus have only mildly supersonic velocity dispersions (M ∼ 2-4). The obtained velocity dispersions (M × c s ) are in the range 0.4-1 km s −1 , in agreement with observations of pillars on these scales (Klaassen et al 2019).…”

Section: Pillar Regionssupporting

confidence: 90%

“…Figure 1 shows that the tips of the pillars have the highest density enhancements. It is at these pillar tips that star formation is observed to occur (e.g., Smith et al 2010;Reiter & Smith 2013;Klaassen et al 2014Klaassen et al , 2019. Thus, we define three different pillar regions for more detailed analysis below: Pillar A, B and C of sizes 0.4 pc in each direction.…”

Section: Gas Structure and Evolutionmentioning

confidence: 99%

“…The expanding HII regions are also known to sculpt the surrounding neutral gas into structures reminiscent of the iconic 'Pillars of Creation' imaged by the Hubble Space Telescope (Hester et al 1996). Since then, there have been a wealth of observations using multiwavelength surveys that image these pillars and related structures such as ⋆ E-mail: Shyam.Menon@anu.edu.au globules, energetic evaporating globules (EEG's) and proplyds, and deduce dynamical quantities in and around them (Preibisch et al 2012;Klaassen et al 2014;Hartigan et al 2015;Schneider et al 2016;Klaassen, P. D. et al 2018;Klaassen et al 2019). Models proposed to explain their formation lie broadly in two categories: the classic collectand-collapse model by Elmegreen & Lada (1977) where the HII region sweeps up and accumulates cold gas creating density enhancements and eventually pillars in their shadows; or the more recent radiation-driven implosion (RDI) model where clouds with pre-existing density enhancements are sculpted to form pillars by impinging ionizing radiation.…”

Section: Introductionmentioning

confidence: 99%

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On the turbulence driving mode of expanding H ii regions

Menon

Federrath

Kuiper

2020

Monthly Notices of the Royal Astronomical Society

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We investigate the turbulence driving mode of ionizing radiation from massive stars on the surrounding interstellar medium (ISM). We run hydrodynamical simulations of a turbulent cloud impinged by a plane-parallel ionization front. We find that the ionizing radiation forms pillars of neutral gas reminiscent of those seen in observations. We quantify the driving mode of the turbulence in the neutral gas by calculating the driving parameter b, which is characterised by the relation σ 2 s = ln(1 + b 2 M 2 ) between the variance of the logarithmic density contrast σ 2 s (where s = ln(ρ/ρ 0 ) with the gas density ρ and its average ρ 0 ), and the turbulent Mach number M. Previous works have shown that b ∼ 1/3 indicates solenoidal (divergence-free) driving and b ∼ 1 indicates compressive (curl-free) driving, with b ∼ 1 producing up to ten times higher star formation rates than b ∼ 1/3. The time variation of b in our study allows us to infer that ionizing radiation is inherently a compressive turbulence driving source, with a time-averaged b ∼ 0.76 ± 0.08. We also investigate the value of b of the pillars, where star formation is expected to occur, and find that the pillars are characterised by a natural mixture of both solenoidal and compressive turbulent modes (b ∼ 0.4) when they form, and later evolve into a more compressive turbulent state with b ∼ 0.5-0.6. A virial parameter analysis of the pillar regions supports this conclusion. This indicates that ionizing radiation from massive stars may be able to trigger star formation by producing predominately compressive turbulent gas in the pillars.

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Section: Pillar Regionssupporting

confidence: 90%

Section: Gas Structure and Evolutionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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On the turbulence driving mode of expanding H ii regions

Menon

Federrath

Kuiper

2020

Monthly Notices of the Royal Astronomical Society

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“…The infrared to submillimeter images (see Smith et al 2010;Preibisch et al 2012Preibisch et al , 2011c revealed numerous pillar-like cloud structures in the southern parts of the Carina Nebula. Such pillars are thought to be a natural outcome of the feedback from strong ionizing radiation fields on clouds (see, e.g., Gritschneder et al 2010;Dale et al 2013;McLeod et al 2016;Klaassen et al 2020). While almost all pillars in the Carina Nebula point toward the massive stars around η Car in Tr 16, the Spitzer image (see Fig.…”

Section: Introductionmentioning

confidence: 99%

Detection of new O-type stars in the obscured stellar cluster Tr 16-SE in the Carina Nebula with KMOS

Preibisch

Flaischlen

Göppl

et al. 2021

A&A

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Context. The Carina Nebula harbors a large population of high-mass stars, including at least 75 O-type and Wolf-Rayet (WR) stars, but the current census is not complete since further high-mass stars may be hidden in or behind the dense dark clouds that pervade the association. Aims. With the aim of identifying optically obscured O- and early B-type stars in the Carina Nebula, we performed the first infrared spectroscopic study of stars in the optically obscured stellar cluster Tr 16-SE, located behind a dark dust lane south of η Car. Methods. We used the integral-field spectrograph KMOS at the ESO VLT to obtain H- and K-band spectra with a resolution of R ≈ 4000 (Δλ ≈ 5 Å) for 45 out of the 47 possible OB candidate stars in Tr 16-SE, and we derived spectral types for these stars. Results. We find 15 stars in Tr 16-SE with spectral types between O5 and B2 (i.e., high-mass stars with M ≥ 8 M⊙), only two of which were known before. An additional nine stars are classified as (Ae)Be stars (i.e., intermediate-mass pre-main-sequence stars), and most of the remaining targets show clear signatures of being late-type stars and are thus most likely foreground stars or background giants unrelated to the Carina Nebula. Our estimates of the stellar luminosities suggest that nine of the 15 O- and early B-type stars are members of Tr 16-SE, whereas the other six seem to be background objects. Conclusions. Our study increases the number of spectroscopically identified high-mass stars (M ≥ 8 M⊙) in Tr 16-SE from two to nine and shows that Tr 16-SE is one of the larger clusters in the Carina Nebula. Our identification of three new stars with spectral types between O5 and O7 and four new stars with spectral types O9 to B1 significantly increases the number of spectroscopically identified O-type stars in the Carina Nebula.

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“…Expanding H regions are known to sculpt the surrounding neutral gas in the ISM into structures reminiscent of the iconic 'Pillars of Creation' imaged by the Hubble Space Telescope (Hester et al 1996). There have been a wealth of observations that image these pillars and related structures such as globules, energetic evaporating globules (EEG's) and proplyds, to deduce dynamical quantities in and around them (Preibisch et al 2012;Mann et al 2014;Grenman & Gahm 2014;Klaassen et al 2014;Hartigan et al 2015;Schneider et al 2016b;Djupvik et al 2017;Klaassen et al 2018;Reiter et al 2019;Klaassen et al 2019). Models proposed to explain their formation fall broadly into two categories: the classic collect-and-collapse model by Elmegreen & Lada (1977), where the H region sweeps up and accumulates cold gas, creating density enhancements and eventually pillars in their shadows; or the more recent radiation-driven implosion (RDI) model, where clouds with pre-existing density enhancements are sculpted to form pillars by impinging ionizing radiation.…”

Section: Introductionmentioning

confidence: 99%

On the compressive nature of turbulence driven by ionising feedback in the pillars of the Carina Nebula

Menon,

Federrath,

Klaassen

et al. 2020

Preprint

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The ionizing radiation of massive stars sculpts the surrounding neutral gas into pillar-like structures. Direct signatures of star formation through outflows and jets are observed in these structures, typically at their tips. Recent numerical simulations have suggested that this star formation could potentially be triggered by photoionising radiation, driving compressive modes of turbulence in the pillars. In this study we use recent high-resolution ALMA observations of 12 CO, 13 CO, and C 18 O, 𝐽 = 2 − 1 emission to test this hypothesis for pillars in the Carina Nebula. We analyse column density and intensity-weighted velocity maps, and subtract any large-scale bulk motions in the plane of the sky to isolate the turbulent motions. We then reconstruct the dominant turbulence driving mode in the pillars, by computing the turbulence driving parameter 𝑏, characterised by the relation 𝜎 𝜌/𝜌 0 = 𝑏M between the standard deviation of the density contrast 𝜎 𝜌/𝜌 0 (with gas density 𝜌 and its average 𝜌 0 ) and the turbulent Mach number M. We find values of 𝑏 ∼ 0.7-1.0 for most of the pillars, suggesting that predominantly compressive modes of turbulence are driven in the pillars by the ionising radiation from nearby massive stars. We find that this range of 𝑏 values can produce star formation rates in the pillars that are a factor ∼ 3 greater than with 𝑏 ∼ 0.5, a typical average value of 𝑏 for spiral-arm molecular clouds. Our results provide further evidence for the potential triggering of star formation in pillars through compressive turbulent motions.

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Carina’s pillars of destruction: the view from ALMA

Cited by 12 publications

References 66 publications

On the turbulence driving mode of expanding H ii regions

On the turbulence driving mode of expanding H ii regions

Detection of new O-type stars in the obscured stellar cluster Tr 16-SE in the Carina Nebula with KMOS

On the compressive nature of turbulence driven by ionising feedback in the pillars of the Carina Nebula

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