Gaia-DR2 distance to the W3 Complex in the Perseus Arm

Navarete, Felipe; Galli, P. A. B.; Damineli, A.

doi:10.1093/mnras/stz1442

Cited by 25 publications

(21 citation statements)

References 58 publications

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“…The W3 IRS5 cluster system has a well known double IR source at the centre of an embedded cluster of a few hundred low mass stars (Megeath et al 1996). Located in the W3-Main region at a distance of 2.1 kpc (Megeath et al 2008;Navarete et al 2019) and a total luminosity of 2 × 10 5 L (Campbell et al 1995), it is considered to be at the early stages of star formation. We detect the blended HFS transitions of o-CH 2 near 70 GHz toward this region in emission, centred around −40 km s −1 (with an S /N > 5), a typical velocity found for molecular lines in this region (Dickel et al 1980) (see Fig.…”

Section: W3 Irs5mentioning

confidence: 99%

Hunting for the elusive methylene radical

Jacob

Menten

Gong

et al. 2021

A&A

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Context. The NKaKc = 404−313 transitions of ortho-CH2 between 68 and 71 GHz were first detected toward the Orion-KL and W51 Main star-forming regions. Given their high upper level energies (225 K) above the ground state, they were naturally thought to arise in dense, hot molecular cores near newly formed stars. However, this has not been confirmed by further observations of these lines and their origin has remained unclear. Generally, there is a scarcity of observational data for CH2 and, while it is an important compound in the astrochemical context, its actual occurrence in astronomical sources is poorly constrained. Aims. In this work, we aim to investigate the nature of the elusive CH2 emission, address its association with hot cores, and examine alternative possibilities for its origin. Owing to its importance in carbon chemistry, we also extend the search for CH2 lines by observing an assortment of regions, guided by the hypothesis that the observed CH2 emission is likely to arise from the hot gas environment of photodissociation regions (PDRs). Methods. We carried out our observations first using the Kitt Peak 12 m telescope to verify the original detection of CH2 toward different positions in the central region of the Orion Molecular Cloud 1. These were followed-up by deep integrations using the higher angular resolution of the Onsala 20 m telescope. We also searched for the NKaKc = 212−303 transitions of para-CH2 between 440–445 GHz toward the Orion giant molecular cloud complex using the APEX 12 m telescope. We also obtained auxiliary data for carbon recombination lines with the Effelsberg 100 m telescope and employing archival far infrared data. Results. The present study, along with other recent observations of the Orion region reported here, rule out the possibility of an association with gas that is both hot and dense. We find that the distribution of the CH2 emission closely follows that of the [CII] 158 μm emission, while CH2 is undetected toward the hot core itself. The observations suggest, rather, that its extended emission arises from hot but dilute layers of PDRs and not from the denser parts of such regions as in the case of the Orion Bar. This hypothesis was corroborated by comparisons of the observed CH2 line profiles with those of carbon radio recombination lines (CRRLs), which are well-known PDR tracers. In addition, we report the detection of the 70 GHz fine- and hyperfine structure components of ortho-CH2 toward the W51 E, W51 M, W51 N, W49 N, W43, W75 N, DR21, and S140 star-forming regions, and three of the NKaKc = 404−313 fine- and hyperfine structure transitions between 68–71 GHz toward W3 IRS5. While we have no information on the spatial distribution of CH2 in these regions, aside from that in W51, we again see a correspondence between the profiles of CH2 lines and those of CRRLs. We see a stronger CH2 emission toward the extended HII region W51 M rather than toward the much more massive and denser W51 E and N regions, which strongly supports the origin of CH2 in extended dilute gas. We also report the non-detection of the 212−303 transitions of para-CH2 toward Orion. Furthermore, using a non-LTE radiative transfer analysis, we can constrain the gas temperatures and H2 density to (163 ± 26) K and (3.4 ± 0.3) × 103 cm−3, respectively, for the 68–71 GHz ortho-CH2 transitions toward W3 IRS5, for which we have a data set of the highest quality. This analysis confirms our hypothesis that CH2 originates inwarm and dilute PDR layers. Our analysis suggests that for the excitation conditions under the physical conditions that prevail in such an environment, these lines are masering, with weak level inversion. The resulting amplification of the lines’ spontaneousemission greatly aids in their detection.

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Section: W3 Irs5mentioning

confidence: 99%

Hunting for the elusive methylene radical

Jacob

Menten

Gong

et al. 2021

A&A

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“…In order to evaluate the error-weighted parallax, we adopted the calculation used by Navarete et al (2019), based on the uncertainty on measured parallax ( ) and the spatial correlation between the position of the sources. We obtained for our sample the mean parallax π = 0.91±0.02 mas that was converted to the distance of 1099 +25 −24 pc.…”

Section: Selection Of Membersmentioning

confidence: 99%

Comparing the spatial and kinematic distribution of gas and young stars around the shell-like structure in the CMa OB1 association

Gregorio-Hetem,

Lefloch,

Hetem

et al. 2021

Preprint

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Context. The relationship between young stellar clusters and respective parental molecular clouds is still an open issue: for instance, are the similarities between substructures of clouds and clusters just a coincidence? Or would they be the indication of a physical relationship? In order to address these issues, we have studied the CMa OB1/R1 region that shows evidence for a complex star formation history. Aims. We obtained molecular clouds mapping with the IRAM-30 metre telescope to reveal the physical conditions of an unexplored side of the CMa region aiming to compare the morphology of the clouds with the distribution of the young stellar objects (YSOs). We also study the clouds kinematics searching for gradients and jet signatures that could trace different star formation scenarios. Methods. The YSOs were selected on the basis of astrometric data from Gaia EDR3 that characterise the moving groups. The distance of 1099 +25 −24 pc was obtained for the sample, based on the mean error-weighted parallax. Optical and near-infrared photometry is used to verify the evolutionary status and circumstellar characteristics of the YSOs. Results. Among the selected candidates we found 40 members associated with the cloud: 1 Class I, 11 Class II, and 28 Class III objects. Comparing the spatial distribution of the stellar population with the cores revealed by the 13 CO map, we verify that peaks of emission coincide with the position of YSOs confirming the association of these objects to their dense natal gas. Conclusions. Our observations support the large-scale scenario of the CMa shell-like structure formed as a relic of successive supernova events.

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“…It is the most active site of star formation in the Perseus Arm (Ogura & Ishida 1976;Oey et al 2005;Navarete et al 2011Navarete et al , 2019Kiminki et al 2015). These stars are divided into some clusters; the cluster associated with IC 1795 called W3 cluster (Navarete et al 2019) and W3 Main and W3(OH) are also associated with clusters, respectively (e.g., Megeath et al 2008). W3 Cluster is a most evolved cluster in W3 (Oey et al 2005).…”

Section: The W3 Giant Molecular Complexmentioning

confidence: 99%

“…Further, five early-type stars of B0-B3 are identified (Navarete et al 2011;Bik et al 2012;Kiminki et al 2015;Navarete et al 2019).…”

Section: The W3 Giant Molecular Complexmentioning

confidence: 99%

A Kinematic Analysis of the Giant Molecular Complex W3; Possible Evidence for Cloud-Cloud Collisions that Triggered OB Star Clusters in W3 Main and W3(OH)

Yamada,

Sano,

Tachihara

et al. 2021

Preprint

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The Hii region W3 is one of the most outstanding regions of high-mass star formation. Based on a new analysis of the 12 CO(J = 2-1) data obtained at 38 ′′ resolution, we have found that 1 each of the two active regions of high-mass star formation, W3 Main and W3(OH), is associated with two clouds of different velocities separated by 3-4 km s −1 , having cloud mass of 2000-4000 M ⊙ in each. In the two regions we have found typical signatures of a cloudcloud collision, i.e.,the complementary distribution with/without a displacement between the two clouds and/or a V-shape in the position-velocity diagram. We frame a hypothesis that a cloud-cloud collision triggered the high-mass star formation in the two regions. The collision in W3 Main involves a small cloud of ∼5 pc in diameter which collided with a large cloud of 10 pc × 20 pc. The collision in W3 Main compressed the gas in the direction of the collision path toward the west over a timescale of ∼1 Myr, where the dense gas W3 core associated with ten O stars are formed. The collision also produced a cavity in the large cloud having a size similar to the small cloud. The collision in W3(OH) has a younger timescale of ∼0.5 Myr and the forming-star candidates are heavily embedded in the clouds. The results reinforce the idea that a cloud-cloud collision is an essential process in high-mass star formation by rapidly creating the initial condition of 1 g cm −2 in the natal gas.

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Gaia-DR2 distance to the W3 Complex in the Perseus Arm

Cited by 25 publications

References 58 publications

Hunting for the elusive methylene radical

Hunting for the elusive methylene radical

Comparing the spatial and kinematic distribution of gas and young stars around the shell-like structure in the CMa OB1 association

A Kinematic Analysis of the Giant Molecular Complex W3; Possible Evidence for Cloud-Cloud Collisions that Triggered OB Star Clusters in W3 Main and W3(OH)

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