The Mysterious Sickle Object in the Carina Nebula: A Stellar Wind Induced Bow Shock Grazing a Clump?

Ngoumou, J.; Preibisch, Thomas; Ratzka, Thorsten; Burkert, Andreas

doi:10.1088/0004-637x/769/2/139

Cited by 8 publications

(11 citation statements)

References 65 publications

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“…1 of Ascenso et al 2007). As shown by Ngoumou et al (2013), the star appears to be moving past a dense clump observed in 870µm images, and the shape and offset of the bow shock from the stellar image is consistent with a wind from the star impacting denser material in the vicinity of the globule. The star has a large proper motion of 8.7 mas yr −1 at PA = 307 degrees (95 km s −1 at a distance of 2.3 kpc), consistent with producing the bow shock (Zacharias et al 2013), and is most likely a runaway star ejected as its companion underwent a supernova explosion.…”

Section: The Runaway Star Trumpler 14 Mj 218mentioning

confidence: 57%

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A Survey of Irradiated Pillars, Globules, and Jets in the Carina Nebula

Hartigan

Reiter

Smith

et al. 2015

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We present wide-field, deep narrowband H 2 , Brγ, Hα, [S II], [O III], and broadband I and K-band images of the Carina star formation region. The new images provide a large-scale overview of all the H 2 and Brγ emission present in over a square degree centered on this signature star forming complex. By comparing these images with archival HST and Spitzer images we observe how intense UV radiation from O and B stars affects star formation in molecular clouds. We use the images to locate new candidate outflows and identify the principal shock waves and irradiated interfaces within dozens of distinct areas of star-forming activity. Shocked molecular gas in jets traces the parts of the flow that are most shielded from the intense UV radiation. Combining the H 2 and optical images gives a more complete view of the jets, which are sometimes only visible in H 2 . The Carina region hosts several compact young clusters, and the gas within these clusters is affected by radiation from both the cluster stars and the massive stars nearby. The Carina Nebula is ideal for studying the physics of young H II regions and PDR's, as it contains multiple examples of walls and irradiated pillars at various stages of development. Some of the pillars have detached from their host molecular clouds to form proplyds. Fluorescent H 2 outlines the interfaces between the ionized and molecular gas, and after removing continuum, we detect spatial offsets between the Brγ and H 2 emission along the irradiated interfaces. These spatial offsets can be used to test current models of PDRs once synthetic maps of these lines become available.

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Section: The Runaway Star Trumpler 14 Mj 218mentioning

confidence: 57%

“…The arc has recently been discussed in some detail by Ngoumou et al (2013), who refer to it as the 'Sickle' (see also Fig. 1 of Ascenso et al 2007).…”

Section: The Runaway Star Trumpler 14 Mj 218mentioning

confidence: 99%

A Survey of Irradiated Pillars, Globules, and Jets in the Carina Nebula

Hartigan

Reiter

Smith

et al. 2015

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“…The runway star interpretation, however, has some important caveats. Ngoumou et al (2013) note that the proper motion of MJ 218 is consistent with a runaway B star from Tr 16. They also note that the star is detected in X-rays (Broos et al 2011), and explain (reasonably) that the Xrays are produced by a low-mass, binary companion to the B star.…”

Section: Anomalous Arc-shaped Erosmentioning

confidence: 71%

“…c Identification and spectral type from Ascenso et al (2007). The driving star is identified as Trumpler 14 MJ 218 by Ngoumou et al (2013). d New Galactic O Star Catalog spectral type from (Sota et al 2014).…”

Section: Additional Bow Shock Candidates From Color Analysis Of Erosmentioning

confidence: 99%

“…We measured a standoff distance of 0.084 pc, similar to the 8.0 µm MBSc listed in Table 2, giving ambient ISM properties around ERO 21 of v0n 1/2 0,3 ≈ 4 and p0,−9 = 2.2, both on the low range compared to other EROs, especially the nearby (in projection) ERO 2 ( Figure 3). Ngoumou et al (2013) named ERO 21 "the sickle" and proposed a model in which the wind of a runaway B star interacts with an ambient density gradient in a low-density envelope surrounding a nearby, compact clump of molecular material. The bow-shock hence forms as a consequence of the high velocity of the driving star, Trumpler 14 MJ 218, which has a UCAC proper motion of 95 km s −1 at position angle 37 • (W of N).…”

Section: Anomalous Arc-shaped Erosmentioning

confidence: 99%

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Extended red objects and stellar-wind bow shocks in the Carina Nebula

Sexton

Povich

Smith

et al. 2014

Monthly Notices of the Royal Astronomical Society

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We report the results of infrared photometry on 39 extended red objects (EROs) in the Carina Nebula, observed with the Spitzer Space Telescope. Most EROs are identified by bright, extended 8.0 µm emission, which ranges from 10 to 40 in size, but our sample also includes 4 EROs identified by extended 24 µm emission. Of particular interest are nine EROs associated with late O or early B-type stars and characterized by arc-shaped morphology, suggesting dusty, stellar-wind bow shocks. These objects are preferentially oriented towards the central regions of the Carina Nebula, suggesting that these bow shocks are generally produced by the interactions of OB winds with the bulk expansion of the H II region rather than high proper motion. We identify preferred regions of mid-infrared color space occupied by our bow shock candidates, which also contain bow shock candidates in M17 and RCW 49 but are well-separated from polycyclic aromatic hydrocarbon emission or circumstellar discs. Color cuts identify an additional 12 marginally-resolved bow shock candidates, 10 of which are also associated with known late O or early B stars. H II region expansion velocities derived from bow shock candidate standoff distances are ∼10 km s −1 , assuming typical H II region gas densities, comparable to expansion velocities derived from bow shocks in M17 and RCW 49. One candidate bow shock provides direct evidence of physical interaction between the massive stellar winds originating in the Trumpler 15 and Trumpler 14 clusters, supporting the conclusion that both clusters are at similar heliocentric distances.

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NewXMM-Newtonobservation of the thermally emitting isolated neutron star 2XMM J104608.7-594306

Pires

Motch

Turolla

et al. 2015

A&A

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Context. The isolated neutron star (INS) 2XMM J104608.7-594306 is one of the only two to be discovered through their thermal emission since the ROSAT era. Possibly a remnant of a former generation of massive stars in the Carina nebula, the exact nature of the source is unclear, and it might be unique amongst the several classes of Galactic INSs. Aims. In a first dedicated XMM-Newton observation of the source, we found intriguing evidence of a very fast spin period of P ∼ 18.6 ms at the 4σ confidence level. Moreover, spectral features in absorption have also been identified. We re-observed 2XMM J104608.7-594306 with XMM-Newton to better characterise the spectral energy distribution of the source, confirm the candidate spin period, and possibly constrain the pulsar spin-down. Methods. We used the two XMM-Newton observations of 2XMM J104608.7-594306 to perform detailed timing and spectral X-ray analysis. Both the spin-down rate and the energy of the spectral features provide estimates on the neutron star magnetic field, which are crucial for investigating the evolutionary state of the neutron star. Results. Statistically acceptable spectral fits and meaningful physical parameters for the source are only obtained when the residuals at energies 0.55 keV and 1.35 keV are taken into account by the spectral modelling. While the former can result from the inhomogeneous temperature distribution on the surface of the neutron star or can be related to a local overabundance of oxygen in the Carina nebula, the one at 1.35 keV is only satisfactorily accounted for by invoking a line in absorption. In this case, the best-fit neutron star atmosphere models constrain the hydrogen column density, the effective temperature, and the luminosity of the source within N H = (2.5−3.3) × 10 21 cm −2 , T eff = (6−10) × 10 5 K, and L X = (1.1−7.4) × 10 32 erg s −1 . The implied distance is consistent with a location in (or in front of) the Carina nebula, and radiation radii are compatible with emission originating on most of the surface. Non-thermal X-ray emission is ruled out at levels above 0.5% (3σ) of the source luminosity. Unfortunately, the second XMM-Newton observation proved inconclusive in terms of confirming (discarding) the fast candidate spin, providing an upper limit on the pulsed fraction of the source that is very close to the limiting sensitivity for detecting the modulation found previously. Conclusions. In the absence of an unambiguous period determination and an estimate of the magnetic field, the nature of the source remains open to interpretation. Its likely association with the Carina cluster and its overall spectral properties (only shared by a handful of other peculiar INSs) disfavour a standard evolutionary path or one in which the source was previously recycled by accretion in a binary system. The star 2XMM J104608.7-594306 may be similar to Calvera (1RXS J141256.0+792204), a neutron star for which the scenario of an evolved anti-magnetar has been discussed. A better age estimate and deeper radio and γ-ray l...

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The Mysterious Sickle Object in the Carina Nebula: A Stellar Wind Induced Bow Shock Grazing a Clump?

Cited by 8 publications

References 65 publications

A Survey of Irradiated Pillars, Globules, and Jets in the Carina Nebula

A Survey of Irradiated Pillars, Globules, and Jets in the Carina Nebula

Extended red objects and stellar-wind bow shocks in the Carina Nebula

NewXMM-Newtonobservation of the thermally emitting isolated neutron star 2XMM J104608.7-594306

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