3D Astrophysics Newsletter

6.9 Today´s new entry:

Anatomy of the internal bow shocks in the IRAS 04166+2706 protostellar jet

M. Tafalla, Y.-N. Su, H. Shang, D. Johnstone, Q. Zhang, J. Santiago-Garcia, C.-F. Lee, N. Hirano, L.-Y. Wang

Abstract: Context. Highly collimated jets and wide-angle outflows are two related components of the mass-ejection activity associated with stellar birth. Despite decades of research, the relation between these two components remains poorly understood.

Aims. We study the relation between the jet and the outflow in the IRAS 04166+2706 protostar. This Taurus protostar drives a molecular jet that contains multiple emission peaks symmetrically located from the central source. The protostar also drives a wide-angle outflow consisting of two conical shells.

Methods. We have used the Atacama Large Millimeter/submillimeter Array (ALMA) interferometer to observe two fields along the IRAS 04166+2706 jet. The fields were centered on a pair of emission peaks that correspond to the same ejection event. The observations were carried out in CO(2–1), SiO(5–4), and SO(65-54).

Results. Both ALMA fields present spatial distributions that are approximately elliptical and have their minor axes aligned with the jet direction. As the velocity increases, the emission in each field moves gradually across the elliptical region. This systematic pattern indicates that the emitting gas in each field lies in a disk-like structure that is perpendicular to the jet axis and whose gas is expanding away from the jet. A small degree of curvature in the first-moment maps indicates that the disks are slightly curved in the manner expected for bow shocks moving away from the IRAS source. A simple geometrical model confirms that this scenario fits the main emission features.

Conclusions. The emission peaks in the IRAS 04166+2706 jet likely represent internal bow shocks where material is being ejected laterally away from the jet axis. While the linear momentum of the ejected gas is dominated by the component in the jet direction, the sideways component is not negligible, and can potentially affect the distribution of gas in the surrounding outflow and core.

Journal: Astronomy & Astrophysics, in press
URL of preprint: https://arxiv.org/pdf/1610.01614v1
Comments : Accepted 27 September 2016, 12 pages, 12 figures
Submitted by: Mario Tafalla

3D Astrophysics Newsletter

6.8 Today´s new entry:

Marcus J. Freeman and Joel H. Kastner

A multi-wavelength 3D model of BD+30°3639

Abstract: We present a 3D multi-wavelength reconstruction of BD+30°3639, one of the best-studied planetary nebulae in the solar neighborhood. BD+30°3639, which hosts a [WR]-type central star, has been imaged at wavelength regimes that span the electromagnetic spectrum, from radio to X-rays. We have used the astrophysical modeling software SHAPE to construct a 3D morpho-kinematic model of BD+30°3639. This reconstruction represents the most complete 3D model of a PN to date from the standpoint of the incorporation of multi-wavelength data. Based on previously published kinematic data in optical emission lines and in lines of CO (radio) and H₂(near-IR), we were able to reconstruct BD+30’s basic velocity components assuming a set of homologous velocity expansion laws combined with collimated flows along the major axis of the nebula. We confirm that the CO “bullets” in the PN lie along an axis that is slightly misaligned with respect to the major axis of the optical nebula, and that these bullets are likely responsible for the disrupted structures of the ionized and H₂-emitting shells within BD+30. Given the relative geometries and thus dynamical ages of BD+30’s main structural components, it is furthermore possible that the same jets that ejected the CO bullets are responsible for the generation of the X-ray-emitting hot bubble within the PN. Comparison of alternative viewing geometries for our 3D reconstruction of BD+30°3639 with imagery of NGC 40 and NGC 6720 suggests a common evolutionary path for these nebulae.

Journal: The Astrophysical Journal, 226:15 (16pp), 2016 October
URL: http://iopscience.iop.org/article/10.3847/0067-0049/226/2/15/meta

3D Astrophysics Newsletter

6.7 Today´s new entry:

Cosmic Sculpture: A new way to visualise the Cosmic Microwave Background

Clements, D. L., Sato, S., Portela Fonseca, A.

Abstract: 3D printing presents an attractive alternative to visual representation of physical datasets such as astronomical images that can be used for research, outreach or teaching purposes, and is especially relevant to people with a visual disability. We here report the use of 3D printing technology to produce a representation of the all-sky Cosmic Microwave Background (CMB) intensity anisotropy maps produced by the Planck mission. The success of this work in representing key features of the CMB is discussed as is the potential of this approach for representing other astrophysical data sets. 3D printing such datasets represents a highly complementary approach to the usual 2D projections used in teaching and outreach work, and can also form the basis of undergraduate projects. The CAD files used to produce the models discussed in this paper are made available.

Journal: European Journal of Physics, in press
URL of preprint: http://cdsads.u-strasbg.fr/abs/2016arXiv161000501C
Submitted by: Dave Clements

3D Astrophysics Newsletter

6.6 Today´s new entry:

Dissecting a SN impostor’s circumstellar medium: MUSEing about the SHAPE of eta Car’s outer ejecta

A. Mehner, W. Steffen, J.H. Groh, F.P.A. Vogt, D. Baade, H.M.J. Boffin, K. Davidson, W.J. de Wit, R.M. Humphreys, C. Martayan, R.D. Oudmaijer, T. Rivinius, and F. Selman

Abstract:
Aims. The structural inhomogeneities and kinematics of massive star nebulae are tracers of their mass-loss history. We conduct a three-dimensional morpho-kinematic analysis of the ejecta of eta Car outside its famous Homunculus nebula.
Methods. We carried out the first large-scale integral field unit observations of eta Car in the optical, covering a field of view of 1’x1′ centered on the star. Observations with the Multi Unit Spectroscopic Explorer (MUSE) at the Very Large Telescope (VLT) reveal the detailed three dimensional structure of eta Car’s outer ejecta. Morpho-kinematic modeling of these ejecta is conducted with the code SHAPE.
Results. The largest coherent structure in eta Car’s outer ejecta can be described as a bent cylinder with roughly the same symmetry axis as the Homunculus nebula. This large outer shell is interacting with the surrounding medium, creating soft X-ray emission. We establish the shape and extent of the ghost shell in front of the southern Homunculus lobe and confirm that the NN condensation can best be modeled as a bowshock in the orbital/equatorial plane.
Conclusions. The SHAPE modeling of the MUSE observations indicates that the kinematics of the outer ejecta measured with MUSE can be described by a spatially coherent structure, and this structure also correlates with the extended soft X-ray emission associated with the outer debris field. The ghost shell just outside the southern Homunculus lobe hints at a sequence of eruptions within the time frame of the Great Eruption from 1837-1858 or possibly a later shock/reverse shock velocity separation. Our 3D morpho-kinematic modeling and the MUSE observations constitute an invaluable dataset to be confronted with future radiation-hydrodynamics simulations. Such a comparison may shed light on the yet elusive physical mechanism responsible for eta Car-like eruptions.

Journal: Astronomy & Astrophysics
URL of preprint: https://arxiv.org/pdf/1610.01688.pdf
Submitted by: Wolfgang Steffen