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We present proper-motion measurements and long-slit spectroscopy of the Mg  ii nebula around η Carinae obtained with the Wide Field Camera 3 and Space Telescope Imaging Spectrograph (STIS) aboard the Hubble Space Telescope. Detailed kinematics of the Mg  ii -emitting material constrain the geometry and history of mass-loss from η Car, and provide estimated ejection dates, assuming linear, ballistic motions. These measurements show that the neutral gas immediately outside the Homunculus – i.e. material into which the Homunculus is now expanding – was expelled over several decades prior to the Great Eruption, thus representing unshocked pre-eruption stellar wind. Material outside the Homunculus is therefore not part of a Hubble-like flow from the Great Eruption itself. This result discriminates between versions of merger-in-a-triple models for η Car. The STIS spectrum of Mg  ii -emitting gas along the projected outflow axis displays radial velocities consistent with bipolar expansion, redshifted several hundred km s−1 towards the northwest, similarly blueshifted towards the southeast, and with low internal velocity dispersion. The η Car system was therefore losing mass in a relatively fast, low-density polar wind for several decades that probably traces the critical inspiral phase preceding a merger event. [ABSTRACT FROM AUTHOR]

We present a detailed analysis of the protostellar outflow activity in the massive star-forming region NGC 3324, as revealed by new Early Release Observations (EROs) from the James Webb Space Telescope (JWST). Emission from numerous outflows is revealed in narrow-band images of hydrogen Paschen α (Paα) and molecular hydrogen. In particular, we report the discovery of 24 previously unknown outflows based on their H2 emission. We find three candidate driving sources for these H2 flows in published catalogues of young stellar objects (YSOs), and we identify 15 infrared point sources in the new JWST images as potential driving protostars. We also identify several Herbig–Haro (HH) objects in Paα images from JWST ; most are confirmed as jets based on their proper motions measured in a comparison with previous Hubble Space Telescope (HST) Hα images. This confirmed all previous HST -identified HH jets and candidate jets, and revealed seven new HH objects. The unprecedented capabilities of JWST allow the direct comparison of atomic and molecular outflow components at comparable angular resolution. Future observations will allow quantitative analysis of the excitation, mass-loss rates, and velocities of these new flows. As a relatively modest region of massive star formation (larger than Orion but smaller than starburst clusters), NGC 3324 offers a preview of what star formation studies with JWST may provide. [ABSTRACT FROM AUTHOR]

We present the first images of the nebula around η Carinae obtained with the Wide Field Camera 3 (WFC3) onboard the Hubble Space Telescope (HST), including an ultraviolet (UV) image in the F280N filter that traces Mg  ii  emission, plus contemporaneous imaging in the F336W, F658N, and F126N filters that trace near-UV continuum, [N  ii ], and [Fe  ii ], respectively. The F336W and F658N images are consistent with previous images in these filters, and F126N shows that for the most part, [Fe  ii ] λ12567 traces clumpy shocked gas seen in [N  ii ]. The F280N image, however, reveals Mg  ii  emission from structures that have not been seen in any previous line or continuum images of η Carinae. This image shows diffuse Mg  ii  emission immediately outside the bipolar Homunculus nebula in all directions, but with the strongest emission concentrated over the poles. The diffuse structure with prominent radial streaks, plus an anticorrelation with ionized tracers of clumpy shocked gas, leads us to suggest that this is primarily Mg  ii  resonant scattering from unshocked, neutral atomic gas. We discuss the implied structure and geometry of the Mg  ii  emission, and its relation to the Homunculus lobes and various other complex nebular structures. An order of magnitude estimate of the neutral gas mass traced by Mg  ii  is 0.02 M⊙, with a corresponding kinetic energy around 1047 erg. This may provide important constraints on polar mass-loss in the early phases of the great eruption. We argue that the Mg  ii  line may be an excellent tracer of significant reservoirs of freely expanding, unshocked, and otherwise invisible neutral atomic gas in a variety of stellar outflows. [ABSTRACT FROM AUTHOR]