Protostars and Planets V 2005
HST AND SPITZER SURVEYS OF THE CARINA NEBULA: NEW IRRADIATED HERBIG-HARO JETS. Nathan Smith1, John Bally1, Ed Churchwell2, Barbara Whitney2, Brian Babler2, Marilyn Meade2, Keivan Stassun3, Kate J. Brooks4, Jon A. Morse5,6, & Nolan R. Walborn7. 1 CASA, University of Colorado (389 UCB, Boulder, CO 80309; [email protected]
), 2Astronomy Department, University of Wisconsin, 3Physics & Astronomy Dept., Vanderbilt university, 4ATNF, Sydney, 5Dept. of Physics & Astron., Arizona State University, 6GSFC, 7STScI.
Introduction: The Carina Nebula (NGC3372) is our most accessible laboratory in which to study the effect that feedback from extremely massive stars is having on an emerging second generation of low and intermediate-mass stars. It is caught in an early phase in the evolution of a massive OB association, before any supernova explosions have disturbed the environment. The Carina nebula contains several of the most massive stars known, and harbors at least 63 O-type stars , including the prototypical O2 If* supergiant HD93129A  and several original members of the O3 spectral type, not to mention 3 luminous WNL stars and the enigmatic object Eta Carinae itself, all four of which may have been similar to HD93129A when they were on the mainsequence. The collective effect of all these massive stars produces a Lyman continuum luminosity about 200 times stronger than θ1C Ori in the Orion Nebula . These stars are powering the expansion of a proto-superbubble that is already breaking out of the Galactic plane , even before any supernova explosions have occurred. Located only 2.3 kpc away [8,13,14] in an adjacent spiral arm, the Carina Nebula is closer and suffers less extinction than other star clusters that contain the same types of extremely massive stars in greater concentration, like NGC3603 , the clusters in the Galactic center , and 30 Doradus . In just the past decade, the Carina Nebula has begun to be recognized as a hotbed of active, ongoing star formation, including small, isolated cometary globules or proplyd candidates , the erosion of giant dust pillars and the triggering of a second generation of stars and even star clusters within them [6,9,12], PDRs on the surfaces of molecular clouds across the region [1,8,9], and at least one giant parsec-scale irradiated Herbig-Haro (HH) jet , although current work adds to this number. All these phenomena are exposed to the intense radiation and stellar winds of the massive stars that power the region. Here we focus on irradiated stellar HH jets, including the parsec-scale jet HH666 discovered from the ground, as well as several new HH jets revealed by a cycle 13 and 14 HST imaging survey. Spitzer and ground-based IR observations reveal the embedded IR sources that power these jets.
Irradiated jets are of particular interest for the study of stellar outflows , because their emission is dominated by relatively simple photo-excitation, rather than the complex non-linear excitation in shocks, which only illuminated a fraction of the jet material. HH666 – The Axis of Evil. HH666 was the first HH jet to be discovered in the Carina Nebula . Even though Carina is more than 2 kpc away, this 4pc long jet was clearly visible on ground-based narrowband images of the region (see Figure 1). Within about 20” of the source, the jet shows a Hubble-like flow, with velocities reaching 200 km/s. The jet is extremely bright in the IR line [Fe II] 1.644 µm. Even though the source is deeply embedded in a molecular globule, it shows no emission from H2 at 2.122 µm, however. New HH jets. Several other HH jet candidates were visible in ground-based images, but their nature was not clear to due inadequate spatial resolution. A new HST imaging survey of Carina using the WCS/WFC camera and the F658N (Hα+[N II]) filter, however, reveals the nature of these candidates as true HH jets. These irradiated jets are bursting into the interior of the HII region from young stars embedded inside cometary clouds and dust pillars. The driving sources are identified as highly reddened sources seen in ground-based near-IR images and Spitzer images. The brightest and most spectacular of these jets is seen as a high surface-brightness bipolar jet emerging from a small cometary globule or proplyd candidate just a few arcminutes north of the massive cluster Trumpler 14. This may be one of the brightest HH jets in the sky, due to the inense UV radiation field illuminating it.
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Protostars and Planets V 2005
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Figure 1. Ground-based Hα image of the irradiated parsec-scale jet HH666 . This was the first HH jet to be discovered in Carina. The jet emerges from an embedded Class I source in the head of a dust pillar that points toward the massive star Eta Carinae. The presumed bipolar axis of the jet is shown with a dashed line.