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Register a new userHH 175: A Giant HH Flow Emanating From A Multiple Protostar
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HH 175 is an isolated Herbig-Haro object seen towards the B35 cloud in the lambda Ori region. We use deep Subaru 8m interference filter images and Spitzer images to show that HH 175 is a terminal shock in a large collimated outflow from the nearby embedded source IRAS 05417+0907. The body of the eastern outflow lobe is hidden by a dense ridge of gas. The western outflow breaks out of the front of the cometary-shaped B35 cloud, carrying cloud fragments along, which are optically visible due to photoionization by the massive lambda Ori stars. The total extent of the bipolar outflow is 13.7 arcmin, which at the adopted distance of 415 pc corresponds to a projected dimension of 1.65 pc. The embedded source IRAS 05417+0907 is located on the flow axis approximately midway between the two lobes, and near-infrared images show it to be a multiple system of 6 sources, with a total luminosity of 31 Lsun. Millimeter maps in CO, 13CO, and C18O show that the B35 cloud is highly structured with multiple cores, of which the one that spawned IRAS 05417+0907 is located at the apex of B35. It is likely that the embedded source is the result of compression by an ionization-shock front driven by the lambda Ori OB stars.
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We present high angular resolution, high sensitivity 8.46 GHz (3.6 cm) radio continuum observations made toward the core of the HH~92 outflow with the Very Large Array in 2002-2003 and with the Expanded Very Large Array in 2011. We detect a group of three compact sources distributed in a region 2$$ in extension and discuss their nature. We conclude that one of the objects (VLA 1) is the exciting source of the giant outflow associated with HH~92. In the case of HH~34 we present new 43.3 GHz (7 mm) observations that reveal the presence of a structure associated with the exciting source and elongated perpendicular to the highly collimated optical jet in the region. We propose that this 7 mm source is a circumstellar disk with radius of $sim$80 AU and mass of $sim$0.21 $M_odot$.
HH 212 is a Class 0 protostellar system found to host a hamburger-shaped dusty disk with a rotating disk atmosphere and a collimated SiO jet at a distance of ~ 400 pc. Recently, a compact rotating outflow has been detected in SO and SO2 toward the center along the jet axis at ~ 52 au (0.13) resolution. Here we resolve the compact outflow into a small-scale wide-opening rotating outflow shell and a collimated jet, with the observations in the same S-bearing molecules at ~ 16 au (0.04) resolution. The collimated jet is aligned with the SiO jet, tracing the shock interactions in the jet. The wide-opening outflow shell is seen extending out from the inner disk around the SiO jet and has a width of ~ 100 au. It is not only expanding away from the center, but also rotating around the jet axis. The specific angular momentum of the outflow shell is ~ 40 au km/s. Simple modeling of the observed kinematics suggests that the rotating outflow shell can trace either a disk wind or disk material pushed away by an unseen wind from the inner disk or protostar. We also resolve the disk atmosphere in the same S-bearing molecules, confirming the Keplerian rotation there.
We present subarcsecond angular resolution observations carried out with the Submillimeter Array (SMA) at 880 $mu$m centered at the B0-type protostar GGD27~MM1, the driving source of the parsec scale HH 80-81 jet. We constrain its polarized continuum emission to be $lesssim0.8%$ at this wavelength. Its submm spectrum is dominated by sulfur-bearing species tracing a rotating disk--like structure (SO and SO$_2$ isotopologues mainly), but also shows HCN-bearing and CH$_3$OH lines, which trace the disk and the outflow cavity walls excavated by the HH 80-81 jet. The presence of many sulfurated lines could indicate the presence of shocked gas at the disks centrifugal barrier or that MM1 is a hot core at an evolved stage. The resolved SO$_2$ emission traces very well the disk kinematics and we fit the SMA observations using a thin-disk Keplerian model, which gives the inclination (47$^{circ}$), the inner ($lesssim170$ AU) and outer ($sim950-1300$~AU) radii and the disks rotation velocity (3.4 km s$^{-1}$ at a putative radius of 1700 AU). We roughly estimate a protostellar dynamical mass of 4-18msun. MM2 and WMC cores show, comparatively, an almost empty spectra suggesting that they are associated with extended emission detected in previous low-angular resolution observations, and therefore indicating youth (MM2) or the presence of a less massive object (WMC).
For an affine toric variety $spec(A)$, we give a convex geometric interpretation of the Gerstenhaber product $HH^2(A)times HH^2(A)to HH^3(A)$ between the Hochschild cohomology groups. In the case of Gorenstein toric surfaces we prove that the Gerstenhaber product is the zero map. As an application in commutative deformation theory we find the equations of the versal base space (in special lattice degrees) up to second order for not necessarily isolated toric Gorenstein singularities. Our construction reproves and generalizes results obtained in [1] and [13].
We present a comparison between the time-evolution over the past $sim 20$ years of the radio continuum and H$alpha$ emission of HH~1 and 2. We find that the radio continuum and the H$alpha$ emission of both objects show very similar trends, with HH~1 becoming fainter and HH~2 brightening quite considerably (about a factor of 2). We also find that the $F_{rm Halpha}/F_{ff}$ (H$alpha$ to free-free continuum) ratio of HH~1 and 2 has higher values than the ones typically found in planetary nebulae (PNe) which we interpret as an indication that the H$alpha$ and free-free emission of HH~1/2 is produced in emitting regions with lower temperatures ($sim 2000$~K) than the emission of PNe (with $sim 10^4$~K).
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