J. Greaves
Optical data from the Catalina RealTime Transient Survey (CRTS) reveal an emergent eruptive in the embedded Infrared Star Cluster [C2001b] 11, within the Monoceros R2 Molecular Cloud.
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Long-Slit Spectroscopy Of Herbig-Haro Outflow System, Associated With IRAS 01166+6635
该研究利用6米望远镜和SCORPIO-2焦距缩减器，对与IRAS 01166+6635相关的喷流进行长缝光谱观测，详细研究喷流结构，构建位置-速度图并估计电子密度，发现其密度随距驱动源距离增加而降低。
We investigate supersonic, axisymmetric magnetohydrodynamic (MHD) jets with a time-dependent injection velocity by numerical simulations with the PLUTO code. Using a comprehensive set of parameters, we explore different jet configurations in the attempt to construct models that can be directly compared to observational data of microjets. In particular, we focus our attention on the emitting properties of traveling knots and construct, at the same time, accurate line intensity ratios and surface brightness maps. Direct comparison of the resulting brightness and line intensity ratios distributio…
Localised regions of enhanced emission from HCO+, NH3 and other species near Herbig-Haro objects (HHOs) have been interpreted as arising in a photochemistry stimulated by the HHO radiation on high density quiescent clumps in molecular clouds. Static models of this process have been successful in accounting for the variety of molecular species arising ahead of the jet; however recent observations show that the enhanced molecular emission is widespread along the jet as well as ahead. Hence, a realistic model must take into account the movement of the radiation field past the clump. It was previo…
We have performed a deep [SII]6717/6731 wide field Herbig-Haro (HH) object survey toward the Vela C molecular cloud with a sky coverage of about 2 deg2. In total, 18 new HH objects, HH 1090-1107, are discovered and the two previously known HH objects, HH 73-74, are also detected in our [SII] images. We also present an investigation of mid-infrared outflows in the Vela C molecular cloud using the Wide-field Infrared Survey Explorer images taken from AllWISE data release. Using the method suggested by Zhang & Wang, eleven extended green objects (EGOs) are identified to be the mid-infrared outflo…
We have identified a new externally irradiated Herbig-Haro (HH) jet, HH 1158, within ~2 pc of the massive OB type stars in the sigma Orionis cluster. At an Lbol ~ 0.1 Lsun, HH 1158 is the lowest luminosity irradiated HH jet identified to date in any cluster. Results from the analysis of high-resolution optical spectra indicate asymmetries in the brightness, morphology, electron density, velocity, and the mass outflow rates for the blue and red-shifted lobes. We constrain the position angle of the HH 1158 jet at 102+/-5 degree. The mass outflow rate and the mean accretion rate for HH 1158 using…
We present a new analysis of the physical conditions in three Herbig-Haro complexes (HH 54, HH 212, and the L 1157 protostellar jet) using archival data from the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. As described in detail in Paper I, the emission observed using the 4.5-micron filter is enhanced in molecular shocks (T=1000-4000 K) at relatively high temperature or densities compared with that observed with the 8.0-micron filter. Using these data sets, we investigate different distributions of gas between high and low temperatures/densities. Our analysis reveals the prese…
We report the discovery of new Herbig-Haro (HH) jets in the Carina Nebula, and we discuss the protostellar outflow activity of a young OB association. These are the first results of an HST/ACS H-alpha imaging survey of Carina. Adding to the one previously known example (HH666), we detect 21 new HH jets, plus 17 new candidate jets, ranging in length from 0.005 to 3 pc. We derive jet mass-loss rates ranging from 8e-9 to 1e-6 Msun/yr, but a comparison to the distribution of jet mass-loss rates in Orion suggests that we may be missing a large fraction of the jets below 1e-8 Msun/yr. A key qualitat…
An extended catalogue of Herbig-Haro objects
通过文献综述编制了包含1193个Herbig-Haro天体的扩展星表，并进行了初步统计分析，以促进恒星形成和恒星外流研究。
Wide-field optical imaging was obtained of the cluster and reflection nebula NGC 7023 and the Bok globule B175. We report the discovery of four new Herbig-Haro (HH) objects in NGC 7023, the first HH objects to be found in this region. They were first detected by their H-alpha and [S II] emission but are also visible at 3.6 and 4.5micron in archival Spitzer observations of this field. These HH objects are part of at least two distinct outflows. Both outflows are aligned with embedded "Class I" YSOs in a tight group on the western edge of the nebula. One of the outflows may have a projected dist…
We report the discovery of twelve faint Herbig-Haro (HH) objects in LDN 673 found using a novel color-composite imaging method that reveals faint Hα emission in complex environments. Follow-up observations in [S II] confirmed their classification as HH objects. Potential driving sources are identified from the Spitzer c2d Legacy Program catalog and other infrared observations. The twelve new HH objects can be divided into three groups: Four are likely associated with a cluster of eight YSO class I/II IR sources that lie between them; five are colinear with the T Tauri multiple star system AS 3…
We present results of the narrow-band Halpha and [SII] imaging survey of Mon R1 association, performed with the 1 m Schmidt telescope of the Byurakan Observatory. Our observations covered one degree field near the center of the association. As a result of this study twenty new Herbig-Haro knots were discovered, some of which form collimated outflows. Among the most extended ones are HH 1203 and HH 1196, which have a length near one parsec or even more. In the course of search for the probable sources of HH objects several new nebulous stars were found. A list of all nebulous stellar objects in…
The bipolar jet HH 212, among the finest collimated jets known, has so far been detected only in near-infrared H$_2$ emission. Here we present deep optical images that show two of the major bow shocks weakly detected in optical [SII] emission, as expected for a bona fide Herbig-Haro jet. We present widefield H$_2$ images which reveal two more bow shocks located symmetrically around the source and along the main jet axis. Additionally, examination of Spitzer 4.5 $μ$m images reveals yet another bright bow shock further to the north along the jet axis; no corresponding bow shock is seen to the so…
We present a detailed analysis of Spitzer-IRAC images obtained toward six Herbig-Haro objects (HH 54/211/212, L 1157/1448, BHR 71). Our analysis includes: (1) comparisons in morphology between the four IRAC bands (3.6, 4.5, 5.8 and 8.0 um), and H2 1-0 S(1) at 2.12 um for three out of six objects; (2) measurements of spectral energy distributions (SEDs) at selected positions; and (3) comparisons of these results with calculations of thermal H2 emission at LTE (207 lines in four bands) and non-LTE (32-45 lines, depending on particle for collisions). We show that the morphologies observed at 3.6 …
Herbig-Haro Flows and Young Stars in the Dobashi 5006 Dark Cloud
本文研究孤立暗云Dobashi 5006，发现两个分别与红外源成协的新Herbig-Haro流，并利用Gaia DR3识别贫星团MWSC 0739的17颗成员星，确认其存在持续至今的年轻致密恒星形成活动。
We analyze the physical conditions, chemical composition and other properties of the photoionized Herbig-Haro object HH~204 through Very Large Telescope (VLT) echelle spectroscopy and Hubble Space Telescope (\textit{HST}) imaging. We kinematically isolate the high-velocity emission of HH~204 from the emission of the background nebula and study the sub-arcsecond distribution of physical conditions and ionic abundances across the HH object. We find that low and intermediate-ionization emission arises exclusively from gas at photoionization equilibrium temperatures, whereas the weak high-ionizati…
We studied a small comet-shape reflection nebula, located in the dark cloud SL 4 in the Vela Molecular Ridge cloud C, known as BBWo 192E (GM 1-23), and a young infrared cluster embedded into the nebula, for the evidences of recent star formation. We obtained the images of BBWo 192E in Halpha and [SII] lines and in SDSS i' with Blanco telescope at the Cerro Tololo Interamerican Observatory to discover new Herbig-Haro (HH) flows. 2MASS and WISE surveys were used for the search of the additional member stars of the cluster. We also studied proper motions and parallaxes of the cluster members with…
Simulations of Protostar-Driven Photoionization in Herbig-Haro Jets
研究X射线电离对喷流中电离分数的影响，采用轴对称MHD模拟，考虑电离和光学薄损失，发现X射线电离可使喷流局部电离10%-20%。
We report the discovery of a new Herbig-Haro jet, HH 1165, in SOAR narrow-band imaging of the vicinity of the sigma Orionis cluster. HH 1165 shows a spectacular extended and collimated spatial structure, with a projected length of 0.26 pc, a bent C-shaped morphology, multiple knots, and fragmented bow-shocks at the apparent ends of the flow. The Halpha image shows a bright halo with a clumpy distribution of material seen around the driving source, and curved reflection nebulosity tracing the outflow cavities. The driving source of HH 1165 is a Class I proto-brown dwarf, Mayrit 1701117 (M170111…
New Herbig-Haro Objects associated with Embedded Sources
本文利用比拉坎窄带成像巡天在WISE明亮红外源附近发现多个新的赫比格-哈罗天体和喷流，揭示了暗云中活跃的低质量恒星形成活动。
Jets and outflows are associated with young stellar objects across the stellar mass spectrum, from brown dwarf protostars to massive, Ae/Be stars. Frequently, the jet morphology is spatially discontinuous because of the temporal variability of the ejection from the driving source. Images covering a wide field of view around the jet driving-source are useful to map the large-scale jet emission and to explore the mass ejection history. The aim of this work was to search for large-scale optical Herbig-Haro (HH) objects lying in a wide field around a sample of IRAS sources, candidates to trace you…
Some well-studied Herbig Haro objects have associated with them one or more cold, dense, and quiescent clumps of gas. We propose that such clumps near an HH object can be used as a general measure of clumpiness in the molecular cloud that contains that HH object. Our aim is to make a survey of clumps around a sample of HH objects, and to use the results to make an estimate of the clumpiness in molecular clouds. All known cold, dense, and quiescent clumps near HH objects are anomalously strong HCO+ emitters. Our method is, therefore, to search for strong HCO+ emission as an indicator of a clump…
We present the analysis of physical conditions, chemical composition and kinematic properties of two bow shocks -HH529 II and HH529 III- of the fully photoionized Herbig-Haro object HH 529 in the Orion Nebula. The data were obtained with the Ultraviolet and Visual Echelle Spectrograph at the 8.2m Very Large Telescope and 20 years of Hubble Space Telescope imaging. We separate the emission of the high-velocity components of HH529 II and III from the nebular one, determining $n_{\rm e}$ and $T_{\rm e}$ in all components through multiple diagnostics, including some based on recombination lines (R…
Jets around low- and intermediate-mass young stellar objects (YSOs) contain a fossil record of the recent accretion and outflow activity of their parent star-forming systems. We aim to understand whether the accretion/ejection process is similar across the entire stellar mass range of the parent YSOs. To this end we have obtained VLT/X-shooter spectra of HH 1042 and HH 1043, two newly discovered jets in the massive star-forming region RCW 36. HH 1042 is associated with the intermediate-mass YSO 08576nr292. Over 90 emission lines are detected in the spectra. High-velocity (up to 220 km/s) blue-…
The Herbig-Haro Outflow Content and Star-Forming Environment of Circinus West and East
本研究对Circinus东西分子云开展HH外流巡天，发现新HH天体并揭示二者形态差异，提出Circinus East受中心星团ASCC 79反馈及云碰撞影响，恒星形成环境更活跃。
We analyze the physical conditions and chemical composition of the photoionized Herbig-Haro object HH~514, which emerges from the proplyd 170-337 in the core of the Orion Nebula. We use high-spectral resolution spectroscopy from UVES at the Very Large Telescope and IFU-spectra from MEGARA at the Gran Telescopio de Canarias. We observe two components of HH~514, the jet base and a knot, with $n_{\rm e}= (2.3 \pm 0.1) \times 10^5 \text{cm}^{-3}$ and $n_{\rm e}= (7 \pm 1) \times 10^4 \text{cm}^{-3}$, respectively, both with $T_{\rm e}\approx 9000 \text{ K}$. We show that the chemical composition o…
Intertwined birth and death: a Herbig-Haro outflow resolves the distance to Vela Junior
通过赫比格-哈罗喷流解开了Vela Junior的距离，揭示其在稀疏介质中扩展的特性，修正了距离并影响其能量预算和演化。
We report on the discovery of three candidate eruptive young stars, found during our comprehensive multi-wavelength study of the young stellar population of the dark cloud L1340. These stars are as follows. (1) IRAS 02224+7227 (2MASS 02270555+7241167, HH 487 S) exhibited FUor-like spectrum in our low-resolution optical spectra. The available photometric data restrict its luminosity to 23 L_sun < L_bol < 59 L_sun. (2) 2MASS 02263797+7304575, identified as a classical T Tauri star during our H alpha survey, exhibited an EXor type brightening in 2005 November, at the time of the SDSS observations…
HD 163296 is a Herbig Ae star that underwent a dramatic $\sim$0.8 magnitude drop in brightness in the V photometric band in 2001 and a brightening in the near-IR in 2002. Because the star possesses Herbig-Haro objects travelling in outflowing bipolar jets, it was suggested that the drop in brightness was due to a clump of dust entrained in a disk wind, blocking the line-on-sight toward the star. In order to quantify this hypothesis, we investigated the brightness drop at visible wavelengths and the brightening at near-IR wavelengths of HD 163296 using the Monte Carlo Radiative Transfer Code, H…
We present the results of Keck Telescope laser adaptive optics integral field spectroscopy with OSIRIS of the innermost regions of the NGC 1333 SVS 13 outflow that forms the system of Herbig-Haro objects 7-11. We find a bright 0.2 arc sec long microjet traced by the emission of shock-excited [FeII]. Beyond the extent of this jet, we find a series of bubbles and fragments of bubbles that are traced in the lower excitation H_2 1-0 S(1) line. While the most recent outflow activity is directed almost precisely (PA ~145 deg) to the south-east of SVS 13, there is clear indication that prior bubble e…
We have searched the Lynds 988 dark cloud complex for optical (\ha{} and \sii{}) and near-IR (\mh{} 2.12 $μ$m) shocks from protostellar outflows. We find 20 new Herbig-Haro objects and 6 new \mh{} shocks (MHO objects), 3 of which are cross detections. Using the morphology in the optical and near-IR, we connect several of these shocks into at least 5 distinct outflow systems and identify their source protostars from catalogs of infrared sources. Two outflows in the cloud, from IRAS 21014+5001 and IRAS 21007+4951, are in excess of 1 pc in length. The IRAS 21007+4951 outflow has carved a large ca…
We present a multi-filter HST/WFPC2 UV-optical study of the Hourglass region in M8. We have extracted the stellar photometry of the sources in the area and obtained the separations and position angles of the Herschel 36 multiple system: for Herschel 36 D we detect a possible orbital motion between 1995 and 2009. We have combined our data with archival IUE spectroscopy and measured the Herschel 36 extinction law, obtaining a different result from that of Cardelli et al. (1989) due to the improvement in the quality of the optical-NIR data, in agreement with the results of Maíz Apellániz et al. (…
We present our results from a mid-infrared interferometric survey targeted at the planet-forming region in the circumstellar disks around low- and intermediate-mass young stars. Our sample consist of 82 objects, including T Tauri stars, Herbig Ae stars, and young eruptive stars. Our main results are: 1) Disks around T Tauri stars are similar to those around Herbig Ae stars, but are relatively more extended once we account for stellar luminosity. 2) From the distribution of the sizes of the mid-infrared emitting region we find that inner dusty disk holes may be present in roughly half of the sa…
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