CO Outflow Research Articles

Twin Herbig-Haro Jets and Molecular Outflows in L1228

view Abstract Citations (56) References (28) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Twin Herbig-Haro Jets and Molecular Outflows in L1228 Bally, John ; Devine, David ; Fesen, Robert A. ; Lane, Adair P. Abstract We present new optical, near-infrared, and millimeter wavelength observations of the dark cloud L1228 located in the Cepheus Flare. There are at least two active young stellar objects within a 2' diameter region in the L1228 cloud core that drive two separate Herbig-Haro (HH) outflows, a molecular hydrogen jet, and associated CO outflows. The red nebulous object RNO 129 (HH 198), located 1 north of the L1228 cloud core, is a Herbig-Haro flow from a T Tauri star located near the eastern end of the HH object. The Herbig-Haro object HH 199 is associated with a large molecular outflow (L1228A) centered on a low-luminosity (4 Lsun) young stellar object IRAS 20582+7724, the brightest infrared source in this cloud core. The brightest visual wavelength components, HH 199R1 and R2, lie about 8' to the southwest of the IRAS source, where the redshifted lobe of the CO outflow may be breaking out of the molecular cloud. A chain of faint blueshifted (V ≍-40 to -150 km s-1) HH objects, HH 199B1 through HH 199B6, lies to the northeast of the IRAS source toward the blueshifted lobe of the L1228A CO outflow. The projected distance between HH 199R2 and HH 199B6 is about 20' or nearly 2 pc. Near the center of this outflow, a chain of knots bright in the 2.122 microns wavelength 5(1) line of molecular hydrogen extends for about 1' along a nearly east-west axis on both sides of IRAS 20582+7724. This axis differs from that of the L1228A/HH 199 outflow by about 40°. We consider a model in which the jet from IRAS 20582+7724 varies in its ejection direction. At present, the outflow as traced by the H_{2 }jet appears to be impacting dense C3H_{2 }emitting clumps east and west of the IRAS source. A redshifted CO ridge extends 10' to the west of the IRAS source at the same orientation as the H2 jet, but a more prominent northeast-southwest ridge extends along the HH 199 optical axis from HH 199B6 in the northeast, through the IRAS source, to HH 199R2 in the southwest. A periodic blueshifted (V ≍ -40 to -150 km s-1) chain of Herbig-Haro objects, HH 200, is superimposed on the redshifted lobe of the L1228A outflow. It is associated with the low-velocity blueshifted CO lobe of a second outflow, L1228B. The source of this jet is an embedded T Tauri star located 1'S northwest of IRAS 20582+7724. There is a faint HH object 9' to the northeast of the source of the HH 200 jet, directly opposite the location of the bright bow shock at the end of the blueshifted lobe of the HH 200 jet. This lobe may mark the location of an invisible counterjet HH 200 has a projected length of over 18' corresponding to 1.8 pc (assuming a distance of 300 pc to L1228), and it shows quasi-periodic knot spacing of roughly 1' corresponding to a projected spacing of 0.09 pc. At a flow velocity of 300 km s-1, and an assumed outflow inclination angle of 45°, this spacing may be a result of episodes of enhanced mass loss occurring roughly every 500 years. Publication: The Astrophysical Journal Pub Date: November 1995 DOI: 10.1086/176486 Bibcode: 1995ApJ...454..345B Keywords: INFRARED: ISM: LINES AND BANDS; ISM: INDIVIDUAL ALPHANUMERIC: L1228; ISM: JETS AND OUTFLOWS; STARS: PRE-MAIN-SEQUENCE full text sources ADS | data products SIMBAD (26)

The Infrared Nebula and Outflow in LYNDS 483

view Abstract Citations (46) References (31) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Infrared Nebula and Outflow in Lynds 483 Fuller, G. A. ; Lada, E. A. ; Masson, C. R. ; Myers, P. C. Abstract Near-infrared and submillimeter observations of IRAS 18148-0440 in the Lynds 483 dark cloud are presented. The near-infrared images show nebulous emission extending up to ∼60" from the IRAS position. The IRAS source is not directly detected at any wavelength and is obscured by more than 70 mag of visual extinction. Submillimeter continuum measurements indicate the presence of ∼0.3 Msun of material within about 1900 AU of the central star. At 2.2 microns the near-infrared nebula is bipolar with approximately cylindrical lobes which extend east and west of the IRAS source and coincide with the bipolar lobes of the CO outflow from the source. The western lobe of the nebula is significantly brighter than the eastern lobe and is spatially coincident with the blueshifted CO emission from the outflow. If the nebular lobes have equal intrinsic brightness, their apparent brightness implies that the outflow has an inclination angle of ∼40° to the plane of the sky and that the density distribution within the dense gas around IRAS 18148-0440 has a radial profile steeper than r-1. There is a bright knot of molecular hydrogen emission close to the end of the blueshifted CO with a jet like feature extending from the knot back toward the location of the embedded star. The knot of emission is thought to be tracing the region where the stellar wind is impacting the surrounding dense gas. The observations suggest that IRAS 18148-0440 is very young and that its outflow is driven by a jet from the central star. Publication: The Astrophysical Journal Pub Date: November 1995 DOI: 10.1086/176437 Bibcode: 1995ApJ...453..754F Keywords: INFRARED: ISM: CONTINUUM; ISM: INDIVIDUAL ALPHANUMERIC: L483; ISM: JETS AND OUTFLOWS; ISM: STRUCTURE; RADIO LINES: ISM full text sources ADS | data products SIMBAD (9)

Shocks in the L 1551-IRS 5 outflow optical and near-infrared imaging

We present new images of the well-known molecular outflow and Herbig-Haro complex L 1551-IRS5. Deep, high-resolution images of the central region of the flow in [SII] λλ 6716, 6731 and Hα (6565 A) are complemented by a mosaic of much of the CO outflow in H2 v=l-0 S(l). While the optical data trace the intermediate-to-high excitation shocks in the flow (v shock > 30 – 50 km s−1), the near-IR data reveal the lower-excitation, molecular shocks (v shock ~ 10 – 50 km s−1). In particular, the H2 data highlight the regions where the flow impacts and shocks ambient molecular gas.

CO J = 3--2 and HCO + J = 4--3 Observations of the GL 2591 Molecular Outflow

view Abstract Citations (29) References (30) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS CO J = 3--2 and HCO + J = 4--3 Observations of the GL 2591 Molecular Outflow Hasegawa, Tatsuhiko I. ; Mitchell, George F. Abstract We present maps of the central part of the GL 2591 molecular outflow in CO J = 3-2 and HCO+ J = 4-3 with an angular resolution of 14". The CO J = 3-2 observations show a small-scale, fast outflow extending east to west with an overall size of about 90" x 20". The newly resolved small-scale flow is centered on GL 2591 and superposed on the previously known large-scale (5' x 5') outflow. We interpret the observations as a well-collimated, bipolar molecular flow within a large-scale, less-collimated outflow. This high-velocity small-scale flow coincides in position and extent with recently detected emission from shock-excited molecular hydrogen. Furthermore, blueshifted Herbig-Haro objects seen by [S II] emission coincide spatially with the blueshifted small-scale flow seen in CO J = 3-2. The spatial association of the small-scale CO flow with Herbig-Haro objects and hot molecular hydrogen suggests the entrainment of ambient molecular gas by a fast, collimated neutral jet. However, a momentum comparison shows the momentum transport rate of the postulated neutral jet falls short of explaining that of the large-scale CO flow. Publication: The Astrophysical Journal Pub Date: September 1995 DOI: 10.1086/176214 Bibcode: 1995ApJ...451..225H Keywords: ISM: INDIVIDUAL ALPHANUMERIC: GL 2591; ISM: JETS AND OUTFLOWS; ISM: MOLECULES full text sources ADS | data products SIMBAD (2)

IRAS 08159-3543: Optical Detection of the Dusty, Neutral Bipolar Wind of a Luminous Young Stellar Object

view Abstract Citations (12) References (38) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS IRAS 08159-3543: Optical Detection of the Dusty, Neutral Bipolar Wind of a Luminous Young Stellar Object Neckel, Th. ; Staude, H. J. Abstract We have detected by optical means the neutral bipolar wind from IRAS 08159-3543, a deeply embedded, luminous young stellar object (YSO) (L ∼2.4 × 104 Lsun, AV ≳ 43 mag). The wind is observable, because it carries huge amounts of dust flowing outward in the bright lobes at υf 570 km s-1. The velocity field of the neutral flow was determined by long-slit spectroscopy of the broad Hα line emitted by the ionized envelope near the unseen YSO and scattered by the moving dust. The velocity of the neutral flow far out in the lobes is nearly the same as the outflow velocity reached in the ionized envelope. Therefore, most of the outflowing material in the lobes must have been accelerated by the primary mechanism at work near the YSO. The ionized envelope is bisected in its equatorial plane by an optically thick layer; also, in the scattered spectrum of the YSO several chromospheric Fe II emission lines are observed. These findings can be taken as evidence for an active accretion disk surrounding the YSO and driving the wind seen in the ionized envelope. The outflowing dust observed in the lobes may be carried along by a neutral wind leaving the outer (cooler) parts of the disk. We estimate the spectral type of the YSO (F-K) from the brightness and color of the scattered continuum: in the H-R diagram the YSO is located far above the zero-age main sequence and the theoretical stellar birth- line. The total mass loss in the wind is Mṡ 6 × 10-5 -2 × 10-4 Msun yr-1. The corresponding ratio Mṡ/L lies within the range derived from CO outflows (Levreault 1988). Thus, relative to the luminosity of the source, the wind carries as much momentum as is observed in molecular outflows driven by YSOs of low and intermediate luminosity. Within a volume whose total extent is about 0.5 pc, the neutral outflow in the lobes is interspersed with shock-ionized material (filling factor ∼0.04), which moves outward at about one-fourth of the speed of the neutral flow. Publication: The Astrophysical Journal Pub Date: August 1995 DOI: 10.1086/176011 Bibcode: 1995ApJ...448..832N Keywords: ACCRETION; ACCRETION DISKS; STARS: CIRCUMSTELLAR MATTER; ISM: DUST; EXTINCTION; STARS: MASS LOSS; STARS: PRE-MAIN-SEQUENCE full text sources ADS | data products SIMBAD (10)

Spatially resolved submillimeter continuum emission toward L1551 IRS 5

view Abstract Citations (24) References (24) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Spatially Resolved Submillimeter Continuum Emission toward L1551 IRS 5 Ladd, E. F. ; Fuller, G. A. ; Padman, R. ; Myers, P. C. ; Adams, Fred C. Abstract We present high signal-to-noise ratio 16-20 arcsec resolution submillimeter continuum images of the embedded young stellar object L1551 IRS 5. The images are dominated by a compact sources at the position of IRS 5, which has a deconvolved size of 10 +/- 3 arcsec. Low-level emission extends up to 5000 A.U. from IRS 5 and is distributed nonaxisymetrically. The 1100 micrometer emission is exended in the north-south direction and is elliptical in shape. In contrast, our 730 micrometer map shows emission in a cross-shaped pattern, with arms extending to the north, south, east, and west of IRS 5. The cross emission is not an artifact of our observational methods but rather is intrinsic to the source distribution. We model the submillimeter continuum emission at 1100 micrometers and 730 micrometers using three components: an unresolved point source; a cold (approximately 12 K), massive (approximately 1 solar mass), smoothly distributed envelope; and a warm (approximately equal to greater than 50 K), less massive (approximately equal to or less than 0.02 solar mass) 'cross' centered at the position of IRS 5. We note that the arms of the cross are well aligned with the edges of the CO outflow from IRS 5 and suggest that they may consist of core material warmed and pushed aside by the energetically dominant outflow. Publication: The Astrophysical Journal Pub Date: February 1995 DOI: 10.1086/175215 Bibcode: 1995ApJ...439..771L Keywords: Data Reduction; Early Stars; Pre-Main Sequence Stars; Spatial Resolution; Stellar Envelopes; Submillimeter Waves; Contours; Flux Density; Mathematical Models; Spectrum Analysis; Astrophysics; INFRARED: ISM: CONTINUUM; ISM: INDIVIDUAL ALPHANUMERIC: L1551 IRS 5; ISM: JETS AND OUTFLOWS; STARS: PRE--MAIN-SEQUENCE full text sources ADS | data products SIMBAD (4)

Low-mass protostars and protostellar stages

The use of sensitive receivers on large ground-based radiotelescopes such as the JCMT, the IRAM 30 m MRT, and the VLA has recently yielded significant progress in our observational understanding of low-mass protostars. Submillimeter continuum observations suggest that the youngest stellar objects detected in the near-/mid-IR range —the so-called Class I sources or “infrared protostars” — have only residual amounts of circumstellar material and are thus relatively evolved. At the same time, a smaller number of colder and more obscured YSOs — designated “Class 0” — characterized by virtually no emission below 10 µm but strong submillimeter emission have been identified. These Class 0 or “submillimeter protostars” have not yet assembled the bulk of their final stellar mass, and correspond to the youngest protostar stage known to date (probable age ≲ 104 yr). Direct evidence for gravitational infall has been found in some of these sources confirming their protostellar nature. However, most (if not all) Class 0 protostars already drive highly collimated CO outflows.

Discovery of a molecular hydrogen jet near IC 348

view Abstract Citations (162) References (36) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Discovery of a Molecular Hydrogen Jet near IC 348 McCaughrean, Mark J. ; Rayner, John T. ; Zinnecker, Hans Abstract We present near-infrared images of a newly discovered molecular hydrogen jet (HH 211) near the young stellar cluster IC 348 in the Perseus dark cloud complex. A wide-field true-color JHK' image locates HH 211 relative to the embedded source IC 348 IR, and a high-resolution image taken in the H2 upsilon = 1 - 0 S(1) line at 2.122 micrometers delineates the shock-excited gas. The jet is very young, with a dynamical age of less than 1000 yr. We suggest that the H2 emission arises in a turbulent sheath around the true jet, leading to an unusual symmetric limb-brightened appearance. This boundary layer is probably where ambient molecular material is being entrained to form a coincident bipolar CO outflow. We discuss possible models for the knots in HH 211, including internal working surfaces in an episodic outflow and crossing shocks in a recollimating jet. The exciting source of the jet and outflow was detected at lambda greater than or = 350 micrometers, and our observations imply that the exciting source is a young star deeply embedded in a dense NH3 core, perhaps an edge-on circumstellar disk. The HH 211 system of jet, molecular outflow, and embedded exciting source is the first discovered through near-infrared imaging. Publication: The Astrophysical Journal Pub Date: December 1994 DOI: 10.1086/187664 Bibcode: 1994ApJ...436L.189M Keywords: Hydrogen; Interstellar Gas; Jet Flow; Molecular Clouds; Molecular Flow; Star Clusters; Star Formation; Stellar Envelopes; Rosat Mission; Stellar Luminosity; Astrophysics; STARS: CIRCUMSTELLAR MATTER; INFRARED: ISM: CONTINUUM; INFRARED: ISM: LINES AND BANDS; ISM: JETS AND OUTFLOWS; ISM: MOLECULES; STARS: FORMATION full text sources ADS | data products SIMBAD (39)

Shocked molecular gas around the extremely young source IRAS 03282+3035

We present observations of the shock tracers H2 and SiO around the young stellar object IRAS 03282+3035. This unusual low-luminosity (L approximately = 2 solar luminosity) source drives a strong highly collimated CO outflow, and it is one of the youngest stellar objects known so far. The near-infrared H2 emission, tracing 2000 K gas, comes from extremely high velocity CO bullets along the axis of the blueshifted lobe of the outflow. The millimeter SiO emission, tracing roughly 100 K gas, arises from lower velocity material at the end of the outflow lobe. The lack of high-temperature and high-velocity gas at the end of the outflow lobe indicates there is no not bow shock at the outflow termination. In the context of current jet models this appears to rule out a bow shock driven by a steady state jet. Possible explanations for the structure include a time-dependent jet or a jet dominated by turbulent entrainment.

A molecular cloud and a CO outflow associated with IRAS 22134+5834

view Abstract Citations (11) References (19) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Molecular Cloud and a CO Outflow Associated With IRAS 22134+5834 Dobashi, Kazuhito ; Nozawa, Satonori ; Hayashi, Yoshikazu ; Sato, Fumio ; Fukui, Yasuo Abstract (12)CO (J = 1 - 0) and (13)CO (J = 1 - 0) observations are carried out toward a protostellar candidate, IRAS 22134+5834, using the new 4 m millimeter telescope at Nagoya University. A molecular cloud is found around the IRAS point source, of which molecular mass is estimated to be approximately 70 solar mass. Both of the (12)CO and (13)CO distributions show a good spatial correlation with the IRAS point source, indicating that the cloud is likely to be associated with the IRAS source. A molecular outflow is discovered at the position of the IRAS point source. Physical properties such as the mass and the momentum of the outflow are derived. The momentum of the outflow is compared with that of the molecular cloud. Results of the comparison imply that the outflow is likely supplying momentum large enough to prevent the cloud from collapsing. Publication: The Astronomical Journal Pub Date: June 1994 DOI: 10.1086/117025 Bibcode: 1994AJ....107.2148D Keywords: Carbon Monoxide; Infrared Astronomy Satellite; Molecular Clouds; Molecular Flow; Astronomical Spectroscopy; Infrared Sources (Astronomy); Astronomy; ISM: JET AND OUTFLOWS; ISM: INDIVIDUAL: IRAS 22134; 5834 full text sources ADS | data products SIMBAD (4)

A molecular jet from LkH(alpha) 234

view Abstract Citations (23) References (23) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Molecular Jet from LkH alpha 234 Mitchell, George F. ; Matthews, Henry E. Abstract The Herbig Be star LkH(alpha) 234 possesses both a molecular outflow and an optical jet. New CO J = 3-2 observations with 14 sec resolution show that the redshifted CO outflow is collimated, with an axis opposite the blueshifted optical jet. A narrow CO structure or 'CO jet' is found, which terminates in a CO-bright spot coincident with the Herbig-Haro object HH 105. The CO bright spot/HH object is probably the working surface of an unseen (because of extinction) shock-ionized jet, where the head of the jet encounters the ambient cloud gas. The CO jet may be ambient gas entrained by the postulated fast ionized jet. The quiescent gas in the region is found to contain a ridge or shell of CO emission within which LkH(alpha) 234 is embedded. The ridge is very sharply bounded to the west by a molecular cavity, suggesting that the formation of LkH(alpha) 234 was caused by the shell formation event. Triggered star formation is further supported by the detection of a warm CO clump in the ridge which has the narrow lines (FWHM = 2 km/sec), mass (2 solar mass) and density (105/cu,cm.) typical of prestellar cores. The temperature of this clump (63 K) is much higher than less than or equal to 10 K of most cores, so that it may contain an embedded luminous object as a heat source. Publication: The Astrophysical Journal Pub Date: March 1994 DOI: 10.1086/187234 Bibcode: 1994ApJ...423L..55M Keywords: Carbon Monoxide; Interstellar Matter; Jet Flow; Molecular Dynamics; Molecular Flow; Pre-Main Sequence Stars; Radio Astronomy; Star Formation; Stellar Mass Ejection; Acousto-Optics; Radio Telescopes; Red Shift; Spectrometers; Astrophysics; ISM: JETS AND OUTFLOWS; MOLECULAR PROCESSES; STARS: FORMATION; STARS: MASS LOSS; STARS: PRE--MAIN-SEQUENCE full text sources ADS | data products SIMBAD (12)

Submillimetre and near-infrared observations of L1448: a curving Formula jet with multiple bow shocks

A high-resolution (0.6 arcsec pixel −1 ), narrow-band, H 2 v=1-0 S(1) image of the high-velocity CO outflow in L1448 reveals a remarkable jet-like structure. The coincidence of this H 2 jet with the CO bipolar outflow implies a close association between the two phenomena. The H 2 jet comprises a series of knots, and three bow-shaped features equally spaced along the jet length, which we associate with the sporadic nature of this outflow. K-band imaging of the source also shows a conical reflection nebula extending towards the H 2 jet structure, whilst maps in HCO + J=3-2 and CS J=5-4 show two peaks, one towards the source of the H 2 jet and CO outflow, and the other towards the infrared source IRS 3 situated to the north of this region

A Flattened Cloud Core in NGC 2024

With the VLA in the D configuration we have mapped the (J,K) = (1,1) and (2,2) NH3 lines toward a molecular cloud core in NGC 2024. This region, which contains one of the most highly collimated molecular outflows (Richer et al. 1992), has been studied extensively using a variety of techniques, including dust continuum in the far-infrared (FIR) wavelengths (Mezger et al. 1988, 1992), and molecular lines (see Barnes & Crutcher 1992 and references therein). We find that the molecular condensations associated with FIR 5, 6, and 7 (Mezger et al. 1988, 1992) have kinetic temperatures TK ≃ 40 K. We also find a perturbation of the molecular gas near FIR 6 and FIR 7 in terms of broadening of the ammonia lines. These results suggest that these condensations may not be protostars heated by gravitational energy released during collapse, but that they have an internal heating source. A flattened structure of ammonia emission is found extending parallel to the unipolar CO outflow structure, but displaced systematically to the east. The location of the high velocity outflow along the surface of the NH3 structure suggests that a wind is sweeping material from the surface of this elongated cloud core. Figure 1 is an overlay of the VLA ammonia emission (dotted area) on top of the C18O emission (thick contours) and the CO outflow (thin contours).

The structure and nature of NGC 2017 IRS. 1: High-resolution radio continuum maps

We have observed the star formation cluster NGC 2071 IRS 1, 2, and 3, with 0.14 sec spatial resolution at 2 cm. The strong source IRS 1 breaks up into a bright peak sitting on a narrow line emission extending over about 400 AU, with three much weaker peaks. This ridge, which has a p.a. = 100 deg, is not aligned with any of the other structures that have previously been seen around IRS 1: its orientation is about 55 deg from the CO outflow direction, and 35 deg from a hypothetical disk direction. The spectral and spatial results, combined with earlier radio and infrared observations, indicate that most likely the radio and infrared emission from the exciting source, IRS 1, is produced by a dense wind hidden by at least 100 visual magnitudes of extinction; the extended ridge of emission comes from an optically thin H II region with characteristic dimensions of approximately AU and which may result from a clumpy distribution of local gas and dust.

Aperture Synthesis CS(J=1-0) Observations of the Molecular Outflow in NGC 2071: Subclumps in a Wind-Driven Shocked Shell and their Origin

AbstractAperture synthesis CS(J=l-0) observations were made of the expanding clumpy shocked shell that was found around the redshifted CO outflow in NGC 2071 during our previous study (Kitamura et al. 1990). It has been revealed that previously identified clumps in the shell comprise several small subclumps. The decelerating shock and Rayleigh-Taylor instabilities seem to be probable mechanisms by which the subclumps are formed in the shock-compressed shell.

CO Outflows in Low-Mass Protostar Candidates in Taurus

The Taurus dark cloud is one of the nearest active sites of low-mass star formation. The IRAS satellite has discovered numerous low-luminosity far-infrared sources in this cloud, some of which are completely invisible at optical wavelengths. There are several arguments suggesting that the invisible sources are low-mass protostars which are younger than T Tauri stars and powered by the accretion of infalling gas and dust (Adams, Lada, & Shu 1987; Beichman et al. 1986; Myers et al. 1987; Kenyon et al. 1990)Tamura et al. (1991) made a near-infrared imaging survey of a complete, flux-limited sample of cold IRAS sources in the Taurus dark cloud, of which 8 are optical T Tauri-like objects and 16 are optically invisible sources. They identified all 24 sources with near-infrared counterparts; one is entirely nebulous without a point-like source, and the others generally have an unresolved peak with or without an extended component at 2.2 µm 75 % of the 24 sample sources are associated with infrared/optical nebulosity about 1000 AU to 10000 AU in size. A number of the sources show a clear bipolar or monopolar morphology, suggestive of a close relation of the nebulosity with a bipolar mass outflow; the nebulosity is due to scattering of light from the central source by the dust associated with the mass outflow extending to the poles of a circumstellar dust disk.

Molecular Cloud Core and CS Outflow Associated with Haro 4-255 FIR

view Abstract Citations (8) References (30) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Molecular Cloud Core and CS Outflow Associated with Haro 4-255 FIR Tatematsu, Ken'ichi ; Umemoto, Tomofumi ; Murata, Yasuhiro ; Chen, Hua ; Hirano, Naomi ; Takaba, Hiroshi Abstract The region containing the two young stellar objects, Haro 4-255 and Haro 4-255 FIR, has been studied through single-dish and aperture-synthesis CS (1-0) observations. We have detected an intense CS outflow, whose FWZI velocity extent is about 9 km s-1, in the single-dish observations. The distribution of the blue CS lobe is appreciably different from that of the blue CO lobe, whereas the distribution of the red CS lobe is similar to that of the red CO lobe. The CS abundance in this outflow seems to be enhanced nearly by one order of magnitude, although that in the quiescent gas shows a more normal value. The mass of the CS outflow is appreciably larger than that of the CO outflow, while the mechanical luminosity of the CS outflow is smaller than that of the CO outflow. The aperture-synthesis data show no counterpart to the CS outflow but contain two emission features which correspond to two local intensity maxima seen in the single-dish map. One of these features extends from Haro 4-255 to Haro 4-255 FIR: it might represent a density maximum in the molecular cloud core. The blueshifted emission of the CS outflow is less prominent, probably because it is impeded by the densest portion of the core. Publication: The Astrophysical Journal Pub Date: December 1993 DOI: 10.1086/173525 Bibcode: 1993ApJ...419..746T Keywords: ISM: CLOUDS; ISM: INDIVIDUAL NAME: HARO 4-255 FIR; ISM: MOLECULES; ISM: JETS AND OUTFLOWS; STARS: PRE-MAIN-SEQUENCE full text sources ADS | data products SIMBAD (5)

Molecular Hydrogen in the IRAS 03282+3035 Stellar Jet

We detected shock-excited 2.122 μm molecular hydrogen from the blueshifted lobe of the highly collimated CO outflow associated with the young stellar object IRAS 03282+3035 in the Perseus molecular cloud. The H 2 emission has a peak surface brightness of 5×10 -4 ergs s -1 cm -2 sr -1 , making this one of the brightest shock-excited molecular hydrogen sources associated with a low-mass young stellar object. The emission has knotty structure with faint tails lying parallel to the mean outflow axis. These knots coincide with molecular bullets B3 and B4 located near the end of the highest velocity CO-emitting component and may be bow shocks where a fast jet interacts with the surrounding medium. The bulk of the lower velocity CO emission is located downwind from the H 2 emission zone

An IRAS Sample from Co-added Images of L1641

A sample of 224 IRAS sources was obtained from the IRAS co-added images in the dark cloud L1641. Most of these sources were observed in CO and 13 CO (J=1-0). The 122 sources within L1641 are likely to be embedded young stellar objects (YSOs). The sources outside L1641 are mostly extended far-infrared cirrus emission. The infrared and millimeter data were used to search for the indicators of the evolutionary state of YSOs. The IRAS sources associated with CO outflows are significantly different from the nonoutflow sources because those with CO outflows have higher 13 CO column densities, higher far-infrared luminosities, and cooler IRAS color temperatures

Optical and near-infrared observations of S 140N

view Abstract Citations (8) References (14) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Optical and Near-Infrared Observations of S 140N Eiroa, C. ; Lenzen, R. ; Miranda, L. F. ; Torrelles, J. M. ; Anglada, G. ; Estalella, R. Abstract Optical CCD images and polarimetry as well as near-IR observations of the molecular core S 140N are presented. The images reveal a reflection nebulosity associated with the young IRAS source 22178 + 6317. Two pointlike sources are embedded in the reflection nebulosity. The near-IR colors indicate an IR excess characteristic of PMS objects. The CO outflow detected in the region is likely to be driven by these young objects. Four Herbig-Haro objects are detected in our images. This is the first detection of these kinds of objects in the S 140 molecular cloud. The HH objects are aligned in a scale of about 2.3 arcmin (about 0.7 pc) and point to a faint star, located at the northern end of the brighter HH object. This star is therefore a suitable candidate to excite the HH objects and is likely to be a T Tauri-like star. In addition, the star is centered on a previously detected ammonia core and likely heats the high density gas. Finally, these data show that not only high-mass stars, but also low-mass stars have recently formed in the S 140 molecular cloud. Publication: The Astronomical Journal Pub Date: August 1993 DOI: 10.1086/116665 Bibcode: 1993AJ....106..613E Keywords: Herbig-Haro Objects; Infrared Astronomy; Molecular Clouds; Polarimetry; Star Formation; Stellar Mass; Carbon Monoxide; Charge Coupled Devices; Pre-Main Sequence Stars; Stellar Winds; Astrophysics; ISM: CLOUDS; STAR: FORMATION; REFLECTION NEBULAE full text sources ADS | data products SIMBAD (17)