Volume 502, Number 1, July IV 2009
|Page(s)||139 - 153|
|Section||Interstellar and circumstellar matter|
|Published online||29 April 2009|
12CO spectra at the positions of the SCUBA peaks. The line centre velocity is marked with a solid vertical line. The standard linewing criteria of 15 K at is marked with long dashes, and the low-level linewing criteria with short dashes. The positions at which the spectra were extracted are given in the top left. Available in the online version only.
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12CO spectra at the positions of Spitzer low luminosity objects. See Fig. 8 for annotations. Available in the online version only.
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6). The core is detected by SHARC, and HARP clearly images the ESE-WNW red-blue outflow associated with this Class I protostar. The outflow is parsec-scale, driving HH317 30'' to the southeast (Davis et al. 2008).
5). The core is 2' south of HRF49, and a compact SHARC-II 350 emission peak. The spectrum shows moderate blue and red wings and there is redshifted emission starting at LL064 and extending for the full 3' northward extent of the map. A potential blue counterpart extends to the SW but requires more extensive mapping to confirm.
The outflow from LL064 is not the most obvious feature in this map. There is also a strong blueshifted lobe lying between the two SCUBA cores, not associated with a dust continuum peak. The blueshifted gas is coincident with a Herbig-Haro object HH744B (Walawender et al. 2005a) and an IRAC source (presumably H2), and must be the end of an outflow driven by sources to the west, in the south of NGC1333. A good candidate is LL071 (see below).
5). LL065 is associated with a loop of submm emission with HRF71 at its NE apex and Bolo26 to the SW. The IRAC emission for LL065 consists of an arc plus a compact source, with the latter detected by SHARC-II. Although the arc may be explained as a H2 shock, the MIPS and SHARC-II emission suggest that the compact object is protostellar. LL068 (IRAS 03256+3055) lies 1' to the east of HRF75 and HRF71 and only has a faint SCUBA core (140 mJy/beam, detection) but is detected as a northeast-southwest ridge by SHARC. Linewings are detected for LL068 and the map shows a clear redshifted lobe running to the east, with widespread blueshifted gas to the west which may be associated with the redshifted Herbig-Haro objects HH340B (Hodapp et al. 2005). LL065 also shows a clear red wing from with emission strongest close to the source but extending to the NW of the map. This outflow could be entirely locally driven by LL065, but possibly it is confused with the flow from LL068 (IRAS 03256+3055). Alternatively, the shocks could be driven by sources in NGC1333 to the north (Davis et al. 2008); this seems a likely explanation for the widespread blueshifted gas in the region, which continues southwest to Bolo26.
5). It is not clearly associated with a SCUBA peak, Dunham et al. (2008) do not classify it as an embedded source, and it shows no SHARC-II emission at a level of 1.6 Jy/beam (3). Therefore it is highly unlikely to be a protostar. Nonetheless, it satisfies the linewing criteria and shows red and blueshifted components on the map. There are strong H2 shocks in this area (Davis et al. 2008). It is very likely that this flow is driven by a source in the main NGC1333 cluster to the northeast. A good candidate is NGC1333 ASR 114 (HRF45), but further mapping is needed to confirm this.
5), to the south of SVS13 and east of IRAS 4, associated with SCUBA HRF65. The submm core lies on a partial dust shell centred to the north which Sandell & Knee (2001) suggest is created by earlier outflow activity. There is compact 350 emission at the Spitzer position. The spectrum shows convincing red and blue wings and the outflow is confirmed by the map. To the east, the redshifted flow is initially well collimated but becomes confused with the blueshifted flow from IRAS 4A after 1'. The blueshifted flow to the west is almost immediately confused with the heavyweight blueshifted flows coming south from SVS13 (HRF43) and IRAS 2A (HRF44), detected in H2 by Davis et al. (2008), and appears to bend to the south. Possible extensions to this flow are seen in the redshifted gas to the south of SCUBA source HRF59 and in the strong blueshifted lobe which lies between HRF49 and HRF74 (see description of LL065).
4). Both Spitzer sources are coincident with the SCUBA cores and show strong SHARC-II emission. In LL078 the 350 continuum extends 20'' to the southeast. No outflow is detected from LL075, and the flow from LL078 is weak and only detected with the low-level linewing criteria discussed in Sect. 3.1.2. These spectra have a sharply delineated main velocity component between 5 and 11 km s-1 corresponding to the C18O line; the second, weak component at 0-3 km s-1 is widespread in the north of NGC1333 and probably foreground emission. The cores containing these sources have masses of 4 and were classifed Class 0 (Hatchell et al. 2007b). Like other submm cores in this region, they have filamentary tails pointing away from the main NGC1333 cluster which suggest that they are actively being eroded by the stellar winds from the NGC1333 OB population. To explain the outflow non-detection, the disruption must either have halted accretion (by increasing turbulence or removing the reservoir of gas) or have removed enough gas for the outflow detection to fall below our detection limit. There is no evidence for linewings above 300 mK in HRF61.
5). Both are classified in Group 6 by (Dunham et al. 2008) as unlikely to be embedded protostars and indeed there is very little submm emission detected by SCUBA at this position, and none detected by SHARC-II (Fig. 11). The positions of LL076 and LL077 coincide with Herbig-Haro objects HH5A and B respectively, both redshifted (Cohen et al. 1991; Herbig 1974) and extending further to the southeast (Walawender et al. 2005a), and also H2 2.12 emission Davis et al. (2008). This fits with the strong redshifted emission towards both sources, HH5A (LL076) is suggested by Cohen et al. (1991) possibly to harbour the driving source but the absence of SHARC-II emission rules against this. It is more likely that these shocks are driven by NGC1333 IRAS7 5' to the northwest, as suggested by (Davis et al. 2008). Despite the distant driving source, and the lack of an obvious dust clump to collide with, the strong CO emission is compact both in red and blue (further strong emission to the southwest appears to be independent). The outflow orientation must be more or less along the line of sight to explain the strong blueshifted emission as well as red towards LL077. At the position LL077, HH5B appears as a classic NE-SW arc. These sources are Herbig-Haro objects which have mimicked embedded protostars in the Spitzer bands.
3). The weak blueshifted wing at the position of LL081 could be due to this outflow; certainly, nothing in the morphology in the map convinces that LL081 is driving a separate flow. However, there is a strong SHARC-II detection at this position which suggests that this is a real protostar, and the Bolocam detection cannot be due to CO contamination. A higher S/N map would help to confirm the outflow status of this source.
10) suggests that LL090 is a more evolved source, likely Class I, which may explain the relative lack of CO at the source position.
2). This submm core hosts two Spitzer sources. The southern source is the low luminosity source LL104, but it is apparently the source to the north (here labelled LL104N) which is driving a small and faint molecular outflow (Tafalla et al. 2006), also seen with HARP (Figs. 2 and 9). There is no 70 detection for LL104N listed in the c2d catalog, and detection at 70 was required for inclusion in the LLO list (Dunham et al. 2008). Inspection of the MIPS image shows there clearly is a 70 source, but it lies too close to the brighter LL104 70 source to be extracted separately in the c2d pipeline. MIPS and SHARC-II emission suggests that LL104 may also be a second protostar, but any outflow driven by LL104 itself is not evident from the spectra and must be very weak to be confused with the northern flow, which has an estimated mass of only 10-3 . The K-band emission coincident with LL104 takes the form of a bow around the head of the red flow lobe (Tafalla et al. 2006), and it is identified with H2 features (2a,b of Eislöffel et al. 2003, , see Fig. 2) though it is not optically-detected Herbig-Haro objects in Perseus; HH795 is 30'' to the west associated with another H2 knot Eislöffel et al. (2003); Walawender et al. (2005a). It is unclear how much of this Spitzer detection is due to H2 shocks.
2). The SHARC-II emission peak is separated from the IRAC double detection by 15'' and extends only faintly across to the Spitzer position. The CO spectra shows a slight blue wing (0.5 K at 3 km s-1 from line centre), but this is not obviously an outflow as emission at these velocities is widespread in this region in a N-S ridge bowed to the east. The sources LL107/108 are certainly associated with H2 shocks (Eislöffel et al. 2003, 3a,b,e, see Fig. 2) which may be driven by IC 348 MMS, or the same source as the Flying Ghost Nebula (Eislöffel et al. 2003; Walawender et al. 2006). These Spitzer sources appear to be HH objects rather than protostars.
Mean intensity maps of NGC1333 N in five velocity ranges as marked. SCUBA cores are numbered and contoured in green at (1,2,4,8,16,32) 100 mJy/beam (Hatchell et al. 2007b,2005). The two early-type stars are marked with stars and labelled in the first panel, and the Dunham et al. (2008) low-luminosity source indicated with a circle.
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The region in the northern part of NGC1333 deserves some further comment. The nearby, young (1 Myr) cluster NGC1333 is the ongoing subject of studies focussing on its stellar content (Wilking et al. 2004; Aspin 2003), dense cores (Walsh et al. 2007; Sandell & Knee 2001; Hatchell et al. 2005), and the relationship between the two (Gutermuth et al. 2008; Jørgensen et al. 2007; Hatchell et al. 2007b; Enoch et al. 2008). In Paper III, Hatchell determined the outflow status of the SCUBA cores in the main dense cluster using the Knee & Sandell (2000) JCMT RB map. This central region has also now been mapped with HARP and will be discussed elsewhere (Curtis et al. in prep.). Here we concentrate instead on regions of NGC1333 where the outflows have not previously been observed, to the north and south of the main cluster.
The northern part of the NGC1333 region is dominated by the two late-type B stars which power the reflection nebula which gives the region its name. The B5e star SVS3 (Lada et al. 1996; Strom et al. 1976) and, further to the north, B7V BD (Aspin 2003) light up cavities opening northwards away from the main cluster. In terms of the SCUBA cores, SVS3 lies just north of 54 and BD between 57 and 67. These stars strongly heat the gas in this northern region. At the position of SVS3, reaches 50 K; at a position 30'' to the south of BD , 70 K (Fig. 8), indicating kinetic temperatures at least this large. Thus strong CO lines in this region indicate high temperature gas, rather than large flow masses. The B stars also drive winds with their own influence on the molecular gas.
The simple red/blue integrated intensity maps in Fig. 4 do not do full justice to the velocity structure in the molecular gas, which is additionally shown as channel maps in Fig. A.1. The SCUBA cores are associated with the main molecular component at around 7.5 km s-1, from their C18O velocities (Paper I).
At low velocities of around 2 km s-1, the low column density cloud first discovered by Loren (1976) extends across the north of the map (see sources HRF61, HRF64, HRF58, HRF91 below). This is visible in CO 3-2 above 27' though in 12CO 1-0 it can be seen to extend as far south as 22' at increasing in strength and velocity towards the north (Brunt, priv. comm.).
There is a blueshifted gas between 3 and 7 km s-1 in the west of the map forming a N-S structure over 4' in extent with a sharply defined eastern boundary. Peak line intensities are typically 15 K. This component has neither the typical linewings of an outflow nor an obvious driving source. It is possible that it is a fossil flow which has been cut off from a driving source, which could be much further south. An alternative explanation is that winds from BD + 50 459 and SVS3 have excavated a cavity in the molecular gas, and are now heating the inner edge. The morphology of the reflection nebula (Gutermuth et al. 2008) and the dust filaments both suggest that there are strong winds blowing northwards in this region. The highest-velocity redshifted components lie in the centre south of the map, 1' to the northeast of SVS3.
We discuss the outflow status of individual sources below, but because this region is so complex many of our results are necessarily inconclusive. Embedded YSO identification based on Spitzer colours is difficult because of the high probability of finding reddened background sources, and because much of the infrared is also saturated by the bright nebula, and there are several differences between Jørgensen et al. (2007) and Gutermuth et al. (2008). The recent Davis et al. (2008) UKIRT H2 survey only identifies a couple of H2 knots attributed to the HH6 driving source IRAS7 SM1 4' to the south.
This row of submillimetre peaks lies on the northern boundary of the main NGC1333 cluster and just off the (Knee & Sandell 2000) outflow map. Flows northwards from the Class 0 source SK31 (HRF47) and NGC1333 ASR114 (HRF45) to the south may extend across these sources. Looking at the map (Fig. 4) and CO spectra, there is widespread red/blue emission. The blueshifted wing of HRF66 meets the criteria, HRF54 only shows weak wings, but the spectrum for HRF56 clearly shows red and blue wings, also apparent in the maps (Fig. A.1), so this source has all the characteristics of an outflow driving source.
In Hatchell et al. (2007b) we classified HRF54 and HRF56 as Class I and HRF66 as starless. None of the three were identified as protostars by (Jørgensen et al. 2007), but with a different classification of the Spitzer data, Gutermuth et al. (2008) identify a Class I source with HRF56 and another in the filament to the southeast, as well as three without associated SCUBA emission further to the north (see their Fig. 10). The identification of HRF56 as an embedded YSO agrees with its outflow status.
These cores lie on the northeastern boundary of the reflection nebula. Heated by BD 0.1 pc away in projection, 57 and HRF67 may be hotspots rather than true dust cores. Core HRF57 shows no evidence for outflow or embedded infrared sources. The protostellar core HRF63 (Jørgensen et al. 2007; Hatchell et al. 2007b), has evidence for a redshifted flow which extends to the south (Fig. A.1). To its north SCUBA core HRF67, also classified protostellar by Jørgensen et al. (2007) and Paper II but not by Gutermuth et al. (2008), does not classify as an outflow source based on its spectrum. The integrated intensity velocity ranges of (blueshifted) and 10.5-20.5 km s-1 (redshifted) also pick up widespread gas components at small blueshifted velocities; CO components out to 10 km are also widespread.
Low-luminosity Spitzer sources LL075 and LL078 were discussed in Sect. A.1. The other SCUBA cores in the filaments extending north from NGC1333, sources HRF64 and HRF91, show no evidence for either embedded protostars or outflow activity.
The south and west of NGC1333 contain several sources which lie outside the area covered by Knee & Sandell (2000) and have been targetted by HARP, as shown in Fig. 5. This region contains many low-luminosity sources - LL064,LL065,LL066, LL068, LL071, LL076/77, and LL078 - which are discussed in Sect. A.1 along with the nearby SCUBA cores.
Gutermuth et al. (2008) Class I source 18, which lies 40'' to the southeast of the SCUBA peak. (Sect. A.1). Gutermuth et al. (2008) Class I sources 16, 19 and 20 also lie 20'' to the south, 3' to the southeast and 2' to the east, respectively, so there are plenty of potential driving sources for these outflows.
5. The blueshifted emission, which has an associated Herbig-Haro object HH759 (Walawender et al. 2005a), is more localised and the driving source is entirely unclear. The infrared images provide few clues, except that the HH object is extended further to the southeast.
A.1). HRF69 and 75 show no linewings by either criterion. There is widespread low-level blueshifted gas in the region which peaks at the position of Bolo26 and at a position between HRF69 and HRF71. The driving source is unclear but is likely to be a source further north in NGC1333. There are several H2 shocks in this area (Davis et al. 2008, Fig. 8).
Gutermuth et al. (2008) source 13. There are no obvious H2 shocks in this field (Davis et al. 2008).
Maps of the IC348 region are shown in Fig. 2. The well-known outflows in this region are driven by HH211 (HRF12) and IC348 SMM2 (HRF13).
Tafalla et al. 2006) is discussed in detail above (Sect. A.1 source LL104).
Gutermuth et al. 2008; Jørgensen et al. 2007) and shows an outflow just visible in the HARP maps but discovered with RB (Paper III), but none of the other SCUBA cores mapped here show outflows or contain Spitzer YSOs.
3.2 and A.1) and do not drive any outflows.
Per B1 and the filament to the southwest containing IRAS 03271+3013, IRAS 03282+3035 and IRAS 03292+3039 is are shown in Fig. 2. Outflows from the main B1 cluster have been discussed in detail by us (Paper III) and Walawender et al. (2005a). We originally mapped the inner parts of the IRAS 03292+3039 (HRF76), IRAS 03282+3035 (HRF88) and IRAS 03271+3013 flows with RB but return to the latter two sources with HARP.
3.4 because of its dust continuum emission.
Bachiller et al. 1991)) with a clear outflow cavity in the blueshifted flow to the northeast, and a weaker red counterpart to the southwest. The linewings from this Class I source are weak and only qualify by the low-level criteria. The connection with Bolo52/LL081 to the northeast is discussed in Sect. A.1.
Jørgensen et al. (2007) though not by Paper II. A possible outflow can be identified by the low-level criterion and as a redshifted flow extending to the north of the SCUBA core. A better signal-to-noise CO map is required to confirm this.
Outflows from L1448 are shown in Fig. 6. The only new HARP map here is HRF32, as outflows from the main sources were mapped with RB (Paper III) (see also Bachiller et al. 1991,1990; Wolf-Chase et al. 2000). We also have no new maps to add to the L1455 group, but we have mapped two isolated cores: HRF80 (IRAS 03235+3004) 10' to the west of L1455, and HRF86 which lies 15' southeast of L1448.
Wolf-Chase et al. 2000), and there is no Spitzer detection.
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