RNO 43 (Cohen 1980) is the brightest spot of a chain of Herbig-Haro knots
(Jones et al. 1984; Ray 1987; Mundt et al. 1987)
extending 
to the northeast of the source IRAS 05295+1247. This chain is designated as
HH 243 in the new catalog of Herbig-Haro objects of Reipurth (1994).
Another long (
), well collimated chain of Herbig-Haro knots (HH
245) extends to the north of RNO 43. Reipurth (1991) found a large
fragmented counter bow-shock (HH 244) to the southwest of the IRAS source,
suggesting that HH 243 and HH 244 constitute a bipolar HH flow. Anglada
et al. (1992) found several radio continuum sources that could be related
to the HH 243, HH 244 and HH 245 chains. The high-velocity CO emission in
the region has been mapped by Edwards & Snell (1984), Cabrit et al.\
(1988), and Bence et al. (1996). The CO outflow exhibits a complex
distribution with several overlapping red and blueshifted lobes, extending
on both sides of the IRAS source, and aligned roughly in the north-south
direction. The CO lobes located to the north of the IRAS source were
initially proposed to constitute two separate outflows (Edwards & Snell
1984). However, no exciting sources have been found for these proposed
outflows. Also, no 
emission associated with these northern lobes has
been detected (Anglada et al. 1989). On the other hand, Cabrit et al.\
(1988) proposed that the overall high-velocity structure constitutes a
single bipolar CO outflow powered by IRAS 05295+1247. A CS clump (Cabrit
et al. 1988) is associated with the IRAS source. However, the nominal
position of the IRAS source appears to be displaced 
east from the
center of the clump. Anglada et al. (1992) found a 3.6 cm VLA source
(also detected at 1.3 mm by Reipurth et al. 1993) which is better
centered on the CS cloud. Anglada et al. (1992) suggest that the IRAS
catalog position is in error by 
in right ascension, and that
the IRAS and the radio continuum sources are tracing the same embedded
object, which is the powering source of both the molecular and the HH
outflows.
In Fig. 3.1 (click here), we show our 
map of this region. We have detected a weak
condensation centered 
to the west of the IRAS source,
similar to the CS condensation observed by Cabrit et al. (1988). As the
exciting sources of outflows are usually deeply embedded objects, the fact
that the high-density gas (traced by the CS and 
emission; Cabrit et
al. 1988; this paper) is found associated only with the cm-mm-IRAS
source, and that no 
emission was found associated with the northern
CO lobes near RNO 43 (Anglada et al. 1989), further supports that the
radio continuum source represents a deeply embedded young stellar object,
and is the most plausible powering source for the molecular and HH
outflows observed in this region, as suggested by Anglada et al. (1992).
Figure 4: Contour map of the peak antenna temperature of
the main line of the ammonia (J,K)=(1,1) inversion transition (thick line)
in the RNO 43 region. The lowest contour level is 0.1 K, and the
increment is 0.02 K. The observed positions are indicated with small
crosses. The half power beam width of the telescope is shown as a circle.
The positions of several relevant objects in the region are indicated.
The central part of the CO bipolar outflow mapped by Cabrit et al. (1988)
is shown with thin lines (solid contours indicate blueshifted gas, and
dashed contours indicate redshifted gas)
This HH object lies at the western edge of the L1641 molecular cloud. The
optical structure consists of a jet (at least 32'' long), apparently
emanating from the embedded infrared source HH83 IRS (IRAS 05311-0631;
Reipurth 1989), which is associated with a reflection nebula and ending
with a bow-shock. The jet is highly collimated, and presents large
variations in velocity and physical conditions along its length (Reipurth
1989). There is a faint nebulosity 
southeast of the central
infrared source that could be part of the counter bow-shock (Reipurth
1989; Ogura & Walsch 1991). The estimated bolometric luminosity of HH83
IRS is 8 
(Reipurth et al. 1993). This source does not present
detectable radio continuum emission at 3.6 and 2 cm (Rodríguez &
Reipurth 1994). Recently, Bally et al. (1994) have mapped a very low
velocity, poorly collimated asymmetric molecular outflow (with the
redshifted lobe much larger than the blueshifted one) associated with HH83
IRS. These authors suggest that the outflow from HH83 IRS has ``blown
out'' of the molecular cloud and that it may be in a late stage
of evolution. Interferometric CS observations (angular resolution
) of the cloud core associated with HH83 IRS (Nakano et
al. 1994) reveal a high-density structure consisting of a bar
(
long, centered on HH83 IRS and nearly perpendicular to the
HH jet) and two ridges surrounding the base of the jet. These authors
interpret the CS bar as a rotating circumstellar disk and the two
ridges as tracing a small elongated hollow that may be playing an
important role in focusing the HH jet.
We have detected a weak 
clump with the emission peak close to the
proposed exciting source of HH 83 (see Fig. 3.2 (click here)). The 
clump appears
unresolved with our beam of 
, and we cannot study the small
scale structure observed in CS by Nakano et al. (1994). At a larger
scale, the weakest 
emission seems to extend further to the north and
to the west, outside our mapped area. The region we mapped in 
\
corresponds to the core of the molecular clump studied in 
by Bally
et al. (1987, 1994), which also shows a clear northern extension.
Figure 5: Same as Fig. 4, for the HH 83 region. The
ammonia lowest contour level is 0.08 K, and the increment is 0.02 K. The
map of the CO bipolar outflow is from Bally et al. (1994). The position
of IRAS 05311-0631 is indicated
This HH object was identified and studied by Reipurth (1985, 1989). HH 84
is a long (
) chain of HH knots outlining a well-collimated
optical flow with a position angle of 
. Unlike the large
majority of the optical jets, this HH outflow is redshifted with respect
to the ambient cloud. Morgan et al. (1991) found evidence for red wing
emission in CO profiles, but could not confirm whether this is a molecular
outflow. Up to now, no good candidate for the HH flow excitation has been
proposed. IRAS 05317-0638 (identified with SW Ori, an 
star and
X-ray source; Strom et al. 1989a) lies 
south along the jet axis
(see Fig. 3.3 (click here)). However, based on the morphology of the knots, Reipurth
(1989) argues that the flow exciting source should most probably be an
embedded source (still undetected) located to the north of the jet.
We found weak ammonia emission associated with the HH knots. Our 
map
is presented in Fig. 3.3 (click here). The ammonia emission maximum is close to the
northern edge of the jet, and may be tracing the location of a possible
embedded exciting source, then supporting the suggestion of Reipurth
(1989). However, we only mapped a small region and, in particular, our
map does not reach the position of the IRAS source. The 
emission
appears to extend further to the northeast, roughly following the
distribution of the emission of the molecular cloud mapped in 
by
Bally et al. (1987; see detail in Reipurth 1989).
Figure 6: Same as Fig. 4, for the HH 84 region. The ammonia
lowest contour level is 0.08 K, and the increment is 0.02 K. The position of
IRAS 05317-0638 (identified as SW Ori) is indicated
The Herbig-Haro objects HH 86, HH 87 and HH 88 appear to be closely associated, and probably originate in the same flow (Reipurth 1985, 1989). The three objects are roughly aligned, but they exhibit a rather complex substructure and no local exciting source has been found. The knots in HH 86 appear to cluster around a faint star, but this star is probably not related to the flow, as discussed by Reipurth (1989). The T Tauri star V573 Ori (possibly associated with IRAS 05332-0637; Weintraub 1990) is also close by, but it does not lie on the line traced by the HH jet. Bally & Devine (1994) suggest that these HH objects are the southern end of a 3 pc long ``superjet'' emanating from the exciting source of HH 34.
Our 
map is shown in Fig. 3.4 (click here). As it can be
seen in the figure, the 
emission is faint and
displaced to the east of the HH 86/87/88 complex. As
the HH 86/87/88 complex lies along a ridge with
increasing column density to the east (as mapped in
by Bally et al. 1987), it is
plausible that the 
emission continues further to
the east of the region we have mapped. Since no 
\
emission is seen towards the HH complex, this lack of
high-density gas associated with the HH objects seems
to exclude that their exciting source could be an undetected deeply embedded object in this region, then favoring a non local origin for the HH excitation, as suggested by Bally & Devine (1994).
Figure 7: Same as Fig. 4, for the HH 86/87/88 region. The
ammonia lowest contour level is 0.12 K, and the increment is 0.04 K. The
position of IRAS 05332-0637 (possibly associated with V573 Ori) is
indicated
A bipolar CO outflow, L1641-N (Fukui et al. 1986, 1988; Wilking et al.\
1990), has been mapped in the northern part of the L1641 cloud. The
outflow is centered on IRAS 05338-0624, which is proposed as the outflow
exciting source. Although optically invisible, this source is one of the
most luminous (
) IRAS sources in this region.
Near-IR images (Strom et al. 1989c; Chen et al. 1993) reveal a
dense stellar concentration centered on the IRAS position. The IRAS counterpart
has been identified in the near-IR (Chen et al. 1993), millimeter
(Wilking et al. 1989; Chen et al. 1995) and centimeter
(Mundy et al.\
1993; Anglada et al. 1996; Chen et al. 1995) ranges.
Recently, 
\
maser emission has been found in association with IRAS 05338-0624 (Xiang
& Turner 1995). In addition, several faint red nebulous objects of
unknown nature have been found in a CCD image of the region (Reipurth
1985). A centimeter continuum source (Morgan et al. 1990;
Anglada et al.\
1996), also visible in the CCD image by Reipurth (1985), is found 
to the NE of the IRAS source, approximately midway between the red
nebulous objects Re 35 and Re 43.
About 3' to the SW of the center of the L1641-N molecular outflow, lies
the source IRAS 05339-0626. This source (
) is a
typical Class I source (Strom et al. 1989a). Several near-IR sources
(Chen et al. 1993) and a centimeter continuum source (Morgan et al.\
1990 Anglada et al. 1996) are found near the IRAS position. Red wing CO
emission has been observed towards this position, although it is unclear
whether this high-velocity emission originates from IRAS 05339-0626 or
it is just extended high-velocity emission from the L1641-N outflow
(Morgan et al. 1991).
We have mapped in 
a region that includes both IRAS sources. The map
we have obtained is shown in Fig. 8. The 
structure consists of two
subcondensations, peaking near the positions of the IRAS sources. This
result suggests that both IRAS sources are embedded in dense gas. The
condensation around IRAS 05338-0624 has been mapped in several molecular
species (Fukui et al. 1988; Chen et al. 1992; Harju et
al.\
1991; McMullin et al. 1994) with the emission peaking close to the IRAS
position as in our 
map. In particular, the 
map obtained by
Harju et al. (1991) with higher angular resolution (40''), is in good
agreement with our results. The whole region encompassing both IRAS
sources was mapped previously only in HCN (Takaba et al. 1986) and with
lower (
) angular resolution. CS emission was detected but not
mapped, towards the two IRAS sources (Morgan & Bally 1991).
Figure 8: Same as Fig. 4, for the L1641-N region. The ammonia
lowest contour level is 0.15 K, and the increment is 0.15 K. The IRAS
source associated with the northern ammonia peak is IRAS 05338-0624 and
the one associated with the southern ammonia peak is IRAS 05339-0626.
The map of the CO outflow is from Fukui et al. (1986)
L100 (Barnard 62) is a large, very opaque Bok globule in Ophiuchus,
surrounded by bright rims. Reipurth & Gee (1986), based on a photometric
study, estimate a distance of 
pc. These authors found several
emission stars associated with L100 and conclude that IRAS
17130-2053 (0.25 
), an IRAS source
with no optical counterpart, represents the envelope of an embedded PMS
object, more evolved than a protostar. Parker et al. (1988) detected a
bipolar molecular outflow elongated in the NE-SW direction and centered at
the position of IRAS 17130-2053, which was proposed as the outflow
exciting source.
We have mapped in 
the region around IRAS 17130-2053. We have
detected faint and unresolved 
(1,1) emission peaking near the position
of the IRAS source. Our map is shown in Fig. 3.6 (click here). The IRAS position is
near the maximum of the ammonia map, in agreement with the idea that it is
an object embedded in high-density gas. However, the weakness of the
ammonia emission suggests that it is associated with only a small amount
of high-density gas and that the size of the ammonia clump could be much
smaller than our beam.
Figure 9: Same as Fig. 4, for the L100 region. The ammonia
lowest contour level is 0.08 K, and the increment is 0.02 K. The map of the CO
outflow is from Parker et al. (1988)
Parker et al. (1988, 1991) and Fuller et al. (1995) have mapped in
CO a compact bipolar molecular outflow in the L483 dark cloud. The outflow is
clearly elongated along the E-W direction and it is centered on the
low-luminosity infrared source IRAS 18148-0440 (L=14 
, assuming a
distance of 200 pc; Ladd et al. 1991a), which is proposed as the outflow
exciting source. This source has neither optical nor near-infrared
counterpart (Parker 1991). The source has been detected with the VLA at
3.6 cm (Anglada et al. 1996). From the far-IR data and from
submillimeter observations (Ladd et al. 1991b; Fuller et al. 1995),
Fuller et al. (1995) conclude that the IRAS source is a very young object
similar to the so-called Class 0 sources. The source is surrounded by a
bipolar near-IR nebula, and a jet-like region of 
emission, ending in
a bright knot, extends along the blue lobe of the CO outflow (Fuller et
al. 1995). An 
maser near the IRAS position has been detected by
Xiang & Turner (1995) through single-dish observations.
In Fig. 3.7 (click here) we show the ammonia map obtained from our observations. The
emission peaks very close to the IRAS source position. This fact,
together with the infrared results (Fuller et al. 1995), suggest that the
IRAS source is deeply embedded in the dense core, giving support to its
identification as the powering source of the molecular outflow. Our
ammonia map is in good agreement with the ammonia map shown by Fuller &
Myers (1993). Fuller & Myers (1993) found two velocity components
separated by 0.28 
in an 
spectrum obtained towards the peak of
the core, and discuss on their relationship with the overall distribution
of dense gas. The velocity resolution of our observations (
) does not allow us to separate these components in the spectra.
Goodman et al. (1993) report a velocity gradient (
,
PA = 52
) in the region. From our data, we estimate a velocity
gradient of 2-3 
approximately in the SW-NE direction, which is
consistent with the result of Goodman et al. (1993).
Figure 10: Same as Fig. 4, for the L483 region. The ammonia
lowest contour level is 0.20 K, and the increment is 0.15 K. The map of the CO
outflow is from Parker et al. (1988)
The distance to the L673 dark cloud is not well established. Estimates by
different authors range between 150 pc and 400 pc. We will adopt a
distance of 300 pc, based on proper motions studies (Herbig & Jones
1983). Armstrong & Winnewisser (1989) discovered a very extended
(
) bipolar molecular outflow in the northern part of L673.
There are four IRAS point sources within five arcmin of the center of the
outflow. From an analysis of the IRAS colors, Armstrong & Winnewisser
conclude that IRAS 19184+1118 is probably a visible main-sequence star,
while the IRAS colors of the other three sources (IRAS 19180+1116,
19180+1114, 19181+1112) are consistent with those of embedded stars.
In particular, the source IRAS 19180+1116, which coincides with RNO 109
(Cohen 1980), is proposed by Armstrong & Winnewisser (1989) as
the most likely candidate to be the outflow exciting source. Ladd et al. (1991a,
b) obtained far-infrared photometry and images of IRAS 19180+1116 and
IRAS 19180+1114, showing that a large fraction of the luminosity of
these objects is radiated at long wavelengths (
60 
), indicating that they are very young.
Our ammonia map is shown in Fig. 3.8 (click here). The ammonia structure consists of
three subcondensations, peaking near the position of the sources IRAS
19180+1116 (RNO 109), IRAS 19180+1114 and IRAS 19181+1112. This
result suggests that the three sources are embedded in dense gas. The
source IRAS 19180+1114 is located very close to the strongest emission
maximum, suggesting that this source is associated with the largest amount
of high-density gas, being probably the most deeply embedded of these
three objects. The spectral energy distribution of this source (Armstrong
& Winnewisser 1989; Ladd et al. 1991a) is also consistent with this
suggestion. The source IRAS 19180+1114 is also well centered in between
the two outflow lobes, despite of the irregular geometry of the molecular
outflow (see Fig. 3.8 (click here)). Taking into account the ammonia results, the
spectral energy distribution, and the location with respect to the CO
outflow, we favor IRAS 19180+1114 (rather than IRAS 
109) as the best candidate for the excitation of the molecular outflow in
the region.
Although our observations do not reach the position of IRAS 19184+1118,
from the region we have mapped it seems clear that the 
emission
decreases as one moves to the NE, towards the position of this IRAS
source. Thus, this source does not appear to be associated with a
significant amount of dense molecular gas. This result is confirmed by
the CS (
) observations of Morata et al. (1996). Even
though the CS emission appears to be more extended than the 
emission,
the CS map shows that IRAS 19184+1118 lies at the outer edge of the CS
distribution, suggesting that this source is not embedded in high density
gas. These results are in agreement with those of Armstrong &
Winnewisser (1989), which concluded that the IRAS colors of this source
are typical of a visible main-sequence star.
Figure 11: Same as Fig. 4, for the L673 region. The ammonia
lowest contour level is 0.15 K, and the increment is 0.1 K. The IRAS sources
associated with the ammonia structure are (from north to south) IRAS 19180+1116
(RNO 109), IRAS 19180+1114 and IRAS 19181+1112. The IRAS source outside the
ammonia structure is IRAS 19184+1118. The map of the CO outflow is from
Armstrong & Winnewisser (1989)
IRAS 20188+3928 (
; Odenwald &
Schwartz 1993) is associated with a compact molecular cloud located in the
Cygnus region. The distance to this source is very uncertain (0.4 kpc
kpc; Little et al. 1988). We adopt in this paper its
largest value (4 kpc); thus, most of the physical parameters obtained for
this region will be upper limits. Little et al. (1988) mapped in 
\
and 
a bipolar molecular outflow associated with this IRAS source,
concluding that the outflowing gas has a dense and clumpy nature.
We have detected a compact ammonia condensation (Fig. 3.9 (click here)), with the
emission peaking very close to the IRAS 20188+3928 position. This
result suggests that the IRAS source is deeply embedded in the high
density gas, as usually are the exciting sources of molecular outflows.
The ammonia lines in this condensation are significantly wider (
) than in the other regions of our sample (see Table 2 (click here)).
Moreover, there is a north-south velocity gradient in the 
\
condensation, with the line velocity in the northern part being redshifted
(by 
) with respect to the southern part, i.e., roughly in
the same direction as the outflow. These results suggest that the dense
gas around IRAS 20188+3928 is perturbed by the outflow from this star
and is entrained into the high velocity gas, in agreement with the 
\
results obtained by Little et al. (1988).
Palla et al. (1991) detected 
maser emission on January 30, 1989 in
a single observation towards the position of the IRAS source, obtaining a
peak line flux 
Jy and a radial velocity 
. We detected this 
maser on February 10, 1990. From a
seven-point map centered on the IRAS position, we found that the maximum
of emission was displaced 
to the NW of the IRAS source. In
Fig. 2 (click here), we show the spectrum of the 
maser towards this position.
The single feature we observed can be fitted with a Gaussian profile
having peak line flux 
Jy, half-power full width
, and radial velocity with respect to the local
standard of rest, 
. Thus, this 
maser
feature shows high variability on a time scale of one year. Several new
maser features, at different velocities appeared also in observations
carried out in 1990 and 1991 (Xiang & Turner 1995). One of these features
coincides within 4'' with the position of the IRAS source.
Figure 12: Same as Fig. 4, for the IRAS 20188+3928 region.
The ammonia lowest contour level is 0.20 K, and the increment is 0.1 K.
The map of the CO outflow is from Little et al. (1988)
L1228 is a high galactic latitude dark cloud, whose distance is poorly
known. Haikala et al. (1991) estimate a distance between 100 and 200 pc,
while Bally et al. (1995) argue that a better value is 300 pc. In this
paper we have adopted this last value. Haikala & Laureijs (1989)
discovered a large (
, for the
assumed distance of 300 pc) and well-collimated bipolar CO outflow, with
its axis in the NE-SW direction. The outflow is centered on the low
luminosity object IRAS 20582+7724 (
), which was proposed
as the outflow exciting source. Anglada et al. (1996) have detected this
source in the radio continuum at 3.6 cm with the VLA. Very recently,
Bally et al. (1995) have obtained a new CO map of the outflow and
detected several HH objects along the axis of the molecular outflow.
Moreover, these authors detected an 
jet emerging from IRAS
20582+7724, but the jet axis differs from that of the molecular outflow by
, suggesting that the jet ejection direction varies over time.
Bally et al. (1995) also detected a long highly collimated HH jet (HH
200), which may be associated with a very low velocity and faint
blueshifted CO lobe, and whose exciting source appears to be an embedded T
Tauri star located 
of the IRAS source.
Tafalla et al. (1994) have observed the dense gas around the IRAS source
as traced by 
and HCN. These authors found sudden shifts in the
line velocity of these molecules, with a systematic velocity pattern that
agrees in direction and velocity sense with the CO outflow. Tafalla et
al. identified three distinct velocity components in the core, and
interpreted these results as evidence for the disruption of the dense core
by the bipolar outflow from the IRAS source.
Our ammonia map of this region (Fig. 3.10 (click here)) shows a condensation of
in size, elongated in the N-S direction. The ammonia
emission peaks very close to the position of the IRAS and radio continuum
source, suggesting that this source is deeply embedded in the high density
gas, as it is expected for the exciting source of the outflow. For
positions with good signal-to-noise ratio, our data show a velocity shift
in the ammonia line velocity, consistent with the direction and sense of
the bipolar molecular outflow. In Fig. 3.10 (click here) we show the spectra of the
(1,1) main line observed towards the position of the IRAS source, as
well as towards two additional positions displaced 
to the east
and 
to the west, respectively. As it can be seen in the
figure, the central velocity of the lines are clearly displaced, with a
velocity shift between the extreme positions of 
,
corresponding to a velocity gradient of 
. Tafalla et al.\
(1994), from their higher angular resolution data, obtained velocity
gradients of up to 10 
on a scale of 20''. Our lower angular
resolution data do not allow us to detect these sudden shifts in velocity
but, in any case, they provide evidence that the dense gas is perturbed
and accelerated by the molecular outflow.
Figure 13: Same as Fig. 4, for the L1228 region. The
ammonia lowest contour level is 0.20 K, and the increment is 0.15 K. The
map of the CO bipolar outflow is from Haikala & Laureijs (1989)
Figure 14: Spectra of the 
(1,1) main line towards three
selected positions in L1228. The offsets are in arc minutes with respect
to the IRAS position. To make easiest the comparison, the main beam
brightness temperature of the (0,0) spectrum has been divided by 3
HHL 73 is an Herbig-Haro like object, whose position coincides, within
observational errors, with an 
maser (Gyulbudaghian et al. 1987) and
with the source IRAS 21432+4719. A region of 
around
HHL 73 was mapped in ammonia by Verdes-Montenegro et al. (1989), using
also the Haystack radio telescope. Their observations revealed a
condensation with an angular size of 
,
elongated in the NW-SE direction, and with the HHL 73 object located very
close to the ammonia emission peak. Verdes-Montenegro et al. (1989)
detected also a weaker ammonia condensation, located 
northeast of
the main condensation. No signs of star formation associated with this
second clump are known at present.
The region was mapped in CS by Pastor et al. (1991). The CS emitting
region is elongated in the E-W direction and it is more extended
(
) than the region mapped in ammonia by Verdes-Montenegro et
al. (1989). The CS structure presents several emission peaks, three of
them coinciding with IRAS 21429+4726, IRAS 21432+4719 and IRAS
21441+4722. These IRAS sources have faint optical counterparts on the
Palomar Sky Survey red print and were classified as ``protostar type'' by
Dobashi et al. 1992. Recently, Dobashi et al. (1993) have
detected three highly asymmetric molecular outflows associated with these IRAS sources.
To complete the study in 
of this region, we carried out new
observations, completing those of Verdes-Montenegro et al. (1989), in
order to cover the overall region observed in CS. In
Fig. 3.11 (click here) we show the complete 
map of the
region (including the data of Verdes-Montenegro
et al. 1989). Four ammonia clumps,
coinciding with emission peaks in the CS map of
Pastor et al. (1991), are observed in
the figure. Three of the ammonia clumps are associated
with an IRAS source, located very close to the emission peak, thus suggesting that these clumps contain a young embedded object. The mean separation between these clumps (
) is of the order of the typical distance between stars. Therefore, this
region appears to be an example of simultaneous formation of several stars
in the same cloud, as it was suggested by Pastor et al. (1991).
Figure 15: Same as Fig. 4, for the HHL 73 region. The
ammonia lowest contour level is 0.12 K, and the increment is 0.1 K. The
map obtained by Verdes-Montenegro et al. (1989) is also included.
The maps of the CO outflows are from Dobashi et al. (1993)
Figure 16: Same as Fig. 4, for the IRAS 22343+7501
region in L1251. The ammonia lowest contour level is 0.1 K, and the
increment is 0.1 K
L1251 is an elongated dark cloud (Lynds 1962) apparently belonging to the
``Cepheus Flare" giant molecular cloud complex (Lebrun 1986). The
estimated distance of this cloud is between 200 pc to 500 pc. We have
adopted a distance of 300 pc, estimated from a photometric study by Kun &
Prusti (1993). Several indications of low-mass star formation have been
found in L1251, with several 
emission stars and infrared point
sources detected in the cloud (see Kun & Prusti 1993 and references
therein). Our following study of this region focuses on two IRAS sources,
IRAS 22343+7501 and IRAS 22376+7455, which are the most luminous
sources in L1251 and appear to be the powering sources of bipolar CO
outflows.
IRAS 22343+7501 is the driving source of an extended and poorly
collimated outflow, L1251-A (Schwartz et al. 1988; Sato & Fukui
1989). The outflow map differs from one study to the other. The outflow map
obtained by Sato & Fukui (1989) represents molecular gas with relatively
low velocity (
) and is extended (
), with the axis
approximately in the NE-SW direction. On the other hand, the map obtained
by Schwartz et al. (1988), with higher angular resolution, includes
higher velocity gas (
), is more compact and shows a clear
asymmetry in the intensity the two lobes.
Balázs et al. (1992) detected several Herbig-Haro objects (apparently
forming an optical jet with its axis coincident with that of the CO
outflow), and propose that the exciting source of these objects is also
IRAS 22343+7501. Anglada et al. (1996) have detected this source in the
radio continuum at 3.6 cm. Xiang & Turner (1995) have detected an 
\
maser within 
of the IRAS position.
The source IRAS 22350+7502 (probably a T Tauri star; Kun & Prusti 1993) lies about 2' to the north-east of IRAS 22343+7501.
Figure 17: Same as Fig. 4, for the IRAS 22376+7455
region in L1251. The lowest contour level is 0.15 K, and the increment is
0.1 K
Figure 18: Position-velocity diagram of the 
(1,1) main
line along the major axis (
) of the condensation
associated with IRAS 22376+7455, in L1251. The lowest contour level is
0.2 K and the increment is 0.05 K. Right ascension offsets are from the
position of IRAS 22376+7455
In Fig. 3.11 (click here), we show our ammonia map. The two IRAS sources lie at the
edge of the 
condensation, being displaced by 
(
) from the emission peak. At present, no source coincident with the
ammonia emission peak has been found. As the emission peak is displaced
from the outflow center, it is not likely that the outflow exciting source
coincides with this ammonia maximum. The fact that the source proposed as
the exciting source of the outflow, IRAS 22343+7501, is displaced 
in projection from the ammonia emission peak may be due either
because the outflow has disrupted part of the cloud core, or because the
source was formed in the dense cloud but has escaped out of the clump (for
a velocity of the star with respect to the cloud of 
, a time
of 
, which is similar to the time-scale of the outflow, is
required to cover the observed displacement). We note that Morata et al.\
(1996) have mapped this region in CS, obtaining that the CS extends over a
region larger than the 
with IRAS 22343+7501 near a CS emission peak.
CO observations in the region associated with this source (Sato & Fukui
1989; Sato et al. 1994) have revealed a
well collimated and very compact bipolar outflow, L1251-B,
extending over 4' in the NW-SE direction. IRAS 22376+7455
(
; Sato et al. 1994) lies near
the center of the two lobes, suggesting that is driving the bipolar
outflow. IRAS 22376+7455, apparently without optical counterpart
(Kun & Prusti 1993; Eiroa et al.\
1994b), is detected in the radio continuum at 3.6 cm by
Anglada et al. (1996), and is likely to be a protostar embedded in a dense molecular cloud core (Sato et al. 1994). Eiroa et al.\
(1994b) found several Herbig-Haro objects (HH 189A, B and C) that may be
associated with IRAS 22376+7455 or with a nearby nebulous star. Kun &
Prusti (1993) and Eiroa et al. (1994b) also found several infrared
sources and 
emission stars in this region.
In Fig. 3.12.1 (click here) we show our ammonia map. The observed 
condensation
appears to be very elongated (
) in the east-west
direction. IRAS 22376+7455 is located in the midst of the high density
gas, confirming that it is an embedded source. However, this source is
displaced 
(
) from the 
emission peak. Several
other infrared sources are observed towards the 
condensation,
suggesting that they represent embedded sources. One of these sources
coincides positionally with the 
emission peak. There is a secondary
emission peak (located 
to the west of the main one) that appears
not to be associated with any known infrared source. The source IRAS
22385+7457 is located 
to the northeast of IRAS 22376+7455, at
the edge of the 
structure, suggesting that it is not deeply embedded
in the dense cloud. This source is associated positionally with an 
\
emission star, and it is proposed to be a T Tauri star (Kun & Prusti
1993), in agreement with the suggestion that this source is more evolved
than the sources still deeply embedded in dense gas.
From our 
data, we found a velocity gradient of 
in
the NE-SW direction, with sudden velocity shifts of up to 1 
\
(corresponding to gradients of 8 
) along the region. In Fig. 3.12.1 (click here) we
show a position-velocity diagram along the major axis of the clump. The
velocity gradient does not follows the 
condensation axis, but it has
a complex bidimensional structure, so that we do not think that it is due
to a global rotational motion of the dense condensation. Goodman et al.\
(1993) from 
observations, Morata et al. (1996) from CS observations,
and Sato & Fukui (1989) from 
, also found the existence of a velocity
gradient in this region.
In Fig. 3.13 (click here), we show the overall L1251 region, enclosing the two ammonia
condensations we have mapped and their associated molecular outflows. Note
that these two condensations coincide with the two brightest spots in the
map by Sato et al. (1994).
L1262 is an isolated Bok globule with a very high visual extinction (Lynds
1962) located at a distance of 200 pc (Parker et al. 1991). Parker
et al. (1988, 1991) discovered a well-collimated bipolar molecular outflow
approximately 
in extent along its axis. Interferometric 
\
observations (Terebey et al. 1989) show a more compact (
)
outflow. The outflow is elongated in the northeast-southwest direction
and is centered at the position of the source IRAS 23238+7401, which is
proposed as the exciting source of the outflow. This IRAS source has been
classified as a Class I embedded source without optical counterpart
(Parker 1991). The velocity of the outflow decreases gradually as one
moves away from the source (Parker et al. 1988). Anglada et al.\
(1996) found two radio continuum sources at 3.6 cm, one of them being associated
with the IRAS source.
Figure 19: Region enclosing the two ammonia dense cores
observed in L1251 (Figs. 16 and 17). Superposed are shown the two
associated CO outflows, L1251-A and L1251-B (Sato et al. 1994)
Our 
map is shown in Fig. 3.13 (click here). The 
condensation presents two
emission peaks, one of them coinciding with the source IRAS 23238+7401.
Our map is similar to the map obtained by Benson et al. (1984) using the
same ammonia inversion line, but our sensitivity is slightly better and we
are able to distinguish two emission peaks. Zhou et al. (1989) observed
this region in CS, 
and 
, obtaining that
the CS emission is more extended than the 
one, as it is usually found
in other regions.
Figure 20: Same as Fig. 4, for the L1262 region. The
ammonia lowest contour level is 0.15 K, and the increment is 0.1 K. The
map of the CO outflow is from Yun & Clemens (1994)