IRAS Sources Research Articles

Triggered star formation in a molecular shell created by a SNR?

We present a study of a new molecular shell, G 126.1–0.8–14, using available multiwavelength Galactic plane surveys and optical Gemini observations. A well-defined shell-like structure is observed in the CO(1–0) line emission at (l,b) = (126| $_{.}^{\circ}$|1, –0| $_{.}^{\circ}$|8), in the velocity range –10.5 to –15.5 km s−1. The H i emission shows a region of low emissivity inside G 126.1–0.8–14, while radio continuum observations reveal faint non-thermal emission possibly related to this shell. Optical spectra obtained with Gemini South show the existence of B-type stars likely to be associated with G 126.1–0.8–14. An estimate of the stellar wind energy injected by these stars shows that they alone cannot be able to create such a structure. On the other hand, one supernova explosion would provide enough energy to generate the shell. Using the MSX, IRAS and WISE point source catalogues we have found about 30 young stellar object candidates, whose birth could have been triggered by the expansion of G 126.1–0.8–14. In this context, Sh2-187 could be a consequence of the action on its surroundings of the most massive (and thus most evolve) of the stars formed by the expanding molecular shell.

Unstable Objects in Molecular Cloud LDN133

The results of investigation of molecular cloud LDN133 and the unstable objects HHL59, HHL59A, HHL59B and HHL59C connected with it are given. The IR nebula and IR star cluster are also connected with LDN133. It is shown that two different molecular outflows are present: (1) red-shifted molecular outflow from the IR nebula, connected with HHL59, and (2) bipolar molecular outflow from the object HHL59A. An IRAS point source IRAS 17554-2606 is connected with the IR nebula. Observations with narrow band filters revealed the existence of HH objects and jets from several unstable stars of this region. There are three filaments; ejected from the IR nebula with condensation at their ends. Two 8-type cometary nebulae connected with unstable stars were also discovered.

A high-significance measurement of correlation between unresolved IRAS sources and optically-selected galaxy clusters

We cross-correlate the 100 μm Improved Reprocessing of the IRAS Survey (IRIS) map and galaxy clusters at 0.1 < z < 0.3 in the maxBCG catalogue taken from the Sloan Digital Sky Survey, measuring an angular cross-power spectrum over multipole moments 150 < ℓ < 3000 at a total significance of over 40σ. The cross-spectrum, which arises from the spatial correlation between unresolved dusty galaxies that make up the cosmic infrared background (CIB) in the IRIS map and the galaxy clusters, is well-fit by a single power law with an index of −1.28±0.12, similar to the clustering of unresolved galaxies from cross-correlating far-infrared and submillimetre maps at longer wavelengths. Using a recent, phenomenological model for the spectral and clustering properties of the IRIS galaxies, we constrain the large-scale bias of the maxBCG clusters to be 2.6±1.4, consistent with existing analyses of the real-space cluster correlation function. The success of our method suggests that future CIB-optical cross-correlations using Planck and Herschel data will significantly improve our understanding of the clustering and redshiftdistribution of the faint CIB sources.

Annual Parallax Distance and Secular Motion of the Water Fountain Source IRAS 18286–0959

Abstract We report on results of astrometric observations of H$ _{2}$ O masers in the ``water fountain'' source IRAS 18286$-$ 0959 (I18286) with the VLBI Exploration of Radio Astrometry (VERA). These observations yielded an annual parallax of IRAS 18286$-$ 0959, $ \pi$$ =$ 0.277 $ \pm$ 0.041 mas, corresponding to a heliocentric distance of $ D$$ =$ 3.61$ ^{+0.63}_{-0.47}$ kpc. The maser feature, whose annual parallax was measured, showed an absolute proper motion of ($ \mu_{\alpha}$ , $ \mu_{\delta}$ ) $ =$ ($-$ 3.2 $ \pm$ 0.3, $-$ 7.2 $ \pm$ 0.2) [mas yr$ ^{-1}$ ]. The intrinsic motion of the maser feature in the internal motions of the cluster of features in I18286 does not seem to trace the motion of the bipolar jet of I18286. Taking into account this intrinsic motion, the derived motion of the maser feature is roughly equal to that of the maser source I18286 itself. The proximity of I18286 to the Galactic midplane ($ z$$ \approx$ 10 pc) suggests that the parental star of the water fountain source in I18286 should be an intermediate-mass AGB/post-AGB star, but the origin of a large deviation of the systemic source motion from that expected from the Galactic rotation curve is still unclear.

MASSIVE QUIESCENT CORES IN ORION: DYNAMICAL STATE REVEALED BY HIGH-RESOLUTION AMMONIA MAPS

We present combined VLA and Green Bank Telescope images of \ammonia\ inversion transitions (1,1) and (2,2) toward OMC2 and OMC3. We focus on the relatively quiescent Orion cores, which are away from the Trapezium cluster and have no sign of massive protostars nor evolved star formation, such as IRAS source, water maser, and methanol maser. The 5\arcsec\ angular resolution and $0.6 \rm{}km\,s^{-1}$ velocity resolution of these data enable us to study the thermal and dynamic state of these cores at $\sim{}0.02 \rm{}pc$ scales, comparable to or smaller than those of the current dust continuum surveys. We measure temperatures for a total of 30 cores, with average masses of $11\,\Ms$, radii of $0.039 \rm{}pc$, virial mass ratio $\bar{R_{vir}}$ = 3.9, and critical mass ratio $\bar{R_{C}}$ = 1.5. Twelve sources contain \textit{Spitzer} protostars. The thus defined starless and protostellar subsamples have similar temperature, line width, but different masses, with an average of $7.3\,\Ms$ for the former and $16\,\Ms$ for the latter. Compared to others Gould Belt dense cores, mores Orion cores have a high gravitational-to kinetic energy ratio and more cores have a larger thant unity critical mass ratio. Orion dense cores have velocity dispersion similar to those of cores in low-mass star-forming regions but larger masses for fiven size. Some cores appear to have truly supercritical gravitational-to-kinetic energy ratios, even when considering significant observational uncertainties: thermal and non-thermal gas mothins alone cannot prevent collapse.

Different evolutionary stages in massive star formation

We present ATCA observations of the H2O maser line and radio continuum at 18.0GHz and 22.8GHz, toward a sample of 192 massive star forming regions containing several clumps already imaged at 1.2mm. The main aim of this study is to investigate the water maser and centimeter continuum emission (likely tracing thermal free-free emission) in sources at different evolutionary stages, using the evolutionary classifications proposed by Palla et al (1991) and Molinari et al (2008). We used the recently comissioned CABB backend at ATCA obtaining images with 20arcsec resolution in the 1.3cm continuum and H2O maser emission, in all targets. For the evolutionary analysis of the sources we used the millimeter continuum emission from Beltran et al (2006) and the infrared emission from the MSX Point Source Catalogue. We detect centimeter continuum emission in 88% of the observed fields with a typical rms noise level of 0.45mJy/beam. Most of the fields show a single radio continuum source, while in 20% of them we identify multiple components. A total of 214 centimeter continuum sources have been identified, likely tracing optically thin HII regions, with physical parameters typical of both extended and compact HII regions. Water maser emission was detected in 41% of the regions, resulting in a total of 85 distinct components. The low angular (20arcsec) and spectral (14km/s) resolutions do not allow a proper analysis of the water maser emission, but suffice to investigate its association with the continuum sources. We have also studied the detection rate of HII regions in the two types of IRAS sources defined by Palla et (1991) on the basis of the IRAS colours: High and Low. No significant differences are found, with large detection rates (>90%) for both High and Low sources. We classify the millimeter and infrared sources in our fields in three evolutionary stages following the scheme presented by ...

12CO J=2−1 and 12CO J=3−2 observations toward the high-mass protostellar candidate IRAS 20188+3928

We have carried out observations of 12CO J=2−1 and 12CO J=3−2 toward the high-mass protostellar candidate IRAS 20188+3928. Compared with previous observations, the 12CO J=2−1 and 12CO J=3−2 lines both have asymmetric profiles with an absorption dip. The velocity of the absorption dip is ∼ 1.0 km s−1. The spectral shape may be caused by rotation. The velocity-integrated intensity map and position-velocity diagram of the 12CO J=2−1 line present an obvious bipolar component, further verifying that this region has an outflow motion. This region is also associated with an HII region, an IRAS source, and an H2O maser. The H2O maser has the velocity of 1.1 km s−1. Compared with the components of the outflow, we find that the H2O maser is not associated with the outflow. Using the large velocity gradient model, we concluded that possible averaged gas densities of the blueshifted lobe and redshifted lobe are 1.0×105 cm−3 and 2.0×104 cm−3, while kinetic temperatures are 26.9 K and 52.9 K, respectively. Additionally, the outflow has a higher integrated intensity ratio (ICO J=3−2/ICO J=2−1).

MASSIVE STAR FORMATION, OUTFLOWS, AND ANOMALOUS H2EMISSION IN Mol 121 (IRAS 20188+3928)

We have discovered 12 new molecular hydrogen emission-line objects (MHOs) in the vicinity of the candidate massive young stellar object Mol 121, in addition to five that were previously known. H2 2.12-micron/H2 2.25-micron flux ratios indicate another region dominated by fluorescence from a photo-dissociation region (PDR), and one region that displays an anomalously low H2 2.12-micron/H2 2.25-micron flux ratio (<1) and coincides with a previously reported deeply embedded source (DES). Continuum observations at 3 mm reveal five dense cores; the brightest core is coincident with the DES. The next brightest cores are both associated with cm continuum emission. One of these is coincident with the IRAS source; the other lies at the centroid of a compact outflow defined by bipolar MHOs. The brighter of these bipolar MHOs exhibits [Fe II] emission and both MHOs are associated with CH3OH maser emission observed at 95 GHz and 44 GHz. Masses and column densities of all five cores are consistent with theoretical predictions for massive star formation. Although it is impossible to associate all MHOs with driving sources in this region, it is evident that there are several outflows along different position angles, and some unambiguous associations can be made. We discuss implications of observed H2 2.12-micron/H2 2.25-micron and [Fe II] 1.64-micron/H2 2.12-micron flux ratios and compare the estimated total H2 luminosity with the bolometric luminosity of the region. We conclude that the outflows are driven by massive young stellar objects embedded in cores that are likely to be in different evolutionary stages.

HH 588: A giant bipolar outflow in the dark cloud BRC 37

Results of 2D spectroscopy of the complex of Herbig-Haro objects HH 588 in the dark globule BRC 37 are presented. The multipupil spectrograph VAGR has been used to obtain spectra of four parts of this complex, including the objects NE2, NE1, center, and SW2. The kinematic characteristics of these components of the complex confirm the existence of a giant bipolar outflow from the central infrared source IRAS 21388+5622. Spectral studies also show that the central object has the very low excitation and strong [OI] and [SII] emission characteristic of jets emerging from young stellar objects. In terms of their physical parameters, the other objects are typical Herbig-Haro objects. On the other hand, it is found that the entire HH 588 complex is an irradiated Herbig-Haro flow. This is indicated by the comparatively high excitation of the object NE2, and by the fact that the entire HH 588 flow is an arc with its convex side facing the center of the HII region IC 1396.

A survey of CO and its isotope lines for possible cloud-cloud collision candidates

In the 12CO (J=1−0) survey of 1331 cold IRAS sources, 214 sources show profiles with multiple peaks and are selected as cloud-cloud collision candidates. In January 2005, 201 sources were detected with 12CO(1−0), 13CO(1−0), and C18O(1−0) emissions by the 13.7 m telescope at Purple Mount Observatory. This is the first survey of CO and its isotope lines directed toward possible cloud-cloud collision regions. According to the statistics of the 201 sources in the Galactic distribution, the 201 sources show a similar distribution to the parent sample (1331 cold IRAS sources). These sources are located over a wide range of Galactocentric distances, and are partly associated with the star forming region. Based on preliminary criteria which describe the spectral properties of the possible cloud-cloud collision region, the 201 sources are classified into four types by the fit of the spectral profiles between the optically thick and thin lines toward each source. The survey is focused on possible cloud-cloud collision regions, and gives some evidence to help us with selecting the target region. We will continue the process of mapping and studying multi-wavelength observations for the selected region in the future.

DEEP IMAGING SURVEYS OF STAR-FORMING CLOUDS. V. NEW HERBIG-HARO SHOCKS AND GIANT OUTFLOWS IN TAURUS

We report the discovery of new Herbig-Haro shocks in the southeastern portion of the Taurus molecular cloud complex. The embedded protostar IRAS04325+2402, located in the eastern end of the B18 dark cloud in the cloud region known as L1535, drives a parsec-scale outflow with a length of at least 134' (5.5?pc) toward P.A. = 17?/197?? making this the largest protostellar outflow found thus far in Taurus. The southern terminus of this flow located about 65' (~2.7?pc) from the IRAS source consists of a large previously discovered shock, HH 434-436. The northern lobe contains three faint shocks with the most distant being HH 696 located 2.8?pc north of the source. Two smaller shocks, HH 699 and HH 703, are found midway between the IRAS source and HH 434-436. HH 703 has a proper motion of 170 ? 30?km s?1 toward P.A. = 195? ? 10?. Additionally, we report the discovery of a dozen new Herbig-Haro objects tracing outflows and protostellar jets in B18 and near IC 2087, at least two of which have also attained parsec-scale dimensions. These observations demonstrate that some low-mass stars forming from the Taurus clouds drive giant flows which can excite shocks in the inter-cloud medium degrees from their sources, providing further evidence for the generation of large-scale mass motions and turbulence by protostellar outflows.

Low-Resolution Spectroscopy of Hot Post-AGB Candidates II. LS, LSS, LSE Stars and Additional IRAS Sources

Hot (OB) post-asymptotic giant branch (post-AGB) stars are immediate progenitors of planetary nebulae (PNe). Very few hot post-AGB stars are known. Detecting new hot post-AGB candidates and follow-up multiwavelength studies will enable us to further understand the processes during the post-AGB evolution that lead to the formation of PNe. Case-Hamburg OB star surveys and their extension (LS, LSS, and LSE catalogues) and IRAS (point source) catalogues are good sources for detecting new hot post-AGB candidates from low-resolution spectroscopy. Spectral types are determined from low-resolution optical spectra of 44 stars selected from the LS, LSS, and LSE catalogues. Unlike the stars mentioned in the first paper, the stars discussed in this paper were selected using criteria other than positional coincidence with an IRAS source with far-IR (IRAS) colours similar to post-AGB supergiants and planetary nebulae. These included high galactic latitude, spectral types of O, B, A supergiants, emission lines in the spectrum and known spectral peculiarity. From the present study we find that LSS 1179, LSS 1222, LSS 1256, LSS 1276, LSS 1341, LSS 1394, LSS 2241, LSS 2429, LSS 4560, LSE 3, LSE 16, LSE 42, and LSE 67 to be new hot post-AGB candidates. Further studies of these candidates are needed.

The young stellar cluster [DBS2003] 157 associated with the H iiregion GAL 331.31−00.34★

We report a study of the stellar content of the Near-infrared cluster [DBS2003]\,157 embedded in the extended H\,{\sc ii} region GAL\,331.31-00.34, which is associated with the IRAS source 16085-5138. $JHK$ photometry was carried out in order to identify potential ionizing candidates, and the follow-up NIR spectroscopy allowed the spectral classification of some sources, including two O-type stars. A combination of NIR photometry and spectroscopy data was used to obtain the distance of these two stars, with the method of spectroscopic parallax: IRS\,298 (O6\,{\sc V}, $3.35 \pm 0.61$\,kpc) and IRS\,339 (O9\,{\sc V}, $3.24 \pm 0.56$\,kpc). Adopting the average distance of $3.29 \pm 0.58$\,kpc and comparing the Lyman continuum luminosity of these stars with that required to account for the radio continuum flux of the H\,{\sc ii} region, we conclude that these two stars are the ionizing sources of GAL\,331.31-00.34. Young stellar objects (YSOs) were searched by using our NIR photometry and MIR data from the GLIMPSE survey. The analysis of NIR and MIR colour-colour diagrams resulted in 47 YSO candidates. The GLIMPSE counterpart of IRAS\,16085-5138, which presents IRAS colour indices compatible with an ultra-compact H\,{\sc ii} region, has been identified. The analysis of its spectral energy distribution between 2 and $100\,\mu$m revealed that this source shows a spectral index $\alpha = 3.6$ between 2 and $25\,\mu$m, which is typical of a YSO immersed in a protostellar envelope. Lower limits to the bolometric luminosity and the mass of the embedded protostar have been estimated as $L=7.7\times10^3L_{\sun}$ and $M = 10\,M_{\sun}$, respectively, which corresponds to a B0--B1\,{\sc V} ZAMS star.

Globules and pillars seen in the [CII] 158 μm line with SOFIA

Molecular globules and pillars are spectacular features, found only in the interface region between a molecular cloud and an HII-region. Impacting Far-ultraviolet (FUV) radiation creates photon dominated regions (PDRs) on their surfaces that can be traced by typical cooling lines. With the GREAT receiver onboard SOFIA we mapped and spectrally resolved the [CII] 158 micron atomic fine-structure line and the highly excited 12CO J=11-10 molecular line from three objects in Cygnus X (a pillar, a globule, and a strong IRAS source). We focus here on the globule and compare our data with existing Spitzer data and recent Herschel Open-Time PACS data. Extended [CII] emission and more compact CO-emission was found in the globule. We ascribe this emission mainly to an internal PDR, created by a possibly embedded star-cluster with at least one early B-star. However, external PDR emission caused by the excitation by the Cyg OB2 association cannot be fully excluded. The velocity-resolved [CII] emission traces the emission of PDR surfaces, possible rotation of the globule, and high-velocity outflowing gas. The globule shows a velocity shift of ~2 km/s with respect to the expanding HII-region, which can be understood as the residual turbulence of the molecular cloud from which the globule arose. This scenario is compatible with recent numerical simulations that emphazise the effect of turbulence. It is remarkable that an isolated globule shows these strong dynamical features traced by the [CII]-line, but it demands more observational studies to verify if there is indeed an embedded cluster of B-stars.

Multiple outflows from the luminous YSO IRAS 07422-2001

The luminous Young Stellar Object (YSO) IRAS 07422-2001 is studied in the infrared. We discover star forming activity in embedded clusters located in a cloud detected at mid-IR wavelengths in emission. Multiple outflows are discovered from these clusters in the H_2 ro-vibrational line at 2.122 micron. We detect at least six outflows from the cluster associated with the IRAS source and another outflow from a source located in a cluster detected ~2.7 arcmin NE of the IRAS source. Additional star formation is taking place in two other cluster candidates within the cloud. Three of the YSOs in the cluster associated with the IRAS source are detected at 11.2 micron at an angular resolution of ~0.8 arcsec. We have a tentative detection of a circumstellar disk in this cluster, seen as an extinction lane in the J and H-band images. The spectral energy distributions (SEDs) of the dominant YSOs in the cluster associated with the IRAS source and in the NE cluster are studied using radiative transfer models and the properties of the YSOs are estimated. The YSO associated with the IRAS source is probably in a very early Class I stage of formation. The source identified as the dominant YSO in the NE cluster appears to be older than the dominant YSO in the cluster associated with the IRAS source, but its observed flux seems to be contaminated by extra emission, which suggests the presence of a young source contributing to the SED at far-IR wavelengths. The star formation observed in the field of IRAS 07422-2001 supports the idea of hierarchical formation of massive star clusters and the growth of massive young stellar objects near the centres of multiple sub-clusters in a star forming clump through competitive accretion.

Chemical composition of a sample of candidate post-asymptotic giant branch stars

We have derived elemental abundances for a sample of nine IRAS sources with colours similar to those of post-asymptotic giant branch (post-AGB) stars. For IRAS 01259+6823, IRAS 05208−2035, IRAS 04535+3747 and IRAS 08187−1905, this is the first detailed abundance analysis based upon high-resolution spectra. Mild indication of s-processing for IRAS 01259+6823, IRAS 05208−2035 and IRAS 08187−1905 has been found and a more comprehensive study of s-process-enhanced objects IRAS 17279−1119 and IRAS 22223+4327 has been carried out. We have also made a contemporary abundance analysis of the high Galactic latitude supergiants BD+39°4926 and HD 107369. The former is heavily depleted in refractories and estimated [Zn/H] of −0.7 dex most likely gives initial metallicity of the star. For HD 107369 the abundances of α and Fe-peak elements are similar to those of halo objects and moderate deficiency of s-process elements is seen. IRAS 07140−2321, despite being a short-period binary with a circumstellar shell, does not exhibit selective depletion of refractory elements. We have compiled the stellar parameters and abundances for post-AGB stars with s-process enhancement, those showing significant depletion of condensable elements and those showing neither. The compilation shows that the s-process-enhanced group contains a very small number of binaries, and observed [α/Fe] are generally similar to thick-disc values. It is likely that they represent AGB evolution of single stars. The compilation of the depleted group contains a larger fraction of binaries and generally supports the hypothesis of dusty discs surrounding binary post-AGB stars inferred via the shape of their spectral energy distribution and mid-infrared interferometry. IRAS 07140−2321 and BD+39°4926 are difficult to explain with this scenario and indicate the existence of an additional parameter/condition needed to explain the depletion phenomenon. However, the conditions for discernible depletion, minimum temperature of 5000 K and initial metallicity larger than −1.0 dex found from our earlier work still serve as useful criteria.

The spiral structure of the Galaxy revealed by CS sources and evidence for the 4:1 resonance

We present a map of the spiral structure of the Galaxy, as traced by molecular CS emission associated with IRAS sources which are believed to be compact HII regions. The CS line velocities are used to determine the kinematic distances of the sources, in order to investigate their distribution in the galactic plane. This allows us to use 870 objects to trace the arms, a number larger than that of previous studies based on classical HII regions. The distance ambiguity of the kinematic distances, when it exists, is solved by different procedures, including the latitude distribution and an analysis of the longitude-velocity diagram. The well defined spiral arms are seen to be confined inside the co-rotation radius, as is often the case in spiral galaxies. We identify a square-shaped sub-structure in the CS map with that predicted by stellar orbits at the 4:1 resonance (4 epicycle oscillations in one turn around the galactic center). The sub-structure is found at the expected radius, based on the known pattern rotation speed and epicycle frequency curve. An inner arm presents an end with strong inward curvature and intense star formation that we tentatively associate with the region where this arm surrounds the extremity of the bar, as seen in many barred galaxies. Finally, a new arm with concave curvature is found in the Sagitta to Cepheus region of the sky.

CSO BOLOCAM 1.1 mm CONTINUUM MAPPING OF THE BRAID NEBULA STAR FORMATION REGION IN CYGNUS OB7

We present a 1.1 mm map of the Braid Nebula star formation region in Cygnus OB7 taken using Bolocam on the Caltech Submillimeter Observatory. Within the 1 deg2 covered by the map, we have detected 55 cold dust clumps all of which are new detections. A number of these clumps are coincident with IRAS point sources although the majority are not. Some of the previously studied optical/near-IR sources are detected at 1.1 mm. We estimate total dust/gas masses for the 55 clumps together with peak visual extinctions. We conclude that over the whole region, approximately 20% of the clumps are associated with IRAS sources suggesting that these are protostellar objects. The remaining 80% are classed as starless clumps. In addition, both FU Orionis (FUor) like objects in the field, the Braid Star and HH 381 IRS, are associated with strong millimeter emission. This implies that FUor eruptions can occur at very early stages of pre-main-sequence life. Finally, we determine that the cumulative clump mass function for the region is very similar to that found in both the Perseus and ρ Ophiuchus star-forming regions.

MASER PROPERTIES OF THE ENIGMATICIRASSOURCE 19312+1950

The IRAS source, 19312+1950, exhibits SiO maser emission, which is predominantly detected in evolved stars enshrouded by a cold molecular envelope. In fact, the mojority of the observational properties of IRAS 19312+1950 is consistent with the nature of an asymptotic giant branch (AGB) star or post-AGB star. Interestingly, however, some of the observational properties cannot be readily explained within the standard scheme of stellar evolution, and those are rather reminiscent of young stellar objects. In the present research we considered the evolutionary status of IRAS 19312+1950 as revealed by the VLBI and MERLIN observations in SiO, H2O and OH maser lines. The double-peaked profile of the 22 GHz H2O maser line is clearly detected, with the emission regions of its red and blue-shifted components separately located, leaving a space of about 10.9 mas between them. The kinematic properties of H2O maser emission region appear to be more consistent with a bipolar flow rather than other interpretations such as the Keplerian rotation of a disk. The red-shifted component of the SiO maser emission, which exhibits a double-peak profile in previous single-dish observations, is clearly detected in the present interferometry, while the 1612 MHz OH maser line exhibits a complicated line profile consisting of a single strong peak and many weak, high-velocity spikes. The structure of OH maser emission region is partially resolved, and the kinematic properties of the OH maser emission region are reminiscent observations of a spherically expanding shell, even though the evidence is scant. Collectively, the maser observations described here provide additional support for the evolved star hypothesis for IRAS 19312+1950.

Southern YSO GRV10 and its environment

In this paper the southern cometary nebula GRV10 and its environment are investigated. The object is connected with a molecular cloud (its dimensions are ~4 pc). 12CO (1-0) observations toward GRV10 revealed the presence of two molecular outflows (a bipolar outflow), a red and a blue-shifted outflow, which coincide in position, indicating that they are moving along the line of sight in opposite directions. Near GRV10 a bright IR star, GRV10 IR, is discovered (near the southern edge of the nebula) and since its spectra and near IR colors favor it to be a Mira type star, a distance of ~4.4 kpc can be estimated. Star GRV10 IR appears connected with the IRAS point source IRAS 10406-6256. The grouping of stars (YSOs - young stellar objects) connected with GRV10 and embedded in a dark nebulosity is also discussed. This grouping is associated with the IRAS point source IRAS 10406-6253, which has FIR colors typical for embedded, not evolved, YSOs.