IRAS Fluxes Research Articles

Observations of water maser sources at Arcetri

We present the current activity of the Arcetri group in the field of water masers. This is mainly represented by observations with the Medicina radiotelescope, whose main outcome has been the compilation of the Arcetri Catalog and the study of time variability of selected sources. The Arcetri Catalog update reports the results of the observations carried out from January 1993 to April 2000 on a sample of 300 sources. The global properties of the complete Arcetri Catalog (including Comoretto et al. 1990, and Brand et al. 1994) are discussed. Of the 1013 sources, 937 have an IRAS counterpart within 1 arcmin from the nominal position of the maser. We establish a classification scheme based on the IRAS flux densities which allows to distinguish between water masers associated with star forming regions and late-type stars. The time variability study shows a large variety of behaviors. Generally more luminous sources present less variable emission and spectral components over a wider velocity range.

The Active Merging System ESO 202-G23 (Carafe Nebula)

We present the results of observations both in imaging and spectroscopy of the nearby active galaxy ESO 202-G23 (Carafe Nebula). The main result of this investigation is that the peculiar morphology of the galaxy, formerly attributed to the presence of an asymmetric bar, is produced by the merging of two galaxies both hosting an active nucleus. Our deep R image reveals unexpectedly the presence of a knot (G2), not visible in the B image, at 3.5 kpc on the northern of the nucleus (G1), classified in the literature as a Seyfert 2. A long-slit spectrum provides evidence that G1 is a Seyfert 1.5 nucleus and that G2 is also a nucleus, showing features typical of a LINER heavily reddened by dust. The presence of tails and plumes in the outermost parts of the galaxy and the double U shape of the rotation curve of the gas around G1 and G2 strongly support the hypothesis of a merger that occurred 106–109 years ago, as suggested by the comparison of the current (14 M⊙ yr-1) and the recent (24 M⊙ yr-1) star formation rates. The system ESO 202-G23 is an infrared bright source (LFIR/L⊙ = 2.18 × 1010) and the IRAS flux ratios suggest a predominantly thermal origin of the infrared emission. The analysis of the IRAS data allows us to obtain some important properties concerning both the gas and the dust: Td(warm) ~ 36 K; Md(warm) = 4.1 × 106 M⊙; Td(cold) ~ 21 K; Md(cold) = (6.9–8.3) × 107 M⊙; MH I = 8.6 × 109 M⊙; MH II = (2.3–4.3) × 109 M⊙; Mgas = (1.1–1.3) × 1010 M⊙. The derived mass-to-light ratio MH I/LB = 2.23 and the value of the parameter K = vmax/rmax, K(G1) = 201, K(G2) = 179, indicate that the precursor is not later than Sbc.

Radio Properties of Infrared‐Selected Galaxies in theIRAS2 Jy Sample

The radio counterparts to the IRAS Redshift Survey galaxies are identified in the NRAO VLA Sky Survey (NVSS) catalog. Our new catalog of the IR flux-limited (S60 μm ≥ 2 Jy) complete sample of 1809 galaxies lists accurate radio positions, redshifts, and 1.4 GHz radio and IRAS fluxes. This sample is 6 times larger in size and 5 times deeper in redshift coverage (to z ≈ 0.15) than those used in earlier studies of the radio and far-IR (FIR) properties of galaxies in the local volume. The well-known radio-FIR correlation is obeyed by the overwhelming majority (≥98%) of the IR-selected galaxies, and the radio AGNs identified by their excess radio emission constitute only about 1% of the sample, independent of the IR luminosity. These FIR-selected galaxies can account for the entire population of late-type field galaxies in the local volume, and their radio continuum may be used directly to infer the extinction-free star formation rate in most cases. Both the 1.4 GHz radio and 60 μm IR luminosity functions are reasonably well described by linear sums of two Schechter functions, one representing normal, late-type field galaxies and the other representing starbursts and other luminous IR galaxies. The integrated FIR luminosity density for the local volume is (4.8 ± 0.5) × 107 L☉ Mpc-3, less than 10% of which is contributed by the luminous IR galaxies with LFIR ≥ 1011 L☉. The inferred extinction-free star formation density for the local volume is 0.015 ± 0.005 M☉ yr-1 Mpc-3.

Infrared Emission from Clusters in the Star-forming Disk of Henize 2-10

We have made subarcsecond-resolution images of the central 10'' of the Wolf-Rayet dwarf galaxy He 2-10 at 11.7 μm, using the Long Wavelength Spectrometer on the Keck I Telescope. The spatial distribution of the infrared emission roughly agrees with that of the rising spectrum radio sources seen by Kobulnicky & Johnson and confirms that those sources are compact H II regions, rather than supernova remnants or other objects. The infrared sources are more extended than the subarcsecond rising spectrum radio sources, although the entire complex is still less than 5'' in extent. On size scales of 1'' the infrared and radio emission are in excellent agreement, with each source requiring several hundred to a thousand O stars for excitation. The nebulae lie in a flattened disklike distribution about 240 by 100 pc and provide all of the flux measured by IRAS for the entire galaxy in the 12 μm band; 30% of the total IRAS flux from the galaxy emanates from one 15–30 pc source. In this galaxy, intense star formation, probably triggered by an accretion event, is confined to a central disk, which breaks up into distinct nebulae presumably marking the sites of young super–star clusters.

The Arcetri Catalog of H2O maser sources: Update 2000

We present a second update of the Arcetri Catalog of water masers (Comoretto et al. [CITE]; Brand et al. [CITE]). The present study reports the results of the observations carried out with the Medicina 32-m radiotelescope from January 1993 to April 2000 on a sample of 300 sources. This compilation consists of newly discovered maser sources that did not appear in the previous Arcetri Catalogs and is made of: a) detections from the literature, and b) unpublished detections obtained with the Medicina antenna. Overall, 83 out of 300 sources were detected. The detection rate is low (28% ) and we attribute this result to the inclusion in our survey of a rather large number of spurious maser detections that have appeared in one particular paper. The observational parameters are reported in tabular form for all the 300 sources and the spectra of the detected masers are presented. We discuss the global properties of the complete Arcetri Catalog based on Comoretto et al. ([CITE]), Brand et al. ([CITE]) and the present observations, which now contains 1013 galactic water maser sources. Of these, 937 have an IRAS counterpart within 1 arcmin from the nominal position of the maser. We establish a classification scheme based on the IRAS flux densities which allows to distinguish between water masers associated with star forming regions and late-type stars. The Arcetri Catalog represents a useful data base for systematic studies of galactic water maser sources.

The Galactic disc distribution of planetary nebulae with warm dust emission features — I

We investigate the Galactic disc distribution of a sample of planetary nebulae characterized in terms of their mid-infrared spectral features. The total number of Galactic disc PNe with 8–13 μm spectra is brought up to 74 with the inclusion of 24 new objects, the spectra of which we present for the first time. 54 PNe have clearly identified warm dust emission features, and form a sample that we use to construct the distribution of the C/O chemical balance in Galactic disc PNe. The dust emission features complement the information on the progenitor masses brought by the gas-phase N/O ratios: PNe with unidentified infrared emission bands have the highest N/O ratios, while PNe with the silicate signature have either very high N enrichment or close to none. We find a trend for a decreasing proportion of O-rich PNe towards the third and fourth Galactic quadrants. Two independent distance scales confirm that the proportion of O-rich PNe decreases from per cent inside the solar circle to per cent outside. PNe with warm dust are also the youngest. PNe with no warm dust are uniformly distributed in C/O and N/O ratios, and do not appear to be confined to They also have higher 6-cm fluxes, as expected from more evolved PNe. We show that the IRAS fluxes are a good representation of the bolometric flux for compact and IR-bright PNe, which are probably optically thick. Selection of objects with should probe a good portion of the Galactic disc for these young, dense and compact nebulae, and the dominant selection effects are rooted in the PN catalogues.

Dust in the dwarf galaxy NGC 1569: Evidence for an enhancement of small grains

We have mapped the dwarf galaxy NGC 1569 at 1.2 mm with the MPIfR bolometer at the IRAM30m telescope. The total flux density allows us, together with the IRAS fluxes densities at 12, 25, 60and 100 μm, to draw conclusions about the dust properties and to estimate the total dust mass. We find strong evidence for a significant enhancement of very small grains and a depletion of PAHs.

The Henize sample of S stars

This paper presents data collected on the Henize sample of 205 S stars: (i) CORAVEL radial-velocity data; (ii) photometric data in the UBV bands of the Geneva photometric system; (iii) photometric data in the JHKL bands of the SAAO photometric system; (iv) IRAS fluxes; (v) low-resolution spectra of 158 S stars. Close visual companions have been found for Hen 47, 94, 105 and 155. Spectroscopic orbital elements are provided for Hen 2, 108, 121, 137 and 147. The analysis of these data is presented in a companion paper.

The “Water-Fountain Nebula” IRAS 16342−3814: [ITAL]Hubble Space Telescope[/ITAL]/Very Large Array Study of a Bipolar Protoplanetary Nebula

We present Hubble Space Telescope (HST) Wide-Field Planetary Camera 2 images and VLA OH maser emission-line maps of the cold infrared object IRAS 16342-3814, believed to be a protoplanetary nebula. The HST images show an asymmetrical bipolar nebula, with the lobes separated by a dark equatorial waist. The two bright lobes and the dark waist are simply interpreted as bubble-like reflection nebulae illuminated by starlight escaping through polar holes in a dense, flattened, optically thick cocoon of dust, which completely obscures the central star. A faint halo can be seen surrounding each of the lobes. The bubbles are likely to have been created by a fast outflow (evidenced by H2O emission) plowing into a surrounding dense, more slowly expanding, circumstellar envelope of the progenitor asymptotic giant-branch (AGB) star (evidenced by the halo). The IRAS fluxes indicate a circumstellar mass of about 0.7 solar mass (D/2 kpc) and an AGB mass-loss rate of about 10(exp -4) solar mass/yr (V(sub exp)/15 km/s)(D/2 kpc)(sup 2) (assuming a gas-to-dust ratio of 200). OH features with the largest redshifted and blueshifted velocities are concentrated around the bright eastern and western polar lobes, respectively, whereas intermediate-velocity features generally occur at low latitudes, in the dark waist region. We critically examine evidence for the post-AGB classification of IRAS 16342-3814.

Distance Determination of Mass-Losing Stars

Based on the Principal Component Analysis on IRAS colors and the radio data, the distances to 183 mass-losing red giant stars were determined using the radial velocity and Oort's galactic rotation model for a zero-point calibration in the distance modulus. Also, based on the requirement of higher accuracy of the distance determination, the mass-losing red giant stars were divided into two groups by means of the first-principal component representing an intrinsic photometric property of the expanding shell; then, the distances were estimated to be logd(kpc) = 0.458 p<i + 0.09 ± 0.13 for group 1 and logd(kpc) = 0.325 P2 + 0.45 ± 0.15 for group 2, where p<i is the principal component corresponding to the distance, as obtained from the IRAS flux, which was assumed to be inversely proportional to the square of the distance. Thus,these two groups differ from each other not only by their photometric properties, but also by their average distances, by a factor of about 2. Systematic differences exist between the two groups in their population characteristics and in their evolutionary stages.

A Survey for Inward Motions in the Dense Gas around Young Stellar Clusters

We report the results of a spectroscopic search for inward motions of the dense gas around 19 young stellar clusters. Single point observations of CS(2-1) and N2H+(1-0) were made using the Haystack 37 m telescope at 21'' resolution, and CS(2-1) and C34S(2-1) maps were made using the FCRAO 14 m telescope at 50'' resolution. Strong, spatially extended CS self-absorption is seen in Mon OB1-D, IRAS 20050+2720, and Cepheus A, which indicates that these sources are good candidates for follow-up observations of kinematic structure. In Cepheus A, in particular, we identify a region that shows inward motions over a region 0.2 pc in extent, which suggests that models of core collapse should take into account the turbulent motions in these sources. We use the normalized velocity difference, δv=[v(thick)-v(thin)]/Δv(thin), between the optically thick (CS) and thin (N2H+ or C34S) lines to quantify the relative motions between the forward and central layers of dense gas. The average value of this velocity difference is not significantly different from zero for either data set, and there is no correlation with the source bolometric temperature as determined from IRAS flux measurements. Thus this cluster sample has no significant excess of sources with inward motions, unlike the samples of individual YSOs recently reported by Gregerson et al. and Mardones et al. The lower incidence of high absolute values of δv in our sample can be attributed to a lower optical depth in the CS line due to the greater distance, and therefore poorer linear resolution, of the sources here, and to the higher kinetic and excitation temperatures in these more massive, cluster forming environments.

The Discovery of a New Outflow Object: AFGL 490-iki

A survey with the James Clerk Maxwell Telescope of 12CO J = 2–1 emission at 230 GHz was undertaken to examine the molecular emission in the Cam OB1 region to search for the presence of early star-forming activity, i.e., outflows. A second outflow, AFGL 490-iki, was detected in the vicinity of AFGL 490. It is found, on the basis of the data presented here, that AFGL 490-iki has been active for ~2 × 104 yr, has a total mass of ~3.4 M⊙ in its wings, and has injected ~2.7 × 1046 ergs into the surrounding interstellar medium. Assuming the central star, identified as IRAS 03234+5843, is nearly on the main sequence, then it would have a mass, derived from its IRAS fluxes, of ~7 M⊙.

A Survey of Dust Features in the 3 Micron Spectra of YSO Candidates

We present the results of spectrophotometry from 1.3 to 4.2 μm of 45 IRAS sources in the list of Campbell, Persson, & Matthews that have been presumed to be luminous young stellar objects because of their infrared colors and large IRAS fluxes. About 70% of the objects show 3.1 μm H2O ice absorption or 3.3 μm unidentified infrared emission, or both. Among those with 3.1 μm H2O ice absorption, three objects seem to have a distinct absorption near 3.4 μm, and their absorption profiles are different than the optical depth profiles of young stellar objects in the literature. In the HKL two-color diagram, objects with ice absorption occupy the same region as previously known young stellar objects with the ice feature, and those with unidentified infrared emission overlap with Herbig Ae/Be stars. We interpret the distribution in the HKL two-color diagram as indicating the evolutionary sequence of intermediate- to high-mass young stars.

First Detection of a Counterrotating Molecular Gas Disk in a Spiral Galaxy: NGC 3626

In this paper we report the detection of a massive counterrotating molecular gas disk in the early-type spiral NGC 3626, observed in the 1-0 and 2-1 lines of 12CO, mapped with the 30 m telescope and Bure interferometer.12CO emission is concentrated in a compact nuclear disk of average radius r ~ 12'' (1.2 kpc). In the outer disk, from r = 20'' to r = 100'' (2-10 kpc),12CO is not detected, and the neutral gas content is largely dominated by H I. The observed 12CO velocity field pattern corresponds to a gaseous disk with a sense of rotation opposite to that of the stars. Counterrotation is shared by molecular and ionized gas in the center. There is no strong evidence of 12CO emission from gas in direct rotation. The estimated molecular mass in the 12CO nuclear disk is M(H2) ~ 0.3 × 109 M☉, 3 times lower than the mass of the H I disk. Within the nuclear disk,12CO is distributed in a central source of ~1'' (100 pc) radius, where the derived 12CO rotation curve reaches ~240 km s-1, surrounded by a pseudoring of average radius ~6'' (600 pc) characterized by strong noncircular motions. The dynamics of molecular gas, characterized by a regular counterrotating pattern and streaming motions typical of a steady density-wave driven flow and normal 12CO line widths, preclude the occurrence of violent large-scale shocks or of a nonequilibrium dynamical state for the gas. The available optical (Hα, N [II] and S [II]) and radio continuum data (at 12.6 cm and 21 cm) indicate that no violent burst of star formation is associated with the nuclear molecular gas. This is confirmed by the lack of IRAS flux record for the nucleus of NGC 3626. The present 12CO observations suggest that we are probably seeing a late stage of a merger happened in NGC 3626.

A Near‐Infrared Search for Hidden Broad‐Line Regions in Ultraluminous Infrared Galaxies

We report the results of a sensitive new near-infrared search for hidden broad-line regions (BLRs: ΔVFWHM 2000 km s-1) in a sample of 25 ultraluminous infrared galaxies (ULIGs) selected for their lack of BLRs at optical wavelengths. These objects constitute a representative subset of the (non-Seyfert 1) 1 Jy sample of 111 ULIGs (Kim & Sanders), both in terms of their redshift and infrared luminosity distributions. In contrast to previous studies of ULIGs at lower redshift, the redshifts for our current subsample (z ~ 0.1-0.2) allow us to search for broad-line emission from the strong Paα λ1.8751 μm and [Si VI] λ1.962 μm emission lines, two powerful AGN diagnostic lines which are generally inaccessible in lower redshift objects. Broad Paα emission is detected for the first time in two sources—PKS 1345+12, F23499+2423 (object names that begin with F are sources identified in the IRAS Faint Source Catalog, Version 2), and the presence of a hidden BLR is confirmed in two additional sources—F20460+1925, F23060+0505. Broad Paα emission may also be present in three other sources—F08559+1053, F17179+5444, F23233+2817—but new data are needed to make sure that H2 λλ1.8665, 1.8721 is not contributing to this excess emission. In addition, the [Si VI] feature appears to be present in three objects—F12072-0444, PKS 1345+12, F23233+2817—and perhaps also in F17179+5444. Combining our new data with previously published spectra for Mrk 463E, we find that all of the galaxies with evidence for a hidden BLR at near-infrared wavelengths present an optical Seyfert 2 spectrum. Overall, seven (and perhaps nine) of the 10 optical Seyfert 2 galaxies in our sample present either a BLR or strong [Si VI] emission. Also, galaxies with warm IRAS colors (f25/f60 > 0.2) (the quantities f25, f60 are the IRAS flux densities in Jy at 25 and 60 μm, respectively) show a tendency to harbor obscured BLRs in the near-infrared and to have large Paα-to-infrared luminosity ratios. These results suggest that the screen of dust in most warm Seyfert 2 galaxies is optically thin at 2 μm. However, no correlation is found between narrow-line extinctions and the presence of a hidden BLR. The narrow emission lines in our spectra mainly reflect the properties of the circumnuclear gas rather than the dust content of the material along the line of sight to the nucleus. The dereddened emission-line luminosities of the obscured BLRs detected in the warm Seyfert 2 ULIGs are similar to those of optically selected quasars at similar bolometric luminosities, which suggests that an important fraction of the bolometric luminosity in these ULIGs is powered by the same mechanism as that in optical quasars. These objects therefore truly appear to be buried quasars, spanning the gap between cool ULIGs and optical quasars. None of the 15 optically classified LINERs and H II galaxies in our sample shows any obvious signs of an obscured BLR or strong [Si VI] emission. The LINERs typically have cool IRAS colors (f25/f60 < 0.2) and a deficit of Paα emission, which suggest that the optical thickness due to dust is still significant at 2 μm and may be sufficient to hide an AGN in the cores of these ULIGs. The H II galaxies span a wide range of f25/f60 ratios and are strong emitters of narrow Paα. Dust obscuration therefore appears to be relatively unimportant in many of these objects. When the results from this near-infrared survey are combined with those from a recent optical spectroscopic study of the entire 1 Jy sample of 111 ULIGs (Veilleux, Kim, & Sanders), we find that the fraction of all ULIGs with optical or near-infrared signs of genuine AGN activity (either a BLR or [Si VI] emission) is 25%-30%. This fraction increases with increasing infrared luminosity.

Optical polarimetry, high–resolution spectroscopy and IR analysis of the Chamaeleon I dark cloud

We present optical polarimetry and high res- olution spectroscopy of a sample of stars toward the Chamaeleon I dark cloud. We use our polarimetry which includes 33 stars to study the wavelength dependence of the degree and position angle of polarization. From ts to the normalized wavelength dependence of interstellar polarization, we derive estimates of Max ranging from 4500 A to 6700 A, and PMax ranging from 3 to 8%. The values ofMax were found to be well correlated with the IRAS 100 m intensity, whilePMax was found to increase with EB V. High resolution spectra of the Ca II, CH, and CH + lines were obtained for 10 stars, which show two compo- nents of Ca II in absorption at 3.0 <v LSR < 5k m s 1 , andvLSR= 3.0 km s 1 and a single strong molecular CH absorption component at 3.0 <v LSR < 5.0 km s 1 . From our data we found, by interpretation of the vari- ous correlations between the polarimetry, photometry and IRAS fluxes, the following: the probable presence of shocked molecular gas; a warm molecular CH component; small dust grains at the edges of the cloud, and larger grains in the central parts, which are causing the polarization. Our results provide a consistent picture of the gas and dust content in the Cha I region, where larger grains, re- sponsible of the starlight polarization, exist in the center of the cloud, surrounded by envelopes of warmer molecular and atomic material.

The Structure of the Galactic Magnetic Field toward the High‐Latitude Clouds

We present the results of an optical polarization survey toward the galactic anticenter, in the area 5(h) greater than or equal to alpha greater than or equal to 2(h) and 6 degrees less than or equal to delta less than or equal to 12 degrees. This region is characterized by the presence of a stream of high-velocity H I as well as high galactic latitude molecular clouds. We used our polarization data together with 100 mu m IRAS maps of the region to study the relation between the dust distribution and the geometry of the magnetic field. We find that there is a correlation between the percent polarization and the 100 mu m flux such that P(%) less than or equal to (0.16 +/- 0.05)F-100. When the IRAS flux is converted into H I column densities this becomes P(%) less than or equal to (0.13 +/- 0.03)N-20 - 0.22, which is consistent with previous interstellar medium studies on the relation between reddening and polarization. This correlation indicates that our survey is as deep as IRAS and that the magnetic field geometry does not change strongly with the optical depth in the lines of sight that we have studied. The implied lower limit to the distance of our survey is 500-700 pc at galactic latitudes b = -20 degrees and 100 pc at b = -50 degrees. Our main finding is that the magnetic field is perpendicular to the H I high-velocity stream as well as the molecular cloud MBM 16 in the high-latitude region. The field is also perpendicular to the velocity gradient in the stream. Closer to the plane, the magnetic field is parallel to the dust filaments that extend like a plume toward the halo. Our observations indicate that the galactic magnetic field toward the high-latitude clouds is toroidal. We propose a model in which flux tubes that rise out of the galactic plane become force-free and predominantly toroidal at high latitudes. The high-latitude clouds may be gas streams that are falling back toward the galactic plane within such buoyant braided ropes of magnetic flux.

A new distance indicator to the Galactic Planetary Nebulae based upon IRAS Fluxes

The distance to Planetary Nebulae (PNe) is a most important parameter to study their evolution and the distribution among our Galaxy, but it has been very difficult to determine it precisely. On the other hand, it is well-known that the IRAS colors of PNe are very similar to the blackbody colors. Taking into account of this characteristic, we define a new method to get some information about the distance to PNe by the blackbody fitting of IRAS 4-band fluxes, assuming these fluxes are due to the thermal emission from the nebular dust envelope.

Spectral Irradiance Calibration in the Infrared.VII.New Composite Spectra, Comparison with Model Atmospheres, and Far-Infrared Extrapolations

view Abstract Citations (104) References (36) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Spectral Irradiance Calibration in the Infrared.VII.New Composite Spectra, Comparison with Model Atmospheres, and Far-Infrared Extrapolations Cohen, Martin ; Witteborn, Fred C. ; Carbon, Duane F. ; Davies, John K. ; Wooden, Diane H. ; Bregman, Jesse D. Abstract We present five new absolutely calibrated continuous stellar spectra constructed as far as possible from spectral fragments observed from the ground, the Kuiper Airborne Observatory (KAO), and the IRAS Low Resolution Spectrometer. These stars -- α Boo, γ Dra, α Cet, γ Cru, and μ UMa -- augment our six, published, absolutely calibrated spectra of K and early-M giants. All spectra have a common calibration pedigree. A revised composite for a Boo has been constructed from higher quality spectral fragments than our previously published one. The spectrum of γ Dra was created in direct response to the needs of instruments aboard the Infrared Space Observatory (ISO); this star's location near the north ecliptic pole renders it highly visible throughout the mission. We compare all our low-resolution composite spectra with Kurucz model atmospheres and find good agreement in shape, with the obvious exception of the SiO fundamental, still lacking in current grids of model atmospheres. The CO fundamental seems slightly too deep in these models, but this could reflect our use of generic models with solar metal abundances rather than models specific to the metallicities of the individual stars. Angular diameters derived from these spectra and models are in excellent agreement with the best observed diameters. The ratio of our adopted Sirius and Vega models is vindicated by spectral observations. We compare IRAS fluxes predicted from our cool stellar spectra with those observed and conclude that, at 12 and 25 μm, flux densities measured by IRAS should be revised downwards by about 4.1% and 5.7%, respectively, for consistency with our absolute calibration. We have provided extrapolated continuum versions of these spectra to 300 μm, in direct support of ISO (PHT and LWS instruments). These spectra are consistent with IRAS flux densities at 60 and 100 μm. Publication: The Astronomical Journal Pub Date: November 1996 DOI: 10.1086/118180 Bibcode: 1996AJ....112.2274C Keywords: INFRARED: STARS; STARS: ATMOSPHERES full text sources ADS | data products SIMBAD (13) CDS (1) Related Materials (16) Part 1: 1992AJ....104.1650C Part 2: 1992AJ....104.2030C Part 3: 1992AJ....104.2045C Part 4: 1995AJ....110..275C Part 5: 1995MNRAS.276..715C Part 6: 1996AJ....112..241C Part 8: 1998AJ....115.1671C Part 9: 1998AJ....115.2092C Part 10: 1999AJ....117.1864C Part 11: 1999AJ....117.2552W Part 12: 2001AJ....121.1180C Part 13: 2003AJ....125.2645C Part 14: 2003AJ....126.1090C Part 15: 2004AJ....128..889P Part 16: 2006AJ....132.1445E Part 17: 2010AJ....140.1919E

SiO Maser Sources in the Outer Disk of the Galaxy

view Abstract Citations (42) References (59) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS SiO Maser Sources in the Outer Disk of the Galaxy Jiang, B. W. ; Deguchi, S. ; Yamamura, I. ; Nakada, Y. ; Cho, S. H. ; Yamagata, T. Abstract The observations in the 28SiO j = 1-0 V = 1, J = 1-0 V = 2 lines and the 29SiO j = 1-0, V = 0 lines were simultaneously made toward 181 color-selected IRAS sources in the outer disk of the Galaxy (at longitudes between 90° and 250°). The 28SiO lines were detected in 63 sources (56 new) and the 29SiO line in 11 sources (9 new). Most of the detections are optically variable stars, mainly Mira-type variables and a few semiregular variables. The detection rate (35%) is much lower than that of the bulge survey performed by the same observational system the 45 m telescope at Nobeyama Radio Observatory. The lower detection rate of SiO maser emission is partly attributed to the increase of contaminations by stars with C-rich circumstellar envelopes and young stellar objects in the outer disk sample. The kinematical implications of the observational results are also discussed. The luminosity distances to the SiO maser sources are estimated from their IRAS fluxes at 12 μm and colors. By combining the SiO radial velocity and the luminosity distance, the rotation curve of the outer Galactic disk is found to be slightly falling within the Galactocentric distance between 8.5 and 12 kpc. The sources located within 20° from the Galactic anticenter direction are used to check for a peculiar motion of the local standard of rest. Publication: The Astrophysical Journal Supplement Series Pub Date: October 1996 DOI: 10.1086/192345 Bibcode: 1996ApJS..106..463J Keywords: GALAXY: KINEMATICS AND DYNAMICS; ISM: MOLECULES; MASERS; STARS: VARIABLES: OTHER LONG-PERIOD VARIABLES full text sources ADS | data products SIMBAD (182) CDS (2) Related Materials (1) Catalog: 1997yCat..21060463J