Dust Emissivity Index Research Articles

A massive disk/envelope in shocked H2emission around an UCHII region

A multi-wavelength study of IRAS 07427-2400 in line and continuum emission was conducted to investigate the nature of a H2 v = 1-0 S(1) line emitting feature around this ultra-compact HII region. High resolution 3.6 cm continuum observations from the Very Large Array and 350 µm continuum observations from the Caltech Submillimeter Observatory, combined with archival far-infrared data of IRAS 07427-2400 show a flux density distribution indicating a luminous (L = 5.6 × 10 4 L� ) point source associated with an ultra-compact HII region. A Grey body model fit to the flux density distribution yields a dust emissivity index (β ∼ 0.66) indicative of a circumstellar disk/envelope. Our C 18 O map shows a dense core centered on the continuum source, with the major axis roughly aligned with the H2 feature. A position-velocity diagram of the C 18 Oc ore obtained along the major axis shows rotation with a velocity gradient of ∼0.1 km s −1 arcsec −1 .N ew COJ = 3-2 maps of the region are presented which reveal a massive molecular outflow from the IRAS source. We argue that the H2 feature arises in a disk/envelope around IRAS 07427-2400 and not in an outflow. We present a near-infrared HK band spectrum of the H2 features that shows several ro-vibrational emission lines of H2 and (FeII). Analysis of the line ratios indicates that the line emission is shock-excited and not due to fluorescence. We estimate an excitation temperature of ∼1600 K and an average extinction of Av ∼ 11 mag to the H2 feature. The line fluxes yield a mass accretion rate of u M ∼ 2.6 ± 0.9 × 10 −2 Myr −1 and a lifetime of ∼5360 ± 1200 yr resulting in a disk/envelope mass of 140 ± 50 M� . The resulting Jeans Mass of 2420 Mindicates that the disk/envelope will not undergo fragmentation. IRAS 07427-2400 represents one of the most massive YSOs known to date forming by means of accretion.

The 69-μm forsterite band as a dust temperature indicator

A band of pure crystalline forsterite (100 per cent Mg2SiO4) occurs at 69.67 μm at room temperature (295 K); for olivines with ≳10 per cent Fe the corresponding feature is at ≳73 μm. The Mg-rich forsterite feature is observed in a variety of ISO LWS spectra, but the corresponding Fe-rich olivine feature is not. For the 10 astronomical sources in our sample, the forsterite band peaks in the 68.9–69.3 μm range and narrows with decreasing peak wavelength. This is consistent with the shortwards shifting of the peak observed when laboratory samples are cooled to 77 K (69.07 μm) and 3.5 K (68.84 μm). The shifted peak is produced by lattice contraction and the sharpening is due to a decrease in phonon density at lower temperatures. However, the astronomical bands are narrower than those of the laboratory samples. By comparing the laboratory and astronomical peak wavelengths, we deduce characteristic forsterite 69-μm band temperatures that are in the 27–84 K range for the eight post-main-sequence objects in our sample. These values are shown to be consistent with the local continuum temperatures derived using a β=1.5 dust emissivity index, similar to derived interstellar values of the opacity index. For the pre-main sequence-objects HD 100546 and MWC 922, the characteristic 69-μm forsterite band temperatures (127±18 and 139±10 K, respectively) are significantly higher than those of the post-main-sequence objects and are more than twice as high as their local continuum temperatures deduced using β=1.5. The assumption of large grains (β=0) can produce agreement between the derived 69-μm and continuum temperatures for one of these objects but not for the other – a spatial separation between the forsterite and continuum-emitting grains may therefore be implied for it. We conclude that observations of the peak wavelength and FWHM of the 69-μm forsterite band show great promise as a new diagnostic of characteristic grain temperatures.

Temperature-dependent FIR/sub-mm dust emissivity indices: some implications for the diffuse ISM dust composition

We have studied the effects of the laboratory-measured, temperature-dependent dust emissivity indices on the FIR/sub-mm emission properties of amorphous silicate and amorphous carbonaceous dust. When the experimentally-determined temperature dependence of the dust emissivity index is taken into account we find temperatures that can differ by as much as 1.5 K and emissivity indices that can differ by ~15%, with respect to the values obtained using published refractive index data as is to calculate these quantities. In addition, we find that the observed diffuse ISM dust temperature of ~17.5 K and emissivity index of 2 can seemingly be produced with a mixture of amorphous carbon and silicate grains only if temperature-dependent dust emissivity indices are adopted. We find that dust masses determined using the temperature-dependent dust emissivity indices are not significantly different from those derived using standard dust properties.

The SCUBA Local Universe Galaxy Survey - II. 450- m data: evidence for cold dust in bright IRAS galaxies

This is the second in a series of papers presenting results from the SCUBA Local Universe Galaxy Survey. In our first paper we provided 850-μm flux densities for 104 galaxies selected from the IRAS Bright Galaxy Sample and we found that the 60-, 100-μm (IRAS) and 850-μm (SCUBA) fluxes could be adequately fitted by emission from dust at a single temperature. In this paper we present 450-μm data for the galaxies. With the new data, the spectral energy distributions of the galaxies can no longer be fitted with an isothermal dust model – two temperature components are now required. Using our 450-μm data and fluxes from the literature, we find that the 450/850-μm flux ratio for the galaxies is remarkably constant, and this holds from objects in which the star formation rate is similar to our own Galaxy, to ultraluminous infrared galaxies (ULIRGs) such as Arp 220. The only possible explanation for this is if the dust emissivity index for all of the galaxies is ∼2 and the cold dust component has a similar temperature in all galaxies . The 60-μm luminosities of the galaxies were found to depend on both the dust mass and the relative amount of energy in the warm component, with a tendency for the temperature effects to dominate at the highest L60. The dust masses estimated using the new temperatures are higher by a factor of ∼2 than those determined previously using a single temperature. This brings the gas-to-dust ratios of the IRAS galaxies into agreement with those of the Milky Way and other spiral galaxies which have been intensively studied in the submm.

Millimeter-Wave Aperture Synthesis Imaging of Vega: Evidence for a Ring Arc at 95 AU

We present the first millimeter-wave aperture synthesis map of dust around a main sequence star. A 3'' resolution image of 1.3 mm continuum emission from Vega reveals a clump of emission 12'' from the star at PA 45 deg, consistent with the location of maximum 850 micron emission in a lower resolution JCMT/SCUBA map. The flux density is 4.0+/-0.9 mJy. Adjacent 1.3 mm peaks with flux densities 3.4+/-1.0 mJy and 2.8+/-0.9 mJy are located 14'' and 13'' from the star at PA 67 deg and 18 deg, respectively. An arc-like bridge connects the two strongest peaks. There is an additional 2.4 +/-0.8 mJy peak to the SW 11'' from the star at PA 215 deg and a marginal detection, 1.4+/-0.5 mJy, at the stellar position, consistent with photospheric emission. An extrapolation from the 850 micron flux, assuming F_{1.3mm-0.85mm} proportional to lambda^{-2.8}, agrees well with the total detected flux for Vega at 1.3 mm, and implies a dust emissivity index, beta, of 0.8. We conclude that we have detected all but a very small fraction of the dust imaged by SCUBA in our aperture synthesis map and that these grains are largely confined to segments of a ring of radius 95 AU.

A Submillimeter Study of the Star‐forming Region NGC 7129

New molecular (13CO J 3¨2) and dust continuum (450 and 850 km) maps of the NGC 7129 starforming region are presented. The maps include the Herbig Ae/Be star LkHa 234, the far-infrared source NGC 7129 FIRS 2, and several other prestellar sources embedded within the molecular ridge. The data are complemented with C18O J 3¨2 spectra at several positions within the mapped region. Both the submillimeter and the 13CO emission show a similar morphology, displaying a sharp boundary toward the cavity. The submillimeter maps also reveal a second source, SMM 2, which is not clearly seen in any earlier data set. This is either a prestellar core or possibly a protostar. Also, the highest continuum peak emission is identi—ed with the deeply embedded source IRS 6 a few arcseconds away from LkHa 234. These new 450 and 850 km observations are combined with previous continuum observations of the three compact far-infrared sources in the —eld, in order to make —ts to the spectral energy distributions and to obtain the source sizes, dust temperatures, luminosities, and masses. For nine positions where both 13CO and C18O spectra are available, gas masses have been obtained and compared with masses derived from the continuum —uxes. The masses are found to be consistent, implying little or no CO depletion onto grains. The dust emissivity index is found to be low toward the dense compact sources, b D 1¨1.6, and high, b D 2.0, in the surrounding cloud.

The Ultraviolet–Far-Infrared Energy Budget of the Gravitationally Lensed Lyman Break Galaxy MS 1512-[CSC]c[/CSC]B58

A 2 hr service-mode SCUBA observation of the gravitationally lensed Lyman break galaxy MS 1512-cB58 (hereafter cB58) resulted in a 3 σ upper limit of 3.9 mJy at 850 μm. A comparison of this upper limit with values expected from rest-UV–optical measurements of extinction suggests that the dust temperature (Td) and/or emissivity index (β) in cB58 may be substantially higher than is seen in local galaxies, or that the attenuation curve in cB58 may be even gentler than the already quite mild SMC dust law. If dust temperature Td and emissivity index β in cB58 are similar to those seen in local IRAS-selected galaxies, then cB58's dust mass is Md 107.7 M⊙, and its star formation rate is SFR 10 M⊙ yr-1 (for q0 = 0.1, H0 = 75 km s-1 Mpc-1). This SFR upper limit is lower than the star formation rate measured from Hα, thus giving further support to the notion that (Td, β) values in cB58 are higher than those seen in local galaxies. It thus appears that our understanding of dust in this extensively studied Lyman break galaxy is poor, and observations at other wavelengths are needed to better understand dust at high redshift. Such observations can be provided by the upcoming SIRTF mission for which cB58's expected flux densities are calculated.

The SCUBA Local Universe Galaxy Survey -- I. First measurements of the submillimetre luminosity and dust mass functions

This is the first of a series of papers presenting results from the SCUBA Local Universe Galaxy Survey (SLUGS), the first statistical survey of the submillimetre properties of the local Universe. As the initial part of this survey, we have used the SCUBA camera on the James Clerk Maxwell Telescope to observe 104 galaxies from the IRAS Bright Galaxy Sample. We present here the 850-μm flux measurements. The 60-, 100-, and 850-μm flux densities are well fitted by single-temperature dust spectral energy distributions, with the sample mean and standard deviation for the best-fitting temperature being Td=35.6±4.9 K and for the dust emissivity index β=1.3±0.2. The dust temperature was found to correlate with 60-μm luminosity. The low value of β may simply mean that these galaxies contain a significant amount of dust that is colder than these temperatures. We have estimated dust masses from the 850-μm fluxes and from the fitted temperature, although if a colder component at around 20 K is present (assuming a β of 2), then the estimated dust masses are a factor of 1.5–3 too low. We have made the first direct measurements of the submillimetre luminosity function (LF) and of the dust mass function. Unlike the IRAS 60-μm LF, these are well fitted by Schechter functions. The slope of the 850-μm LF at low luminosities is steeper than −2, implying that the LF must flatten at luminosities lower than we probe here. We show that extrapolating the 60-μm LF to 850 μm using a single temperature and β does not reproduce the measured submillimetre LF. A population of ‘cold’ galaxies (Td<25 K) emitting strongly at submillimetre wavelengths would have been excluded from the 60-μm-selected sample. If such galaxies do exist, then this estimate of the 850-μm flux is biased (it is underestimated). Whether such a population does exist is unknown at present. We correlate many of the global galaxy properties with the FIR/submillimetre properties. We find that there is a tendency for less luminous galaxies to contain hotter dust and to have a greater star formation efficiency (cf. Young). The average gas-to-dust ratio for the sample is 581±43 (using both the atomic and molecular hydrogen), which is significantly higher than the Galactic value of 160. We believe that this discrepancy is probably due to a ‘cold dust’ component at Td≤20 K in our galaxies. There is a surprisingly tight correlation between dust mass and the mass of molecular hydrogen, estimated from CO measurements, with an intrinsic scatter of ≃50 per cent.

The Dust Content and Opacity of Actively Star‐forming Galaxies

We present far-infrared (FIR) photometry at 150 and 205 micron(s) of eight low-redshift starburst galaxies obtained with the Infrared Space Observatory (ISO) ISOPHOT. Five of the eight galaxies are detected in both wave bands, and these data are used, in conjunction with IRAS archival photometry, to model the dust emission at lambda approximately greater than 40 microns. The FIR spectral energy distributions (SEDs) are best fitted by a combination of two modified Planck functions, with T approx. 40 - 55 K (warm dust) and T approx. 20-23 K (cool dust) and with a dust emissivity index epsilon = 2. The cool dust can be a major contributor to the FIR emission of starburst galaxies, representing up to 60% of the total flux. This component is heated not only by the general interstellar radiation field, but also by the starburst itself. The cool dust mass is up to approx. 150 times larger than the warm dust mass, bringing the gas-to-dust ratios of the starbursts in our sample close to Milky Way values, once resealed for the appropriate metallicity. The ratio between the total dust FIR emission in the range 1-1000 microns and the IRAS FIR emission in the range 40 - 120 microns is approx. 1.75, with small variations from galaxy to galaxy. This ratio is about 40% larger than previously inferred from data at millimeter wavelengths. Although the galaxies in our sample are generally classified as bright, for four of them the UV energy emerging shortward of 0.2 microns is less than 15% of the FIR energy. On average, about 30% of the bolometric flux is coming out in the UV-to-near-IR wavelength range; the rest is emitted in the FIR. Energy balance calculations show that the FIR emission predicted by the dust reddening of the UV-to-near-IR stellar emission is within a factor of approx. 2 of the observed value in individual galaxies and within 20% when averaged over a large sample. If our sample of local starbursts is representative of high-redshift (z approx. greater than 1), UV - bright star-forming galaxies, these galaxies' FIR emission will be generally undetected in submillimeter surveys, unless: (1) their bolometric luminosity is comparable to or larger than that of ultraluminous FIR galaxies and (2) their FIR SED contains a cool dust component.

V633 Cassiopeiae (LkHα 198) and V628 Cassiopeiae (MWC 1080) Revisited!

We present the results of millimeter observations carried out at the James Clerk Maxwell Telescope (JCMT) during 1993 August and 1994 August of two Herbig Ae/Be stars, namely V633 Cas and V628 Cas. We follow up on the discovery reported by Hajjar & Bastien in 1994 of a probable protostellar object 20'' northwest of V633 Cas, which was also reported later that year by Sandell & Weintraub. It is the main source of emission in the region at millimeter wavelengths and probably the major contributor in the submillimeter up to 100 μm. We estimate a total mass of 0.12 M☉ with a dust emissivity index of 0.35 ± 0.21. As seen in the 1990 maps by Nakano et al., V633 Cas C is at the center of a 13CO cavity and at the position of observed molecular concentrations. Since it also falls at the center of a flattened structure seen in HCO+, it is most likely the source of the large-scale CO outflow studied by Levreault in 1988. From the dimension of the CO cavity, we estimate an age of 3 × 104 yr for the object. Based on a first estimate of its spectral energy distribution, we find a ratio of Lbol/L1.3 mm > 2 × 104. Based on all these facts, we conclude that V633 Cas C is not a class 0 object but an extreme class I object. The dust emission from MWC 1080 is extended and flat with some features correlated with the optical ones. It is not evident that the grains we are sampling are related directly to the stellar environment.

Submillimeter Imaging of T Tauri’s Circumbinary Disk and the Discovery of a Protostar in Hind’s Nebula

We have obtained images at 2.2, 450, and 850 μm of the pre-main-sequence binary T Tauri and of Hind's Nebula, which is located less than 1' west of T Tauri. The three maps reveal that the nebulosity around T Tauri is extended, with an FWHM size of several hundred AU in thermal emission and more than 1000 AU in reflected light. Dust clearly connects the circumstellar nebula around T Tauri to the southwestern tip of Hind's Nebula, where we have identified a secondary intensity peak in the submillimeter maps. Calculations of the long-wavelength emissivity demonstrate that the dust emissivity index β is ~2 for the large nebula but is ~1.2 for the secondary intensity peak. These results for β suggest that we have found a class I protostar 30'' southwest of T Tauri and that star formation is more active in the vicinity of T Tauri than previously had been thought. This protostar is detected directly at submillimeter wavelengths; however, polarization mapping at 2.2 μm demonstrates that the disk-shaped dust cloud around the protostar is illuminated externally at short wavelengths, making it similar to the Orion proplyds.

The submillimetre colour of young stellar objects

A survey is presented of the submillimetre continuum spectra from dust around 73 young stellar objects (YSOs) associated with Herbig–Haro objects and molecular outflows. Spectra at millimetre to submillimetre wavelengths taken with similar beamsizes have been obtained for 42 of the objects, and the remainder either have been detected or have upper limits at 800 μm. The data are combined with far-infrared IRAS fluxes, and then compared with published submillimetre data from other types of YSO; this results in a data set of ∼150 submillimetre spectra. We have then employed colour–colour diagrams to investigate the differences in submillimetre continuum spectra between classes of YSOs. The majority of targets are optically obscured YSOs (generally Lada Class I); all are found to have a submillimetre spectral index (αmm) of ∼3.5. None of these objects has αmm ≤ 3.0. This is significantly different from published optically visible T Tauri stars (Class II–III), many of which have αmm ≤ 2.5. The few main-sequence stars so far observed in the submillimetre generally also have a relatively low value of αmm. We find that objects which might be classified as T Tauri stars, but which are not directly visible, have higher values of αmm. Assuming isothermal optically thin dust emission, this implies a dust emissivity index β of ∼1.5 for embedded objects, and ∼0.5 for visible objects. The reduced αmm in low optical extinction sources can be attributed to either grain growth or the formation of a compact optically thick circumstellar disc, and we discuss these two options in the light of the new data. If, as the results suggest, large fractal grains are present in the more evolved systems, then these will have higher millimetre mass opacity, implying that the determination of the circumstellar mass evolution from submillimetre continuum fluxes must take into account the evolution of the dust itself. High-mass embedded YSOs also have spectra very similar to their low-mass counterparts, but with higher dust temperature (again, under the isothermal optically thin assumption). Also, most Class 0 YSOs have high values of αmm, although three have flatter spectra more typical of fractal dust, which is difficult to explain under simple grain coagulation models. The submillimetre continuum flux is also compared with the intensity of two molecular lines: C18O J = 2–1 and H2CO 303 − 202. The integrated emission from the higher density tracer, H2CO, is well correlated with continuum flux. The C18O line shows a less significant correlation, particularly at low masses, suggesting that this may not be a good molecule to search for low-mass YSOs. By comparing T Tauri stars and younger YSOs with the same continuum flux, we find evidence that T Tauri stars are unusually weak in C18O emission, and we give some possible explanations.

High-resolution far-infrared observations of the Ring Nebula

High spatial resolution 50 and 100 micron observations of the Ring Nebula reveal a far-infrared emission peak close to the center of the nebula where atomic and molecular emission is at a minimum. Dust in this central peak emission region is heated by direct absorption of radiation from the central star. While the dust temperature in the central peak region is about 50 K (dust emissivity index of 1.5), the temperature of the bulk of the dust located in the regions of the ionized nebular core and the neutral molecular gas is on average lower than 50 K. Ly(alpha) photons are sufficient for heating the dust grains within the nebular core. Far-infrared emission is also found from grains mixed with the molecular gas outside the main ionized nebular core.

The dust content of evolved circumstellar envelopes and the optical properties of dust at submillimeter to radio wavelengths

This paper describes continuum observations at wavelengths between 2 mm and 350 μm of five highly evolved stars: the oxygen-rich stars VY CMa and OH 231.8 + 4.2, and the carbon-rich stars CRL 2688, CRL 618, and NGC 7027, all of which are surrounded by extended cool dusty molecular envelopes produced by mass loss. The submillimeter data are combined with infrared data and compared with models of circumstellar dust shells. The dust emissivity index β for all of these stars is found to be slightly less than 1 throughout the submillimeter range, showing that the dust in both carbon- and oxygen-rich circumstellar environments is likely to have layered amorphous structure. The models give gas-to-dust ratios of about 100:1 by mass

Chemistry in circumstellar disks - CS toward HL Tauri

High spatial and spectral resolution dust continuum and CS line-emission maps of the material immediately surrounding HL Tauri are presented. The 3.06-thermal dust map gives an upper limit to the source size of roughly 200 AU. When combined with previous millimeter continuum measurements, a beta value of 1.2 +/-0.3 is derived along with a disk mass of 0.1 solar mass, in agreement with previous disk radiative transfer models of the IR and submillimeter flux from HL Tau. The low dust emissivity index as compared to particles in the diffuse ISM is best explained by grain growth or composition evolution. The present observations of the CS and CO emission lines forming the molecular cloud surrounding HL Tauri are consistent with the 'canonical' temperatures, densities, and abundances derived in other Taurus cloud cores. In contrast, the CS emission in aperture synthesis maps at 650-AU spatial resolution is most consistent with CS/CO ratios at least 25-50 times lower in the gas immediately surrounding HL Tauri if the CS emission is optically thin. The continuum and spectral line results obtained are strong indicators of conditions thought to be similar to those in the presolar nebula some 4.5 AE ago.

Submillimeter measurements of T Tauri and FU Orionis stars

view Abstract Citations (192) References (16) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Submillimeter Measurements of T Tauri and FU Orionis Stars Weintraub, David A. ; Sandell, G. ; Duncan, W. D. Abstract Millimeter and submillimeter detections of 12 low-mass, premain-sequence stars are reported: nine T Tauri stars, one SU Aurigae star, and two FU Orionis stars. The submm spectra of T Tauri stars are found to be less steep than that expected from optically thin thermal dust emission. The dust emissivity index, beta, is found to range between 0 and 1.5 for the T Tauri stars. For the two FU Ori stars in our sample, beta is greater than 1 which is more similar to the beta index range 1-2 found for dust associated with molecular clouds and compact H II regions. The low values for beta indicate that column density and temperature gradients cannot be neglected for the dusty T Tauri environments and/or that the grains are large in the accretion disks surrounding T Tauri stars. Although most of the stars in the sample appear unresolved, the stars T Tau, DG Tau, and possibly HL Tau appear to have structure on 1000-2000 AU scales at 800 microns. Total circumstellar masses of a few times 0.01 solar masses for the T Tauri stars and greater than 0.1 solar masses for the FU Ori stars are estimated. Publication: The Astrophysical Journal Pub Date: May 1989 DOI: 10.1086/185441 Bibcode: 1989ApJ...340L..69W Keywords: Radio Emission; Stellar Envelopes; Stellar Spectra; T Tauri Stars; Cosmic Dust; Optical Thickness; Radiant Flux Density; Submillimeter Waves; Astrophysics; STARS: CIRCUMSTELLAR SHELLS; STARS: PRE--MAIN-SEQUENCE; STARS: RADIO RADIATION full text sources ADS | data products SIMBAD (16)

Submillimetre Mapping and Photometry of Bipolar Flows - Evidence for Compact Disks

ABSTRACT:The mm/sub-mm dust emission from bipolar outflow sources is discussed. In nearby outflows the stars driving the flows appear point like and unresolved, i.e. apparent angular sizes &lt; 7” (i.e. 700AU at lOOpc). The spectra are surprisingly flat, suggesting that the dust emission is affected by temperature and density gradients or that the dust surrounding these stars differs from that of the general interstellar medium. If the spectra are characterized with a conventional dust emissivity index, our sample gives an average value of 1.1, rather than the figure of 2, which is usually claimed at these wavelengths for dust in molecular clouds. The total dust and gas masses associated with these stars are a few tenths of a solar mass for nearby low luminosity sources and the gas densities are &gt;107 cm−3, if the gas is in a shell, and the densities could be much higher if the gas densities fall off as a function of radius, or if the mass is distributed in a disk. These masses correspond to extremely high extinctions, which are not observed, and we therefore argue that the mass distribution must be anisotropic, most likely as an inclined disk surrounding the star. Hence, stars driving outflows are surrounded by a dense disk, possibly an accretion disks and/or collimating disk. If these stars are compared to the more evolved T Tauri stars, we find that the difference in disk mass could account for the mass loss observed in these stars. Because of the high gas densities in the disk, most commonly used molecular lines will be optically thick, and molecular observations should be done in rare isotopes and high density tracers in order to yield reliable results of gas densities and gas dynamics.

A large-beam sky survey at millimeter and submillimeter wavelengths made from balloon altitudes

A survey has been made of a quarter of the celestial sphere from balloon altitudes with a telescope having a 1.6-deg beamwidth and two spectral bands: 3-10 kaysers and 10-25 kaysers. The limiting sensitivity of the survey was 10,000 Jy. The galactic disk was detected from 358 to 45 deg galactic longitude. The total far-infrared flux from several regions on the galactic plane measured in this survey is 5-10 times larger than that observed by others using smaller beamwidths and small-amplitude spatial chopping, indicating that a substantial part of the emission comes from extended sources. Two other extended sources were also observed, one in the Cygnus region and the other a spur running off the galactic plane at 130 deg galactic longitude toward the north celestial pole. In addition, lower limits for the spectral index of interstellar dust emission are presented.