D.J. Barry - Academia.edu (original) (raw)
Papers by D.J. Barry
We present spectra taken with the Infrared Spectrograph on Spitzer covering the 5− 38μm region of... more We present spectra taken with the Infrared Spectrograph on Spitzer covering the 5− 38μm region of three Ultraluminous Infrared Galaxies (ULIRGs): Mrk 1014 (z = 0.163), and Mrk 463 (z = 0.051), and UGC 5101 (z = 0.039). The continua of UGC 5101 and Mrk 463 show strong silicate absorption suggesting significant optical depths to the nuclei at 10μm. UGC 5101 also shows the clear presence of water ice in absorption. PAH emission features are seen in both Mrk 1014 and UGC 5101, including the 16.4μm line in UGC 5101. The fine structure lines are consistent with dominant AGN power sources in both Mrk 1014 and Mrk 463. In UGC 5101 we detect the [NeV] 14.3μm emission line providing the first direct evidence for a buried AGN in the mid-infrared. The detection of the 9.66μm and 17.03μm H2 emission lines in both UGC 5101 and Mrk 463 suggest that the warm molecular gas accounts for 22% and 48% of the total molecular gas masses in these galaxies.
We report near-infrared photometry, spectroscopy, and speckle imaging of the hot, luminous star w... more We report near-infrared photometry, spectroscopy, and speckle imaging of the hot, luminous star we identify as LBV 1806-20. We also present photometry and spectroscopy of 3 nearby stars, which are members of the same star cluster containing LBV 1806-20 and SGR 1806-20. The spectroscopy and photometry show that LBV 1806-20 is similar in many respects to the luminous ``Pistol Star'',
The first observations of the infrared spectrum of the LMC planetary nebula SMP 83 as observed by... more The first observations of the infrared spectrum of the LMC planetary nebula SMP 83 as observed by the recently launched Spitzer Space Telescope are presented. The high resolution (R ∼ 600) spectrum shows strong emission lines but no significant continuum. The infrared fine structure lines are used, together with published optical spectra, to derive the electron temperature of the ionized gas for several ions. A correlation between the electron temperature with ionization potential is found. Ionic abundances for the observed infrared ions have been derived and the total neon and sulfur abundances have been determined. These abundances are compared to average LMC abundances of H II regions to better understand the chemical evolution of these elements. The nature of the progenitor star is also discussed.
![Research paper thumbnail of The [Ne III]/[Ne II] line ratio in NGC 253](https://attachments.academia-assets.com/100769988/thumbnails/1.jpg)
](AIP Conference Proceedings, 2005
We present results of the mapping of the nucleus of the starburst galaxy NGC 253 and its immediat... more We present results of the mapping of the nucleus of the starburst galaxy NGC 253 and its immediate surroundings using the Infrared Spectrograph 1 on board the Spitzer Space Telescope. The map is centered on the nucleus of the galaxy and spans the inner 800 × 688 pc 2. We perform a brief investigation of the implications of these measurement on the properties of the star formation in this region using theories developed to explain the deficiency of massive stars in starbursts.
The Astrophysical Journal, 2008
We use the previously-identified 15 infrared star-cluster counterparts to Xray point sources in t... more We use the previously-identified 15 infrared star-cluster counterparts to Xray point sources in the interacting galaxies NGC 4038/4039 (the Antennae) to study the relationship between total cluster mass and X-ray binary number. This significant population of X-Ray/IR associations allows us to perform, for the first time, a statistical study of X-ray point sources and their environments. We define a quantity, η, relating the fraction of X-ray sources per unit mass as a function of cluster mass in the Antennae. We compute cluster mass by fitting spectral evolutionary models to K s luminosity. Considering that this method depends on cluster age, we use four different age distributions to explore the effects of cluster age on the value of η and find it varies by less than a factor of four. We find a mean value of η for these different distributions of η = 1.7×10 −8 M −1 ⊙ with σ η = 1.2×10 −8 M −1 ⊙. Performing a χ 2 test, we demonstrate η could exhibit a positive slope, but that it depends on the assumed distribution in cluster ages. While the estimated uncertainties in η are factors of a few, we believe this is the first estimate made of this quantity to "order of magnitude" accuracy. We also compare our findings to theoretical models of open and globular cluster evolution, incorporating the X-ray binary fraction per cluster.
The Astrophysical Journal, 2005
We present Spitzer Infrared Spectrograph (IRS) observations of two objects of the Taurus populati... more We present Spitzer Infrared Spectrograph (IRS) observations of two objects of the Taurus population that show unambiguous signs of clearing in their inner disks. In one of the objects, DM Tau, the outer disk is truncated at 3 AU; this object is akin to another recently reported in Taurus, CoKu Tau/4, in that the inner disk region is free of small dust. Unlike CoKu Tau/4, however, this star is still accreting, so optically thin gas should still remain in the inner disk region. The other object, GM Aur, also accreting, has ∼0.02 lunar masses of small dust in the inner disk region within ∼5 AU, consistent with previous reports. However, the IRS spectrum clearly shows that the optically thick outer disk has an inner truncation at a much larger radius than previously suggested, ∼24 AU. These observations provide strong evidence for the presence of gaps in protoplanetary disks.
The Astrophysical Journal, 2005
We present the infrared spectrum of the young binary system St 34 obtained with the Infrared Spec... more We present the infrared spectrum of the young binary system St 34 obtained with the Infrared Spectrograph (IRS) on the Spitzer Space Telescope. The IRS spectrum clearly shows excess dust emission, consistent with the suggestion of White & Hillenbrand that St 34 is accreting from a circumbinary disk. The disk emission of St 34 is low in comparison with the levels observed in typical T Tauri stars; silicate features at ∼10 and 20 mm are much weaker than typically seen in T Tauri stars; and excess emission is nearly absent at the shortest wavelengths observed (∼5 mm). These features of the infrared spectrum suggest substantial grain growth (to eliminate silicate features) and possible settling of dust to the disk midplane (to reduce the continuum excess emission levels), along with a relatively evacuated inner disk, as expected due to gravitational perturbations by the binary system. Although the position of St 34 in the H-R diagram suggests an age of Myr, assuming that it lies at the 8 ע 3 distance of the Taurus-Auriga molecular clouds, White & Hillenbrand could not detect any Li i absorption, which would indicate a Li depletion age of roughly 25 Myr or more. We suggest that St 34 is closer than the Taurus clouds by ∼ 30-40 pc and has an age roughly consistent with Li depletion models. Such an advanced age would make St 34 the oldest known low-mass pre-main-sequence object with a dusty accretion disk. The persistence of optically thick dust emission well outside the binary orbit may indicate a failure to make giant planets that could effectively remove dust particles.
The Astrophysical Journal, 2005
We present spectra of four Herbig AeBe stars obtained with the Infrared Spectrograph (IRS) 1 on t... more We present spectra of four Herbig AeBe stars obtained with the Infrared Spectrograph (IRS) 1 on the Spitzer Space Telescope. All four of the sources show strong emission from polycyclic aromatic hydrocarbons (PAHs), with the 6.2 µm emission feature shifted to 6.3 µm and the strongest C−C skeletal-mode feature occuring at 7.9 µm instead of at 7.7 µm as is often seen. Remarkably, none of the four stars have silicate emission. The strength of the 7.9 µm feature varies with respect to the 11.3 µm feature among the sources, indicating that we have observed PAHs with a range of ionization fractions. The ionization fraction is higher for systems with hotter and brighter central stars. Two sources, HD 34282 and HD 169142, show emission features from aliphatic hydrocarbons at 6.85 and 7.25 µm. The spectrum of HD 141569 shows a previously undetected emission feature at 12.4 µm which may be related to the 12.7 µm PAH feature. The spectrum of HD 135344, the coolest star in our sample, shows an unusual profile in the 7-9 µm region, with the peak emission to the red of 8.0 µm and no 8.6 µm PAH feature.
![Research paper thumbnail of Erratum: “Infrared Counterparts to Chandra X‐Ray Sources in the Antennae” (ApJ, 658, 319 [2007])](https://attachments.academia-assets.com/100769991/thumbnails/1.jpg)
](The Astrophysical Journal, 2007
The Astrophysical Journal, 2004
We report near-infrared photometry, spectroscopy, and speckle imaging of the hot, luminous star w... more We report near-infrared photometry, spectroscopy, and speckle imaging of the hot, luminous star we identify as candidate LBV 1806-20 1. We also present photometry and spectroscopy of 3 nearby stars, which are members of the same star cluster containing LBV 1806-20 and SGR 1806-20. The spectroscopy and photometry show that LBV 1806-20 is similar in many respects to the luminous 1 Based on data obtained with the Cerro Tololo Interamerican Observatory 4-meter telescope operated by NOAO. NOAO is operated by the Association of Universities for Research in Astronomy (AURA), Inc. under cooperative agreement with the National Science Foundation.
The Astrophysical Journal Supplement Series, 2004
We have used the Spitzer Infrared Spectrograph to observe seven members of the TW Hya association... more We have used the Spitzer Infrared Spectrograph to observe seven members of the TW Hya association, the nearest stellar association whose age (10 Myr) is similar to the timescales thought to apply to planet formation and disk dissipation. Only two of the seven targets display infrared excess emission, indicating that substantial amounts of dust still exist closer to the stars than is characteristic of debris disks; however, in both objects we confirm an abrupt short-wavelength edge to the excess, as is seen in disks with cleared-out central regions. The mid-infrared excesses in the spectra of Hen 3-600 and TW Hya include crystalline silicate emission features, indicating that
![Research paper thumbnail of Spitzer Infrared Spectrograph (IRS) Mapping of the Inner Kiloparsec of NGC 253: Spatial Distribution of the [Ne iii ], Polycyclic Aromatic Hydrocarbon 11.3 Micron, and H 2 (0–0) S (1) lines and a Gradient in the [Ne iii ]/[Ne ii ] Line Ratio](https://attachments.academia-assets.com/100769994/thumbnails/1.jpg)
](The Astrophysical Journal Supplement Series, 2004
We present our early results of the mapping of the nucleus of the starburst galaxy NGC 253 and it... more We present our early results of the mapping of the nucleus of the starburst galaxy NGC 253 and its immediate surroundings using the Infrared Spectrograph on board the Spitzer Space Telescope. The map is centered on the nucleus of the galaxy and spans the inner 800 ; 688 pc 2. The spatial distribution of the [ Ne iii] line at 15.55 m and the polycyclic aromatic hydrocarbon feature at 11.3 m peaks at the center, while the purely rotational transition of molecular hydrogen at 17.03 m is strong over several slit positions. We perform a brief investigation of the implications of these measurements on the properties of the star formation in this region, using theories developed to explain the deficiency of massive stars in starbursts.
The Astrophysical Journal Supplement Series, 2004
We present Spitzer Space Telescope Infrared Spectrograph observations in the 5.3-20 m range of fi... more We present Spitzer Space Telescope Infrared Spectrograph observations in the 5.3-20 m range of five young stellar objects in Taurus that have Class I continuum spectral energy distributions (kF k k n ; n ! 0), often taken to represent the youngest stellar objects in this star formation region. The spectra include a rich collection of broad absorption features that we identify with amorphous silicates and various ices, notably those of carbon dioxide and water. We show that the absorption features are produced mainly in the envelopes of these systems. The apparent depths of silicate and 15.2 m CO 2 ice features vary among the objects in a manner that is consistent with a variation of inclination with respect to the line of sight, contribution to the silicate features from material throughout the envelopes, and an origin for the CO 2 ice feature in the outer parts of the envelope. Thus, these features provide new and useful constraints on models of the physical structure of Class I protostars.
The Astrophysical Journal Supplement Series, 2004
We present spectra taken with the Infrared Spectrograph on the Spitzer Space Telescope covering t... more We present spectra taken with the Infrared Spectrograph on the Spitzer Space Telescope covering the 5-38 m region of three ultraluminous infrared galaxies (ULIRGs): Mrk 1014 (z ¼ 0:163), Mrk 463 (z ¼ 0:051), and UGC 5101 (z ¼ 0:039). The continua of UGC 5101 and Mrk 463 show strong silicate absorption suggesting significant optical depths to the nuclei at 10 m. UGC 5101 also shows the clear presence of water ice in absorption. Polycyclic aromatic hydrocarbon (PAH) emission features are seen in both Mrk 1014 and UGC 5101, including the 16.4 m line in UGC 5101. The fine-structure lines are consistent with dominant active galactic nucleus (AGN) power sources in both Mrk 1014 and Mrk 463. In UGC 5101 we detect the [Ne v] 14.3 m emission line, providing the first direct evidence for a buried AGN in the mid-infrared. The detection of the 9.66 m and 17.03 m H 2 emission lines in both UGC 5101 and Mrk 463 suggest that the warm molecular gas accounts for 22% and 48% of the total molecular gas masses in these galaxies.
The Astrophysical Journal Supplement Series, 2004
The Infrared Spectrograph (IRS) is one of three science instruments on the Spitzer Space Telescop... more The Infrared Spectrograph (IRS) is one of three science instruments on the Spitzer Space Telescope. The IRS comprises four separate spectrograph modules covering the wavelength range from 5.3 to 38 µm with spectral resolutions, R = λ/∆λ ∼ 90 and 600, and it was optimized to take full advantage of the very low background in the space environment. The IRS is performing at or better than the pre-launch predictions. An autonomous target acquisition capability enables the IRS to locate the mid-infrared centroid of a source, providing the information so that the spacecraft can accurately offset that centroid to a selected slit. This feature is particularly useful when taking spectra of sources with poorly known coordinates. An automated data reduction pipeline has been developed at the Spitzer Science Center.
The Astrophysical Journal Supplement Series, 2004
We report spectra obtained with the Spitzer Space Telescope in the λ = 14-35 µm range of 19 nearb... more We report spectra obtained with the Spitzer Space Telescope in the λ = 14-35 µm range of 19 nearby main-sequence stars with infrared excesses. The six stars with strong dust emission show no recognizable spectral features, suggesting that the bulk of the emitting particles have diameters larger than 10 µm. If the observed dust results from collisional grinding of larger solids, we infer minimum masses of the parent body population between 0.004 M ⊕ and 0.06 M ⊕. We estimate grain production rates of ∼10 10 g s −1 around λ Boo and HR 1570; selective accretion of this matter may help explain their peculiar surface abundances.
The Astrophysical Journal Supplement Series, 2011
We present the spectral atlas of sources observed in low resolution with the Infrared Spectrograp... more We present the spectral atlas of sources observed in low resolution with the Infrared Spectrograph on board the Spitzer Space Telescope. More than 11,000 distinct sources were extracted using a dedicated algorithm based on the SMART software with an optimal extraction (AdOpt package). These correspond to all 13,000 low-resolution observations of fixed objects (both single source and cluster observations). The pipeline includes image cleaning, individual exposure combination, and background subtraction. Particular attention is given to bad pixel and outlier rejection at the image and spectra levels. Most sources are spatially unresolved so that optimal extraction reaches the highest possible signal-to-noise ratio. For all sources, an alternative extraction is also provided that accounts for all of the source flux within the aperture. CASSIS provides publishable quality spectra through an online database together with several important diagnostics, such as the source spatial extent and a quantitative measure of detection level. Ancillary data such as available spectroscopic redshifts are also provided. The database interface will eventually provide various ways to interact with the spectra, such as on-the-fly measurements of spectral features or comparisons among spectra.
Archives of General Psychiatry, 1972
We present spectra taken with the Infrared Spectrograph on Spitzer covering the 5− 38μm region of... more We present spectra taken with the Infrared Spectrograph on Spitzer covering the 5− 38μm region of three Ultraluminous Infrared Galaxies (ULIRGs): Mrk 1014 (z = 0.163), and Mrk 463 (z = 0.051), and UGC 5101 (z = 0.039). The continua of UGC 5101 and Mrk 463 show strong silicate absorption suggesting significant optical depths to the nuclei at 10μm. UGC 5101 also shows the clear presence of water ice in absorption. PAH emission features are seen in both Mrk 1014 and UGC 5101, including the 16.4μm line in UGC 5101. The fine structure lines are consistent with dominant AGN power sources in both Mrk 1014 and Mrk 463. In UGC 5101 we detect the [NeV] 14.3μm emission line providing the first direct evidence for a buried AGN in the mid-infrared. The detection of the 9.66μm and 17.03μm H2 emission lines in both UGC 5101 and Mrk 463 suggest that the warm molecular gas accounts for 22% and 48% of the total molecular gas masses in these galaxies.
We report near-infrared photometry, spectroscopy, and speckle imaging of the hot, luminous star w... more We report near-infrared photometry, spectroscopy, and speckle imaging of the hot, luminous star we identify as LBV 1806-20. We also present photometry and spectroscopy of 3 nearby stars, which are members of the same star cluster containing LBV 1806-20 and SGR 1806-20. The spectroscopy and photometry show that LBV 1806-20 is similar in many respects to the luminous ``Pistol Star'',
The first observations of the infrared spectrum of the LMC planetary nebula SMP 83 as observed by... more The first observations of the infrared spectrum of the LMC planetary nebula SMP 83 as observed by the recently launched Spitzer Space Telescope are presented. The high resolution (R ∼ 600) spectrum shows strong emission lines but no significant continuum. The infrared fine structure lines are used, together with published optical spectra, to derive the electron temperature of the ionized gas for several ions. A correlation between the electron temperature with ionization potential is found. Ionic abundances for the observed infrared ions have been derived and the total neon and sulfur abundances have been determined. These abundances are compared to average LMC abundances of H II regions to better understand the chemical evolution of these elements. The nature of the progenitor star is also discussed.
AIP Conference Proceedings, 2005
We present results of the mapping of the nucleus of the starburst galaxy NGC 253 and its immediat... more We present results of the mapping of the nucleus of the starburst galaxy NGC 253 and its immediate surroundings using the Infrared Spectrograph 1 on board the Spitzer Space Telescope. The map is centered on the nucleus of the galaxy and spans the inner 800 × 688 pc 2. We perform a brief investigation of the implications of these measurement on the properties of the star formation in this region using theories developed to explain the deficiency of massive stars in starbursts.
The Astrophysical Journal, 2008
We use the previously-identified 15 infrared star-cluster counterparts to Xray point sources in t... more We use the previously-identified 15 infrared star-cluster counterparts to Xray point sources in the interacting galaxies NGC 4038/4039 (the Antennae) to study the relationship between total cluster mass and X-ray binary number. This significant population of X-Ray/IR associations allows us to perform, for the first time, a statistical study of X-ray point sources and their environments. We define a quantity, η, relating the fraction of X-ray sources per unit mass as a function of cluster mass in the Antennae. We compute cluster mass by fitting spectral evolutionary models to K s luminosity. Considering that this method depends on cluster age, we use four different age distributions to explore the effects of cluster age on the value of η and find it varies by less than a factor of four. We find a mean value of η for these different distributions of η = 1.7×10 −8 M −1 ⊙ with σ η = 1.2×10 −8 M −1 ⊙. Performing a χ 2 test, we demonstrate η could exhibit a positive slope, but that it depends on the assumed distribution in cluster ages. While the estimated uncertainties in η are factors of a few, we believe this is the first estimate made of this quantity to "order of magnitude" accuracy. We also compare our findings to theoretical models of open and globular cluster evolution, incorporating the X-ray binary fraction per cluster.
The Astrophysical Journal, 2005
We present Spitzer Infrared Spectrograph (IRS) observations of two objects of the Taurus populati... more We present Spitzer Infrared Spectrograph (IRS) observations of two objects of the Taurus population that show unambiguous signs of clearing in their inner disks. In one of the objects, DM Tau, the outer disk is truncated at 3 AU; this object is akin to another recently reported in Taurus, CoKu Tau/4, in that the inner disk region is free of small dust. Unlike CoKu Tau/4, however, this star is still accreting, so optically thin gas should still remain in the inner disk region. The other object, GM Aur, also accreting, has ∼0.02 lunar masses of small dust in the inner disk region within ∼5 AU, consistent with previous reports. However, the IRS spectrum clearly shows that the optically thick outer disk has an inner truncation at a much larger radius than previously suggested, ∼24 AU. These observations provide strong evidence for the presence of gaps in protoplanetary disks.
The Astrophysical Journal, 2005
We present the infrared spectrum of the young binary system St 34 obtained with the Infrared Spec... more We present the infrared spectrum of the young binary system St 34 obtained with the Infrared Spectrograph (IRS) on the Spitzer Space Telescope. The IRS spectrum clearly shows excess dust emission, consistent with the suggestion of White & Hillenbrand that St 34 is accreting from a circumbinary disk. The disk emission of St 34 is low in comparison with the levels observed in typical T Tauri stars; silicate features at ∼10 and 20 mm are much weaker than typically seen in T Tauri stars; and excess emission is nearly absent at the shortest wavelengths observed (∼5 mm). These features of the infrared spectrum suggest substantial grain growth (to eliminate silicate features) and possible settling of dust to the disk midplane (to reduce the continuum excess emission levels), along with a relatively evacuated inner disk, as expected due to gravitational perturbations by the binary system. Although the position of St 34 in the H-R diagram suggests an age of Myr, assuming that it lies at the 8 ע 3 distance of the Taurus-Auriga molecular clouds, White & Hillenbrand could not detect any Li i absorption, which would indicate a Li depletion age of roughly 25 Myr or more. We suggest that St 34 is closer than the Taurus clouds by ∼ 30-40 pc and has an age roughly consistent with Li depletion models. Such an advanced age would make St 34 the oldest known low-mass pre-main-sequence object with a dusty accretion disk. The persistence of optically thick dust emission well outside the binary orbit may indicate a failure to make giant planets that could effectively remove dust particles.
The Astrophysical Journal, 2005
We present spectra of four Herbig AeBe stars obtained with the Infrared Spectrograph (IRS) 1 on t... more We present spectra of four Herbig AeBe stars obtained with the Infrared Spectrograph (IRS) 1 on the Spitzer Space Telescope. All four of the sources show strong emission from polycyclic aromatic hydrocarbons (PAHs), with the 6.2 µm emission feature shifted to 6.3 µm and the strongest C−C skeletal-mode feature occuring at 7.9 µm instead of at 7.7 µm as is often seen. Remarkably, none of the four stars have silicate emission. The strength of the 7.9 µm feature varies with respect to the 11.3 µm feature among the sources, indicating that we have observed PAHs with a range of ionization fractions. The ionization fraction is higher for systems with hotter and brighter central stars. Two sources, HD 34282 and HD 169142, show emission features from aliphatic hydrocarbons at 6.85 and 7.25 µm. The spectrum of HD 141569 shows a previously undetected emission feature at 12.4 µm which may be related to the 12.7 µm PAH feature. The spectrum of HD 135344, the coolest star in our sample, shows an unusual profile in the 7-9 µm region, with the peak emission to the red of 8.0 µm and no 8.6 µm PAH feature.
The Astrophysical Journal, 2007
The Astrophysical Journal, 2004
We report near-infrared photometry, spectroscopy, and speckle imaging of the hot, luminous star w... more We report near-infrared photometry, spectroscopy, and speckle imaging of the hot, luminous star we identify as candidate LBV 1806-20 1. We also present photometry and spectroscopy of 3 nearby stars, which are members of the same star cluster containing LBV 1806-20 and SGR 1806-20. The spectroscopy and photometry show that LBV 1806-20 is similar in many respects to the luminous 1 Based on data obtained with the Cerro Tololo Interamerican Observatory 4-meter telescope operated by NOAO. NOAO is operated by the Association of Universities for Research in Astronomy (AURA), Inc. under cooperative agreement with the National Science Foundation.
The Astrophysical Journal Supplement Series, 2004
We have used the Spitzer Infrared Spectrograph to observe seven members of the TW Hya association... more We have used the Spitzer Infrared Spectrograph to observe seven members of the TW Hya association, the nearest stellar association whose age (10 Myr) is similar to the timescales thought to apply to planet formation and disk dissipation. Only two of the seven targets display infrared excess emission, indicating that substantial amounts of dust still exist closer to the stars than is characteristic of debris disks; however, in both objects we confirm an abrupt short-wavelength edge to the excess, as is seen in disks with cleared-out central regions. The mid-infrared excesses in the spectra of Hen 3-600 and TW Hya include crystalline silicate emission features, indicating that
The Astrophysical Journal Supplement Series, 2004
We present our early results of the mapping of the nucleus of the starburst galaxy NGC 253 and it... more We present our early results of the mapping of the nucleus of the starburst galaxy NGC 253 and its immediate surroundings using the Infrared Spectrograph on board the Spitzer Space Telescope. The map is centered on the nucleus of the galaxy and spans the inner 800 ; 688 pc 2. The spatial distribution of the [ Ne iii] line at 15.55 m and the polycyclic aromatic hydrocarbon feature at 11.3 m peaks at the center, while the purely rotational transition of molecular hydrogen at 17.03 m is strong over several slit positions. We perform a brief investigation of the implications of these measurements on the properties of the star formation in this region, using theories developed to explain the deficiency of massive stars in starbursts.
The Astrophysical Journal Supplement Series, 2004
We present Spitzer Space Telescope Infrared Spectrograph observations in the 5.3-20 m range of fi... more We present Spitzer Space Telescope Infrared Spectrograph observations in the 5.3-20 m range of five young stellar objects in Taurus that have Class I continuum spectral energy distributions (kF k k n ; n ! 0), often taken to represent the youngest stellar objects in this star formation region. The spectra include a rich collection of broad absorption features that we identify with amorphous silicates and various ices, notably those of carbon dioxide and water. We show that the absorption features are produced mainly in the envelopes of these systems. The apparent depths of silicate and 15.2 m CO 2 ice features vary among the objects in a manner that is consistent with a variation of inclination with respect to the line of sight, contribution to the silicate features from material throughout the envelopes, and an origin for the CO 2 ice feature in the outer parts of the envelope. Thus, these features provide new and useful constraints on models of the physical structure of Class I protostars.
The Astrophysical Journal Supplement Series, 2004
We present spectra taken with the Infrared Spectrograph on the Spitzer Space Telescope covering t... more We present spectra taken with the Infrared Spectrograph on the Spitzer Space Telescope covering the 5-38 m region of three ultraluminous infrared galaxies (ULIRGs): Mrk 1014 (z ¼ 0:163), Mrk 463 (z ¼ 0:051), and UGC 5101 (z ¼ 0:039). The continua of UGC 5101 and Mrk 463 show strong silicate absorption suggesting significant optical depths to the nuclei at 10 m. UGC 5101 also shows the clear presence of water ice in absorption. Polycyclic aromatic hydrocarbon (PAH) emission features are seen in both Mrk 1014 and UGC 5101, including the 16.4 m line in UGC 5101. The fine-structure lines are consistent with dominant active galactic nucleus (AGN) power sources in both Mrk 1014 and Mrk 463. In UGC 5101 we detect the [Ne v] 14.3 m emission line, providing the first direct evidence for a buried AGN in the mid-infrared. The detection of the 9.66 m and 17.03 m H 2 emission lines in both UGC 5101 and Mrk 463 suggest that the warm molecular gas accounts for 22% and 48% of the total molecular gas masses in these galaxies.
The Astrophysical Journal Supplement Series, 2004
The Infrared Spectrograph (IRS) is one of three science instruments on the Spitzer Space Telescop... more The Infrared Spectrograph (IRS) is one of three science instruments on the Spitzer Space Telescope. The IRS comprises four separate spectrograph modules covering the wavelength range from 5.3 to 38 µm with spectral resolutions, R = λ/∆λ ∼ 90 and 600, and it was optimized to take full advantage of the very low background in the space environment. The IRS is performing at or better than the pre-launch predictions. An autonomous target acquisition capability enables the IRS to locate the mid-infrared centroid of a source, providing the information so that the spacecraft can accurately offset that centroid to a selected slit. This feature is particularly useful when taking spectra of sources with poorly known coordinates. An automated data reduction pipeline has been developed at the Spitzer Science Center.
The Astrophysical Journal Supplement Series, 2004
We report spectra obtained with the Spitzer Space Telescope in the λ = 14-35 µm range of 19 nearb... more We report spectra obtained with the Spitzer Space Telescope in the λ = 14-35 µm range of 19 nearby main-sequence stars with infrared excesses. The six stars with strong dust emission show no recognizable spectral features, suggesting that the bulk of the emitting particles have diameters larger than 10 µm. If the observed dust results from collisional grinding of larger solids, we infer minimum masses of the parent body population between 0.004 M ⊕ and 0.06 M ⊕. We estimate grain production rates of ∼10 10 g s −1 around λ Boo and HR 1570; selective accretion of this matter may help explain their peculiar surface abundances.
The Astrophysical Journal Supplement Series, 2011
We present the spectral atlas of sources observed in low resolution with the Infrared Spectrograp... more We present the spectral atlas of sources observed in low resolution with the Infrared Spectrograph on board the Spitzer Space Telescope. More than 11,000 distinct sources were extracted using a dedicated algorithm based on the SMART software with an optimal extraction (AdOpt package). These correspond to all 13,000 low-resolution observations of fixed objects (both single source and cluster observations). The pipeline includes image cleaning, individual exposure combination, and background subtraction. Particular attention is given to bad pixel and outlier rejection at the image and spectra levels. Most sources are spatially unresolved so that optimal extraction reaches the highest possible signal-to-noise ratio. For all sources, an alternative extraction is also provided that accounts for all of the source flux within the aperture. CASSIS provides publishable quality spectra through an online database together with several important diagnostics, such as the source spatial extent and a quantitative measure of detection level. Ancillary data such as available spectroscopic redshifts are also provided. The database interface will eventually provide various ways to interact with the spectra, such as on-the-fly measurements of spectral features or comparisons among spectra.
Archives of General Psychiatry, 1972