S. Guieu, L. M. Rebull, J. R. Stauffer, F. J. Vrba, A. Noriega-Crespo, T. Spuck, T. Roelofsen Moody, B. Sepulveda, C. Weehler, A. Maranto, D. M. Cole, N. Flagey… 展开作者
S. Guieu, L. M. Rebull, J. R. Stauffer, F. J. Vrba, A. Noriega-Crespo, T. Spuck, T. Roelofsen Moody, B. Sepulveda, C. Weehler, A. Maranto, D. M. Cole, N. Flagey, R. Laher, B. Penprase, S. Ramirez, S. Stolovy
IC 2118, also known as the Witch Head Nebula, is a wispy, roughly cometary, ~5 degree long reflection nebula, and is thought to be a site of triggered star formation. In order to search for new young stellar objects (YSOs), we have observed this region in 7 mid- and far-infrared bands using the Spitzer Space Telescope and in 4 bands in the optical using the U. S. Naval Observatory 40-inch telescope. We find infrared excesses in 4 of the 6 previously-known T Tauri stars in our combined infrared maps, and we find 6 entirely new candidate YSOs, one of which may be an edge-on disk. Most of the YSOs seen in the infrared are Class II objects, and they are all in the "head" of the nebula, within the most massive molecular cloud of the region.
Using photometric data of infrared surveys, young stellar object (YSO) status is verified for 141 objects selected in our previous papers in the Cassiopeia and Camelopardalis segment of the Milky Way bounded by Galactic coordinates (l, b) = (132--158 deg, p/m 12 deg). The area includes the known star-forming regions in the emission nebulae W3, W4 and W5 and the massive YSO AFGL 490. Spectral energy distribution (SED) curves between 700 nm and 160 microns, constructed from the GSC2, 2MASS, IRAS, MSX, Spitzer and AKARI data, are used to estimate the evolutionary stages of these stars. We confirm…
The Pipe Nebula, a large nearby molecular cloud lacks obvious signposts of star formation in all but one of more than 130 dust extinction cores that have been identified within it. In order to quantitatively determine the current level of star formation activity in the Pipe Nebula, we analyzed 13 square degrees of sensitive mid-infrared maps of the entire cloud, obtained with the Multiband Imaging Photometer for Spitzer (MIPS) at wavelengths of 24 micron and 70 micron to search for candidate Young Stellar Objects (YSOs) in the high-extinction regions. We argue that our search is complete for c…
The Spitzer Space Telescope mapped the Perseus molecular cloud complex with IRAC and MIPS as part of the c2d Spitzer Legacy project. This paper combines the observations from both instruments giving an overview of low-mass star formation across Perseus from 3.6 to 70 micron. We provide an updated list of young stellar objects with new classifications and source fluxes from previous works, identifying 369 YSOs in Perseus with the Spitzer dataset. By synthesizing the IRAC and MIPS maps of Perseus and building on the work of previous papers in this series (Jorgensen et al. 2006, Rebull et al. 200…
We present Spitzer 3.6, 4.5, 5.8, 8.0, and 24 micron images of the Mon OB1 East giant molecular cloud, which contains the young star forming region NGC 2264, as well as more extended star formation. With Spitzer data and 2MASS photometry, we identify and classify young stellar objects (YSOs) with dusty circumstellar disks and/or envelopes in Mon OB1 East by their infrared-excess emission and study their distribution with respect to cloud material. We find a correlation between the local surface density of YSOs and column density of molecular gas as traced by dust extinction that is roughly des…
We have used archival HST H$α$ images to study the immediate environments of massive and intermediate-mass young stellar object (YSO) candidates in the Large Magellanic Cloud (LMC). The sample of YSO candidates, taken from Gruendl & Chu (2009), was selected based on Spitzer IRAC and MIPS observations of the entire LMC and complementary ground-based optical and near-infrared observations. We found HST H$α$ images for 99 YSO candidates in the LMC, of which 82 appear to be genuine YSOs. More than 95% of the YSOs are found to be associated with molecular clouds. YSOs are seen in three different ki…
We present results from our spectroscopic study, using the Infrared Spectrograph (IRS) onboard the Spitzer Space Telescope, designed to identify massive young stellar objects (YSOs) in the Galactic Center (GC). Our sample of 107 YSO candidates was selected based on IRAC colors from the high spatial resolution, high sensitivity Spitzer/IRAC images in the Central Molecular Zone (CMZ), which spans the central ~300 pc region of the Milky Way Galaxy. We obtained IRS spectra over 5um to 35um using both high- and low-resolution IRS modules. We spectroscopically identify massive YSOs by the presence o…
We report the first results of imaging the Carina Nebula with Spitzer/IRAC, providing a catalog of point sources and YSOs based on SED fits. We discuss several aspects of the extended emission, including dust pillars that result when a clumpy molecular cloud is shredded by massive star feedback. There are few "extended green objects" (EGOs) normally taken as signposts of outflow activity, and none of the HH jets detected optically are seen as EGOs. A population of "extended red objects" tends to be found around OB stars, some with clear bow-shocks. These are dusty shocks where stellar winds co…
Young Stellar Objects (YSOs) in the early evolutionary stages are very embedded, and thus they emit most of their energy at long wavelengths such as far-infrared (FIR) and submillimeter (Submm). Therefore, the FIR observational data are very important to classify the accurate evolutionary stages of these embedded YSOs, and to better constrain their physical parameters in the dust continuum modeling. We selected 28 YSOs, which were detected in the AKARI Far-Infrared Surveyor (FIS), from the Spitzer c2d legacy YSO catalogs to test the effect of FIR fluxes on the classification of their evolution…
We present Spitzer Space Telescope IRAC and MIPS observations of a 0.85 deg^2 field including the Corona Australis (CrA) star-forming region. At a distance of 130 pc, CrA is one of the closest regions known to be actively forming stars, particularly within its embedded association, the Coronet. Using the Spitzer data, we identify 51 young stellar objects (YSOs) in CrA which include sources in the well-studied Coronet cluster as well as distributed throughout the molecular cloud. Twelve of the YSOs discussed are new candidates, one of which is located in the Coronet. Known YSOs retrieved from t…
(Abridged) Photometry of archival Spitzer observations of the Large Magellanic Cloud (LMC) are used to search for young stellar objects (YSOs). Simple mid-infrared selection criteria were used to exclude most normal and evolved stars and background galaxies. We identify a sample of 2,910 sources in the LMC that could potentially be YSOs. We then simultaneously considered images and photometry from the optical through mid-IR wavelengths to assess the source morphology, spectral energy distribution (SED), and the surrounding interstellar environment to determine the most likely nature of each so…
We present spectral observations of 130 young stellar objects (YSOs) in the Serpens Cloud Core and NGC 1333 embedded clusters. The observations consist of near-IR spectra in the H and K-bands, from SpeX on the IRTF and far-red spectra (6000 - 9000 A) from Hectospec on the MMT. These YSOs were identified in previous Spitzer and Chandra observations, and the evolutionary classes of the YSOs were determined from the Spitzer mid-IR photometry. With these spectra, we search for corroborating evidence for the pre-main sequence nature of the objects, study the properties of the detected emission line…
We present the results from Chandra X-ray observations, and near- and mid-infrared analysis, using VISTA/VVV and Spitzer/GLIMPSE catalogs, of the high-mass star-forming region IRAS 16562-3959, which contains a candidate for a high mass protostar. We detected 249 X-ray sources within the ACIS-I field-of-view. The majority of the X-ray sources have low count rates (< 0.638 cts/ks), and hard X-ray spectra. The search for YSOs in the region using VISTA/VVV and Spitzer/GLIMPSE catalogs resulted in a total of 799 YSOs, with 66 Class I and 733 Class II YSOs. The search for near- and mid-infrared coun…
We analyze near-infrared UKIDSS observations of a sample of 8325 objects taken from a catalog of intrinsically red sources in the Galactic plane selected in the Spitzer-GLIMPSE survey. Given the differences in angular resolution (factor >2 better in UKIDSS), our aim is to investigate whether there are multiple UKIDSS sources that might all contribute to the GLIMPSE flux, or there is only one dominant UKIDSS counterpart. We then study possible corrections to estimates of the SFR based on counts of GLIMPSE young stellar objects (YSOs). This represents an exploratory work towards the construction…
In this paper we undertake a study of the 21 square degree SMOG field, a Spitzer cryogenic mission Legacy program to map a region of the outer Milky Way towards the Perseus and Outer spiral arms with the IRAC and MIPS instruments. We identify 4648 YSOs across the field. Using the DBSCAN method we identify 68 clusters or aggregations of YSOs in the region, having 8 or more members. We identify 1197 class Is, 2632 class IIs, 819 class IIIs, of which 45 are candidate transition disk objects, utilizing the MIPS 24 photometry. The ratio of YSOs identified as members of clusters was 2872/4648, or 62…
We present the photometric catalogs for the star-forming cluster NGC 602 in the wing of the Small Magellanic Cloud covering a range of wavelengths from optical HST/ACS (F555W, F814W) and SMARTS/ANDICAM (V, I) to infrared (Spitzer/IRAC 3.6, 4.5, 5.8, and 8 micron and MIPS 24 micron). Combining this with IRSF (InfraRed Survey Facility) near-infrared photometry (J, H, Ks), we compare the young main sequence (MS) and pre-main sequence (PMS) populations prominent in the optical with the current young stellar object (YSO) populations revealed by the infrared (IR). We analyze the MS and PMS populatio…
We present initial results from a population synthesis model aimed at determining the star formation rate of the Milky-Way. We find that a total star formation rate of 0.68 to 1.45 Msun/yr is able to reproduce the observed number of young stellar objects in the Spitzer/IRAC GLIMPSE survey of the Galactic plane, assuming simple prescriptions for the 3D Galactic distributions of YSOs and interstellar dust, and using model SEDs to predict the brightness and color of the synthetic YSOs at different wavelengths. This is the first Galaxy-wide measurement derived from pre-main-sequence objects themse…
Tracing star formation across the Rosette nebula using deep Spitzer imaging
University of St Andrews（圣安德鲁斯大学）；Universidade de Lisboa（里斯本大学）；Univ. Bordeaux（波尔多大学）；European Southern Observatory（欧洲南方天文台）；Istituto Nazionale di Astrofisica (INAF) – Osservatorio Astronomico di Palermo（意大利国家天体物理研究所（INAF）- 巴勒莫天文台）
When studying the evolutionary stages of protostars that form in clusters, the role of any intracluster medium cannot be neglected. High foreground extinction can lead to situations where young stellar objects (YSOs) appear to be in earlier evolutionary stages than they actually are, particularly when using simple criteria like spectral indices. To address this issue, we have assembled detailed SED characterizations of a sample of 56 Spitzer-identified candidate YSOs in the clusters NGC 2264 and IC 348. For these, we use spectra obtained with the Infrared Spectrograph onboard the Spitzer Space…
We present ~120,000 Spitzer/IRAC candidate young stellar objects (YSOs) based on surveys of the Galactic midplane between l~255 deg and 110 deg, including the GLIMPSE I, II, and 3D, Vela-Carina, Cygnus X, and SMOG surveys (613 square degrees), augmented by near-infrared catalogs. We employed a classification scheme that uses the flexibility of a tailored statistical learning method and curated YSO datasets to take full advantage of IRAC's spatial resolution and sensitivity in the mid-infrared ~3-9 micron range. Multi-wavelength color/magnitude distributions provide intuition about how the clas…
We investigate the distribution of different classes of spectroscopically identified sources and theoretical models in the color-color diagrams (CCDs) combining the near-infrared (NIR) and mid-infrared (MIR) data to develop a method to classify Outer Galaxy sources detected with the Spitzer Space Telescope (hereafter Spitzer) SMOG survey in the IRAC 3.6 and 8.0 micrometer and MIPS 24 micrometer bands. We supplement the Spitzer data with the data from other satellite and ground-based surveys. The main goal of our study is to discover and characterize the population of intermediate- and low-mass…
We investigate the young stellar objects (YSOs) in the Lynds~1641 (L1641) cloud using multi-wavelength data including Spitzer, WISE, 2MASS, and XMM covering ~1390 YSOs across a range of evolutionary stages. In addition, we targeted a sub-sample of YSOs for optical spectroscopy. We use this data, along with archival photometric data, to derive spectral types, extinction values, masses, ages, as well as accretion rates. We obtain a disk fraction of ~50% in L1641. The disk frequency is almost constant as a function of stellar mass with a slight peak at log(M_*/M_sun)\approx-0.25. The analysis of …
We present Spitzer, NIR and millimeter observations of the massive star forming regions W5-east, S235, S252, S254-S258 and NGC7538. Spitzer data is combined with near-IR observations to identify and classify the young population while 12CO and 13CO observations are used to examine the parental molecular cloud. We detect in total 3021 young stellar objects (YSOs). Of those, 539 are classified as Class I, and 1186 as Class II sources. YSOs are distributed in groups surrounded by a more scattered population. Class I sources are more hierarchically organized than Class II and associated with the m…
We analyze the spatial distribution of dusty young stellar objects (YSOs) identified in the Spitzer Survey of the Orion Molecular clouds, augmenting these data with Chandra X-ray observations to correct for incompleteness in dense clustered regions. We also devise a scheme to correct for spatially varying incompleteness when X-ray data are not available. The local surface densities of the YSOs range from 1 pc$^{-2}$ to over 10,000 pc$^{-2}$, with protostars tending to be in higher density regions. This range of densities is similar to other surveyed molecular clouds with clusters, but broader …
We present and categorize Spitzer IRS spectra of 294 objects in the Large Magellanic Cloud (LMC) to create the largest and most complete catalog of massive young stellar object (YSO) spectra in the LMC. Target sources were identified from infrared photometry and multi-wavelength images indicative of young, massive stars highly enshrouded in their natal gas and dust clouds. Our sample primarily consists of 277 objects we identify as having spectral features indicative of embedded YSOs. The remaining sources are comprised of 7 C-rich evolved sources, 8 sources dominated by broad silicate emissio…
We have used Spitzer/IRAC to conduct a photometric monitoring program of the IC1396A dark globule in order to study the mid-IR (3.6 - 8 micron) variability of the heavily embedded Young Stellar Objects (YSOs) present in that area. We obtained light curves covering a 14 day timespan with a twice daily cadence for 69 YSOs, and continuous light curves with approximately 12 second cadence over 7 hours for 38 YSOs. Typical accuracies for our relative photometry were 1-2% for the long timespan data and a few mmag, corresponding to less than 0.5%, for the 7 hour continuous "staring-mode" data. More t…
X-ray emission is characteristic of young stellar objects (YSOs) and is known to be highly variable. We investigate, via an infrared and multi-epoch X-ray study of the L1630 dark cloud, whether and how X-ray variability in young stellar objects is related to protostellar evolutionary state. We have analyzed 11 Chandra X-ray Observatory observations, obtained over the course of four years and totaling ~240 ks exposure time, targeting the eruptive Class I YSO V1647 Ori in L1630. We used 2MASS and Spitzer data to identify and classify IR counterparts to L1630 X-ray sources and identified a total …
Recent studies have identified several young stellar objects (YSOs) which exhibit significant mid-infrared (mid-IR) variability. A wide range of physical mechanisms may be responsible for these variations, including changes in a YSO's accretion rate or in the extinction or emission from the inner disk. We have obtained and analyzed multi-epoch near-infrared (NIR) spectra for five actively accreting YSOs in the $ρ$ Oph star-forming region along with contemporaneous mid-IR light curves obtained as part of the YSOVAR Spitzer/IRAC survey. Four of the five YSOs exhibit mid-IR light curves with mode…
We aim to estimate and analyse the physical properties of the infrared counterparts of HMPOs by comparing their spectral energy distributions (SED) with those predicted by radiative transfer accretion models of YSOs. The SED of 68 IRCs are extended beyond the GLIMPSE photometry to the possible limits, from the near-infrared to the millimetre wavelengths by using the 2MASS, GLIMPSE version 2.0 catalogs, MSX, IRAS and some single dish (and interferometric) (sub)mm data. An online SED fitting tool that uses 2D radiative transfer accretion models of YSOs is employed to fit the observed SED to obta…
We present the comparison of the three most important ice constituents (water, CO and CO2) in the envelopes of massive Young Stellar Objects (YSOs), in environments of different metallicities: the Galaxy, the Large Magellanic Cloud (LMC) and, for the first time, the Small Magellanic Cloud (SMC). We present observations of water, CO and CO2 ice in 4 SMC and 3 LMC YSOs (obtained with Spitzer-IRS and VLT/ISAAC). While water and CO2 ice are detected in all Magellanic YSOs, CO ice is not detected in the SMC objects. Both CO and CO2 ice abundances are enhanced in the LMC when compared to high-lumino…
Characterising stellar and circumstellar properties of embedded young stellar objects (YSOs) is mandatory for understanding the early stages of the stellar evolution. This task requires the combination of both spectroscopy and photometry, covering the widest possible wavelength range, to disentangle the various protostellar components and activities. As part of the POISSON project, we present a multi-wavelength spectroscopic and photometric investigation of embedded YSOs in L1641, aimed to derive the stellar parameters and evolutionary stages and to infer their accretion properties. Our databa…
Accurate measurements of statistical properties, such as the star formation rate and the lifetime of young stellar objects (YSOs) in different stages, is essential for constraining star formation theories. However, it is a difficult task to separate galaxies and YSOs based on spectral energy distributions (SEDs) alone, because they contain both thermal emission from stars and dust around them and no reliable theories can be applied to distinguish them. Here we compare different machine learning algorithms and develop the Spectrum Classifier of Astronomical Objects (SCAO), based on Fully Connec…
Active star forming regions are excellent laboratories for studying the origins and evolution of young stellar object (YSO) clustering. The W40 - Serpens South region is such a region, and we compile a super near-and-mid-infrared catalog of point sources in it, based on deep NIR observations of CFHT in combination with 2MASS, UKIDSS, and Spitzer catalogs. From this catalog, we identify 832 YSOs, and classify 15, 135, 647, and 35 of them to be the deeply embedded sources, Class I, Class II YSOs, and transition disk sources, respectively. In general, these YSOs are well correlated with the filam…
Using the IRAC images from the Spitzer c2d program, we have made a survey of mid-infrared outflows in the rho Ophiuchi molecular cloud. Extended objects that have prominent emission in IRAC channel 2 (4.5 micron) compared to IRAC channel 1 (3.6 micron) and stand out as green objects in the three-color images (3.6 micron in blue, 4.5 micron in green, 8.0 micron in red) are identified as mid-infrared outflows. As a result, we detected 13 new outflows in the rho Ophiuchi molecular cloud that have not been previously observed in optical or near-infrared. In addition, at the positions of previously…
G79.3+0.3 is an infrared dark cloud in the Cygnus-X complex that is home to massive deeply embedded young stellar objects (YSOs). We have produced a submillimeter array (SMA) 1.3 mm continuum image and $^{12}$CO line maps of the eastern section of G79.3+0.3 in which we detect five separate YSOs. We have estimated physical parameters for these five YSOs and others in the vicinity of G79.3+0.3 by fitting existing photometry from Spitzer, Herschel, and ground-based telescopes to spectral energy distribution models. Through these model fits we find that the most massive YSOs seen in the SMA 1.3mm …
Accretion in young stellar objects (YSOs) is at least partially episodic, i.e. periods with high accretion rates ('bursts') are interspersed by quiescent phases. These bursts manifest themselves as eruptive variability. Here we present a systematic survey for eruptive YSOs aiming to constrain the frequency of accretion bursts. We compare mid-infrared photometry from Spitzer and WISE separated by ~5 yr for two samples of YSOs, in nearby star forming regions and in the Galactic plane, each comprising about 4000 young sources. All objects for which the brightness at 3.6 and 4.5 mu is increased by…
We present the results of our investigation of the star-forming complexes W51 and W43, two of the brightest in the first Galactic quadrant. In order to determine the young stellar object (YSO) populations in W51 and W43 we used color-magnitude relations based on Spitzer mid-infrared and 2MASS/UKIDSS near-infrared data. We identified 302 Class I YSOs and 1178 Class II/transition disk candidates in W51, and 917 Class I YSOs and 5187 Class II/transition disk candidates in W43. We also identified tens of groups of YSOs in both regions using the Minimal Spanning Tree (MST) method. We found similar …
OB associations are home to newly formed massive stars, whose turbulent winds and ionizing flux create H II regions rich with star formation. Studying the distribution and abundance of young stellar objects (YSOs) in these ionized bubbles can provide essential insight into the physical processes that shape their formation, allowing us to test competing models of star formation. In this work, we examined one such OB association, Cepheus OB4 (Cep OB4) - a well-suited region for studying YSOs due to its Galactic location, proximity, and geometry. We created a photometric catalog from Spitzer/IRAC…
We present near infrared spectroscopic observations of 19 molecular clouds made using the AKARI satellite, and the data reduction pipeline written to analyse those observations. The 2.5 --~5 $μ$m spectra of 30 objects -- 22 field stars behind quiescent molecular clouds and eight low mass YSOs in cores -- were successfully extracted using the pipeline. Those spectra are further analysed to calculate the column densities of key solid phase molecular species, including H$_2$O, CO$_2$, CO, and OCN$^-$. The profile of the H$_2$O ice band is seen to vary across the objects observed and we suggest th…
We present a multiwavelength investigation of the young stellar population and star formation activities around the \hii region Sharpless 311. Using our deep near-infrared observations and archival {\it Spitzer}-IRAC observations, we have detected a total of 125 young stellar objects (YSOs) in an area of $\sim$86 arcmin$^2$. The YSOs sample include 8 Class I and 117 Class II candidate YSOs. The mass completeness of the identified YSOs sample is estimated to be 1.0 \msun. The ages and masses of the majority of the candidate YSOs are estimated to be in the range of $\sim$0.1$-$5 Myr and $\sim$0.…
We present new images and photometry of the massive star forming complex Cygnus X obtained with IRAC and MIPS on the Spitzer Space Telescope. A combination of IRAC, MIPS, UKIDSS, and 2MASS data are used to identify and classify young stellar objects. Of the 8,231 sources detected exhibiting infrared excess in Cygnus X North, 670 are classified as Class I and 7,249 are classified as Class II. Using spectra from the FAST spectrograph at the Fred L. Whipple Observatory and Hectospec on the MMT, we spectrally typed 536 sources in the Cygnus X complex to identify the massive stars. We find that YSO…
We present the initial results of our investigation of the star-forming complex W49, one of the youngest and most luminous massive star forming regions in our Galaxy. We used Spitzer/Infrared Array Camera (IRAC) data to investigate massive star formation with the primary objective to locate a representative set of protostars and the clusters of young stars that are forming around them. We present our source catalog with the mosaics from the IRAC data. In this study we used a combination of IRAC, MIPS, Two Micron All Sky Survey (2MASS) and UKIRT Deep Infrared Sky Survey (UKIDSS) data to identif…
We present the analysis of the stellar content of NGC~2282, a young cluster in the Monoceros constellation, using deep optical $BVI$ and IPHAS photometry along with infrared (IR) data from UKIDSS and $Spitzer$-IRAC. Based on the stellar surface density analysis using nearest neighborhood method, the radius of the cluster is estimated as $\sim$ 3.15$\arcmin$. From optical spectroscopic analysis of 8 bright sources, we have classified three early B-type members in the cluster, which includes, HD 289120, a previously known B2V type star, a Herbig Ae/Be star (B0.5 Ve) and a B5 V star. From spectro…
We report Spitzer observations of five newly identified bow shocks in the massive star-forming region RCW 38. Four are visible at IRAC wavelengths, the fifth is visible only at 24 microns. Chandra X-ray emission indicates that winds from the central O5.5 binary, IRS~2, have caused an outflow to the NE and SW of the central subcluster. The southern lobe of hot ionised gas is detected in X-rays; shocked gas and heated dust from the shock-front are detected with Spitzer at 4.5 and 24 microns. The northern outflow may have initiated the present generation of star formation, based on the filamentar…
We present new observations of 34 YSO candidates in the SMC. The anchor of the analysis is a set of Spitzer-IRS spectra, supplemented by groundbased 3-5 micron spectra, Spitzer and NIR photometry, optical spectroscopy and radio data. The sources' SEDs and spectral indices are consistent with embedded YSOs; prominent silicate absorption is observed in the spectra of at least ten sources, silicate emission is observed towards four sources. PAH emission is detected towards all but two sources. Based on band ratios (in particular the strength of the 11.3 micron and the weakness of the 8.6 micron b…
Wide-field searches for young stellar objects (YSOs) can place useful constraints on the prevalence of clustered versus distributed star formation. The Spitzer/IRAC Candidate YSO (SPICY) catalog is one of the largest compilations of such objects (~120,000 candidates in the Galactic midplane). Many SPICY candidates are spatially clustered, but, perhaps surprisingly, approximately half the candidates appear spatially distributed. To better characterize this unexpected population and confirm its nature, we obtained Palomar/DBSP spectroscopy for 26 of the optically-bright (G<15 mag) "isolated" YSO…
While searches for young stellar objects (YSOs) with the Spitzer Space Telescope focused on known molecular clouds, photometry from the Wide-field Infrared Survey Explorer (WISE) can be used to extend the search to the entire sky. As a precursor to more expansive searches, we present results for a 100 square degree region centered on the Canis Major clouds.
We present observations of ~7 square degrees of the North American and Pelican Nebulae region at 24, 70, and 160 microns with the Spitzer Space Telescope Multiband Imaging Photometer for Spitzer (MIPS). We incorporate the MIPS observations with earlier Spitzer Infrared Array Camera (IRAC) observations, as well as archival near-infrared (IR) and optical data. We use the MIPS data to identify 1286 young stellar object (YSO) candidates. IRAC data alone can identify 806 more YSO candidates, for a total of 2076 YSO candidates. Prior to the Spitzer observations, there were only ~200 YSOs known in th…
We report the detection of several molecular gas-phase and ice absorption features in three photometrically-selected young stellar object (YSO) candidates in the central 280 pc of the Milky Way. Our spectra, obtained with the Infrared Spectrograph (IRS) onboard the Spitzer Space Telescope, reveal gas-phase absorption from CO2 (15.0um), C2H2 (13.7um) and HCN (14.0um). We attribute this absorption to warm, dense gas in massive YSOs. We also detect strong and broad 15um CO2 ice absorption features, with a remarkable double-peaked structure. The prominent long-wavelength peak is due to CH3OH-rich …
In this paper an extensive survey of the star forming complex Sh2-252 has been undertaken with an aim to explore its hidden young stellar population as well as to understand the structure and star formation history. This complex is composed of five embedded clusters associated with the sub-regions A, C, E, NGC 2175s and Teu 136. Using 2MASS-NIR and Spitzer-IRAC, MIPS photometry we identified 577 young stellar objects (YSOs), of which, 163 are Class I, 400 are Class II and 14 are transition disk YSOs. Spatial distribution of the candidate YSOs shows that they are mostly clustered around the sub…
We present multi-epoch, large-scale ($\sim$ 2000 arcmin${}^2$), fairly deep ($\sim$ 16 $μ$Jy), high-resolution ($\sim$ 1") radio observations of the Perseus star-forming complex obtained with the Karl G. Jansky Very Large Array at frequencies of 4.5 GHz and 7.5 GHz. These observations were mainly focused on the clouds NGC 1333 and IC 348, although we also observed several fields in other parts of the Perseus complex. We detect a total of 206 sources, 42 of which are associated with young stellar objects (YSOs). The radio properties of about 60% of the YSOs are compatible with a non-thermal rad…
We present the full catalog of Young Stellar Objects (YSOs) identified in the 18 molecular clouds surveyed by the Spitzer Space Telescope "cores to disks" (c2d) and "Gould Belt" (GB) Legacy surveys. Using standard techniques developed by the c2d project, we identify 3239 candidate YSOs in the 18 clouds, 2966 of which survive visual inspection and form our final catalog of YSOs in the Gould Belt. We compile extinction corrected SEDs for all 2966 YSOs and calculate and tabulate the infrared spectral index, bolometric luminosity, and bolometric temperature for each object. We find that 326 (11%),…
The Spitzer Space Telescope has three science instruments (IRAC, MIPS, and IRS) that can take images at 3.6, 4.5, 5.8, 8.0, 24, 70, and 160 microns, spectra over 5--38 microns, and spectral energy distribution over 52--100 microns. The Spitzer archive contains targeted imaging observations for more than 100 PNe. Spitzer legacy surveys, particularly the GLIMPSE survey of the Galactic plane, contain additional serendipitous imaging observations of PNe. Spitzer imaging and spectroscopic observations of PNe allow us to investigate atomic/molecular line emission and dust continuum from the nebulae …
The MYStIX project (Massive Young Star-Forming Complex Study in Infrared and X-rays) provides a comparative study of 20 Galactic massive star-forming complexes (d = 0.4 to 3.6 kpc). Probable stellar members in each target complex are identified using X-ray and/or infrared data via two pathways: (1) X-ray detections of young/massive stars with coronal activity/strong winds; or (2) infrared excess (IRE) selection of young stellar objects (YSOs) with circumstellar disks and/or protostellar envelopes. We present the methodology for the second pathway, using Spitzer/IRAC, 2MASS, and UKIRT imaging a…
The Magellanic clouds are uniquely placed to study the stellar contribution to dust emission. Individual stars can be resolved in these systems even in the mid-infrared, and they are close enough to allow detection of infrared excess caused by dust.We have searched the Spitzer Space Telescope data archive for all Infrared Spectrograph (IRS) staring-mode observations of the Small Magellanic Cloud (SMC) and found that 209 Infrared Array Camera (IRAC) point sources within the footprint of the Surveying the Agents of Galaxy Evolution in the Small Magellanic Cloud (SAGE-SMC) Spitzer Legacy programm…
