Spitzer Infrared Spectrographic point source classification in the Small Magellanic Cloud
Paul M. E. Ruffle, F. Kemper, O. C. Jones, G. C. Sloan, K. E. Kraemer, Paul M. Woods, M. L. Boyer, S. Srinivasan, V. Antoniou, E. Lagadec, M. Matsuura, I. McDon… 展开作者
Paul M. E. Ruffle, F. Kemper, O. C. Jones, G. C. Sloan, K. E. Kraemer, Paul M. Woods, M. L. Boyer, S. Srinivasan, V. Antoniou, E. Lagadec, M. Matsuura, I. McDonald, J. M. Oliveira, B. A. Sargent, M. Sewilo, R. Szczerba, J. Th. van Loon, K. Volk, A. A. Zijlstra
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 programme were targeted, within a total of 311 staring mode observations. We classify these point sources using a decision tree method of object classification, based on infrared spectral features, continuum and spectral energy distribution shape, bolometric luminosity, cluster membership and variability information. We find 58 asymptotic giant branch (AGB) stars, 51 young stellar objects (YSOs), 4 post-AGB objects, 22 Red Supergiants (RSGs), 27 stars (of which 23 are dusty OB stars), 24 planetary nebulae (PNe), 10Wolf-Rayet (WR) stars, 3 Hii regions, 3 R Coronae Borealis (R CrB) stars, 1 Blue Supergiant and 6 other objects, including 2 foreground AGB stars. We use these classifications to evaluate the success of photometric classification methods reported in the literature.
K-band spectra are presented for a sample of 39 Spitzer IRS SAGE-Spec sources in the Large Magellanic Cloud. The spectra exhibit characteristics in very good agreement with their positions in the near infrared - Spitzer color-magnitude diagrams and their properties as deduced from the Spitzer IRS spectra. Specifically, the near infrared spectra show strong atomic and molecular features representative of oxygen-rich and carbon-rich asymptotic giant branch stars, respectively. A small subset of stars were chosen from the luminous and red extreme "tip" of the color magnitude diagram. These object…
The Infrared Spectrograph (IRS) on the {\em Spitzer Space Telescope} observed nearly 800 point sources in the Large Magellanic Cloud (LMC), taking over 1,000 spectra. 197 of these targets were observed as part of the Sage-Spec Spitzer Legacy program; the remainder are from a variety of different calibration, guaranteed time and open time projects. We classify these point sources into types according to their infrared spectral features, continuum and spectral energy distribution shape, bolometric luminosity, cluster membership, and variability information, using a decision-tree classification m…
We present our study on the infrared variability of point sources in the Small Magellanic Cloud (SMC). We use the data from the Spitzer Space Telescope Legacy Program "Surveying the Agents of Galaxy Evolution in the Tidally Stripped, Low Metallicity Small Magellanic Cloud" (SAGE-SMC) and the "Spitzer Survey of the Small Magellanic Cloud" (S$^{3}$MC) survey, over three different epochs, separated by several months to three years. Variability in the thermal infrared is identified using a combination of Spitzer's IRAC 3.6, 4.5, 5.8, and 8.0 $μ$m bands, and the MIPS 24 $μ$m band. An error-weighted…
Red Supergiant Stars in the Large Magellanic Cloud: I. The Period-Luminosity Relation
从以前的样本的红超巨星(RSG)的各个团体,191个对象组装组成一个大样本的RSG候选人在LMC。对于其中的189个,通过它们在与2 MASS JHKs波段和斯皮策/IRAC和斯皮策/MIPS波段相关的几个近红外和中红外波段的亮度和颜色指数来验证它们作为RSG的身份。利用ASAS和CANOO近8-10年的目视测光观测资料,分别采用PDM和Period 04方法,分析了光变的周期和幅度。根据光变的性质,这些物体分为五类:(1)20个天体光度饱和或位于拥挤的星场中,光度结果很差;(2)35个天体光度变化太复杂,没有任何确定的周期;(3)23个天体光度变化不规则;(4)16个天体光度变化半规则;(5)95个具有长次级周期(LSP)的天体,其中31个具有可分辨的短周期,51个具有小于3000天的长周期,可以以合理的精度确定。对于半正则变星和具有可分辨短周期的LSP变星,分析了可见光、近红外和中红外波段的周期-光度关系。研究发现,在2 MASS JHKs波段和Spitzer/IRAC波段等红外波段,P-L关系较紧,尤其是Spitzer/IRAC [3.6]和[4.5]波段;而在V波段,P-L关系相对较稀疏,这可能是由于星际消光不均匀造成的。并将所得结果与前人的RSG和LMC红巨星的P-L关系进行了比较。
We use Spitzer observations of the rich population of Asymptotic Giant Branch stars in the Large Magellanic Cloud (LMC) to test models describing the internal structure and nucleosynthesis of the most massive of these stars, i.e. those with initial mass above $\sim 4M_{\odot}$. To this aim, we compare Spitzer observations of LMC stars with the theoretical tracks of Asymptotic Giant Branch models, calculated with two of the most popular evolution codes, that are known to differ in particular for the treatment of convection. Although the physical evolution of the two models are significantly dif…
With the entire Small Magellanic Cloud (SMC) mapped by the Spitzer Space Telescope and Herschel Space Observatory, we were able to search 8-250 micron images in order to identify infrared (IR) emission associated with SMC supernova remnants (SNRs). A valid detection had to correspond with known X-ray, Halpha and radio emission from the SNRs. From the 24 known SNRs, we made 5 positive detections with another 5 possible detections. Two detections are associated with pulsars or pulsar wind nebula, and another three detections are part of the extended nebulous emission from the SNRs. We modelled d…
The \textit{Spitzer} SAGE survey has allowed the identification and analysis of significant samples of Young Stellar Object (YSO) candidates in the Large Magellanic Cloud (LMC). However the angular resolution of \textit{Spitzer} is relatively poor meaning that at the distance of the LMC, it is likely that many of the \textit{Spitzer} YSO candidates in fact contain multiple components. We present high resolution \textit{K}-band integral field spectroscopic observations of the three most prominent massive YSO candidates in the N113 H\,{\sc ii} region using VLT/SINFONI. We have identified six \te…
We present the first results from the SAGE-Var program, a follow on to the Spitzer legacy program Surveying the Agents of Galaxy Evolution (SAGE; Meixner, et al. 2006). We obtained 4 epochs of photometry at 3.6 & 4.5 microns covering the bar of the Large Magellanic Cloud (LMC) and the central region of the Small Magellanic Cloud (SMC) in order to probe the variability of extremely red sources missed by variability surveys conducted at shorter wavelengths, and to provide additional epochs of observation for known variables. Our 6 total epochs of observations allow us to probe infrared variabili…
We present the results of optical spectroscopic observations of 54 candidate evolved massive stars revealed through the detection of mid-infrared nebulae of various shapes surrounding them with the {\it Spitzer Space Telescope} and {\it Wide-field Infrared Survey Explorer}. These observations, carried out with the Southern African Large Telescope (SALT) in 2010-2015, led to the discovery of about two dozens emission-line stars, of which 15 stars we classify as candidate luminous blue variables (cLBVs). Spectroscopic and photometric monitoring revealed significant changes in the spectra and bri…
We present the mid-infrared (mid-IR) period$-$luminosity relations (PLRs) using over 1000 Mira variables in the Large Magellanic Cloud (LMC), for the four Wide-Field Infrared Survey Explorer (WISE) and the four Spitzer bands. These PLRs cover a mid-IR wavelength range from $3.4$ $μ$m to $22$ $μ$m and are presented separately for the oxygen-rich (O-rich) and carbon-rich (C-rich) Miras. These relations can be used to measure distances to individual O-rich and/or C-rich Mira stars with the accuracy of $5\%$ and $12\%$, respectively. They are the most accurate Mira PLRs in the mid-IR to date.
(abridged)Variability is a key property of stars on the asymptotic giant branch (AGB). Their pulsation period is related to the luminosity and mass-loss rate of the star. The long-period variables (LPVs) and Mira variables are the most prominent of all types of variability of evolved stars. The reddest, most obscured AGB stars are too faint in the optical and have eluded large variability surveys. Selection criteria are derived based on colour-colour and colour-magnitude diagrams from the combination of VISTA Magellanic Cloud (VMC) survey, Spitzer IRAC and AllWISE data. After eliminating LPVs …
The independence of the mid-infrared RR Lyrae Period-Luminosity relation from metallicity from a study of three globular clusters in the Large Magellanic Cloud
Department of Physics, University of Bath(巴斯大学物理系)
We used Spitzer's Infrared Spectrograph (IRS) to observe stars in the Small Magellanic Cloud (SMC) selected from the Midcourse Space Experiment (MSX) Point Source Catalog. We concentrate on the dust properties of oxygen-rich evolved stars, which show less alumina than Galactic stars. This difference may arise from the SMC's lower metallicity, but it could be a selection effect: the SMC sample includes more stars which are brighter and thus more massive. The distribution of SMC stars along the silicate sequence looks more like that of Galactic red supergiants than asymptotic giant branch stars …
We performed a spectroscopic and photometric analysis to study new eruptions in two luminous blue variables (LBVs) in the Magellanic Clouds. We detected a strong new eruption in the LBV R40 that reached $V \sim 9.2$ in 2016, which is around $1.3$ mag brighter than the minimum registered in 1985. During this new eruption, the star changed from an A-type to a late F-type spectrum. Based on photometric and spectroscopic empirical calibrations and synthetic spectral modeling, we determine that R\,40 reached $T_{\mathrm{eff}} = 5800-6300$~K during this new eruption. This object is thereby probably …
Variable stars have been used for over one hundred years as probes for determining astronomical distances; these distances can be used to map the three-dimensional (3D) structure of nearby galaxies. Exploiting the effect that moving to the mid-infrared has on Cepheid magnitudes and light curves, we can now map our nearest galaxies in 3D at fidelities never before achievable. Combining data from the OGLE-IV catalogue with mid-infrared photometry from the Spitzer Space Telescope, around 5000 fundamental mode Cepheids are being used to trace the 3D structure of the Magellanic Clouds. An automated…
The stars in the Magellanic Clouds with the largest degree of obscuration are used to probe the highly uncertain physics of stars in the asymptotic giant branch (AGB) phase of evolution. Carbon stars in particular, provide key information on the amount of third dredge-up (TDU) and mass loss. We use two independent stellar evolution codes to test how a different treatment of the physics affects the evolution on the AGB. The output from the two codes are used to determine the rates of dust formation in the circumstellar envelope, where the method used to determine the dust is the same for each c…
We investigate infrared properties of asymptotic giant branch (AGB) stars in our Galaxy and the Magellanic Clouds using various infrared observational data and theoretical models. We use catalogs for the sample of 4996 AGB stars in our Galaxy and about 39,000 AGB stars in the Magellanic Clouds from the available literature. For each object in the sample, we cross-identify the 2MASS, WISE, and Spitzer counterparts. To compare the physical properties of O-rich and C-rich AGB stars in our Galaxy and the Magellanic Clouds, we present IR two color diagrams (2CDs) using various photometric data. We …
大质量演化恒星通过大量的恒星风或瞬间爆发而失去大部分质量,在某些演化阶段,它们可以通过其星周星云的存在来识别。在本文中,我们提出了紧凑的星云(让人想起拱星星云周围的大质量恒星)使用档案24 $μ$米的数据与斯皮策多波段成像光度计的搜索结果。我们发现了115个星云,其中大部分与银河系中的亮蓝变星(LBV)和晚期WN型(WNL)沃尔夫-拉叶(WR)恒星以及大麦云(LMC)的星周星云有着惊人的相似之处。我们将这种相似性解释为一种迹象,即探测到的星云的中心恒星要么是LBV,要么是相关的大质量恒星。我们的解释得到了20多颗中心恒星的后续光谱的支持,其中大多数是候选LBV(cLBV),蓝超巨星或WNL恒星。我们预计,即将到来的光谱从我们的列表中剩余的对象,伴随着已经发现的cLBV的分光光度监测,将进一步增加已知的银河系LBV的人口,这反过来又将产生深远的影响,更好地理解LBV现象及其在氢燃烧O星和氦燃烧WR星之间的过渡作用。我们还报告了在LMC中检测到连接到cLBV HD 326823的弧形结构和与LBV R99(HD269445)相关的弧形。
Mid-infrared JWST spectra of carbon stars in the Large Magellanic Cloud
Space Telescope Science Institute(太空望远镜科学研究所);University of North Carolina, Chapel Hill(北卡罗来纳大学教堂山分校);Uppsala University(乌普萨拉大学);University of Vienna(维也纳大学);Boston College(波士顿学院);The University of Western Ontario(韦仕敦大学);Chalmers University of Technology(查尔姆斯理工大学);Université Côte d’Azur(蔚蓝海岸大学)
We present new Spitzer/IRAC observations of 55 dusty Long Period Variables (LPVs, 48 AGB and 6 RSG stars) in the Galaxy that have different chemistry, variability type, and mass-loss rate. O-rich AGB stars (including intrinsic S-type) tend to have redder [3.6]-[8.0] colors than carbon stars for a given [3.6]-[4.5] color due to silicate features increasing the flux in the 8.0 μm IRAC band. For colors including the 5.8 μm band, carbon stars separate into two distinct sequences, likely due to a variable photospheric C$_3$ feature that is only visible in relatively unobscured, low mass-loss rate s…
The survey for DUST in Nearby Galaxies with Spitzer (DUSTiNGS) identified several candidate Asymptotic Giant Branch (AGB) stars in nearby dwarf galaxies and showed that dust can form even in very metal-poor systems (Z ~ 0.008 $Z_\odot$). Here, we present a follow-up survey with WFC3/IR on the Hubble Space Telescope (HST), using filters that are capable of distinguishing carbon-rich (C-type) stars from oxygen-rich (M-type) stars: F127M, F139M, and F153M. We include six star-forming DUSTiNGS galaxies (NGC 147, IC 10, Pegasus dIrr, Sextans B, Sextans A, and Sag DIG), all more metal-poor than the …
The survey for DUST In Nearby Galaxies with Spitzer (DUSTiNGS) has identified hundreds of candidate dust-producing Asymptotic Giant Branch (AGB) stars in several nearby metal-poor galaxies. We have obtained multi-epoch follow-up observations for these candidates with the Spitzer Space Telescope and measured their infrared (IR) lightcurves. This has allowed us to confirm their AGB nature and investigate pulsation behavior at very low metallicity. We have obtained high-confidence pulsation periods for 88 sources in seven galaxies. We have confirmed DUSTiNGS variable star candidates with a 20% su…
Studies of young stellar objects (YSOs) in the Galaxy have found that a significant fraction exhibit photometric variability. However, no systematic investigation has been conducted on the variability of extragalactic YSOs. Here we present the first variability study of massive YSOs in a $\sim 1.5\,\mathrm{deg^2}$ region of the Large Magellanic Cloud (LMC). The aim is to investigate whether the different environmental conditions in the metal-poor LMC ($\sim$ 0.4-0.5 Z_sun) have an impact on the variability characteristics. Multi-epoch near-infrared (NIR) photometry was obtained from the VISTA …