星形成ゼミ2019/03/01 SFN 313 #41-#48長谷川哲夫(国立天文台) : 313 #41 Identifying Young Stellar Objects in the Outer Galaxy: I = 224° Region in Canis Major Marta Sewi lo1,2, Barbara A. Whitney3,4, Bosco H. K. Yung5,6, Thomas P. Robitaille7, Davide Elia8, Remy Indebetouw9,10, Eugenio Schisano8,11, Ryszard Szczerba5, Agata Karska12, Jennifer Wiseman13, Brian Babler4, Martha Boyer14, William J. Fischer14, Marilyn Meade4, Luca Olmi15, Deborah Padgett16 and Natasza Sio´dmiak5 The Astrophysical Journal Supplement Series, 240:26 (30pp), 2019 February
Abstract
We study a very young star-forming region in the outer Galaxy that is the most concentrated source of outflows in the Spitzer Space Telescope GLIMPSE360 survey. This region, dubbed CMa–/224, is located in the Canis Major OB1 association. CMa–/224 is relatively faint in the mid-infrared, but it shines brightly at the far-infrared wavelengths as revealed by the Herschel Space Observatory data from the Hi-GAL survey. Using the 3.6 and 4.5 μ m data from the Spitzer/GLIMPSE360 survey, combined with the JHK, Two Micron All Sky Survey (2MASS) and the 70–500 μ m Herschel/Hi-GAL data, we develop young stellar object (YSO) selection criteria based on color–color cuts and fitting of the YSO candidates’ spectral energy distributions with YSO 2D radiative transfer models. We identify 293 YSO candidates and estimate physical parameters for 210 sources well fit with YSO models. We select an additional 47 sources with GLIMPSE360-only photometry as “possible YSO candidates." The vast majority of these sources are associated with high H 2 column density regions and are good targets for follow-up studies. The distribution of YSO candidates at different evolutionary stages with respect to Herschel filaments supports the idea that stars are formed in the filaments and become more dispersed with time. Both the supernova-induced and spontaneous star formation scenarios are plausible in the environmental context of CMa–/224. However, our results indicate that a spontaneous gravitational collapse of filaments is a more likely scenario. The methods developed for CMa–1224 can be used for larger regions in the Galactic plane where the same set of photometry is available. GLIMPSE360 Completing the Spitzer Galactic Plane Survey A Spitzer_Cycle 6 Exploration Science Program冷媒が尽きたあとの運用プログラムGLIMPSE360 Areal Coverage strip is not shown, and is placed vertically on the figure.
http://www.astro.wisc.edu/sirtf/glimpse360/
® “The GLIMPSE360 survey can detect low-mass star formation throughout the Perseus spiral arm (at a distance of ~3.6 kpc http://www.astro.wisc toward I = 225°) and higher-mass star formation beyond." 1 / 3ページThe circles centered on the Sun shows the GLIMPSE360 detection limit distance for a solar type star (solid line) is about twice that of WISE (dashed line). -

Notes.
² The number in parentheses corresponds to point sources ( ext_flg = 0). b Based on the Hi-GAL catalog from Elia et al. ( 2013 ). In order to be included in the catalog, a source had to be detected in at least three consecutive bands. c AllWISE catalog sources with the ph_qual of "A," "B," or "C" (i.e., no upper limits) in a corresponding band. d The matching radii between the GLIMPSE360 catalog and AllWISE, AKARI , MSX , Herschel/E10, and Herschel/Full are l ″ , 1 ″ , 1 ″ 3, 5 ″ , and 5 ″ , respectively. All the constraints described in Section 3 are applied. c The numbers represent the number of sources with valid data points (left) and upper limits (right) at a corresponding wavelength(s). 1 The number in parentheses corresponds to sources with valid 70 μ m flux. Out of 72 sources, 26 are SPIRE-only and are not used in the analysis. 8 The number in parentheses corresponds to sources with valid 70 μ m flux. Out of 206 sources, 111 are SPIRE-only and are not used in the analysis.
処理の流れ
1. Catalog Matching Spitzer/GLIMPSE360のカタログ(2MASSと対応済み)を、AllWISE, AKARI, MSX, Hi-GALと比較し対応天体を見つけ、長波長の情報を補う2.   Distance Determination
まず2MASSとSpitzer dataからIR-excessのある天体を選び、それにフィルターをかけてコンタミ（unresolved extragalactic sources, PNe, evolved stars)を除く

Notes.
² n e is the number of valid data points used for the fitting. b See Table 3 footnotes for the meaning of characters in the model set names. ~ ( ) ( inin /pt) uet is χ 2 per data point for the best-fit model from the most likely model set. d ( nowhat is the number of fits with χ 2 /pt between ( χ 2 π ) μα and ( χ 2 π ) μα + 2 in the most likely model set. * We provide stellar masses (M,) and ages (Age) only for sources with the most reliable estimates of these parameters (see Section 6.1 for details). (This table is available in its entirety in machine-readable form.) Agc' (Myr) : : 0.766 0.275 : 3.93 3.85 : : : 2
V CE
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7 : 313

#42
dynamics of the Class 0 protostar at the edge of an HII region Aurora Sicilia-Aguilar1, Nimesh Patel2, Min Fang3, Veronica Roccatagliata4, Konstantin Getman5 and Paul Goldsmith6 A&A 622, A118 (2019)
ABSTRACT
Context.  IC 1396A is a cometary globule that contains the Class 0 source IC 1396A-PACS-1, which was discovered with Herschel. Aims.  We use IRAM 30m telescope and Gaia DR2 data to explore the star formation history of IC 1396A and investigate the possi- bilities of triggered star formation. Methods.  IRAM and Herschel continuum data were used to obtain dust temperature and column density maps. Heterodyne data reveal the velocity structure of the gas. Gaia DR2 proper motions for the stars complete the kinematics of the region. Results.  IC 1396A-PACS-1 presents molecular emission similar to a hot corino with warm carbon chain chemistry due to the UV irradiation. The source is embedded in a dense clump surrounded by gas at velocities that are significantly different from the velocities of the Tr 37 cluster. CN emission reveals photoevaporation, while continuum data and high-density tracers (C 18 O, HCO+, DCO+, and N 2 D+) reveal distinct gaseous structures with a range of densities and masses. Conclusions. By combining the velocity, column density, and temperature information and Gaia DR2 kinematics, we confirm that the globule has experienced various episodes of star formation. IC 1396A-PACS-1 is probably the last intermediate-mass protostar !hat will form within IC 1396A; it shows evidence of being triggered by radiation-driven implosion. Chemical signatures such as CCS place IC 1396A-PACS-1 among the youngest known protostars. Gaia DR2 data reveal velocities in the plane of the sky ~4 kms¬¹ for IC 1396A with respect to Tr 37. The total velocity difference (8 kms-1) between the Tr 37 cluster and IC 1396A is too small for IC 1396A to have undergone substantial rocket acceleration, which imposes constraints on the distance to the ionizing source in time and the possibilities of triggered star formation. The three stellar populations in the globule reveal that objects located within relatively close distances (<0.5pc) can be formed in various star-forming episodes within ~1–2 Myr. Once the remaining cloud disperses, we expect substantial differences in evolutionary stage and initial conditions for the resulting objects and their protoplanetary disks, which may affect their evolution. Finally, evidence for short-range feedback from the embedded protostars, and in particular, the A-type star V390 Cep, is also observed. : 313 Chandra Observations of the Massive Star-Forming Region Onsala 2 Stephen L. Skinner1, Kimberly R. Sokal2 and Manuel Guedel3 #43 The Astrophysical Journal, 871:116 (20pp), 2019 January 20
Abstract
Previous radio and infrared observations have revealed an obscured region of high-mass star formation in Cygnus known as Onsala 2 (ON2). Within this region lies the optically revealed young stellar cluster Berkeley 87, which contains several OB stars and the rare oxygen-type Wolf–Rayet star WR 142. Previous radio studies of ON2 have also discovered masers and several H II regions excited by embedded OB stars. Radio and Gaia parallaxes have now shown that the H II regions are more distant than Berkeley 87. We summarize two Chandra X-ray observations of ON2, which detected more than 300 X-ray sources. Several optically identified stars in Berkeley 87 were detected, including massive OB stars and WR 142, the latter being a faint hard source whose X-ray emission likely arises in hot thermal plasma. Intense X-ray emission was detected near the compact H II regions G75.77 +0.34 and G75.84+0.40, consisting of numerous point sources and diffuse emission. Heavily absorbed X-ray sources and their near-IR counterparts that may be associated with the exciting OB stars of the H II regions are identified. Shocked winds from embedded massive stars offer a plausible explanation of the diffuse emission. Young stellar object candidates in the ON2 region are identified using near-IR colors, but surprisingly few counterparts of X-ray sources have near-IR excesses typical of classical T Tauri stars. ~3-5 Myr Berkeley 87:距離1.75 kpc,年齢
WR 142
WR 142 is a Wolf-Rayet star in the constellation Cygnus, an extremely rare star on the WO oxygen sequence.
Contents
Discovery Features Evolutionary status See also In 1966, a search for Wolf-Rayet stars in the northern celestial hemisphere discovered seven new examples. One, designated as Stephenson 3 , was classified as WC.[7] It was later found to show unusual emission lines of highly-ionised O ν π . [8] Because of the unusual oxygen lines, seen in only a handful of other stars, it was given the spectral type WC5pec in the Sixth Catalogue of Galactic Wolf-Rayet Stars.[5] In 1981, described as a WC-OVI star, it was identified as being associated with the active star-forming region ON2,[9] and then a heavily-obscured open cluster designated Berkeley 87, 9.5' south of the red supergiant BC Cygni [4] In 1982, the WC-OVI stars were grouped as members of the new WO class. The class at that time consisted of five stars, two of which were in the Magellanic Clouds and one of which was later found to be the central star of a planetary nebula. [10] Location of WR 142, circled (the bright star at the centre is γ Cygni and north is to the right) dust [11] WR 142 is usually assumed to be a member of the open cluster Berkeley 87, whose distance from the Sun is not very well known but thought to be around 1.23 kiloparsecs (4,000 light-years). As with its home cluster its light is very reddened and extinguished by interstellar This star, of spectral classification WO2, is one of the very few known oxygen-sequence Wolf-Rayet stars, just four in the Milky Way galaxy and five in external galaxies. It is also one of the hottest known with a surface temperature of 200,000 K [3] Modelling the atmosphere gives a luminosity around 245,000 L , while calculations from brightness and distance give luminosities of 500,000 L or more. It is a very small dense star, with a radius 40% of the Sun's but a mass 20 times greater. Very strong stellar winds, with a terminal velocity of 5,000 kilometers per second are causing WR 142 to lose 10~5 M   /year.[2] For comparison, the Sun loses (2-3) x 10−14 solar masses per year due to its solar wind, several hundred million times less than WR 142. WR 142
Other designations WR 142, 2MASS J20214434+3722306, GSC 02684-0001, Sand 5, St 3, UCAC2 44891902 Database references
WO Wolf-Rayet stars are the last evolutionary stage of the most massive stars before exploding as supernovae, possibly with a gamma-ray burst (GRB).[12] It is very likely that WR 142 is on its last stages of nuclear fusion, near or beyond the end of helium burning.[13] It is estimated to explode as a supernova in approximately 2,000 years. The mass and rapid rotation make a GRB likely.[3] Hard X-Ray emission has been detected from this star with the help of the Chandra space telescope, that has been suggested to be caused by the presence of a companion, a B-type main sequence star located at a distance of 1 AU from WR 142. There is no other indication of a companion and other reasons for the x-ray luminosity are considered more likely.[11] 11 800X-fayse,26(ur)20(cs.)275(is.)278(ve)21(ry.)276(ha)21(rd.)276(wi)21(th.)277(a.)291(ha)21(r)15(dn)21(es.25(s.)292(ra.25(ti)22(o.)JTJ /T153010 Tf20328761. Td !~)Tj /T154010 esses and the program 9,000 Tf6.8217 1. 06.8212 75106083438.83220Tm (!~)Tj /T154010 Tf1.31961. Td =~7461. Td !~ : 313 #44 Vlas Sokolov1, Ke Wang2,3, Jaime E. Pineda1, Paola Caselli1, Jonathan D. Henshaw4, Ashley T. Barnes5, Jonathan C. Tan6,7, Francesco Fontani8 and Izaskun Jiḿenez-Serra9 The Astrophysical Journal, 872:30 (17pp), 2019 February 10 To probe the initial conditions for high-mass star and cluster formation, we investigate the properties of dense filaments within the infrared dark cloud (IRDC) G035.39–00.33 (G035.39) in a combined Very Large Array and Green Bank Telescope mosaic tracing the NH 3 (1, 1) and (2, 2) emission down to 0.08 pc scales. Using agglomerative hierarchical clustering on multiple line-of-sight velocity component fitting results, we identify seven extended velocity-coherent components in our data, likely representing spatially coherent physical structures, some exhibiting complex gas motions. The velocity gradient magnitude distribution peaks at its mode of 0.35 km s-1 pc-1 and has a long tail extending into higher values of 1.5-2 km s-1 pc-1 , and it is generally consistent with those found toward the same cloud in other molecular tracers and with the values found toward nearby low-mass dense cloud cores at the same scales. Contrary to observational and theoretical expectations, we find the nonthermal ammonia line widths to be systematically narrower (by about 20%) than those of N 2 H + (1–0) line transition observed with similar resolution. If the observed ordered velocity gradients represent the core envelope solid-body rotation, we estimate the specific angular momentum to be about 2 × 10 21 cm 2 s −1 , similar to the low-mass star-forming cores. Together with the previous finding of subsonic motions in G035.39, our results demonstrate high levels of similarity between kinematics of a high-mass star-forming IRDC and the low-mass star formation regime. Our main results can be summarized as follows: 1. In the first interferometric mapping of the entire IRDC G035.39 cloud, we have mapped the NH 3 (1, 1) and (2, 2) inversion transitions, combining the VLA and GBT observations. 2. Our data reveal the convoluted kinematics in the cloud, bridging the cloud and core scales. We identify seven principal structures in PPV space and find velocity gradients within them that are comparable to the dynamics of the low-mass star-forming cores imaged with similar resolution. 3. Contrary to expectations from theoretical observational perspectives, we find a systematic line width difference between NH 3 and N 2 H + , with ammonia line width being about 30% smaller, a discrepancy also found toward low- mass dense cores. 4. We construct a gas temperature map for the IRDC, with the highest angular resolution available to date for this source and, wherever deemed significant, for separate line-of-sight velocity components. We report significant heating from the embedded protostellar sources that has not been seen individually from previous studies of gas and dust temperature in G035.39. The temperature of the seemingly starless core in the IRDC is typical of low- mass dense cores. 5. We have identified a number of sources, of both protostellar and starless nature, that exhibit complex gas motions around them. A few of these sources show an ordered velocity field in their vicinity and appear to influence the dynamics of the gas around them. For the selected sources, we calculate the corresponding specific angular momentum, assuming solid-body rotation of a uniform-density core, to be about 2 × 10 21 cm ² s−1, similar to that of the low-mass dense cores. : 313 On the Gravitational Instabilities of Protoplanetary Disks Ning Sui1,2, Ping He1,3,4, and Min Li5 #45 Publications of the Astronomical Society of the Pacific, 131:034301 (11pp), 2019 March Gravitational instabilities are important to the evolution of the disks and the planet formation in the disks. We calculate the evolution of the disks that form from the collapse of the molecular cloud cores. By changing the properties of the cloud cores and the hydrodynamical viscosity parameters, we explore their effects on the properties of the gravitational instabilities. We find that the disk is unstable when the angular velocity of the molecular cloud core is larger than a critical value. The time duration of the instability increases as the angular velocity of the core increases. The increase of the hydrodynamical viscosity parameter hardly affects the stability of the disk, but decreases the time duration of the critical state of the gravitational instability in the disk. The instability of the disks can happen at very early time of evolution of the disk, which is consistent with the observations. : 313 #46 The CARMA-NRO Orion Survey: The filamentary structure as seen in C18O emission S. T. Suri1, A. Sanchez-Monge1, P. Schilke1, S. D. Clarke1, R. J. Smith2, V. Ossenkopf-Okada1, R. Klessen3, P. Padoan4,5, P. Goldsmith6, H. G. Arce7, J. Bally8, J. M. Carpenter9, A. Ginsburg10, D. Johnstone11,12, J. Kauffmann13, S. Kong7, D. C. Lis14,15, S. Mairs16, T. Pillai17, J. E. Pineda18 and A. Duarte-Cabral19 arXiv 1901.00176 Context. We present an initial overview of the filamentary structure in the Orion A molecular cloud utilizing a high angular and velocity resolution C 18 O(1–0) emission map that was recently produced as part of the CARMA-NRO Orion Survey. Aims. The main goal of this study is to build a credible method to study varying widths of filaments which has previously been linked to star formation in molecular clouds. Due to the diverse star forming activities taking place throughout its ~20 pc length, together with its proximity of 388 pc, the Orion A molecular cloud provides an excellent laboratory for such an experiment to be carried out with high resolution and high sensitivity. Methods. Using the widely-known structure identification algorithm, DisPerSE, on a 3-dimensional (PPV) C!8O cube, we identified 625 relatively short (the longest being 1.74 pc) filaments over the entire cloud. We study the distribution of filament widths using FI ChaP, a python package that we have developed and made publicly available. Results. We find that the filaments identified in a 2 square degree PPV cube do not overlap spatially, except for the complex OMC-4 region that shows distinct velocity components along the line of sight. The filament widths vary between 0.02 and 0.3 pc depending on the amount of ,substructure that a filament possesses. The more substructure a filament has, the larger is its width. We also find that despite this variation, the 'filament width shows no anticorrelation with the central column density which is in agreement with previous Herschel observations. : : 313
E. Szegedi-Elek1, M. Kun1, A. Mo or1, G. Marton1 and B. Reipurth2 MNRAS 484, 1800–1814 (2019)