VISION – Vienna survey in Orion

We have extended and refined the existing young stellar object (YSO) catalogs for the Orion A molecular cloud, the closest massive star-forming region to Earth. This updated catalog is driven by the large spatial coverage (18.3 deg2, ∼950 pc2), seeing limited resolution (∼0.7″), and sensitivity (Ks < 19 mag) of the ESO-VISTA near-infrared survey of the Orion A cloud (VISION). Combined with archival mid- to far-infrared data, the VISTA data allow for a refined and more robust source selection. We estimate that among previously known protostars and pre-main-sequence stars with disks, source contamination levels (false positives) are at least ∼6.4% and ∼2.3%, respectively, mostly due to background galaxies and nebulosities. We identify 274 new YSO candidates using VISTA/Spitzer based selections within previously analyzed regions, and VISTA/WISE based selections to add sources in the surroundings, beyond previously analyzed regions. The WISE selection method recovers about 59% of the known YSOs in Orion A’s low-mass star-forming part L1641, which shows what can be achieved by the all-sky WISE survey in combination with deep near-infrared data in regions without the influence of massive stars. The new catalog contains 2980 YSOs, which were classified based on the de-reddened mid-infrared spectral index into 188 protostars, 185 flat-spectrum sources, and 2607 pre-main-sequence stars with circumstellar disks. We find a statistically significant difference in the spatial distribution of the three evolutionary classes with respect to regions of high dust column-density, confirming that flat-spectrum sources are at a younger evolutionary phase compared to Class IIs, and are not a sub-sample seen at particular viewing angles.

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The VMC survey – XXXIV. Morphology of stellar populations in the Magellanic Clouds

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2400 ◽

2019 ◽

Vol 490 (1) ◽

pp. 1076-1093 ◽

Cited By ~ 4

Author(s):

Dalal El Youssoufi ◽

Maria-Rosa L Cioni ◽

Cameron P M Bell ◽

Stefano Rubele ◽

Kenji Bekki ◽

...

Keyword(s):

Main Sequence ◽

Near Infrared ◽

Stellar Populations ◽

Magellanic Clouds ◽

Main Sequence Stars ◽

Spiral Arms ◽

Star Forming ◽

Star Forming Regions ◽

Tidal Interactions ◽

Using Data

ABSTRACT The Magellanic Clouds are nearby dwarf irregular galaxies whose morphologies show different properties when traced by different stellar populations, making them an important laboratory for studying galaxy morphologies. We study the morphology of the Magellanic Clouds using data from the Visible and Infrared Survey Telescope for Astronomy survey of the Magellanic Clouds system. We used about 10 and 2.5 million sources across an area of ∼105 and ∼42 deg2 towards the Large and Small Magellanic Cloud (LMC and SMC), respectively. We estimated median ages of stellar populations occupying different regions of the near-infrared (J − Ks, Ks) colour–magnitude diagram. Morphological maps were produced and detailed features in the central regions were characterized for the first time with bins corresponding to a spatial resolution of 0.13 kpc (LMC) and 0.16 kpc (SMC). In the LMC, we find that main-sequence stars show coherent structures that grow with age and trace the multiple spiral arms of the galaxy, star-forming regions become dimmer as we progress in age, while supergiant stars are centrally concentrated. Intermediate-age stars, despite tracing a regular and symmetrical morphology, show central clumps and hints of spiral arms. In the SMC, young main-sequence stars depict a broken bar. Intermediate-age populations show signatures of elongation towards the Magellanic Bridge that can be attributed to the LMC–SMC interaction ∼200 Myr ago. They also show irregular central features suggesting that the inner SMC has also been influenced by tidal interactions.

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Starbursts in and out of the star-formation main sequence

Astronomy and Astrophysics ◽

10.1051/0004-6361/201732370 ◽

2018 ◽

Vol 616 ◽

pp. A110 ◽

Cited By ~ 53

Author(s):

D. Elbaz ◽

R. Leiton ◽

N. Nagar ◽

K. Okumura ◽

M. Franco ◽

...

Keyword(s):

Star Formation ◽

Main Sequence ◽

Near Infrared ◽

Compact Star ◽

Far Infrared ◽

High Mass ◽

Star Forming ◽

Stellar Component ◽

Public Data ◽

Gas Fractions

Aims. We use high-resolution continuum images obtained with the Atacama Large Millimeter Array (ALMA) to probe the surface density of star formation in z ~ 2 galaxies and study the different physical properties between galaxies within and above the star-formation main sequence of galaxies. Methods. We use ALMA images at 870 μm with 0.2 arcsec resolution in order to resolve star formation in a sample of eight star-forming galaxies at z ~ 2 selected among the most massive Herschel galaxies in the GOODS-South field. This sample is supplemented with eleven galaxies from the public data of the 1.3 mm survey of the Hubble Ultra-Deep Field, HUDF. We derive dust and gas masses for the galaxies, compute their depletion times and gas fractions, and study the relative distributions of rest-frame ultraviolet (UV) and far-infrared (FIR) light. Results. ALMA reveals systematically dense concentrations of dusty star formation close to the center of the stellar component of the galaxies. We identify two different starburst regimes: (i) the classical population of starbursts located above the SFR-M⋆ main sequence, with enhanced gas fractions and short depletion times and (ii) a sub-population of galaxies located within the scatter of the main sequence that experience compact star formation with depletion timescales typical of starbursts of ~150 Myr. In both starburst populations, the FIR and UV are distributed in distinct regions and dust-corrected star formation rates (SFRs) estimated using UV-optical-near-infrared data alone underestimate the total SFR. Starbursts hidden in the main sequence show instead the lowest gas fractions of our sample and could represent the last stage of star formation prior to passivization. Being Herschel-selected, these main sequence galaxies are located in the high-mass end of the main sequence, hence we do not know whether these “starbursts hidden in the main sequence” also exist below 1011 M⊙. Active galactic nuclei (AGNs) are found to be ubiquitous in these compact starbursts, suggesting that the triggering mechanism also feeds the central black hole or that the active nucleus triggers star formation.

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The dust and cold gas content of local star-forming galaxies

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1737 ◽

2020 ◽

Vol 496 (3) ◽

pp. 2531-2541

Author(s):

P Popesso ◽

A Concas ◽

L Morselli ◽

G Rodighiero ◽

A Enia ◽

...

Keyword(s):

Main Sequence ◽

Far Infrared ◽

Gas Content ◽

Molecular Gas ◽

Lower Efficiency ◽

Star Forming ◽

The Galaxy ◽

Formation Efficiency ◽

Balmer Decrement ◽

Infrared Data

ABSTRACT We use dust masses (Mdust) derived from far-infrared data and molecular gas masses (Mmol) based on CO luminosity to calibrate proxies based on a combination of the galaxy Balmer decrement, disc inclination, and gas metallicity. We use such proxies to estimate Mdust and Mmol in the local SDSS sample of star-forming galaxies (SFGs). We study the distribution of Mdust and Mmol along and across the main sequence (MS) of SFGs. We find that Mdust and Mmol increase rapidly along the MS with increasing stellar mass (M*), and more marginally across the MS with increasing SFR (or distance from the relation). The dependence on M* is sub-linear for both Mdust and Mmol. Thus, the fraction of dust (fdust) and molecular gas mass (fmol) decreases monotonically towards large M*. The star formation efficiency (SFE, inverse of the molecular gas depletion time) depends strongly on the distance from the MS and it is constant along the MS. As nearly all galaxies in the sample are central galaxies, we estimate the dependence of fdust and fgas on the host halo mass and find a tight anticorrelation. As the region where the MS is bending is numerically dominated by massive haloes, we conclude that the bending of the MS is due to a lower availability of molecular gas mass in massive haloes rather than a lower efficiency in forming stars.

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Massive pre-main sequence stars in M17

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316008292 ◽

2015 ◽

Vol 11 (S315) ◽

Author(s):

Maria C. Ramirez-Tannus ◽

Lex Kaper ◽

Bram B. Ochsendorf ◽

Lucas E. Ellerbroek

Keyword(s):

Physical Properties ◽

Massive Star ◽

Main Sequence ◽

Near Infrared ◽

Band Head ◽

Emission Lines ◽

Spectral Features ◽

Main Sequence Stars ◽

Infrared Excess ◽

Star Forming

AbstractWe have obtained optical to near-infrared (300-2500 nm) VLT/X-shooter spectra of six candidate mYSOs, deeply embedded in the massive star forming region M17. These mYSO candidates have been identified based on their infrared excess and spectral features (double-peaked emission lines, CO band-head emission) indicating the presence of a disk (Hanson et al. 1997). In most cases, we detect a photospheric spectrum allowing us to measure the physical properties of the mYSOs and to confirm their PMS nature.

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Infrared observations of GGD objects

Symposium - International Astronomical Union ◽

10.1017/s0074180900156190 ◽

1987 ◽

Vol 122 ◽

pp. 125-126

Author(s):

R. Carballo ◽

C. Eiroa ◽

A. Mampaso

Keyword(s):

Main Sequence ◽

Near Infrared ◽

Far Infrared ◽

Infrared Emission ◽

Be Stars ◽

Main Sequence Stars ◽

Infrared Excess ◽

Dark Clouds ◽

Infrared Sources ◽

Different Characteristics

We present accurate positions and near infrared photometry (Table I) of 11 point-like objects in the neighbourhood of GGD objects obtained on the 1.55 m and on the 1.23 m in Teide Obs. and Calar Alto Obs. respectively, in Spain. Several of the near infrared sources are directly associated with the GGD nebulae and/or are candidate for their excitation. In addition some of them seem to be the near infrared counterparts of IRAS sources. We believe, on the basis of their infrared excess, far infrared emission (IRAS), association with nebulosity, coincidence with H2O masers or the fact that in most cases the observed luminosities are higher than those expected for main sequence stars, that most of them (9/12) are young stars embedded in the dark clouds which contain the GGD objects. The loci of the detected sources in an (H-K,K-L) infrared two-colour diagram is the same as that obtained for known pre-main sequence stars, such as T Tauris and Herbig Ae-Be stars, indicating the presence of dust shells with temperatures in the range 800–1500 K. The observed range in luminosity, 10–4600 L⊙, added to other different characteristics found between them, such' as the presence, or absence, of H2O masers, indicates the interest for a detailed study of the infrared sources and related GGD nebulae.

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Dust formation of Be stars with large infrared excess

Proceedings of the International Astronomical Union ◽

10.1017/s1743921311010787 ◽

2010 ◽

Vol 6 (S272) ◽

pp. 366-371

Author(s):

Chien-De Lee ◽

Wen-Ping Chen

Keyword(s):

Main Sequence ◽

Near Infrared ◽

Thermal Emission ◽

Far Infrared ◽

Dust Particles ◽

Be Stars ◽

Ionized Gas ◽

Infrared Excess ◽

Star Forming ◽

Infrared Wavelengths

AbstractClassical Be stars, in addition to their emission-line spectra, are associated with infrared excess which is attributable to free-free emission from ionized gas. However, a few with exceptionally large near-infrared excess, namely with J–H, and H–Ks both greater than 0.6 mag—and excess emission extending to mid- and far-infrared wavelengths—must be accounted for by thermal emission from circumstellar dust. Evolved Be stars on the verge of turning off the main sequence may condense dust in their expanding cooling envelopes. The dust particles should be very small in size, hence reprocess starlight efficiently. This is in contrast to Herbig Ae/Be stars for which the copious infrared excess arises from relatively large grains as part of the surplus star-forming materials.

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The Formation of Massive Stars: from Herschel to Near-Infrared

Acta Polytechnica CTU Proceedings ◽

10.14311/app.2014.01.0103 ◽

2014 ◽

Vol 1 (1) ◽

pp. 103-107

Author(s):

Paolo Persi ◽

Mauricio Tapia

Keyword(s):

Near Infrared ◽

Narrow Band ◽

Narrow Band Imaging ◽

Spectral Energy Distribution ◽

Far Infrared ◽

High Mass ◽

Spectral Energy ◽

Mass Star ◽

Stellar Cluster ◽

Star Forming

We have studied a number of selected high mass star forming regions, including high resolution near-infrared broad- and narrow-band imaging, Herschel (70, 160, 250, 350 and 500 μm) and Spitzer (3.6, 4.5, 5.8 and 8.0 m) images. The preliminary results of one of this region, IRAS 19388+2357(MOL110) are discussed. In this region a dense core has been detected in the far-infrared, and a young stellar cluster has been found around this core. Combining near-IR data with Spitzer and Herschel photometry we have derived the spectral energy distribution of Mol110. Finally comparing our H2 and Kc narrow-band images, we have found an H2 jet in this region.

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Luminosity functions of YSO clusters in Sh-2 255, W3 Main and NGC 7538 star forming regions

Proceedings of the International Astronomical Union ◽

10.1017/s1743921307002463 ◽

2006 ◽

Vol 2 (S237) ◽

pp. 458-458

Author(s):

Devendra Ojha ◽

Motohide Tamura ◽

Keyword(s):

Main Sequence ◽

Near Infrared ◽

Infrared Camera ◽

Young Stellar Objects ◽

Main Sequence Stars ◽

Stellar Objects ◽

Star Forming ◽

Star Forming Regions ◽

Luminosity Functions ◽

Infrared Surveys

AbstractWe have conducted deep near-infrared surveys of the Sh-2 255, W3 Main and NGC 7538 massive star forming regions using simultaneous observations of the JHKs-band with the near-infrared camera SIRIUS on the UH 88-inch telescope and with SUBARU. The near-infrared surveys cover a total area of ~ 72 arcmin2 of three regions with 10-σ limiting magnitudes of ~ 19.5, 18.4 and 17.3 in J, H and Ks-band, respectively. Based on the color-color and color-magnitude diagrams and their clustering properties, the candidate young stellar objects are identified and their luminosity functions are constructed in Sh-2 255, W3 Main and NGC 7538 star forming regions. A large number of previously unreported red sources (H-K > 2) have also been detected around these regions. We argue that these red stars are most probably pre-main-sequence stars with intrinsic color excesses. The detected young stellar objects show a clear clustering pattern in each region: the Class I-like sources are mostly clustered in molecular cloud region, while the Class II-like sources are in or around more evolved optical HII regions. We find that the slopes of the Ks-band luminosity functions of Sh-2 255, W3 Main and NGC 7538 are lower than the typical values reported for the young embedded clusters, and their stellar populations are primarily composed of low mass pre-main-sequence stars. From the slopes of the Ks-band luminosity functions, we infer that Sh-2 255, W3 Main and NGC 7538 star forming regions are rather young (age ≤ 1 Myr).

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The effect of stellar multiplicity on protoplanetary discs: a near-infrared survey of the Lupus star-forming region

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3674 ◽

2020 ◽

Vol 501 (2) ◽

pp. 2305-2315

Author(s):

Alice Zurlo ◽

Lucas A Cieza ◽

Megan Ansdell ◽

Valentin Christiaens ◽

Sebastián Pérez ◽

...

Keyword(s):

Adaptive Optics ◽

Molecular Cloud ◽

Near Infrared ◽

Main Sequence Stars ◽

Multiple Systems ◽

Star Forming ◽

Very Large Telescope ◽

Pms Stars ◽

First Time ◽

Infrared Survey

ABSTRACT We present results from a near-infrared (NIR) adaptive optics (AO) survey of pre-main-sequence stars in the Lupus molecular cloud with NACO at the Very Large Telescope (VLT) to identify (sub)stellar companions down to ∼20-au separation and investigate the effects of multiplicity on circumstellar disc properties. We observe for the first time in the NIR with AO a total of 47 targets and complement our observations with archival data for another 58 objects previously observed with the same instrument. All 105 targets have millimetre Atacama Large Millimetre/sub-millimetre Array (ALMA) data available, which provide constraints on disc masses and sizes. We identify a total of 13 multiple systems, including 11 doubles and 2 triples. In agreement with previous studies, we find that the most massive (Mdust > 50 M⊕) and largest (Rdust > 70 au) discs are only seen around stars lacking visual companions (with separations of 20–4800 au) and that primaries tend to host more massive discs than secondaries. However, as recently shown in a very similar study of >200 PMS stars in the Ophiuchus molecular cloud, the distributions of disc masses and sizes are similar for single and multiple systems for Mdust < 50 M⊕ and radii Rdust < 70 au. Such discs correspond to ∼80–90 per cent of the sample. This result can be seen in the combined sample of Lupus and Ophiuchus objects, which now includes more than 300 targets with ALMA imaging and NIR AO data, and implies that stellar companions with separations >20 au mostly affect discs in the upper 10${{\ \rm per\ cent}}$ of the disc mass and size distributions.

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Tracing young SMBHs in the dusty distant universe – a Chandra view of DOGs

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320004032 ◽

2020 ◽

Vol 15 (S359) ◽

pp. 17-21

Author(s):

Karín Menéndez-Delmestre ◽

Laurie Riguccini ◽

Ezequiel Treister

Keyword(s):

Star Formation ◽

Main Sequence ◽

Far Infrared ◽

Host Galaxy ◽

X Ray ◽

Star Forming ◽

Near Ir ◽

X Ray Imaging ◽

Combined Use ◽

Dusty Galaxies

AbstractThe coexistence of star formation and AGN activity has geared much attention to dusty galaxies at high redshifts, in the interest of understanding the origin of the Magorrian relation observed locally, where the mass of the stellar bulk in a galaxy appears to be tied to the mass of the underlying supermassive black hole. We exploit the combined use of far-infrared (IR) Herschel data and deep Chandra ˜160 ksec depth X-ray imaging of the COSMOS field to probe for AGN signatures in a large sample of >100 Dust-Obscured Galaxies (DOGs). Only a handful (˜20%) present individual X-ray detections pointing to the presence of significant AGN activity, while X-ray stacking analysis on the X-ray undetected DOGs points to a mix between AGN activity and star formation. Together, they are typically found on the main sequence of star-forming galaxies or below it, suggesting that they are either still undergoing significant build up of the stellar bulk or have started quenching. We find only ˜30% (6) Compton-thick AGN candidates (NH > 1024 cm–2), which is the same frequency found within other soft- and hard-X-ray selected AGN populations. This suggests that the large column densities responsible for the obscuration in Compton-thick AGNs must be nuclear and have little to do with the dust obscuration of the host galaxy. We find that DOGs identified to have an AGN share similar near-IR and mid-to-far-IR colors, independently of whether they are individually detected or not in the X-ray. The main difference between the X-ray detected and the X-ray undetected populations appears to be in their redshift distributions, with the X-ray undetected ones being typically found at larger distances. This strongly underlines the critical need for multiwavelength studies in order to obtain a more complete census of the obscured AGN population out to higher redshifts. For more details, we refer the reader to Riguccini et al. (2019).

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