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51. IR nebulae around bright massive stars
ID:
ivo://CDS.VizieR/J/A+A/618/A110
Title:
IR nebulae around bright massive stars
Short Name:
J/A+A/618/A110
Date:
21 Oct 2021
Publisher:
CDS
Description:
Recent studies show that more than 70% of massive stars do not evolve as effectively single stars, but as members of interacting binary systems. The evolution of these stars is thus strongly altered compared to similar but isolated objects. We investigate the occurrence of parsec-scale mid-infrared nebulae around early-type stars. If they exist over a wide range of stellar properties, one possible overarching explanation is non-conservative mass transfer in binary interactions, or stellar mergers. For ~3850 stars (all OBA stars in the Bright Star Catalogue (BSC, Cat. V/50), Be stars, BeXRBs, and Be+sdO systems), we visually inspect WISE 22um images. Based on nebular shape and relative position, we distinguish five categories: offset bow shocks structurally aligned with the stellar space velocity, unaligned offset bow shocks, and centered, unresolved, and not classified nebulae. In the BSC, we find that 28%, 13%, and 0.4% of all O, B, and A stars, respectively, possess associated infrared (IR) nebulae. Additionally, 34/234 Be stars, 4/72 BeXRBs, and 3/17 Be+sdO systems are associated with IR nebulae. Aligned or unaligned bow shocks result from high relative velocities between star and interstellar medium (ISM) that are dominated by the star or the ISM, respectively. About 13% of the centered nebulae could be bow shocks seen head- or tail-on. For the rest, the data disfavor explanations as remains of parental disks, supernova remnants of a previous companion, and dust production in stellar winds. The existence of centered nebulae also at high Galactic latitudes strongly limits the global risk of coincidental alignments with condensations in the ISM. Mass loss during binary evolution seems a viable mechanism for the formation of at least some of these nebulae. In total, about 29% of the IR nebulae (2% of all OBA stars in the BSC) may find their explanation in the context of binary evolution.
52. IR properties of stellar bowshock nebulae
ID:
ivo://CDS.VizieR/J/AJ/154/201
Title:
IR properties of stellar bowshock nebulae
Short Name:
J/AJ/154/201
Date:
21 Oct 2021
Publisher:
CDS
Description:
Arcuate infrared nebulae are ubiquitous throughout the Galactic Plane and are candidates for partial shells, bubbles, or bowshocks produced by massive runaway stars. We tabulate infrared photometry for 709 such objects using images from the Spitzer Space Telescope, the Wide-field Infrared Explorer, and the Herschel Space Observatory (HSO). Of the 709 objects identified at 24 or 22 {mu}m, 422 are detected at the HSO 70 {mu}m bandpass. Of these, only 39 are detected at HSO 160 {mu}m. The 70 {mu}m peak surface brightnesses are 0.5-2.5 Jyr/arcmin^2^. Color temperatures calculated from the 24 to 70 {mu}m ratios range from 80 to 400 K. Color temperatures from 70 to 160 {mu}m ratios are systematically lower, 40-200 K. Both of these temperature are, on average, 75% higher than the nominal temperatures derived by assuming that dust is in steady-state radiative equilibrium. This may be evidence of stellar wind bowshocks sweeping up and heating-possibly fragmenting but not destroying-interstellar dust. Infrared luminosity correlates with standoff distance, R_0_, as predicted by published hydrodynamical models. Infrared spectral energy distributions are consistent with interstellar dust exposed to either single radiant energy density, U=10^3^-10^5^ (in more than half of the objects) or a range of radiant energy densities U_min_=25 to U_max_=10^3^-10^5^ times the mean interstellar value for the remainder. Hence, the central OB stars dominate the energetics, making these enticing laboratories for testing dust models in constrained radiation environments. The spectral energy densities are consistent with polycyclic aromatic hydrocarbon fractions q_PAH_~<1% in most objects.
53. IR sources in Magellanic Clouds
ID:
ivo://CDS.VizieR/II/181
Title:
IR sources in Magellanic Clouds
Short Name:
II/181
Date:
21 Oct 2021
Publisher:
CDS
Description:
The authors have used the IRAS data to construct maps of the Magellanic Clouds at wavelengths of 12, 25, 60, and 100 microns. These are contained in the published volume only. The position and characteristics of each source are included in this compilation. Also included are cross references to sources at other wavelengths (H-alpha emission nebulae, dark clouds, and stars) when these could be reasonably identified with the IR sources. IRAS IDs and the DPM field are also given.
54. JHK photometry in NGC 6334 IV
ID:
ivo://CDS.VizieR/J/A+A/357/1020
Title:
JHK photometry in NGC 6334 IV
Short Name:
J/A+A/357/1020
Date:
21 Oct 2021
Publisher:
CDS
Description:
Sub-arcsecond JHK images of the star formation region NGC 6334 IV covering 14.7arcmin^2^ have been obtained. These were supplemented by H_2_ and Br{gamma} images of the central 2arcmin^2^. A total of 1238sources brighter than K=~17 were detected. Due to the very high extinction in this region, only 685 of these are brighter at 1.2{mu}m than our limit, J=~20. Only less than 5% of the sources exhibit excess emission at {lambda}>2.0{mu}m and they are scattered over the whole area covered. No evidence of a developed stellar cluster was found, but a small number of luminous (O-B2) young stellar objects were detected. These are embedded in the densest part of the molecular cloud that is at the centre of a giant bipolar structure seen in the radio and the infrared. This morphology is the result of the effect of massive stellar winds originating from the centre of a dense molecular toroid which collimates the outflow material giving rise to two lobes of thermal gas and dust emission. We confirm that the extinction is higher toward the southern lobe than toward the northern one but both are less reddened than their immediate surroundings. A new centre of active massive star formation is reported to the east of the central region. Close to a (sub)millimeter emission peak, a large infrared nebula with several point-like sources was found at 2.2{mu}m. The discovery of a small embedded low-luminosity bipolar object in the vicinity of one of the giant lobes is also reported. For a description of the JHK photometric system, see e.g. <GCPD/09>
55. JHK photometry of NGC1333
ID:
ivo://CDS.VizieR/J/AJ/111/1964
Title:
JHK photometry of NGC1333
Short Name:
J/AJ/111/1964
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of an extensive near-infrared (JHK) imaging survey of the NGC 1333 star forming region. Our survey covers an area more than 4 times larger than the previous imaging survey of this cloud reported by Aspin et al. (1994, Cat. <J/A+AS/106/165>) and is sufficiently sensitive to render an accurate census of the embedded stellar population in the cloud. We detected 275 sources with m_K_<14.5mag within the 432 square arcminute region surveyed.
56. JHKs photometry of Hourglass nebula
ID:
ivo://CDS.VizieR/J/MNRAS/366/739
Title:
JHKs photometry of Hourglass nebula
Short Name:
J/MNRAS/366/739
Date:
21 Oct 2021
Publisher:
CDS
Description:
A detailed study of the Hourglass nebula in the M8 star-forming region is presented. The study is mainly based on recent subarcsec-resolution JHKs images taken at Las Campanas Observatory and complemented with archival Hubble Space Telescope (HST) images and long-slit spectroscopy retrieved from the European Southern Observatory Archive Facility. Using the new numerical code CHORIZOS, we estimate the distance to the earliest stars in the region to be 1.25kpc. Infrared photometry of all the sources detected in the field is given.
57. K2 ugri & H{alpha} photometry in the Lagoon Nebula
ID:
ivo://CDS.VizieR/J/AJ/162/101
Title:
K2 ugri & H{alpha} photometry in the Lagoon Nebula
Short Name:
J/AJ/162/101
Date:
14 Mar 2022 06:42:13
Publisher:
CDS
Description:
Space observatories have provided unprecedented depictions of the many variability behaviors typical of low-mass, young stars. However, those studies have so far largely omitted more massive objects (~2M{sun} to 4-5M{sun}) and were limited by the absence of simultaneous, multiwavelength information. We present a new study of young star variability in the ~1-2Myr old, massive Lagoon Nebula region. Our sample encompasses 278 young, late B to K-type stars, monitored with Kepler/K2. Auxiliary u, g, r, i, H{alpha} time-series photometry, simultaneous with K2, was acquired at the Paranal Observatory. We employed this comprehensive data set and archival infrared photometry to determine individual stellar parameters, assess the presence of circumstellar disks, and tie the variability behaviors to inner disk dynamics. We found significant mass-dependent trends in variability properties, with B/A stars displaying substantially reduced levels of variability compared to G/K stars for any light-curve morphology. These properties suggest different magnetic field structures at the surface of early-type and later-type stars. We also detected a dearth of some disk-driven variability behaviors, particularly dippers, among stars earlier than G. This indicates that their higher surface temperatures and more chaotic magnetic fields prevent the formation and survival of inner disk dust structures corotating with the star. Finally, we examined the characteristic variability timescales within each light curve and determined that the day-to-week timescales are predominant over the K2 time series. These reflect distinct processes and locations in the inner disk environment, from intense accretion triggered by instabilities in the innermost disk regions to variable accretion efficiency in the outer magnetosphere.
58. LMC extended catalog
ID:
ivo://CDS.VizieR/J/AJ/117/238
Title:
LMC extended catalog
Short Name:
J/AJ/117/238
Date:
21 Oct 2021
Publisher:
CDS
Description:
A survey of extended objects in the Large Magellanic Cloud was carried out on the ESO/SERC R and J Sky Survey Atlases, checking entries in previous catalogs and searching for new objects. The census provided 6659 objects including star clusters, emission-free associations, and objects related to emission nebulae. Each of these classes contains three subclasses with intermediate properties, which are used to infer total populations. The survey includes cross identifications among catalogs, and we present 3246 new objects. We provide accurate positions, classification, and homogeneous measurements of sizes and position angles, as well as information on cluster pairs and hierarchical relation for superimposed objects. This unification and enlargement of catalogs is important for future searches of fainter and smaller new objects. We discuss the angular and size distributions of the objects of the different classes. The angular distributions show two off-centered systems with different inclinations, suggesting that the LMC disk is warped. The present catalog together with its previous counterpart for the SMC and the inter-Cloud region provide a total population of 7847 extended objects in the Magellanic System. The angular distribution of the ensemble reveals important clues on the interaction between the LMC and SMC.
59. LMC & SMC PNe optical spectroscopy. I
ID:
ivo://CDS.VizieR/J/ApJS/75/407
Title:
LMC & SMC PNe optical spectroscopy. I
Short Name:
J/ApJS/75/407
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present optical spectroscopy in the range 3300-7400A for a total of 30 planetary nebulae in the LMC and 11 in the SMC, with measurements of line intensities down to ~1% of H{beta}. Agreement with other authors is on the whole excellent, especially for lines >+10%-20% of H{beta}. Reddening estimates from Balmer line ratios have been determined, and the line intensities dereddened accordingly. Nebular [O III] electron temperature and, where measurable, [N II] temperatures and [S II] densities are given. [O II] electron densities are recalculated using appropriate electron temperatures. A number of spectra exhibit interesting spectral features (including symbiotic-type profiles, unidentified emission lines, and nonsimple Balmer decrements). These objects are discussed in some detail. Zanstra temperatures are derived for a total of 25 objects possessing detectable stellar continua. These temperatures are in agreement with the few published values from various methods, and preliminary photoionization modeling of this sample. The homogeneity and size of the sample make it possible to investigate several interesting correlations between measured parameters.
60. LMC & SMC PNe optical spectroscopy. II
ID:
ivo://CDS.VizieR/J/ApJS/76/1085
Title:
LMC & SMC PNe optical spectroscopy. II
Short Name:
J/ApJS/76/1085
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present optical spectroscopy in the range 3300-7400A for a total of 37 planetary nebulae in the LMC and seven in the SMC. Together with the object from the first paper in the series (1991ApJS...75..407M), we now have accurate emission-line intensities down to a few percent of H{beta} for 77 nebulae in the Magellanic Clouds. Agreement with other authors is excellent. Reddening estimates from Balmer line ratios have been determined, and the line intensities have been dereddened accordingly. Nebular [O III] electron temperature and, where measurable, [S II] densities, are derived. [O II] electron densities are recalculated using appropriate electron temperatures. The [S II] and [O II] electron densities correlate well, with n_e_([O II])>n_e_([S II]). Zanstra temperatures are in derived for 22 objects possessing detectable stellar continua. These temperatures are in agreement with photoionization modeling of this sample.