scholarly journals Dust in the Wolf–Rayet nebula M 1-67

2020 ◽  
Vol 497 (4) ◽  
pp. 4128-4142
Author(s):  
P Jiménez-Hernández ◽  
S J Arthur ◽  
J A Toalá
Keyword(s):  
Mass Loss ◽  
Galactic Plane ◽  
Spectral Synthesis ◽  
Mass Loss Rate ◽  
Spectral Energy Distribution ◽  
Optical Data ◽  
Spectral Energy ◽  
Wide Field ◽  
Power Law Distribution ◽  
Massive Star Evolution

ABSTRACT The Wolf–Rayet nebula M 1-67 around WR 124 is located above the Galactic plane in a region mostly empty of interstellar medium, which makes it the perfect target to study the mass-loss episodes associated with the late stages of massive star evolution. Archive photometric observations from Wide-field Infrared Survey Explorer(WISE), Spitzer (MIPS), and Herschel (PACS and SPIRE) are used to construct the spectral energy distribution (SED) of the nebula in the wavelength range of 12–500 μm. The infrared (photometric and spectroscopic) data and nebular optical data from the literature are modelled simultaneously using the spectral synthesis code cloudy, where the free parameters are the gas density distribution and the dust grain-sized distribution. The infrared SED can be reproduced by dust grains with two size distributions: an MRN power-law distribution with grain sizes between 0.005 and 0.05 μm and a population of large grains with representative size of 0.9 μm. The latter points towards an eruptive origin for the formation of M 1-67. The model predicts a nebular ionized gas mass of $M_\mathrm{ion} = 9.2^{+1.6}_{-1.5}~\mathrm{M}_\odot$ and the estimated mass-loss rate during the dust formation period is $\dot{M} \approx 6 \times 10^{-4}~ \mathrm{M}_\odot$ yr−1. We discuss the implications of our results in the context of single and binary stellar evolution and propose that M 1-67 represents the best candidate for a post-common envelope scenario in massive stars.

scholarly journals Unveiling the stellar origin of the Wolf–Rayet nebula NGC 6888 through infrared observations

2020 ◽  
Vol 499 (1) ◽  
pp. 415-427
Author(s):  
G Rubio ◽  
J A Toalá ◽  
P Jiménez-Hernández ◽  
G Ramos-Larios ◽  
M A Guerrero ◽  
...  
Keyword(s):  
Spectral Synthesis ◽  
Spectral Energy Distribution ◽  
Spectral Energy ◽  
Wide Field ◽  
Infrared Observations ◽  
Photometric Observations ◽  
Dust Mass ◽  
Red Supergiants ◽  
Current Mass ◽  
Ir Study

ABSTRACT We present a comprehensive infrared (IR) study of the iconic Wolf–Rayet (WR) wind-blown bubble NGC 6888 around WR 136. We use Wide-field Infrared Survey Explorer, Spitzer IRAC, and MIPS and Herschel PACS IR images to produce a sharp view of the distribution of dust around WR 136. We complement these IR photometric observations with Spitzer IRS spectra in the 5–38-μm wavelength range. The unprecedented high-resolution IR images allowed us to produce a clean spectral energy distribution, free of contamination from material along the line of sight, to model the properties of the dust in NGC 6888. We use the spectral synthesis code cloudy to produce a model for NGC 6888 that consistently reproduces its optical and IR properties. Our best model requires a double distribution with the inner shell composed only of gas, whilst the outer shell requires a mix of gas and dust. The dust consists of two populations of grain sizes, one with small-sized grains asmall  = [0.002–0.008] $\mu$m and another one with large-sized grains abig  = [0.05–0.5] $\mu$m. The population of big grains is similar to that reported for other red supergiants stars and dominates the total dust mass, which leads us to suggest that the current mass of NGC 6888 is purely due to material ejected from WR 136, with a negligible contribution of the swept up interstellar medium. The total mass of this model is 25.5$^{+4.7}_{-2.8}$ M⊙, a dust mass of $M_\mathrm{dust} = 0.14^{+0.03}_{-0.01}$ M⊙, for a dust-to-gas ratio of 5.6 × 10−3. Accordingly, we suggest that the initial stellar mass of WR 136 was ≲50 M⊙, consistent with current single stellar evolution models.

scholarly journals Are the silicate crystallinities of oxygen-rich evolved stars related to their mass loss rates?

2018 ◽  
Vol 14 (S343) ◽  
pp. 425-426
Author(s):  
Biwei Jiang ◽  
Jiaming Liu ◽  
Aigen Li
Keyword(s):  
Energy Distribution ◽  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Spectral Energy Distribution ◽  
Spectral Energy ◽  
Evolved Stars ◽  
Loss Rates

AbstractA sample of 28 oxygen-rich evolved stars is selected based on the presence of crystalline silicate emission features in their ISO/SWS spectra. The crystallinity, measured as the flux fraction of crystalline silicate features, is found not to be related to mass loss rate that is derived from fitting the spectral energy distribution.

scholarly journals A multiwavelength study of filamentary cloud G341.244-00.265

2019 ◽  
Vol 622 ◽  
pp. A155 ◽  
Author(s):  
Nai-Ping Yu ◽  
Jing-Long Xu ◽  
Jun-Jie Wang
Keyword(s):  
Star Formation ◽  
Molecular Cloud ◽  
Galactic Plane ◽  
Mass Density ◽  
Spectral Energy Distribution ◽  
Radio Continuum ◽  
Spectral Energy ◽  
Wide Field ◽  
Molecular Line ◽  
Filamentary Structure

We present a multiwavelength study toward the filamentary molecular cloud G341.244-00.265, to investigate the physical and chemical properties, as well as star formation activities taking place therein. Our radio continuum and molecular line data were obtained from the Sydney University Molonglo Sky Survey (SUMSS), Atacama Pathfinder Experiment Telescope Large Area Survey of the Galaxy (ATLASGAL), Structure, excitation, and dynamics of the inner Galactic interstellar medium (SEDIGISM) and Millimeter Astronomy Legacy Team Survey at 90 GHz (MALT90). The infrared archival data come from Galactic Legacy Infrared Midplane Survey Extraordinaire (GLIMPSE), Wide-field Infrared Survey Explorer (WISE), and Herschel InfraRed Galactic Plane Survey (Hi-GAL). G341.244-00.265 displays an elongated filamentary structure both in far-infrared and molecular line emissions; the “head” and “tail” of this molecular cloud are associated with known infrared bubbles S21, S22, and S24. We made H2 column density and dust temperature maps of this region by the spectral energy distribution (SED) method. G341.244-00.265 has a linear mass density of about 1654 M⊙ pc−1 and has a projected length of 11.1 pc. The cloud is prone to collapse based on the virial analysis. Even though the interactions between this filamentary cloud and its surrounding bubbles are evident, we found these bubbles are too young to trigger the next generation of star formation in G341.244-00.265. From the ATLASGAL catalog, we found eight dense massive clumps associated with this filamentary cloud. All of these clumps have sufficient mass to form massive stars. Using data from the GLIMPSE and WISE survey, we search the young stellar objects (YSOs) in G341.244-00.265. We found an age gradient of star formation in this filamentary cloud: most of the YSOs distributed in the center are Class I sources, while most Class II candidates are located in the head and tail of G341.244-00.265, indicating star formation at the two ends of this filament is prior to the center. The abundance ratio of N(N2H+)/N(C18O) is higher in the center than that in the two ends, also indicating that the gas in the center is less evolved. Taking into account the distributions of YSOs and the N(N2H+)/N(C18O) ratio map, our study is in agreement with the prediction of the so-called “end-dominated collapse” star formation scenario.

scholarly journals Long-term evolution of AGB wind envelopes: Insights from hydrodynamical models

1999 ◽  
Vol 191 ◽  
pp. 379-388
Author(s):  
M. Steffen ◽  
D. Schönberner ◽  
R. Szczerba
Keyword(s):  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Spectral Energy Distribution ◽  
Spectral Energy ◽  
Alternative Mechanism ◽  
Agb Stars ◽  
Hydrodynamical Simulations ◽  
Thermal Pulses

Up to now, hydrodynamical models of dust-driven AGB winds do not generally take into account the ‘long-term’ changes of the stellar parameters (on stellar evolution time scales of 103 to 105 yrs), although it is well known that the luminosity and (very likely) the mass loss rate undergo significant variations when so called ‘thermal pulses’ occur on the upper AGB. In this review we demonstrate that time-dependent radiation hydrodynamics calculations are needed to understand the formation, structure, and spectral energy distribution of detached dust shells detected by IRAS and ISO. Combined with appropriate models, these observations can reveal part of the previous mass loss history on the AGB and allow an empirical check of presently adopted mass loss laws.Based on insights from hydrodynamical simulations, we discuss the two competing scenarios that have been put forward to explain the origin of the very thin molecular shells recently discovered around some carbon stars. We find that the signature of a short mass loss ‘eruption’ broadens quickly with time due to the related velocity gradient across the shell. Hence, this scenario is not considered a likely explanation of detached CO shells. On the other hand, the alternative mechanism, interaction of winds, is shown to be capable of producing very thin shells of greatly enhanced gas density in the dusty outflows from AGB stars by sweeping up matter at the interface between both type of winds.

The Spectral Energy Distribution and Mass‐Loss Rate of the A‐Type Supergiant Deneb

2002 ◽  
Vol 570 (1) ◽  
pp. 344-368 ◽  
Author(s):  
J. P. Aufdenberg ◽  
P. H. Hauschildt ◽  
E. Baron ◽  
T. E. Nordgren ◽  
A. W. Burnley ◽  
...  
Keyword(s):  
Energy Distribution ◽  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Spectral Energy Distribution ◽  
Spectral Energy

scholarly journals ISO Observations of AGB Stars in the Small Magellanic Cloud

1999 ◽  
Vol 192 ◽  
pp. 95-99
Author(s):  
J.A.D.L. Blommaert ◽  
M.A.T. Groenewegen ◽  
M. R. Cioni ◽  
H. J. Habing ◽  
J.Th. van Loon ◽  
...  
Keyword(s):  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Spectral Energy Distribution ◽  
Magellanic Cloud ◽  
Radiative Transfer Model ◽  
Spectral Energy ◽  
Transfer Model ◽  
Agb Stars ◽  
Small Magellanic Cloud

We used ISOCAM and ISOPHOT to observe the spectral energy distribution between 3.6 and 60 μm of AGB stars in the Small Magellanic Cloud detected by IRAS. CAM-CVF spectra are made which enable us to establish the carbon- or oxygen-rich nature of the stars.We are in the process of analysing this data using a radiative transfer model. This will provide us with accurate determinations of luminosity and mass loss rate. Combining the results on the SMC, LMC and Galaxy we hope to address the open question of the metallicity dependencies of the mass loss rate. This in turn is important in the ejection of matter by AGB stars into the interstellar medium.

scholarly journals Extinction-free Census of AGNs in the AKARI/IRC North Ecliptic Pole Field from 23-band infrared photometry from Space Telescopes

2020 ◽  
Vol 499 (3) ◽  
pp. 4068-4081 ◽  
Author(s):  
Ting-Wen Wang ◽  
Tomotsugu Goto ◽  
Seong Jin Kim ◽  
Tetsuya Hashimoto ◽  
Denis Burgarella ◽  
...  
Keyword(s):  
Spectral Energy Distribution ◽  
Cosmic Time ◽  
Spectral Energy ◽  
Wide Field ◽  
Space Telescopes ◽  
Distribution Modelling ◽  
Star Forming ◽  
The North ◽  
Band Filter ◽  
Infrared Survey

ABSTRACT In order to understand the interaction between the central black hole and the whole galaxy or their co-evolution history along with cosmic time, a complete census of active galactic nucleus (AGN) is crucial. However, AGNs are often missed in optical, UV, and soft X-ray observations since they could be obscured by gas and dust. A mid-infrared (MIR) survey supported by multiwavelength data is one of the best ways to find obscured AGN activities because it suffers less from extinction. Previous large IR photometric surveys, e.g. Wide field Infrared Survey Explorer and Spitzer, have gaps between the MIR filters. Therefore, star-forming galaxy-AGN diagnostics in the MIR were limited. The AKARI satellite has a unique continuous nine-band filter coverage in the near to MIR wavelengths. In this work, we take advantage of the state-of-the-art spectral energy distribution modelling software, cigale, to find AGNs in MIR. We found 126 AGNs in the North Ecliptic Pole-Wide field with this method. We also investigate the energy released from the AGN as a fraction of the total IR luminosity of a galaxy. We found that the AGN contribution is larger at higher redshifts for a given IR luminosity. With the upcoming deep IR surveys, e.g. JWST, we expect to find more AGNs with our method.

scholarly journals A quantitative in-depth analysis of the prototype sdB+BD system SDSS J08205+0008 revisited in the Gaia era

2020 ◽  
Author(s):  
V Schaffenroth ◽  
S L Casewell ◽  
D Schneider ◽  
D Kilkenny ◽  
S Geier ◽  
...  
Keyword(s):  
Mass Loss ◽  
Rotational Velocity ◽  
Spectral Energy Distribution ◽  
Quality Data ◽  
Spectral Energy ◽  
Chemical Abundances ◽  
Tidal Interactions ◽  
Depth Analysis ◽  
Red Giant ◽  
Period Decrease

Abstract Subdwarf B stars are core-helium burning stars located on the extreme horizontal branch. Extensive mass loss on the red giant branch is necessary to form them. It has been proposed that substellar companions could lead to the required mass-loss when they are engulfed in the envelope of the red giant star. J08205+0008 was the first example of a hot subdwarf star with a close, substellar companion candidate to be found. Here we perform an in-depth re-analysis of this important system with much higher quality data allowing additional analysis methods. From the higher resolution spectra obtained with ESO-VLT/XSHOOTER we derive the chemical abundances of the hot subdwarf as well as its rotational velocity. Using the Gaia parallax and a fit to the spectral energy distribution in the secondary eclipse, tight constraints to the radius of the hot subdwarf are derived. From a long-term photometric campaign we detected a significant period decrease of $-3.2(8)\cdot 10^{-12} \, \rm dd^{-1}$. This can be explained by the non-synchronised hot subdwarf star being spun up by tidal interactions forcing it to become synchronised. From the rate of period decrease we could derive the synchronisation timescale to be 4 Myr, much smaller than the lifetime on EHB. By combining all different methods we could constrain the hot subdwarf to a mass of $0.39-0.50\, \rm M_\odot$ and a radius of $R_{\rm sdB}=0.194\pm 0.008\, \rm R_\odot$, and the companion to $0.061-0.071\rm \, M_\odot$ with a radius of $R_{\rm comp}=0.092 \pm 0.005\, \rm R_\odot$, below the hydrogen burning limit. We therefore confirm that the companion is most likely a massive brown dwarf.

scholarly journals SALT3: An Improved Type Ia Supernova Model for Measuring Cosmic Distances

2021 ◽  
Vol 923 (2) ◽  
pp. 265
Author(s):  
W. D. Kenworthy ◽  
D. O. Jones ◽  
M. Dai ◽  
R. Kessler ◽  
D. Scolnic ◽  
...  
Keyword(s):  
Spectral Energy Distribution ◽  
Cosmological Parameters ◽  
Training Sample ◽  
Training Data ◽  
Optical Data ◽  
Spectral Energy ◽  
Model Framework ◽  
Type Ia ◽  
Estimation Of Uncertainties ◽  
Improved Model

Abstract A spectral-energy distribution (SED) model for Type Ia supernovae (SNe Ia) is a critical tool for measuring precise and accurate distances across a large redshift range and constraining cosmological parameters. We present an improved model framework, SALT3, which has several advantages over current models—including the leading SALT2 model (SALT2.4). While SALT3 has a similar philosophy, it differs from SALT2 by having improved estimation of uncertainties, better separation of color and light-curve stretch, and a publicly available training code. We present the application of our training method on a cross-calibrated compilation of 1083 SNe with 1207 spectra. Our compilation is 2.5× larger than the SALT2 training sample and has greatly reduced calibration uncertainties. The resulting trained SALT3.K21 model has an extended wavelength range 2000–11,000 Å (1800 Å redder) and reduced uncertainties compared to SALT2, enabling accurate use of low-z I and iz photometric bands. Including these previously discarded bands, SALT3.K21 reduces the Hubble scatter of the low-z Foundation and CfA3 samples by 15% and 10%, respectively. To check for potential systematic uncertainties, we compare distances of low (0.01 < z < 0.2) and high (0.4 < z < 0.6) redshift SNe in the training compilation, finding an insignificant 3 ± 14 mmag shift between SALT2.4 and SALT3.K21. While the SALT3.K21 model was trained on optical data, our method can be used to build a model for rest-frame NIR samples from the Roman Space Telescope. Our open-source training code, public training data, model, and documentation are available at https://saltshaker.readthedocs.io/en/latest/, and the model is integrated into the sncosmo and SNANA software packages.

scholarly journals A massive nebula around the luminous blue variable star RMC 143 revealed by ALMA

2019 ◽  
Vol 626 ◽  
pp. A126 ◽  
Author(s):  
C. Agliozzo ◽  
A. Mehner ◽  
N. M. Phillips ◽  
P. Leto ◽  
J. H. Groh ◽  
...  
Keyword(s):  
Mass Loss Rate ◽  
Large Fraction ◽  
Spectral Energy Distribution ◽  
High Mass ◽  
Spectral Energy ◽  
Star Forming ◽  
High Mass Loss ◽  
Luminous Blue Variable ◽  
30 Doradus

The luminous blue variable (LBV) RMC 143 is located in the outskirts of the 30 Doradus complex, a region rich with interstellar material and hot luminous stars. We report the 3σ sub-millimetre detection of its circumstellar nebula with ALMA. The observed morphology in the sub-millimetre is different than previously observed with HST and ATCA in the optical and centimetre wavelength regimes. The spectral energy distribution (SED) of RMC 143 suggests that two emission mechanisms contribute to the sub-mm emission: optically thin bremsstrahlung and dust. Both the extinction map and the SED are consistent with a dusty massive nebula with a dust mass of 0.055 ± 0.018 M⊙ (assuming κ850 = 1.7 cm2 g−1). To date, RMC 143 has the most dusty LBV nebula observed in the Magellanic Clouds. We have also re-examined the LBV classification of RMC 143 based on VLT/X-shooter spectra obtained in 2015/16 and a review of the publication record. The radiative transfer code CMFGEN is used to derive its fundamental stellar parameters. We find an effective temperature of ∼8500 K, luminosity of log(L/L⊙) = 5.32, and a relatively high mass-loss rate of 1.0 × 10−5 M⊙ yr−1. The luminosity is much lower than previously thought, which implies that the current stellar mass of ∼8 M⊙ is comparable to its nebular mass of ∼5.5 M⊙ (from an assumed gas-to-dust ratio of 100), suggesting that the star has lost a large fraction of its initial mass in past LBV eruptions or binary interactions. While the star may have been hotter in the past, it is currently not hot enough to ionize its circumstellar nebula. We propose that the nebula is ionized externally by the hot stars in the 30 Doradus star-forming region.

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