scholarly journals Population III microquasars

2018 ◽  
Vol 27 (10) ◽  
pp. 1844019 ◽  
Author(s):  
Gustavo E. Romero ◽  
P. Sotomayor Checa
Keyword(s):  
Mass Loss ◽  
Spectral Energy Distribution ◽  
Compact Object ◽  
Spectral Energy ◽  
Stellar Winds ◽  
Object A ◽  
First Results ◽  
Intense Mass ◽  
Hadronic Model ◽  
Population Iii

We present the first results obtained in the elaboration of a complete model of a microquasar where the donor star is from Population III. These stars do not produce stellar winds so we consider that the mass loss is due exclusively to matter overflowing the Roche lobe towards the compact object, a maximally rotating black hole. The rate of accretion is extremely super-Eddington, with an intense mass loss from the system in the form of winds and jets. We calculate the relativistic particle content of the jet and the corresponding spectral energy distribution (SED) considering a lepto-hadronic model. Prospects for the cosmological implications of these objects are briefly discussed.

scholarly journals Model for Population III microquasars

2019 ◽  
Vol 629 ◽  
pp. A76
Author(s):  
P. Sotomayor Checa ◽  
G. E. Romero
Keyword(s):  
Binary Systems ◽  
Intergalactic Medium ◽  
Spectral Energy Distribution ◽  
Spectral Energy ◽  
First Stars ◽  
Nonthermal Emission ◽  
Concrete Model ◽  
Relativistic Particles ◽  
Hadronic Model ◽  
Population Iii

Context. Current simulations indicate that the first stars were formed predominantly in binary systems. Studying the contribution of the first accreting binary systems to the reionization and heating of the intergalactic medium requires formulating a concrete model for Population III microquasars. Aims. We aim at constructing a complete model for microquasars with a Population III donor star. Methods. We considered that the mass loss of the star is exclusively caused by the spill of matter through the Roche lobe toward the black hole. We calculated the spectral energy distribution of the radiation produced by the accretion disk, the radiation-pressure-driven wind, and the relativistic particles in the jets, within the framework of a lepto-hadronic model. In addition, we estimated the effect on the reionization by the first microquasars. Results. We determine that Population III microquasars are powerful sources of ultraviolet radiation produced by the winds of their super-critical disks, and that they generate a broadband nonthermal emission in jets. Conclusions. Our results indicate that microquasars in the early Universe could have been important for the reionization and heating of the intergalactic medium.

scholarly journals CCD photometry and spectroscopy of 14 IRAS sources having far-IR colours similar to Planetary Nebulae

1997 ◽  
Vol 180 ◽  
pp. 365-365
Author(s):  
B. E. Reddy ◽  
M. Parthasarathy
Keyword(s):  
Spectral Energy Distribution ◽  
Planetary Nebulae ◽  
Spectral Energy ◽  
Galactic Latitude ◽  
Ccd Photometry ◽  
Ccd Imaging ◽  
Evolved Stars ◽  
Molecular Features ◽  
Intense Mass ◽  
Low Mass

CCD imaging and BVRI photometry of 14 IRAS sources with far-IR colours similar to planetary nebulae and post-AGB stars are presented. Also results of optical and near-IR spectroscopy of 10 of these candidates are given. Based on the spectral energy distribution from 0.4 μm to 100 μm, the sample of program stars are put into two groups. The sources IRAS 08187-1905, IRAS 05238-0626 and IRAS 17086-2403 present similar flux distributions. These three sources have detached cold dust components with dust radii Rd ≈ 1000 R∗. The low infrared variability of theses sources suggests that the intense mass loss has been ceased. All three sources are at high galactic latitude (1>9°) suggesting that these are old low-mass evolved stars. In the IRAS colour-colour diagram of Likkel et al (1991) these sources fall in the region where most of the stars are evolved stars and PNe but without CO detection. This is consistent with at least one source IRAS 17086-2403, in which OH and CO molecular features are not detected. The far-IR excess, non-variability and high latitude of these objects suggest that these are post-AGB supergiants, slowly evolving towards planetary nebula phase.

scholarly journals The influence of mass loss on the evolution of binaries

1981 ◽  
Vol 59 ◽  
pp. 405-430 ◽  
Author(s):  
C. de Loore
Keyword(s):  
Neutron Star ◽  
Mass Loss ◽  
Massive Stars ◽  
Compact Object ◽  
Supernova Explosion ◽  
Sequence Evolution ◽  
Chemical Abundances ◽  
Low Mass Stars ◽  
Object A ◽  
The Masses

Mass loss can affect the evolution of binaries in various ways, during different stages of the evolution.1. For massive stars stellar wind mass loss will change the masses of the components during their main sequence evolution.2. During the Roche lobe overflow phase (or tidal interaction phase) matter can leave the system.3. For low mass stars matter can leave the system during the mass exchange phase and can be stored in envelopes, disks or rings.4. Sufficiently massive stars(>8-15M0) undergo at the end of their life a supernova explosion, where most of the matter is blown away and a compact object, a neutron star or a black hole can be left.5. For intermediate stars one of the components can evolve into a degenerate He or CO dwarf; a reverse mass transfer can dump matter on this degenerate dwarf. If the conditions are favorable the white dwarf can explode with loss of matter, and a neutron star can be the result.6. The chemical abundances in the outer layers change.

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.

STUDY OF THE OBJECT HD 87643

2012 ◽  
Vol 18 ◽  
pp. 53-57
Author(s):  
EDUARDO LENHO COELHO ◽  
DALTON DE FARIA LOPES
Keyword(s):  
Energy Distribution ◽  
Mass Loss ◽  
Transfer Equation ◽  
Spectral Energy Distribution ◽  
Astronomical Observatory ◽  
Spectral Energy ◽  
Spherically Symmetric ◽  
Balmer Series ◽  
Exact Integration ◽  
Different Time Scales

HD 87643 is one of the B[e] stars that still defy our understanding to better classify it. The spectroscopic observations of HD 87643 performed in the Astronomical Observatory of La Silla (ESO) between December 1998 and April 2000 show an object far more complex than was already known, with profiles of the Balmer series showing variability on different time scales. This work examine the formation of Hα and Hβ profiles with the SEI method (Sobolev approximation with Exact Integration of the transfer equation), as well as their spectral energy distribution by means of codes Cloudy and Dusty. For a homogeneous and spherically symmetric nebula around a star with T ef ~ 15, 000 K and log L/L⊙ > 4.2, the reproduction of the profiles mentioned was only achieved for Hβ and to some extent, considering two distinct regions with different laws for the expansion of the wind and with different rates of mass loss.

scholarly journals Collimated radiation in SS 433

2019 ◽  
Vol 624 ◽  
pp. A127 ◽  
Author(s):  
Idel Waisberg ◽  
Jason Dexter ◽  
Pierre Olivier-Petrucci ◽  
Guillaume Dubus ◽  
Karine Perraut
Keyword(s):  
Spectral Synthesis ◽  
Spectral Energy Distribution ◽  
Compact Object ◽  
Spectral Energy ◽  
X Ray ◽  
Ss 433 ◽  
Heating Mechanism ◽  
Ionization Balance ◽  
First Time ◽  
Optical Bullets

Context. The microquasar SS 433 is well known for its precessing, relativistic, and highly collimated baryonic jets, which manifest in its optical spectrum as pairs of hydrogen and helium emission lines moving with large Doppler shifts. Depending on their heating mechanism, the optical jet bullets may serve as a probe of the collimated radiation coming from the inner region close to the compact object, and which is not directly visible to observers on Earth. Aims. We aim to better understand the baryonic jet phenomenon in SS 433, in particular the properties of the optical bullets and their interaction with the ionizing collimated radiation. Methods. The optical interferometer VLTI/GRAVITY has allowed us to spatially resolve the optical jets in SS 433 for the first time. We present here the second such observation taken over three nights in July 2017. In addition, we used the X-shooter spectrograph at VLT to study the optical bullets in SS 433 in detail. Over the full wavelength range 0.3−2.5 μm, we identified up to twenty pairs of jet lines observed simultaneously, which we modeled with the spectral synthesis code Cloudy. Results. GRAVITY reveals elongated exponential-like radial spatial profiles for the optical jets on scales ≲1−10 mas, suggestive of a heating mechanism acting throughout a long portion of the jet and naturally explained by photoionization by the collimated radiation. We also spatially resolve the movement of the optical bullets for the first time, detecting more extended jet components corresponding to previous ejections. Cloudy photoionization models can explain the spatial intensity profiles measured with GRAVITY and the emission line ratios from X-shooter, and constrain the properties of the optical bullets and the ionizing radiation. We find that the latter must peak in the UV with an isotropic luminosity (as inferred by a face-on observer) ∼1041 erg s−1. Provided that the X-ray spectral energy distribution is sufficiently hard, the collimated X-ray luminosity could still be high enough so that the face-on observer would see SS 433 as ultraluminous X-ray source and it would still be compatible with the H/He/He+ ionization balance of the optical bullets. The kinetic power in the optical jets is constrained to 2−20 × 1038 erg s−1, and the extinction in the optical jets to AV = 6.7 ± 0.1. We suggest there may be substantial AV ≳ 1 and structured circumstellar extinction in SS 433, likely arising from dust formed in equatorial outflows.

scholarly journals Identification of a new ultraluminous X-ray source in NGC 1316

2020 ◽  
Vol 499 (4) ◽  
pp. 5682-5689
Author(s):  
S Allak ◽  
A Akyuz ◽  
N Aksaker ◽  
M Ozdogan Ela ◽  
S Avdan ◽  
...  
Keyword(s):  
Hubble Space Telescope ◽  
Spectral Energy Distribution ◽  
Compact Object ◽  
Optical Emission ◽  
Absolute Magnitude ◽  
Spectral Energy ◽  
Model Parameters ◽  
Wide Field ◽  
X Ray ◽  
Blackbody Model

ABSTRACT In this study, we report identification of a new ultraluminous X-ray source (ULX) named as X-7 in NGC 1316, with an unabsorbed luminosity of 2.1 × 1039 erg s−1 using the two recent Chandra archival observations. The X-7 was detected in the Chandra 2001 observation and was included in the source list of the NGC 1316 as CXOUJ032240.8−371224 with a luminosity of 5.7 × 1038 erg s−1. Present luminosity implies a luminosity increase of a factor of ∼4. The best-fitting spectral model parameters indicate that X-7 has a relatively hot disc and hard spectra. If explained by a disc blackbody model, the mass of compact object is estimated as ∼8 M⊙ which is in the range of a stellar-mass black hole. The X-7 shows a relatively long-term count rate variability while no short-term variability is observed. We also identified a unique optical candidate within 0.22 arcsec error circle at 95 per cent confidence level for X-7 using the archival HST/ACS (Hubble Space Telescope/Advanced Camera for Surveys) and HST/WFC3 (The Wide Field Camera 3) data. Absolute magnitude (MV) of this candidate is −7.8 mag. Its spectral energy distribution is adequately fitted a blackbody model with a temperature of 3100 K indicating an M type supergiant, assuming the donor star dominates the optical emission. In addition, we identified a transient ULX candidate (XT-1) located 6 arcsec away from X-7 has a (high) luminosity of ∼1039 erg s−1 with no visible optical candidate.

scholarly journals Integrated photometric redshifts and SED fitting as tool for galaxy evolution studies

2012 ◽  
Vol 8 (S289) ◽  
pp. 292-295
Author(s):  
Ralf Kotulla
Keyword(s):  
Energy Distribution ◽  
Galaxy Evolution ◽  
High Redshift ◽  
Spectral Energy Distribution ◽  
Spectral Energy ◽  
Photometric Redshifts ◽  
First Results ◽  
The Common ◽  
High Redshift Universe ◽  
Fixed Input

AbstractPhotometric redshifts, i.e. redshifts derived by comparing an observed spectral-energy distribution (SED) to a range of empirical or theoretical SED templates, are commonly used in studies of the high-redshift Universe. Often, the next step is to use these redshifts as fixed input parameters for SED fitting to derive physical properties for each galaxy. However, this two-step approach ignores degeneracies between redshift and, e.g., stellar mass. Here I present first results using an improved approach that integrates both methods. I find that mass determinations are, on average, three times more uncertain than they seem from the common two-step approach. If not accounted for, these underestimated uncertainties can impact our ability of making meaningful comparisons between observations and simulations of galaxy evolution.

scholarly journals The spectral energy distribution and mass-loss history of IRC + 10420

1996 ◽  
Vol 280 (4) ◽  
pp. 1062-1070 ◽  
Author(s):  
René D. Oudmaijer ◽  
M. A. T. Groenewegen ◽  
H. E. Matthews ◽  
J. A. D. L. Blommaert ◽  
K. C. Sahu
Keyword(s):  
Energy Distribution ◽  
Mass Loss ◽  
Spectral Energy Distribution ◽  
Spectral Energy ◽  
History Of

scholarly journals The changing-type SN 2014C may come from an 11-M⊙ star stripped by binary interaction and violent eruption

2020 ◽  
Vol 497 (4) ◽  
pp. 5118-5135 ◽  
Author(s):  
Ning-Chen Sun ◽  
Justyn R Maund ◽  
Paul A Crowther
Keyword(s):  
Mass Loss ◽  
Hubble Space Telescope ◽  
Spectral Energy Distribution ◽  
Binary Interaction ◽  
Spectral Energy ◽  
Extended Component ◽  
Dense Shell ◽  
Helium Star ◽  
Cluster Age ◽  
Luminous Blue Variable

ABSTRACT SN 2014C was an unprecedented supernova (SN) that displayed a metamorphosis from Type Ib to Type IIn over ∼200 d. This transformation is consistent with a helium star having exploded in a cavity surrounded by a dense shell of the progenitor’s stripped hydrogen envelope. For at least 5 yr post-explosion, the ejecta continued to interact with an outer, extended component of circumstellar medium (CSM) that was ejected even before the dense shell. It is still unclear, however, what kind of progenitor could have undergone such a complicated mass-loss history before it produced this peculiar SN. In this paper, we report a new analysis of SN 2014C’s host star cluster based on data from the Hubble Space Telescope (HST). By carefully fitting its spectral energy distribution (SED), we derive a precise cluster age of 20.0$^{+3.5}_{-2.6}$ Myr, which corresponds to the progenitor’s lifetime assuming coevolution. Combined with binary stellar evolution models, we find that SN 2014C’s progenitor may have been an ∼11-M⊙ star in a relatively wide binary system. The progenitor’s envelope was partially stripped by Case C or Case BC mass transfer via binary interaction, followed by a violent eruption that ejected the last hydrogen layer before terminal explosion. Thus, SN 2014C, in common with SNe 2006jc and 2015G, may be a third example that violent eruptions, with mass-loss rates matching luminous blue variable (LBV) giant eruptions, can also occur in much lower mass massive stars if their envelopes are partially or completely stripped in interacting binaries.

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