A METHOD FOR ESTIMATING PARALLAXES OF VCBS: MODIFICATION TO HIPPARCOS PARALLAX MEASUREMENTS

We presented a method useful for estimating parallaxes of visually close binary stars (VCBS). The method depends on atmospheric modeling of the components of the VCBS. We construct model atmospheres by using a grid of Kurucz solar metalicity blanketed models1, which can be applied to calculate the synthetic spectral energy distribution for each component of the binary separately. In addition to study the entire system. However, the entire observational spectral energy distribution of the system was used as a reference for the comparison with the synthetic ones. We choose Hip4809 system to investigate the method, and we also study its physical and geometrical parameters. The new parallax of the system was estimated as π = 40.32 ± 5.00 mas, which disagrees with the Hipparcos parallax measurement (13.94 ± 0.90 mas). Furthermore the model atmosphere parameters of the components of the system were derived as: [Formula: see text], [Formula: see text], log ga = 4.50 ± 0.13, log gb = 4.50 ± 0.13, Ra = 0.94 ± 0.12R⊙, Rb = 0.93 ± 0.12R⊙, Depending on the derived parameters, the masses of the system's components were estimated as 1.03 ± 0.02M⊙ and 1.01 ± 0.02M⊙ for the primary and secondary components respectively, and their spectral types were concluded as G6V for both of them.

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The single-sided pulsator CO Camelopardalis

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa989 ◽

2020 ◽

Vol 494 (4) ◽

pp. 5118-5133 ◽

Cited By ~ 2

Author(s):

D W Kurtz ◽

G Handler ◽

S A Rappaport ◽

H Saio ◽

J Fuller ◽

...

Keyword(s):

Binary Stars ◽

Binary Star ◽

Spectral Energy Distribution ◽

Radial Velocities ◽

Close Binary ◽

Theoretical Modelling ◽

Spectral Energy ◽

Primary Star ◽

Pulsating Stars ◽

Secondary Star

ABSTRACT CO Cam (TIC 160268882) is the second ‘single-sided pulsator’ to be discovered. These are stars where one hemisphere pulsates with a significantly higher amplitude than the other side of the star. CO Cam is a binary star comprised of an Am δ Sct primary star with Teff = 7070 ± 150 K, and a spectroscopically undetected G main-sequence secondary star. The dominant pulsating side of the primary star is centred on the L1 point. We have modelled the spectral energy distribution combined with radial velocities, and independently the TESS light curve combined with radial velocities. Both of these give excellent agreement and robust system parameters for both stars. The δ Sct star is an oblique pulsator with at least four low radial overtone (probably) f modes with the pulsation axis coinciding with the tidal axis of the star, the line of apsides. Preliminary theoretical modelling indicates that the modes must produce much larger flux perturbations near the L1 point, although this is difficult to understand because the pulsating star does not come near to filling its Roche lobe. More detailed models of distorted pulsating stars should be developed. These newly discovered single-sided pulsators offer new opportunities for astrophysical inference from stars that are oblique pulsators in close binary stars.

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A radiative transfer model for the spiral galaxy M33★

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa905 ◽

2020 ◽

Vol 495 (1) ◽

pp. 835-863 ◽

Cited By ~ 1

Author(s):

Jordan J Thirlwall ◽

Cristina C Popescu ◽

Richard J Tuffs ◽

Giovanni Natale ◽

Mark Norris ◽

...

Keyword(s):

Star Formation ◽

Radiative Transfer ◽

Energy Distribution ◽

Surface Density ◽

Main Sequence ◽

Spectral Energy Distribution ◽

Radiative Transfer Model ◽

Spectral Energy ◽

Geometrical Parameters ◽

Transfer Model

ABSTRACT We present the first radiative transfer (RT) model of a non-edge-on disc galaxy in which the large-scale geometry of stars and dust is self-consistently derived through the fitting of multiwavelength imaging observations from the ultraviolet to the submm. To this end, we used the axisymmetric RT model of Popescu et al. and a new methodology for deriving geometrical parameters, and applied this to decode the spectral energy distribution (SED) of M33. We successfully account for both the spatial and spectral energy distribution, with residuals typically within $7{{\ \rm per\ cent}}$ in the profiles of surface brightness and within $8{{\ \rm per\ cent}}$ in the spatially integrated SED. We predict well the energy balance between absorption and re-emission by dust, with no need to invoke modified grain properties, and we find no submm emission that is in excess of our model predictions. We calculate that $80\pm 8{{\ \rm per\ cent}}$ of the dust heating is powered by the young stellar populations. We identify several morphological components in M33, a nuclear, an inner, a main and an outer disc, showing a monotonic trend in decreasing star formation surface density (ΣSFR) from the nuclear to the outer disc. In relation to surface density of stellar mass, the ΣSFR of these components defines a steeper relation than the ‘main sequence’ of star-forming galaxies, which we call a ‘structurally resolved main sequence’. Either environmental or stellar feedback mechanisms could explain the slope of the newly defined sequence. We find the star formation rate to be ${\rm SFR}=0.28^{+0.02}_{-0.01}{\rm M}_{\odot }{\rm yr}^{-1}$.

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Blue Stragglers from Primordial Binary Evolution

Proceedings of the International Astronomical Union ◽

10.1017/s1743921308023351 ◽

2008 ◽

Vol 4 (S252) ◽

pp. 417-418

Author(s):

Xuefei Chen ◽

Zhanwen Han

Keyword(s):

Energy Distribution ◽

Spectral Energy Distribution ◽

Close Binary ◽

Spectral Energy ◽

Population Synthesis ◽

Blue Stragglers ◽

Blue Straggler ◽

Binary Evolution

AbstractBinaries exist in all clusters and much evidence suggests that close-binary evolution makes an important contribution to the blue straggler population, at least in some clusters as well as in the field. Here we present different channels to blue stragglers from primordial binary evolution and examine their contributions to the integrated spectral energy distribution of the host clusters in theory via binary population synthesis.

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What makes a galaxy radio-loud?

Proceedings of the International Astronomical Union ◽

10.1017/s174392131200909x ◽

2011 ◽

Vol 7 (S284) ◽

pp. 221-223

Author(s):

R. A. Ortega-Minakata ◽

J. P. Torres-Papaqui ◽

H. Andernach ◽

R. Coziol ◽

J. M. Islas-Islas ◽

...

Keyword(s):

Black Holes ◽

Energy Distribution ◽

Spectral Energy Distribution ◽

Spectral Characteristics ◽

Spectral Energy ◽

Isolated Galaxies ◽

Accretion Rates ◽

The Masses ◽

Lower Luminosity ◽

Eddington Limit

AbstractWe compare the Spectral Energy Distribution (SED) of radio-loud and radio-quiet AGNs in three different samples observed with SDSS: radio-loud AGNs (RLAGNs), Low Luminosity AGNs (LLAGNs) and AGNs in isolated galaxies (IG-AGNs). All these galaxies have similar optical spectral characteristics. The median SED of the RLAGNs is consistent with the characteristic SED of quasars, while that of the LLAGNs and IG-AGNs are consistent with the SED of LINERs, with a lower luminosity in the IG-AGNs than in the LLAGNs. We infer the masses of the black holes (BHs) from the bulge masses. These increase from the IG-AGNs to the LLAGNs and are highest for the RLAGNs. All these AGNs show accretion rates near or slightly below 10% of the Eddington limit, the differences in luminosity being solely due to different BH masses. Our results suggests there are two types of AGNs, radio quiet and radio loud, differing only by the mass of their bulges or BHs.

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Exploring the UV excess in star clusters of different mass

Proceedings of the International Astronomical Union ◽

10.1017/s1743921315010686 ◽

2015 ◽

Vol 12 (S316) ◽

pp. 143-144

Author(s):

Fabiola Hernández-Pérez ◽

Gustavo Bruzual ◽

Magris C. Gladis

Keyword(s):

Energy Distribution ◽

Binary Stars ◽

Spectral Energy Distribution ◽

Star Clusters ◽

Stellar Populations ◽

Spectral Energy ◽

Stochastic Fluctuations ◽

Uv Excess ◽

The Imf

AbstractWe compute the expected spectral energy distribution of stellar populations of mass characteristic of star clusters taking into account stochastic fluctuations in the number of stars populating the IMF, and the presence of interacting binary stars in the cluster population. We evaluate under what circumstances the UV excess phenomenon is expected to appear in star clusters of different mass, and which is its most likely source: the stochastic fluctuations, the result of binary interactions, or a mixture of both.

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Complex Analysis of the Stellar Binary HD25811: A Subgiant System

Publications of the Astronomical Society of Australia ◽

10.1017/pasa.2013.42 ◽

2014 ◽

Vol 31 ◽

Cited By ~ 7

Author(s):

Mashhoor A. Al-Wardat ◽

Hatem S. Widyan ◽

Ahmed Al-thyabat

Keyword(s):

Binary System ◽

Complex Analysis ◽

Spectral Energy Distribution ◽

Close Binary System ◽

Close Binary ◽

Spectral Energy ◽

Geometrical Parameters ◽

Orbital Elements ◽

The Individual ◽

Best Fit

AbstractThe visually close binary system HD25811 is analysed to estimate its physical and geometrical parameters in addition to its spectral type and luminosity class. The method depends on obtaining the best fit between the entire observational spectral energy distribution (SED) of the system and synthetic SEDs created by atmospheric modelling of the individual components, consistent with the system's modified orbital elements. The parameters of the individual components of the system are derived as: Taeff = 6850 ± 50 K, Tbeff = 7000 ± 50 K, log ga = 4.04 ± 0.10, log gb = 4.15 ± 0.10, Ra = 1.96 ± 0.20 R⊙, Rb = 1.69 ± 0.20 R⊙, Mav = 1.m97 ± 0.20, Mbv = 2.m19 ± 0.20, La = 7.59 ± 0.70L⊙, Lb = 6.16 ± 0.70L⊙ with dynamical parallax $\pi (\textrm {mas})=5.095\pm 0.095$. The analysis shows that the system consists of a 1.55M⊙ F2 subgiant star and a less evolved 1.50M⊙ F1 secondary subgiant star with ages around 2 Gy formed by fragmentation. Synthetic magnitudes of both components were calculated under Johnson-Cousins, Strömgren, and Tycho photometrical systems.

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Modelling the Spectral Energy Distribution of Star-Forming Galaxies with Radiative Transfer Methods

Star-Formation Rates of Galaxies ◽

10.1017/9781316875445.012 ◽

2021 ◽

pp. 204-224

Author(s):

Cristina Popescu

Keyword(s):

Radiative Transfer ◽

Energy Distribution ◽

Spectral Energy Distribution ◽

Spectral Energy ◽

Star Forming

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Influence of Microlensing on Spectral Anomalies of the Lensed Objects

Open Astronomy ◽

10.1515/astro-2017-0324 ◽

2011 ◽

Vol 20 (3) ◽

Author(s):

S. Simić ◽

L. Č. Popović ◽

P. Jovanović

Keyword(s):

Energy Distribution ◽

Spectral Energy Distribution ◽

Angular Size ◽

Black Body ◽

Spectral Energy

AbstractHere we consider the influence of microlensing on the spectrum of a lensed object with the angular size 5 μas accepting that the composite emission of this object originates from three different regions arranged around its center. We assume that the lensed object has three concentric regions with a black-body emission; the temperatures of these regions are 10 000 K, 7500 K and 5000 K. We investigate how the integral spectral energy distribution (SED) of such stratified source changes due to microlensing by a group of solarmass stars. We find that the SED and flux ratios in the photometric B, V and R passbands show considerable changes during a microlens event. This indicates that the flux anomaly observed in some lensed quasars may be caused by microlensing of a stratified object.

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