Determination of Planetary Nebulae angular diameters from radio continuum spectral energy distribution modelling

ABSTRACT Powerful new, high-resolution, high-sensitivity, multifrequency, wide-field radio surveys such as the Australian Square Kilometre Array Pathfinder (ASKAP) Evolutionary Map of the Universe are emerging. They will offer fresh opportunities to undertake new determinations of useful parameters for various kinds of extended astrophysical phenomena. Here, we consider specific application to angular-size determinations of Planetary Nebulae (PNe) via a new radio continuum spectral energy distribution fitting technique. We show that robust determinations of angular size can be obtained, comparable to the best optical and radio observations but with the potential for consistent application across the population. This includes unresolved and/or heavily obscured PNe that are extremely faint or even non-detectable in the optical.

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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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Timing the earliest quenching events with a robust sample of massive quiescent galaxies at 2 < z < 5

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1535 ◽

2020 ◽

Vol 496 (1) ◽

pp. 695-707 ◽

Cited By ~ 3

Author(s):

A C Carnall ◽

S Walker ◽

R J McLure ◽

J S Dunlop ◽

D J McLeod ◽

...

Keyword(s):

Energy Distribution ◽

Selection Criteria ◽

Spectral Energy Distribution ◽

Photometric Data ◽

Spectral Energy ◽

Distribution Fitting ◽

Star Forming ◽

Photometric Redshift ◽

The Times ◽

Lower Redshift

ABSTRACT We present a sample of 151 massive (M* > 1010 M⊙) quiescent galaxies at 2 < z < 5, based on a sophisticated Bayesian spectral energy distribution fitting analysis of the CANDELS UDS and GOODS-South fields. Our sample includes a robust sub-sample of 61 objects for which we confidently exclude low-redshift and star-forming solutions. We identify 10 robust objects at z > 3, of which 2 are at z > 4. We report formation redshifts, demonstrating that the oldest objects formed at z > 6; however, individual ages from our photometric data have significant uncertainties, typically ∼0.5 Gyr. We demonstrate that the UVJ colours of the quiescent population evolve with redshift at z > 3, becoming bluer and more similar to post-starburst galaxies at lower redshift. Based upon this, we construct a model for the time evolution of quiescent galaxy UVJ colours, concluding that the oldest objects are consistent with forming the bulk of their stellar mass at z ∼ 6–7 and quenching at z ∼ 5. We report spectroscopic redshifts for two of our objects at z = 3.440 and 3.396, which exhibit extremely weak Ly α emission in ultra-deep VANDELS spectra. We calculate star formation rates based on these line fluxes, finding that these galaxies are consistent with our quiescent selection criteria, provided their Ly α escape fractions are >3 and >10 per cent, respectively. We finally report that our highest redshift robust object exhibits a continuum break at λ ∼ 7000 Å in a spectrum from VUDS, consistent with our photometric redshift of $z_\mathrm{phot}=4.72^{+0.06}_{-0.04}$. If confirmed as quiescent, this object would be the highest redshift known quiescent galaxy. To obtain stronger constraints on the times of the earliest quenching events, high-SNR spectroscopy must be extended to z ≳ 3 quiescent objects.

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Spectral Energy Distribution fitting: Application to Lyα-emitting galaxies

New Astronomy Reviews ◽

10.1016/j.newar.2009.04.006 ◽

2009 ◽

Vol 53 (3) ◽

pp. 50-53 ◽

Cited By ~ 8

Author(s):

Eric Gawiser

Keyword(s):

Energy Distribution ◽

Spectral Energy Distribution ◽

Spectral Energy ◽

Distribution Fitting

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Energy Distribution of Planetary Nebulae (UV to Radio)

Symposium - International Astronomical Union ◽

10.1017/s0074180900170275 ◽

1993 ◽

Vol 155 ◽

pp. 99-108

Author(s):

C.Y. Zhang

Keyword(s):

Energy Distribution ◽

Planetary Nebula ◽

Spectral Energy Distribution ◽

Planetary Nebulae ◽

Central Star ◽

Spectral Energy ◽

Significant Progress ◽

Dust Shell ◽

The Past ◽

Entire Wavelength Range

The past decade has seen significant progress in our understanding of spectral energy distribution of planetary nebulae over the entire wavelength range from UV to radio. In this review we show the detailed breakdown of the energy budget for a planetary nebula as a system of the three components, i.e., the central star, the gaseous nebula and the dust shell. This picture of the energy distribution is further discussed in the context of planetary nebula evolution.

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Direct Measurements of Giant Star Effective Temperatures and Linear Radii: Calibration against Spectral Types and V − K Color

The Astrophysical Journal ◽

10.3847/1538-4357/ac1687 ◽

2021 ◽

Vol 922 (2) ◽

pp. 163

Author(s):

Gerard T. van Belle ◽

Kaspar von Braun ◽

David R. Ciardi ◽

Genady Pilyavsky ◽

Ryan S. Buckingham ◽

...

Keyword(s):

Effective Temperature ◽

Spectral Energy Distribution ◽

Angular Size ◽

Spectral Energy ◽

Distribution Fitting ◽

Data Set ◽

Giant Stars ◽

Direct Measurements ◽

Versus Color ◽

Two Parameters

Abstract We calculate directly determined values for effective temperature (T eff) and radius (R) for 191 giant stars based upon high-resolution angular size measurements from optical interferometry at the Palomar Testbed Interferometer. Narrow- to wideband photometry data for the giants are used to establish bolometric fluxes and luminosities through spectral energy distribution fitting, which allows for homogeneously establishing an assessment of spectral type and dereddened V 0 − K 0 color; these two parameters are used as calibration indices for establishing trends in T eff and R. Spectral types range from G0III to M7.75III, V 0 − K 0 from 1.9 to 8.5. For the V 0 − K 0 = {1.9, 6.5} range, median T eff uncertainties in the fit of effective temperature versus color are found to be less than 50 K; over this range, T eff drops from 5050 to 3225 K. Linear sizes are found to be largely constant at 11 R ⊙ from G0III to K0III, increasing linearly with subtype to 50 R ⊙ at K5III, and then further increasing linearly to 150 R ⊙ by M8III. Three examples of the utility of this data set are presented: first, a fully empirical Hertzsprung–Russell diagram is constructed and examined against stellar evolution models; second, values for stellar mass are inferred based on measures of R and literature values for log g ; finally, an improved calibration of an angular size prediction tool, based upon V and K values for a star, is presented.

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SURVEY DESIGN FOR SPECTRAL ENERGY DISTRIBUTION FITTING: A FISHER MATRIX APPROACH

The Astrophysical Journal ◽

10.1088/0004-637x/749/1/72 ◽

2012 ◽

Vol 749 (1) ◽

pp. 72 ◽

Cited By ~ 3

Author(s):

Viviana Acquaviva ◽

Eric Gawiser ◽

Steven J. Bickerton ◽

Norman A. Grogin ◽

Yicheng Guo ◽

...

Keyword(s):

Energy Distribution ◽

Survey Design ◽

Spectral Energy Distribution ◽

Spectral Energy ◽

Matrix Approach ◽

Distribution Fitting ◽

Fisher Matrix

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J-PLUS: Discovery and characterisation of ultracool dwarfs using Virtual Observatory tools

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935256 ◽

2019 ◽

Vol 627 ◽

pp. A29 ◽

Cited By ~ 1

Author(s):

E. Solano ◽

E. L. Martín ◽

J. A. Caballero ◽

C. Rodrigo ◽

R. E. Angulo ◽

...

Keyword(s):

Spectral Energy Distribution ◽

Theoretical Models ◽

Spectral Energy ◽

Physical Parameters ◽

Wide Field ◽

Virtual Observatory ◽

Distribution Fitting ◽

Data Release ◽

Ultracool Dwarfs ◽

Virtual Observatory Tools

Context. Ultracool dwarfs are objects with spectral types equal to or later than M7. Most of them have been discovered using wide-field imaging surveys. The Virtual Observatory has proven to be very useful for efficiently exploiting these astronomical resources. Aims. We aim to validate a Virtual Observatory methodology designed to discover and characterise ultracool dwarfs in the J-PLUS photometric survey. J-PLUS is a multiband survey carried out with the wide-angle T80Cam optical camera mounted on the 0.83 m telescope JAST/T80 in the Observatorio Astrofísico de Javalambre. We make use of the Internal Data Release covering 528 deg2. Methods. We complemented J-PLUS photometry with other catalogues in the optical and infrared using VOSA, a Virtual Observatory tool that estimates physical parameters from the spectral energy distribution fitting to collections of theoretical models. Objects identified as ultracool dwarfs were distinguished from background M giants and highly reddened stars using parallaxes and proper motions from Gaia DR2. Results. We identify 559 ultracool dwarfs, ranging from i = 16.2 mag to i = 22.4 mag, of which 187 are candidate ultracool dwarfs not previously reported in the literature. This represents an increase in the number of known ultracool dwarfs of about 50% in the region of the sky we studied, particularly at the faint end of our sensitivity, which is interesting as reference for future wide and deep surveys such as Euclid. Three candidates are interesting targets for exoplanet surveys because of their proximity (distances less than 40 pc). We also analysed the kinematics of ultracool dwarfs in our catalogue and found evidence that it is consistent with a Galactic thin-disc population, except for six objects that might be members of the thick disc. Conclusion. The results we obtained validate the proposed methodology, which will be used in future J-PLUS and J-PAS releases. Considering the region of the sky covered by the Internal Data Release used in this work, we estimate that 3000–3500 new ultracool dwarfs will be discovered at the end of the J-PLUS project.

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