scholarly journals Small Galactic Nebulae

1987 ◽  
Vol 115 ◽  
pp. 191-192
Author(s):  
Yervant Terzian ◽  
Kenneth C. Turner
Keyword(s):  
High Resolution ◽  
Planetary Nebula ◽  
Physical Parameters ◽  
H Ii Regions ◽  
Radio Observations ◽  
Cluster Emission ◽  
Active Star ◽  
Star Forming ◽  
Cometary Nebula ◽  
Significant Flux

We have performed high resolution VLA radio observations for several small H II regions, including the cluster emission nebulae S258, S255, S257, and S256. The region (PP56) between S255 and S257 at λ2 cm reveals significant flux structure close to OH, H2O and infrared emitting sources as shown in Figure 1. The flux densities and positions are indicated in Table 1. Observations of the cometary nebula PP59 (S269) also reveal similar characteristics as shown in Figure 2. These regions are considered to be active star-forming clouds. The cometary nebula PP40 was also observed and we note that its physical parameters are very similar to those of a typical planetary nebula.

scholarly journals Stellar populations and physical properties of starbursts in the antennae galaxy from self-consistent modelling of MUSE spectra

2020 ◽  
Vol 497 (3) ◽  
pp. 3860-3895
Author(s):  
M L P Gunawardhana ◽  
J Brinchmann ◽  
P M Weilbacher ◽  
P Norberg ◽  
A Monreal-Ibero ◽  
...  
Keyword(s):  
High Resolution ◽  
Emission Line ◽  
Stellar Populations ◽  
Continuum Emission ◽  
H Ii Regions ◽  
Full Spectrum ◽  
Star Forming ◽  
Self Consistent ◽  
Spectrum Fitting ◽  
Overlap Region

ABSTRACT We have modelled the stellar and nebular continua and emission-line intensity ratios of massive stellar populations in the Antennae galaxy using high resolution and self-consistent libraries of model H ii regions around central clusters of ageing stars. The model libraries are constructed using the stellar population synthesis code, starburst99, and photoionization model, and cloudy. The Geneva and PARSEC stellar evolutionary models are plugged into starburst99 to allow comparison between the two models. Using a spectrum-fitting methodology that allows the spectral features in the stellar and nebular continua [e.g. Wolf–Rayet (WR) features, Paschen jump], and emission-line diagnostics to constrain the models, we apply the libraries to the high-resolution Multi-Unit Spectroscopic Explorer spectra of the starbursting regions in the Antennae galaxy. Through this approach, we were able to model the continuum emission from WR stars and extract stellar and gas metallicities, ages, electron temperatures, and densities of starbursts by exploiting the full spectrum. From the application to the Antennae galaxy, we find that (1) the starbursts in the Antennae galaxy are characterized by stellar and gas metallicities of around solar, (2) the star-forming gas in starbursts in the Western loop of NGC 4038 appears to be more enriched, albeit slightly, than the rest of galaxy, (3) the youngest starbursts are found across the overlap region and over parts of the western-loop, though in comparison, the regions in the western-loop appear to be at a slightly later stage in star formation than the overlap region, and (4) the results obtained from fitting the Geneva and Parsec models are largely consistent.

scholarly journals Distances to PHANGS Galaxies: New Tip of the Red Giant Branch Measurements and Adopted Distances

2020 ◽  
Author(s):  
Gagandeep S Anand ◽  
Janice C Lee ◽  
Schuyler D Van Dyk ◽  
Adam K Leroy ◽  
Erik Rosolowsky ◽  
...  
Keyword(s):  
First Year ◽  
Physical Parameters ◽  
H Ii Regions ◽  
Star Clusters And Associations ◽  
Distance Measurements ◽  
Nearby Star ◽  
Star Forming ◽  
Public Data ◽  
The Galaxy ◽  
Red Giant

Abstract PHANGS-HST is an ultraviolet-optical imaging survey of 38 spiral galaxies within ∼20 Mpc. Combined with the PHANGS-ALMA, PHANGS-MUSE surveys and other multiwavelength data, the dataset will provide an unprecedented look into the connections between young stars, H ii regions, and cold molecular gas in these nearby star-forming galaxies. Accurate distances are needed to transform measured observables into physical parameters (e.g., brightness to luminosity, angular to physical sizes of molecular clouds, star clusters and associations). PHANGS-HST has obtained parallel ACS imaging of the galaxy halos in the F606W and F814W bands. Where possible, we use these parallel fields to derive tip of the red giant branch (TRGB) distances to these galaxies. In this paper, we present TRGB distances for 11 galaxies from ∼4 to ∼15 Mpc, based on the first year of PHANGS-HST observations. Five of these represent the first published TRGB distance measurements (IC 5332, NGC 2835, NGC 4298, NGC 4321, and NGC 4328), and eight of which are the best available distances to these targets. We also provide a compilation of distances for the 118 galaxies in the full PHANGS sample, which have been adopted for the first PHANGS-ALMA public data release.

scholarly journals High-resolution spectroscopic study of the planetary nebula Abell 78

1999 ◽  
Vol 193 ◽  
pp. 374-375
Author(s):  
Selene Medina ◽  
Miriam Peña
Keyword(s):  
Chemical Composition ◽  
High Resolution ◽  
Spectroscopic Study ◽  
Spectral Resolution ◽  
Planetary Nebula ◽  
Planetary Nebulae ◽  
Central Star ◽  
Heavy Elements ◽  
Physical Parameters ◽  
Processed Material

High resolution optical spectra of the planetary nebula Abell 78 were gathered, covering the wavelength ranges 3500–6600 Å and 3358–7361 Å, with a spectral resolution of ∼0.1 Å. Two different regions of Abell 78 are analyzed: the strongest knot near the central star which is thought to be a mass-loaded wind from the central star, and the outer, hydrogen-rich envelope. Physical parameters and chemical composition of both regions are estimated. The inner knot appears to be cooler and denser than the hydrogen-rich envelope. The chemical composition of the inner knot shows that there is almost no hydrogen near the central star and the emission is dominated by helium and processed material which has been dredged-up from the inner layers of the star. The outer, hydrogen-rich envelope appears to be deficient in heavy elements, mainly in oxygen, compared to the average abundances that are found among galactic planetary nebulae.

scholarly journals The morpho-kinematical structure and chemical abundances of the complex planetary nebula NGC 1514

2021 ◽  
Author(s):  
A Aller ◽  
R Vázquez ◽  
L Olguín ◽  
L F Miranda ◽  
M Ressler
Keyword(s):  
High Resolution ◽  
Planetary Nebula ◽  
Current Data ◽  
Time Sequence ◽  
Emission Lines ◽  
Physical Parameters ◽  
Chemical Abundances ◽  
Mid Infrared ◽  
Kinematical Analysis ◽  
Multiple Structures

Abstract We present high-resolution, long-slit optical spectra and images of the planetary nebula NGC 1514. The position velocity maps of the [O iii] emission line reveal complex kinematics with multiple structures. A morpho-kinematical analysis suggests an inner shell, originally spherical and now distorted by several bubbles, and an attached outer shell. The two well-defined, mid-infrared rings of NGC 1514 are not detected in our high-resolution, long-slit spectra, which prevented us from doing a kinematical analysis of them. Based exclusively on their morphology, we propose a barrel-like structure to explain the rings. Several ejection processes have been possibly involved in the formation of the nebula although a time sequence is difficult to establish with the current data. We also analyse intermediate-resolution, long-slit spectra with the goal of studying the physical parameters and chemical abundances of NGC 1514. The nebular spectra reveal a moderate-excitation nebula with weak emission lines of [Ar iii], [Ne iii], He i and He ii. No [N ii] neither other low-excitation emission lines are detected. We found an electron temperature around 14000 K in the gas and an electron density in the range of 2000 and 4000 cm−3.

scholarly journals New Infrared Observations of NGC 3603

1987 ◽  
Vol 115 ◽  
pp. 182-184 ◽  
Author(s):  
M. Roth ◽  
M. Tapia ◽  
M. T. Ruiz ◽  
P. Persi ◽  
M. Ferrari-Toniolo
Keyword(s):  
High Resolution ◽  
Spectral Distribution ◽  
Massive Star ◽  
Near Infrared ◽  
H Ii Regions ◽  
Infrared Observations ◽  
Star Forming ◽  
Photometric Observations ◽  
H Ii Region ◽  
Spectral Distributions

NGC 3603, one of the most massive H II regions in our galaxy, shows recent star forming activity (Frogel et al. 1977; Tapia 1981; Persi et al., 1985). In this paper we report new near-infrared maps and photometric observations in the complex region surrounding Irs 9, Irs 2 and Irs 8. Most data were gathered at the 1.5-m telescope of CTIO, using an InSb photometer. Tables 1 and 2 synthesize the observations and the results of the photometry. While the low resolution K map (Figure 1) shows basically the previously reported features, the high resolution K and L maps (shown superimposed in Figure 2), show that Irs 9 is the brightest source in the field, clearly resolved from Irs 2 and Irs 8. The presence of a previously unreported source some 22″N and 5″W of Irs 2, should be further investigated. The spectral distributions derived from our measurements and from previous ones by Persi et al. (1985) strongly suggest that the 10 and 20 μm fluxes reported by Frogel et al. (1977) at the position of Irs 2, probably correspond to Irs 9. Under this assumption, Irs 9 is probably a highly reddened massive star (1 μm to 20 μm luminosity, L∗ = 2.2 × 104 L⊙) while the luminosity of Irs 2 is less than 102 L⊙. We therefore conclude that Irs 9 is a young massive star surrounded by a warm (Tdust ∼ 250 K) dust envelope; Irs 2 seems to be the less obscured part of an associated H II region, as further corroborated by the Brγ emission and the free-free like spectrum and spectral distribution, as reported by Persi et al. (1985) and in this paper.

High‐Resolution X‐Ray Image of the Hydrogen‐deficient Planetary Nebula Abell 30

1997 ◽  
Vol 482 (2) ◽  
pp. 891-896 ◽  
Author(s):  
You‐Hua Chu ◽  
Thomas H. Chang ◽  
Gail M. Conway
Keyword(s):  
High Resolution ◽  
Planetary Nebula ◽  
X Ray

Twin stars as tracers of binary evolution in the Kepler era

2021 ◽  
Author(s):  
Sara Bulut ◽  
Baris Hoyman ◽  
Ahmet Dervisoglu ◽  
Orkun Özdarcan ◽  
Ömür Cakilrli
Keyword(s):  
High Resolution ◽  
Internal Structure ◽  
Spectroscopic Analysis ◽  
Independent Method ◽  
Eclipsing Binaries ◽  
Physical Parameters ◽  
Evolutionary Status ◽  
Mass Ratio ◽  
Orbital Parameters ◽  
Binary Evolution

Abstract We present results of the combined photometric and spectroscopic analysis of four systems, which are eclipsing binaries with a twin–component (mass ratio q ≃ 1). These are exceptional tools to provide information for probing the internal structure of stars. None of the systems were previously recognized as twin binaries. We used a number of high–resolution optical spectra to calculate the radial velocities and later combined them with photometry to derive orbital parameters. Temperatures and metallicities of systems were estimated from high-resolution spectra. For each binary, we obtained a full set of orbital and physical parameters, reaching precision below 3 per cent in masses and radii for whole pairs. By comparing our results with PARSEC and MIST isochrones, we assess the distance, age and evolutionary status of the researched objects. The primary and/or secondary stars of EPIC 216075815 and EPIC 202843107 are one of the cases where asteroseismic parameters of δ Sct and γ Dor pulsators were confirmed by an independent method and rare examples of the twin–eclipsing binaries, therefore the following analyses and results concern the pulsating nature of the components.

scholarly journals Modelling H2 and its effects on star formation using a joint implementation of gadget-3 and KROME

2021 ◽  
Vol 504 (2) ◽  
pp. 2325-2345
Author(s):  
Emanuel Sillero ◽  
Patricia B Tissera ◽  
Diego G Lambas ◽  
Stefano Bovino ◽  
Dominik R Schleicher ◽  
...  
Keyword(s):  
Star Formation ◽  
Formation Rate ◽  
Physical Parameters ◽  
Density Profiles ◽  
Star Forming ◽  
Chemical Enrichment ◽  
Numerical Resolution ◽  
Stellar Radiation ◽  
Wide Range ◽  
The Impact

ABSTRACT We present p-gadget3-k, an updated version of gadget-3, that incorporates the chemistry package krome. p-gadget3-k follows the hydrodynamical and chemical evolution of cosmic structures, incorporating the chemistry and cooling of H2 and metal cooling in non-equilibrium. We performed different runs of the same ICs to assess the impact of various physical parameters and prescriptions, namely gas metallicity, molecular hydrogen formation on dust, star formation recipes including or not H2 dependence, and the effects of numerical resolution. We find that the characteristics of the simulated systems, both globally and at kpc-scales, are in good agreement with several observable properties of molecular gas in star-forming galaxies. The surface density profiles of star formation rate (SFR) and H2 are found to vary with the clumping factor and resolution. In agreement with previous results, the chemical enrichment of the gas component is found to be a key ingredient to model the formation and distribution of H2 as a function of gas density and temperature. A star formation algorithm that takes into account the H2 fraction together with a treatment for the local stellar radiation field improves the agreement with observed H2 abundances over a wide range of gas densities and with the molecular Kennicutt–Schmidt law, implying a more realistic modelling of the star formation process.

scholarly journals Variability of young stellar objects in the star-forming region Pelican Nebula

2019 ◽  
Vol 627 ◽  
pp. A135 ◽  
Author(s):  
A. Bhardwaj ◽  
N. Panwar ◽  
G. J. Herczeg ◽  
W. P. Chen ◽  
H. P. Singh
Keyword(s):  
Main Sequence ◽  
T Tauri Stars ◽  
Young Stellar Objects ◽  
Spectral Energy ◽  
Physical Parameters ◽  
Main Sequence Stars ◽  
Stellar Objects ◽  
Star Forming ◽  
T Tauri ◽  
Optical Wavelengths

Context. Pre-main-sequence variability characteristics can be used to probe the physical processes leading to the formation and initial evolution of both stars and planets. Aims. The photometric variability of pre-main-sequence stars is studied at optical wavelengths to explore star–disk interactions, accretion, spots, and other physical mechanisms associated with young stellar objects. Methods. We observed a field of 16′ × 16′ in the star-forming region Pelican Nebula (IC 5070) at BVRI wavelengths for 90 nights spread over one year in 2012−2013. More than 250 epochs in the VRI bands are used to identify and classify variables up to V ∼ 21 mag. Their physical association with the cluster IC 5070 is established based on the parallaxes and proper motions from the Gaia second data release (DR2). Multiwavelength photometric data are used to estimate physical parameters based on the isochrone fitting and spectral energy distributions. Results. We present a catalog of optical time-series photometry with periods, mean magnitudes, and classifications for 95 variable stars including 67 pre-main-sequence variables towards star-forming region IC 5070. The pre-main-sequence variables are further classified as candidate classical T Tauri and weak-line T Tauri stars based on their light curve variations and the locations on the color-color and color-magnitude diagrams using optical and infrared data together with Gaia DR2 astrometry. Classical T Tauri stars display variability amplitudes up to three times the maximum fluctuation in disk-free weak-line T Tauri stars, which show strong periodic variations. Short-term variability is missed in our photometry within single nights. Several classical T Tauri stars display long-lasting (≥10 days) single or multiple fading and brightening events of up to two magnitudes at optical wavelengths. The typical mass and age of the pre-main-sequence variables from the isochrone fitting and spectral energy distributions are estimated to be ≤1 M⊙ and ∼2 Myr, respectively. We do not find any correlation between the optical amplitudes or periods with the physical parameters (mass and age) of pre-main-sequence stars. Conclusions. The low-mass pre-main-sequence stars in the Pelican Nebula region display distinct variability and color trends and nearly 30% of the variables exhibit strong periodic signatures attributed to cold spot modulations. In the case of accretion bursts and extinction events, the average amplitudes are larger than one magnitude at optical wavelengths. These optical magnitude fluctuations are stable on a timescale of one year.

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