Physical parameters of reflection nebulae in the galaxy

AbstractWe are reporting some recent results from our long-term program aimed at characterizing the obscured present-day star cluster population in the Galaxy. Our goal is to expand the current census of the Milky Way's inner stellar disk to guide models seeking to understand the structure and recent star-formation history of our Galaxy. The immediate goal is to derive accurate cluster physical parameters using precise infrared photometry and spectroscopy. So far, we observed approximately 60 star cluster candidates selected from different infrared catalogs. Their nature, reddening, distance, age and mass are analyzed. Two of them, Mercer 3 and Mercer 5, are new obscured Milky Way globular clusters. Among the newly identified open clusters, the objects [DBS2003] 179, Mercer 23, Mercer 30, Mercer 70, and [DBS2003] 106 are particularly interesting because they contain massive young OB and Wolf–Rayet stars with strong emission lines.

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Pulsations of Ob-Stars: New Observations

Symposium - International Astronomical Union ◽

10.1017/s0074180900238928 ◽

1998 ◽

Vol 185 ◽

pp. 347-354 ◽

Cited By ~ 1

Author(s):

Dietrich Baade

Keyword(s):

Main Sequence ◽

Physical Parameters ◽

Be Stars ◽

Instability Strip ◽

Ob Stars ◽

Analysis Strategies ◽

The Galaxy ◽

Order Line ◽

Nonradial Pulsation ◽

Radial Pulsations

Improved observing and data analysis strategies have initiated a considerable expansion of the empirical knowledge about the pulsations of OB stars. Possible correlations between physical parameters and associated pulsation characteristics are becoming more clearly perceivable. This starts to include the asteroseismologically fundamental areas of g-modes and rapid rotation. The β Cephei instability strip continues to be the only locus where radial pulsations occur (but apparently not in all stars located in that strip). Except for spectral types B8/B9 near the main sequence, where pulsations are hardly detected even at low amplitudes, any major group of stars in the Galaxy that are obviously not candidate pulsators still remains to be identified. However, the incidence and amplitudes of OB star pulsations decrease steeply with metallicity. The behaviour of high-luminosity stars is less often dominated by very few modes. In broad-lined stars the moving-bump phenomenon is more common than low-order line-profile variability. But its relation to nonradial pulsation is not clear. The beating of low-ℓ nonradial pulsation modes that have identical angular mode indices may be the clockwork of the outbursts of at least some Be stars. The physics of this episodic mass loss process remains to be identified.

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The Twin-Nucleus Merging Galaxy MKN 266

Symposium - International Astronomical Union ◽

10.1017/s0074180900141610 ◽

1989 ◽

Vol 134 ◽

pp. 452-453

Author(s):

J.B. Hutchings ◽

S.G. Neff ◽

J.H. van Gorkom

Keyword(s):

Optical Emission ◽

Physical Parameters ◽

List Type ◽

Imaging Data ◽

Ccd Imaging ◽

Spatially Resolved ◽

The Galaxy ◽

Extended Complex ◽

Double Nucleus ◽

Narrow Bands

We present results of observations of the double-nucleus galaxy Markarian 266 (NGC 5256) from 3 principal sources. These are 1:CCD imaging with the Canada-France-Hawaii telescope in broad and narrow bands. These indicate that the galaxy has extended, complex, faint outer plumes which indicate that a recent merger has occurred. The narrow-band images reveal remarkable knotty structure of the [O III] emitting gas, extending over the whole central part of the galaxy. This is not seen in Hα (see figure 1).2:21cm imaging with the VLA, covering velocity space near that of the optical nuclei. The continuum image reveals resolved triple structure, with the two outer peaks coincident with the optical nuclei. The 21cm velocity profiles indicate the presence of considerable H I absorption near the optical emission line velocities.3:Spatially resolved optical spectroscopy with the DAO 1.8m telescope. These data reveal the details of the [O III] velocity field and some of the physical parameters of the gas. The complexity and extended nature of the gas explains some conflicting redshift measurements in the literature. Together with the imaging data, we derive estimates of nuclear reddening and luminosity.

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Finding and characterising WHIM structures using the luminosity density method

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316010188 ◽

2014 ◽

Vol 11 (S308) ◽

pp. 368-371

Author(s):

Jukka Nevalainen ◽

L. J. Liivamägi ◽

E. Tempel ◽

E. Branchini ◽

M. Roncarelli ◽

...

Keyword(s):

Large Scale ◽

Real Data ◽

Sloan Digital Sky Survey ◽

Physical Parameters ◽

X Ray ◽

Galaxy Surveys ◽

Sky Survey ◽

The Galaxy ◽

Hydrodynamical Simulations ◽

X Ray Absorption

AbstractWe have developed a new method to approach the missing baryons problem. We assume that the missing baryons reside in a form of Warm Hot Intergalactic Medium, i.e. the WHIM. Our method consists of (a) detecting the coherent large scale structure in the spatial distribution of galaxies that traces the Cosmic Web and that in hydrodynamical simulations is associated to the WHIM, (b) mapping its luminosity into a galaxy luminosity density field, (c) using numerical simulations to relate the luminosity density to the density of the WHIM, (d) applying this relation to real data to trace the WHIM using the observed galaxy luminosities in the Sloan Digital Sky Survey and 2dF redshift surveys. In our application we find evidence for the WHIM along the line of sight to the Sculptor Wall, at redshifts consistent with the recently reported X-ray absorption line detections. Our indirect WHIM detection technique complements the standard method based on the detection of characteristic X-ray absorption lines, showing that the galaxy luminosity density is a reliable signpost for the WHIM. For this reason, our method could be applied to current galaxy surveys to optimise the observational strategies for detecting and studying the WHIM and its properties. Our estimates of the WHIM hydrogen column density NH in Sculptor agree with those obtained via the X-ray analysis. Due to the additional NH estimate, our method has potential for improving the constrains of the physical parameters of the WHIM as derived with X-ray absorption, and thus for improving the understanding of the missing baryons problem.

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Probing the Tides in Interacting Galaxy Pairs

International Astronomical Union Colloquium ◽

10.1017/s0252921100005613 ◽

1990 ◽

Vol 124 ◽

pp. 537-542

Author(s):

Kirk D. Borne

Keyword(s):

Gravitational Field ◽

Binary System ◽

Driving Forces ◽

Elliptical Galaxies ◽

Physical Parameters ◽

Tidal Interactions ◽

The Galaxy ◽

Merger Rate ◽

The Masses ◽

Best Fit

AbstractDetailed spectroscopic and imaging observations of colliding elliptical galaxies have revealed unmistakable diagnostic signatures of the tidal interactions. It is possible to compare both the distorted luminosity distributions and the disturbed internal rotation profiles with numerical simulations in order to model the strength of the tidal gravitational field acting within a given pair of galaxies. Using the best-fit numerical model, one can then measure directly the mass of a specific interacting binary system. This technique applies to individual pairs and therefore complements the classical methods of measuring the masses of galaxy pairs in well-defined statistical samples. The “personalized” modeling of galaxy pairs also permits the derivation of each binary’s orbit, spatial orientation, and interaction timescale. Similarly, one can probe the tides in less-detailed observations of disturbed galaxies in order to estimate some of the physical parameters for larger samples of interacting galaxy pairs. These parameters are useful inputs to the more universal problems of (1) the galaxy merger rate, (2) the strength and duration of the driving forces behind tidally-stimulated phenomena (e.g., starbursts and maybe QSOs), and (3) the identification of long-lived signatures of interaction/merger events.

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On the Recovery of Galaxy Properties from Spectral Fits

Proceedings of the International Astronomical Union ◽

10.1017/s174392131300519x ◽

2012 ◽

Vol 8 (S295) ◽

pp. 317-317

Author(s):

G. Magris ◽

C. Mateu ◽

G. Bruzual A. ◽

I. Cabrera

Keyword(s):

Statistical Treatment ◽

Physical Parameters ◽

Assembly Process ◽

Spectral Fitting ◽

Fitting Algorithm ◽

The Galaxy ◽

Bayesian Implementation ◽

Galaxy Assembly ◽

Fully Bayesian ◽

Non Parametric

AbstractWe show the results of a non-parametric, fully bayesian implementation of a spectral fitting algorithm, designed to calculate the main physical parameters that govern the galaxy assembly process. In this work, we present results from a statistical treatment of SED fitting that allows for easy recovery and visualization of the galaxy physical parameters.

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Longslit spectroscopy of the peculiar Seyfert 2 galaxy HRG 10103

Sitientibus Série Ciências Físicas ◽

10.13102/sscf.v6i.5299 ◽

2010 ◽

Vol 6 ◽

pp. 11-16

Author(s):

Paulo C.R. Poppe ◽

Vera A.F. Martin ◽

Max Faúndez-Abans ◽

Mariângela De Oliveira-Abans ◽

Iranderly F. De Fernandes

Keyword(s):

Spectroscopic Data ◽

Rotation Curve ◽

Abundance Ratio ◽

Emission Lines ◽

Physical Parameters ◽

Narrow Line ◽

Optical Range ◽

Peculiar Galaxy ◽

The Galaxy ◽

The Continuum

We present the rst optical longslit spectroscopy for the galaxy HRG 10103, an Sa(r) type peculiar galaxy seen face-on with an asymmetrical elliptical structure. The main goal of this work is to provide the spectral classication of the current object using the `traditional' diagnostic diagrams. However, we also present a diagnostic involving the known emission line ratio R23, usually used to estimate the O/H abundance ratio. The idea is to make a better distinction between the narrow-line AGNs and the H II galaxies. The spectra were obtained in two observatories (OPD-LNA/MCT and Gemini-South) and includes some of the most important emission lines for ionization diagnostic. Based on the observed spectra, HRG 10103 is a Seyfert 2 galaxy with typical line-ratios values in the optical range. We have estimated nuclear redshift of z = 0.039. The resulting reddening values as a function of distance from the nucleus are presented too. The errors in the fluxes were mostly caused by uncertainties in the placement of the continuum level. The rotation curve is typical of spiral disks, rising shallowly and attening at an observed amplitude of about 200 km s^(-1). Some other physical parameters have been derived whenever possible. The spectroscopic data reduction was carried out using the GEMINI.GMOS package as well as the standard IRAF procedures.

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B-supergiants in IC1613: testing low-Z massive star physics and evolution

Proceedings of the International Astronomical Union ◽

10.1017/s1743921317002472 ◽

2016 ◽

Vol 12 (S329) ◽

pp. 389-389

Author(s):

Inés Camacho ◽

Miriam García ◽

Miguel A. Urbaneja ◽

Artemio Herrero

Keyword(s):

Massive Star ◽

Local Group ◽

Uv Spectroscopy ◽

Physical Parameters ◽

Physical Processes ◽

Life And Death ◽

The Galaxy ◽

Nearby Galaxies ◽

Group Galaxy ◽

Local Group Galaxy

AbstractThe physical processes taking place in massive stars during their life and death are highly dependent on the metallicity (Z) of their parent cloud. Observations of these stars in low-Z nearby galaxies are crucial to understand these processes. IC1613 is the nearest Local Group galaxy with ongoing star formation and O-abundance lower than the SMC, although UV spectroscopy suggests it is not so metal poor. We performed a spectral analysis of early B-type stars in the galaxy, obtaining physical parameters and abundances. Our results confirm the low O-abundance of IC1613.

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

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3668 ◽

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.

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ATLASGAL – physical parameters of dust clumps associated with 6.7 GHz methanol masers

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2691 ◽

2019 ◽

Cited By ~ 2

Author(s):

S J Billington ◽

J S Urquhart ◽

C König ◽

T J T Moore ◽

D J Eden ◽

...

Keyword(s):

Galactic Plane ◽

Evolutionary Process ◽

Volume Density ◽

High Mass ◽

Physical Parameters ◽

Mass Star ◽

Large Area ◽

The Galaxy ◽

Area Survey ◽

Methanol Masers

Abstract We have constructed the largest sample of dust-associated class II 6.7 GHz methanol masers yet obtained. New measurements from the the Methanol MultiBeam (MMB) Survey were combined with the 870 $\mu$m APEX Telescope Large Area Survey of the Galaxy (ATLASGAL) and the 850 $\mu$m JCMT Plane Survey (JPS). Together with two previous studies we have now identified the host clumps for 958 methanol masers across the Galactic Plane, covering approximately 99 per cent of the MMB catalogue and increasing the known sample of dust-associated masers by over 30 per cent. We investigate correlations between the physical properties of the clumps and masers using distances and luminosities drawn from the literature. Clumps hosting methanol masers are significantly more compact and have higher volume densities than the general population of clumps. We determine a minimum volume density threshold of n(H2) ≥ 104 cm−3 for the efficient formation of intermediate- and high-mass stars. We find 6.7 GHz methanol masers are associated with a distinct part of the evolutionary process (Lbol/Mfwhm ratios of between 100.6 and 102.2) and have well defined turning on and termination points. We estimate the lower limit for the mass of embedded objects to be ≥6 M⊙ and the statistical lifetime of the methanol maser stage to be ∼3.3 × 104 yrs. This suggests that methanol masers are indeed reliable tracers of high mass star formation, and indicates that the evolutionary period traced by this marker is relatively rapid.

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