R. Szczerba

Polish Academy of Sciences

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M. Schmidt

Nicolaus Copernicus Astronomical Center

J. Cernicharo

Consejo Superior de Investigaciones Científicas

A. A. Zijlstra

University of Manchester

L. Decin

Institute of Astronomy

N. Siódmiak

Nicolaus Copernicus Astronomical Center

Kevin Volk

Space Telescope Science Institute

V. Bujarrabal

Spanish National Observatory

K. M. Menten

Max Planck Institute for Radio Astronomy

D. Teyssier

European Space Astronomy Centre

P. Planesas

Spanish National Observatory

Cooperative Institutions

Centre National de la Recherche Scientifique

167

SRON Netherlands Institute for Space Research

125

Max Planck Society

107

Max Planck Institute for Radio Astronomy

California Institute of Technology

Institut de Planétologie et d'Astrophysique de Grenoble

Leiden University

Observatoire de Paris

Space Telescope Science Institute

University of Cologne

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A $\lambda$ 3 mm line survey towards the circumstellar envelope of the carbon-rich AGB star IRC+10216 (CW Leo)

arXiv (Cornell University) (2024)

Juan Tuo Xiaohu Li Jixian Sun T. J. Millar Yong Zhang

We present an unbiased $\lambda$ 3 mm spectral line survey (between 84.5 and 115.8 GHz), conducted by the Purple Mountain Observatory 13.7 meter radio telescope, together with updated modeling results, towards the carbon-rich Asymptotic Giant Branch star, IRC+10216 (CW Leo). A total of 75 spectral lines (96 transitions) are detected, and identified to arise from 19 molecules: C$_2$H, $l$-C$_3$H, C$_4$H, CN, C$_3$N, HC$_3$N, HC$_5$N, HCN, HNC, CH$_3$CN, MgNC, CO, $c$-C$_3$H$_2$, SiC$_2$, SiO, SiS, CS, C$_2$S, C$_3$S, and their isotopologues. Among them, one molecular emission line (H$^{13}$CCCN $J=13-12$) is discovered in IRC+10216 for the first time. The excitation temperature, column density, and fractional abundance of the detected species are deduced by assuming they are in local thermodynamic equilibrium. In addition, the isotopic ratios of [$^{12}$C]/[$^{13}$C], [$^{32}$S]/[$^{34}$S], [$^{28}$Si]/[$^{29}$Si], and [$^{12}$C$^{34}$S]/[$^{13}$C$^{32}$S] are obtained and found to be consistent with previous studies. Finally, we summarize all of the 106 species detected in IRC+10216 to date with their observed and modeled column densities for the convenience of future studies.

Circumstellar envelope

Carbon star

Asymptotic giant branch

Envelope (radar)

Star (game theory)

Line (geometry)

Circumstellar disk

10.48550/arxiv.2401.16089

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Discovery of a hot post-AGB star in Galactic globular cluster E3

arXiv (Cornell University) (2024)

Ranjan Kumar Ayush Moharana Sonika Piridi Ananta C. Pradhan K. G. Hełminiak

We report a new hot post-asymptotic giant branch (PAGB) star in the Galactic globular cluster (GC) E3, which is one of the first of the identified PAGB stars in a GC to show a binary signature. The star stands out as the brightest source in E3 in the \mbox{{\em Astrosat}}/UVIT images. We confirmed its membership with the cluster E3 using Gaia DR3 kinematics and parallax measurements. We supplemented the photometric observations with radial velocities (RVs) from high-resolution spectroscopic observations at two epochs and with ground- and space-based photometric observations from 0.13 $\mu$m to 22 $\mu$m. We find that the RVs vary over $\sim$6 \kms\ between the two epochs. This is an indication of the star being in a binary orbit. A simulation of possible binary systems with the observed RVs suggests a binary period of either 39.12 days or 17.83 days with mass ratio q$\geq$1.0. The [Fe/H] derived using the high-resolution spectra is $\sim -$0.7 dex, which closely matches the cluster metallicity. The spectroscopic and photometric measurements suggest \Teff\ and $\log g$ of the star as 17\,500$\pm$1\,000~K and 2.37$\pm$0.20~dex, respectively. Various PAGB evolutionary tracks on the Hertzsprung--Russell (H-R) diagram suggest a current mass of the star in the range 0.51$-$0.55 \Msun. The star is enriched with C and O abundances, showing similar CNO abundances compared to the other PAGB stars in GCs with the evidence of the third dredge-up on the AGB phase.

Horizontal branch

Blue straggler

Asymptotic giant branch

10.1051/0004-6361/202449777

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Citations (0)

Velocity elds of planetary nebulae

K. Gȩsicki A. A. Zijlstra A. Acker R. Szczerba Karl Schwarzschild Strasse

Density distributions and velocity elds are derived for four spatially resolved planetary nebulae, based on high- resolution long-slit emission line spectra. We use a photo- ionization code to t the spectra and to derive the nebular struc- ture, assuming spherical symmetry. We present the results for individual nebulae and compare with three objects analyzed earlier. The expansion velocities are found to increase outward: this is shown to be likely related to the presence of an ionization front. Six PN in the sample are found to be ionization bounded. Foroneobject,whichhasaWR-typecentralstar,alargeamount of turbulence or irregular structure in the velocity eld is found. The results are in agreement with hydrodynamical calculations, in which the velocities also tend to increase with distance from the star. However, the common presence of an ionization front was not predicted.

Line (geometry)

Source

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ISO–SWS spectra of [WR] planetary nebulae

Symposium - International Astronomical Union (2003)

R. Szczerba Kevin Volk S. K. Górny

We have analyzed Infrared Space Observatory Short Wavelength Spectrometer (ISO–SWS) observations for 16 Wolf–Rayet ([WR]) planetary nebulae (PNe) with the aim of identifying the dust features present in this group of objects. We have found that Polycyclic Aromatic Hydrocarbon (PAH) molecular bands (which are present in most of the observed [WR] PNe) are more frequent than crystalline silicate features.

Space observatory

10.1017/s0074180900208814

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Citations (2)

Water in massive star-forming regions: HIFI observations of W3 IRS5

Astronomy and Astrophysics (2010)

L. Chavarría F. Herpin T. Jacq J. Braine S. Bontemps

We present Herschel observations of the water molecule in the massive star-forming region W3 IRS5. The o-H17O 110-101, p-H18O 111-000, p-H2O 22 202-111, p-H2O 111-000, o-H2O 221-212, and o-H2O 212-101 lines, covering a frequency range from 552 up to 1669 GHz, have been detected at high spectral resolution with HIFI. The water lines in W3 IRS5 show well-defined high-velocity wings that indicate a clear contribution by outflows. Moreover, the systematically blue-shifted absorption in the H2O lines suggests expansion, presumably driven by the outflow. No infall signatures are detected. The p-H2O 111-000 and o-H2O 212-101 lines show absorption from the cold material (T ~ 10 K) in which the high-mass protostellar envelope is embedded. One-dimensional radiative transfer models are used to estimate water abundances and to further study the kinematics of the region. We show that the emission in the rare isotopologues comes directly from the inner parts of the envelope (T > 100 K) where water ices in the dust mantles evaporate and the gas-phase abundance increases. The resulting jump in the water abundance (with a constant inner abundance of 10^{-4}) is needed to reproduce the o-H17O 110-101 and p-H18O 111-000 spectra in our models. We estimate water abundances of 10^{-8} to 10^{-9} in the outer parts of the envelope (T < 100 K). The possibility of two protostellar objects contributing to the emission is discussed.

Star (game theory)

10.1051/0004-6361/201015113

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Citations (55)

Water content and wind acceleration in the envelope around the oxygen-rich AGB star IK Tauri as seen byHerschel/HIFI

Astronomy and Astrophysics (2010)

L. Decin K. Justtanont E. De Beck R. Lombaert A. de Koter

During their asymptotic giant branch, evolution low-mass stars lose a significant fraction of their mass through an intense wind, enriching the interstellar medium with products of nucleosynthesis. We observed the nearby oxygen-rich asymptotic giant branch star IK Tau using the high-resolution HIFI spectrometer onboard Herschel. We report on the first detection of H_2^{16}O and the rarer isotopologues H_2^{17}O and H_2^{18}O in both the ortho and para states. We deduce a total water content (relative to molecular hydrogen) of 6.6x10^{-5}, and an ortho-to-para ratio of 3:1. These results are consistent with the formation of H_2O in thermodynamical chemical equilibrium at photospheric temperatures, and does not require pulsationally induced non-equilibrium chemistry, vaporization of icy bodies or grain surface reactions. High-excitation lines of 12CO, 13CO, 28SiO, 29SiO, 30SiO, HCN, and SO have also been detected. From the observed line widths, the acceleration region in the inner wind zone can be characterized, and we show that the wind acceleration is slower than hitherto anticipated.

Isotopologue

Asymptotic giant branch

10.1051/0004-6361/201015069

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Citations (64)

ALMA Compact Array observations of the Fried Egg nebula

Astronomy and Astrophysics (2016)

S. H. J. Wallström E. Lagadec S. Müller J. H. Black N. L. J. Cox

Yellow hypergiants are rare and represent a fast evolutionary stage of massive evolved stars. That evolutionary phase is characterised by a very intense mass loss, the understanding of which is still very limited. Here we report ALMA Compact Array observations of a 50$"$-mosaic toward the Fried Egg nebula, around one of the few Galactic yellow hypergiants IRAS 17163-3907. The emission from the $^{12}$CO J=2-1 line, H30$\alpha$ recombination line, and continuum is imaged at a resolution of $\sim$8$"$, revealing the morphology of the molecular environment around the star. The continuum emission is unresolved and peaks at the position of the star. The radio recombination line H30$\alpha$ shows unresolved emission at the star, with an approximately gaussian spectrum centered on a velocity of 21$\pm$3~km/s with a width of 57$\pm$6~km/s. In contrast, the CO 2-1 emission is complex and decomposes into several components beyond the contamination from interstellar gas in the line of sight. The CO spectrum toward the star is a broad plateau, centered at the systemic velocity of +18 km/s and with an expansion velocity of 100$\pm$10 km/s. Assuming isotropic and constant mass-loss, we estimate a mass-loss rate of 8$\pm$1.5 $\times10^{-5}$~M$_\odot$ yr$^{-1}$. At a radius of 25$"$ from the star, we detect CO emission associated with the dust ring previously imaged by {\it Herschel}. The kinematics of this ring, however, is not consistent with an expanding shell, but show a velocity gradient of $v_{sys} \pm$20 km/s. In addition, we find a puzzling bright feature radially connecting the star to the CO ring, at a velocity of +40 km/s relative to the star. This spur feature may trace a unidirectional ejection event from the star. Our ACA observations reveal the complex morphology around IRAS 17163 and illustrate the breakthroughs that ALMA will bring to the field of massive stellar evolution.

Line (geometry)

Line-of-sight

Radial velocity

10.1051/0004-6361/201628416

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Citations (6)

Observational Database and Statistical Properties of Proto-Planetary Nebulae

Astrophysics and space science library (2001)

R. Szczerba S. K. Górny M. Zalfresso-Jundziłło

Statistical Analysis

10.1007/978-94-015-9688-6_2

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Citations (12)

R-L Relation in Realistic FRADO Model

arXiv (Cornell University) (2019)

Mohammad-Hassan Naddaf B. Czerny R. Szczerba

In Failed Radiatively Accelerated Dusty Outflow (FRADO) model which provides the source of material above the accretion disk (AD) as an option to explain the formation mechanism of Broad Line Region (BLR) in AGNs, the BLR inner radius ($\rm{BLR}_{in}$ hereafter) is set by the condition that the dust evaporates immediately upon departure from the AD surface. On the other hand, the location of BLR clouds obtained observationaly via reverberation mapping shows some scaling with the source luminosity, so-called RL relation. We assume $\rm{BLR}_{in}$ to be the location of BLR clouds, then using a realistic expression for the radiation pressure of an AD, and having included the proper values of dust opacity, and shielding effect as well, we report our numerical results on calculation of $\rm{BLR}_{in}$ based on FRADO model. We investigate how it scales with monochromatic luminosity at 5100 angstrom for a grid of blackhole masses and Eddington ratios to compare along with the FRADO analytically predicted RL directly to observational data.

10.48550/arxiv.1912.00278

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Citations (1)

Late Stages of Stellar Evolution

Springer eBooks (2006)

J. A. D. L. Blommaert J. Cami R. Szczerba M. J. Barlow

Asymptotic giant branch

Line (geometry)

Carbon star

10.1007/1-4020-3844-5_10

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Citations (4)