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401. Chromospheric activity of Southern stars
ID:
ivo://CDS.VizieR/J/ApJ/734/70
Title:
Chromospheric activity of Southern stars
Short Name:
J/ApJ/734/70
Date:
21 Oct 2021
Publisher:
CDS
Description:
I present chromospheric-activity measurements of ~670 F, G, K, and M main-sequence stars in the Southern Hemisphere, from ~8000 archival high-resolution echelle spectra taken at Las Campanas Observatory since 2004. These stars were targets from the Old Magellan Planet Search, and are now potential targets for the New Magellan Planet Search that will look for rocky and habitable planets. Activity indices (S values) are derived from CaII H and K line cores and then converted to the Mount Wilson system. From these measurements, chromospheric (log R'_HK_) indices are derived, which are then used as indicators of the level of radial-velocity jitter, age, and rotation periods these stars present.
402. Chromospheric activity of SZ Piscium
ID:
ivo://CDS.VizieR/J/AJ/159/292
Title:
Chromospheric activity of SZ Piscium
Short Name:
J/AJ/159/292
Date:
08 Dec 2021
Publisher:
CDS
Description:
To continue our study on chromospheric activity and detection for possible prominence events of the very active RS Canum Venaticorum star SZ Piscium (SZ Psc), long-term high-resolution spectroscopic observations were obtained during several observing runs from 2014 to 2018. Based on the spectral subtraction technique, the chromospheric emission of the CaII IRT ({lambda}8662, {lambda}8542, and {lambda}8498), H_{alpha}_, NaI D_1_, D_2_ doublet, H_{beta}_, and CaII H & K lines is mainly associated with the K1 IV primary star of the SZ Psc system, in good agreement with the previous studies, and the F8 V secondary star also shows some chromospheric emission, implying its active chromosphere. Moreover, an optical flare characterized by the HeI D3 line emission together with stronger emission in the other indicators was detected. Furthermore, two chromospheric active longitudes around the two quadratures of the system were identified for most of the time, and the chromospheric activity shows significant changes during a few orbital cycles. The chromospheric activity level seems to show a long-term variation during our observations. There were some excess absorption features in the subtracted H{alpha} line and the other activity indicators, which would be caused by prominence-like materials associated with the K1 IV primary star of the system. Prominence materials could absorb the chromospheric emission and continuum from the K1 IV primary star and even the F8 V secondary one.
403. CH 2THz spectra towards 7 molecular clouds
ID:
ivo://CDS.VizieR/J/A+A/632/A60
Title:
CH 2THz spectra towards 7 molecular clouds
Short Name:
J/A+A/632/A60
Date:
21 Oct 2021
Publisher:
CDS
Description:
Despite being a commonly observed feature, the modification of the velocity structure in spectral line profiles by hyperfine structure complicates the interpretation of spectroscopic data. This is particularly true for observations of simple molecules such as CH and OH toward the inner Galaxy, which show a great deal of velocity crowding. In this paper, we investigate the influence of hyperfine splitting on complex spectral lines, with the aim of evaluating canonical abundances by decomposing their dependence on hyperfine structures. This is achieved from first principles through deconvolution. We present high spectral resolution observations of the rotational ground state transitions of CH near 2THz seen in absorption toward the strong FIR-continuum sources AGAL010.62-00.384, AGAL034.258+00.154, AGAL327.293- 00.579, AGAL330.954-00.182, AGAL332.826-00.549, AGAL351.581-00.352 and SgrB2(M). These were observed with the GREAT instrument on board SOFIA. The observed line profiles of CH were deconvolved from the imprint left by the lines' hyperfine structures using the Wiener filter deconvolution, an optimised kernel acting on direct deconvolution. The quantitative analysis of the deconvolved spectra first entails the computation of CH column densities. Reliable N(CH) values are of importance owing to the status of CH as a powerful tracer for H_2_ in the diffuse regions of the interstellar medium. The N(OH)/N(CH) column density ratio is found to vary within an order of magnitude with values ranging from one to 10, for the individual sources that are located outside the Galactic centre. Using CH as a surrogate for H_2_, we determined the abundance of the OH molecule to be X(OH)=1.09x10^-7^ with respect to H_2_. The radial distribution of CH column densities along the sightlines probed in this study, excluding SgrB2(M), showcase a dual peaked distribution peaking between 5 and 7 kpc. The similarity between the correspondingly derived column density profile of H_2_ with that of the CO-dark H_2_ gas traced by the cold neutral medium component of [CII] 158um emission across the Galactic plane, further emphasises the use of CH as a tracer for H_2_.
404. CH 149um spectra of 4 molecular clouds
ID:
ivo://CDS.VizieR/J/A+A/612/A37
Title:
CH 149um spectra of 4 molecular clouds
Short Name:
J/A+A/612/A37
Date:
21 Oct 2021
Publisher:
CDS
Description:
The methylidyne radical CH is commonly used as a proxy for molecular hydrogen in the cold, neutral phase of the interstellar medium. The optical spectroscopy of CH is limited by interstellar extinction, whereas far-infrared observations provide an integral view through the Galaxy. While the HF ground state absorption, another H_2_ proxy in diffuse gas, frequently suffers from saturation, CH remains transparent both in spiral-arm crossings and high-mass star forming regions, turning this light hydride into a universal surrogate for H_2_. However, in slow shocks and in regions dissipating turbulence its abundance is expected to be enhanced by an endothermic production path, and the idea of a "canonical" CH abundance needs to be addressed. The N=2<-1 ground state transition of CH at {lambda}149um has become accessible to high-resolution spectroscopy thanks to GREAT, the German Receiver for Astronomy at Terahertz Frequencies aboard the Stratospheric Observatory for Infrared Astronomy, SOFIA. Its unsaturated absorption and the absence of emission from the star forming regions makes it an ideal candidate for the determination of column densities with a minimum of assumptions. Here we present an analysis of four sightlines towards distant Galactic star forming regions, whose hot cores emit a strong far-infrared dust continuum serving as background signal. Moreover, if combined with the sub-millimeter line of CH at {lambda}560um, environments forming massive stars can be analyzed. For this we present a case study on the "proto-Trapezium" cluster W3 IRS5. While we confirm the global correlation between the column densities of HF and those of CH, both in arm and interarm regions, clear signposts of an over-abundance of CH are observed towards lower densities. However, a significant correlation between the column densities of CH and HF remains. A characterization of the hot cores in the W3 IRS5 proto-cluster and its envelope demonstrates that the sub-millimeter/far-infrared lines of CH reliably trace not only diffuse but also dense, molecular gas. In diffuse gas, at lower densities a quiescent ion-neutral chemistry alone cannot account for the observed abundance of CH. Unlike the production of HF, for CH^+^ and CH, vortices forming in turbulent, diffuse gas may be the setting for an enhanced production path. However, CH remains a valuable tracer for molecular gas in environments reaching from diffuse clouds to sites of high-mass star formation.
405. CI Aql spectra during 2000 outburst
ID:
ivo://CDS.VizieR/J/A+A/544/A26
Title:
CI Aql spectra during 2000 outburst
Short Name:
J/A+A/544/A26
Date:
21 Oct 2021
Publisher:
CDS
Description:
High- and low-resolution optical spectra of CI Aql were obtained during the outburst in 2000. Multiple absorption components of HI and FeII lines were detected at the early decline stage. Their radial velocities were roughly -2500km/s, -2200km/s , -1700km/s, and -1400km/s, among which only the last components were likely still accelerating during the early decline stage. Prominent emission lines of [OIII] and [NII] appeared about one month after light maximum. The duration of the nebular stage, however, was only one month and a few weeks. The ejected gas shells seem to have started to shrink about 70 days after light maximum. The amount of interstellar extinction is estimated to be E(B-V)=0.92+/-0.15 from the equivalent widths of the diffuse interstellar absorption bands. The helium abundance in the ejecta is estimated to be N(He)=0.19+/-0.05 and the mass of the ejecta to be about 2x10^-6^M_{sun}_. This object has been classified as a U Sco type recurrent nova, but its spectral evolution during the outburst resembled those of T Pyx type recurrent novae. It is doubtful whether the peak of m_V_~9mag on 2000 May 5 was the true light maximum or an earlier brighter peak had been overlooked, because the spectral data suggest that the ejections of gas shells occurred prior to the discovery of the outburst on 2000 April 28.
406. CIELO-RGS, soft X-ray ionized emission lines catalog
ID:
ivo://CDS.VizieR/J/A+A/625/A122
Title:
CIELO-RGS, soft X-ray ionized emission lines catalog
Short Name:
J/A+A/625/A122
Date:
21 Oct 2021
Publisher:
CDS
Description:
High-resolution X-ray spectroscopy has advanced our understanding of the hot Universe by revealing physical properties like kinematics, temperature, and abundances of the astrophysical plasmas. Despite technical and scientific achievements, the lack of scientific products at a level higher than count spectra is hampering complete scientific exploitation of high-quality data. This paper introduces the Catalog of Ionized Emission Lines Observed by the Reflection Grating Spectrometer (CIELO-RGS) onboard the XMM-Newton space observatory. The CIELO-RGS catalog aims to facilitate the exploitation of emission features in the public RGS spectra archive. In particular, we aim to analyze the relationship between X-ray spectral diagnostics parameters and measurements at other wavelengths. This paper focuses on the methodology of catalog generation, describing the automated line-detection algorithm. A moderate sample (~2400 observations) of high-quality RGS spectra available at XMM-Newton Science Archive is used as our starting point. A list of potential emission lines is selected based on a multi-scale peak-detection algorithm in a uniform and automated way without prior assumption on the underlying astrophysical model. The candidate line list is validated via spectral fitting with simple continuum and line profile models. We also compare the catalog content with published literature results on a small number of exemplary sources. We generate a catalog of emission lines (1.2x10^4^) detected in ~1600 observations toward stars, X-ray binaries, supernovae remnants, active galactic nuclei, and groups and clusters of galaxies. For each line, we report the observed wavelength, broadening, energy and photon flux, equivalent width, and so on.
407. CIG 638 CCH, HCN. HOC and HNC spectra
ID:
ivo://CDS.VizieR/J/A+A/563/L6
Title:
CIG 638 CCH, HCN. HOC and HNC spectra
Short Name:
J/A+A/563/L6
Date:
21 Oct 2021
Publisher:
CDS
Description:
Multi-molecule observations towards an increasing variety of galaxies have been showing that the relative molecular abundances are affected by the type of activity. However, these studies are biased towards bright active galaxies, which are typically in interaction. We study the molecular composition of one of the most isolated galaxies in the local Universe where the physical and chemical properties of their molecular clouds have been determined by intrinsic mechanisms.
408. CIG sample 3-dimensional environment
ID:
ivo://CDS.VizieR/J/A+A/564/A94
Title:
CIG sample 3-dimensional environment
Short Name:
J/A+A/564/A94
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a study of the 3-dimensional environment for a sample of 386 galaxies in the Catalogue of Isolated Galaxies (CIG, Karachentseva 1973) using the Ninth Data Release of the Sloan Digital Sky Survey (SDSS-DR9). We aim to identify and quantify the effects of the satellite distribution around a sample of galaxies in the CIG, as well as the effects of the Large Scale Structure (LSS). To recover the physically bound galaxies we first focus on the satellites which are within the escape speed of each CIG galaxy. We also propose a more conservative method using the stacked Gaussian distribution of the velocity difference of the neighbours. The tidal strengths affecting the primary galaxy are estimated to quantify the effects of the local and LSS environments. We also define the projected number density parameter at the fifth nearest neighbour to characterise the LSS around the CIG galaxies. Out of the 386 CIG galaxies considered in this study, at least 340 (88% of the sample) have no physically linked satellite. Following the more conservative Gaussian distribution of physical satellites around the CIG galaxies leads to upper limits. Out of the 386 CIG galaxies, 327 (85% of the sample) have no physical companion within a projected distance of 0.3Mpc. The CIG galaxies are distributed following the LSS of the local Universe, although presenting a large heterogeneity in their degree of connection with it. When present around a CIG galaxy, the effect of physically bound galaxies largely dominates (usually by more than 90%) the tidal strengths generated by the LSS. The CIG samples a variety of environments, from galaxies with physical satellites to galaxies with no neighbours within 3Mpc. A clear segregation appears between early-type CIG galaxies with companions and isolated late-type CIG galaxies. Isolated galaxies are in general bluer, with likely younger stellar populations and rather high star formation with respect to older, redder CIG galaxies with companions. Reciprocally, the satellites are redder and with an older stellar populations around massive early-type CIG galaxies, while they have a younger stellar content around massive late-type CIG galaxies. This suggests that the CIG is composed of a heterogeneous population of galaxies, sampling from old to more recent, dynamical systems of galaxies. CIG galaxies with companions might have a mild tendency (0.3-0.4dex) to be more massive, and may indicate a higher frequency of having suffered a merger in the past.
409. [CII] emission in the ISM of 20 nearby galaxies
ID:
ivo://CDS.VizieR/J/ApJ/845/96
Title:
[CII] emission in the ISM of 20 nearby galaxies
Short Name:
J/ApJ/845/96
Date:
21 Oct 2021
Publisher:
CDS
Description:
The [CII]158{mu}m fine-structure line is the brightest emission line observed in local star-forming galaxies. As a major coolant of the gas-phase interstellar medium, [CII] balances the heating, including that due to far- ultraviolet photons, which heat the gas via the photoelectric effect. However, the origin of [CII] emission remains unclear because C+ can be found in multiple phases of the interstellar medium. Here we measure the fractions of [CII] emission originating in the ionized and neutral gas phases of a sample of nearby galaxies. We use the [NII]205{mu}m fine-structure line to trace the ionized medium, thereby eliminating the strong density dependence that exists in the ratio of [CII]/[NII]122{mu}m. Using the FIR [CII] and [NII] emission detected by the KINGFISH (Key Insights on Nearby Galaxies: a Far- Infrared Survey with Herschel) and Beyond the Peak Herschel programs, we show that 60%-80% of [CII] emission originates from neutral gas. We find that the fraction of [CII] originating in the neutral medium has a weak dependence on dust temperature and the surface density of star formation, and has a stronger dependence on the gas-phase metallicity. In metal-rich environments, the relatively cooler ionized gas makes substantially larger contributions to total [CII] emission than at low abundance, contrary to prior expectations. Approximate calibrations of this metallicity trend are provided.
410. CII emission-line stars in LMC with MagE spectra
ID:
ivo://CDS.VizieR/J/ApJ/898/85
Title:
CII emission-line stars in LMC with MagE spectra
Short Name:
J/ApJ/898/85
Date:
21 Mar 2022 08:48:14
Publisher:
CDS
Description:
We present a narrowband imaging survey of the Large Magellanic Cloud (LMC), designed to isolate the CII{lambda}{lambda}7231,7236 emission lines in objects as faint as m_{lambda}7400_~18. The work is motivated by the recent serendipitous discovery in the LMC of the first confirmed extragalactic [WC11] star, whose spectrum is dominated by CII emission, and the realization that the number of such objects is currently largely unconstrained. The survey, which imaged ~50deg^2^ using on-band and off-band filters, will significantly increase the total census of these rare stars. In addition, each new LMC [WC] star has a known luminosity, a quantity quite uncertain in the Galactic sample. Multiple known CII emitters were easily recovered, validating the survey design. We find 38 new CII emission candidates; spectroscopy of the complete sample will be needed to ascertain their nature. In a preliminary spectroscopic reconnaissance, we observed three candidates, finding CII emission in each. One is a new [WC11]. Another shows both the narrow CII emission lines characteristic of a [WC11], but also broad emission of CIV, OV, and HeII characteristic of a much hotter [WC4] star; we speculate that this is a binary [WC]. The third object shows weak CII emission, but the spectrum is dominated by a dense thicket of strong absorption lines, including numerous OII transitions. We conclude it is likely an unusual hot, hydrogen-poor post-AGB star, possibly in transition from [WC] to white dwarf. Even lacking a complete spectroscopic program, we can infer that late [WC] stars do not dominate the central stars of LMC planetary nebulae, and that the detected CII emitters are largely of an old population.

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