Search

Start Over Subject spectroscopy Capability Type Simple Cone Search
1001. Massive SZE clusters observations with ACT
ID:
ivo://CDS.VizieR/J/ApJ/772/25
Title:
Massive SZE clusters observations with ACT
Short Name:
J/ApJ/772/25
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the first dynamical mass estimates and scaling relations for a sample of Sunyaev-Zel'dovich effect (SZE) selected galaxy clusters. The sample consists of 16 massive clusters detected with the Atacama Cosmology Telescope (ACT) over a 455deg^2^ area of the southern sky. Deep multi-object spectroscopic observations were taken to secure intermediate-resolution (R~700-800) spectra and redshifts for {approx}60 member galaxies on average per cluster. The dynamical masses M_200c_ of the clusters have been calculated using simulation-based scaling relations between velocity dispersion and mass. The sample has a median redshift z=0.50 and a median mass M_200c_~12x10^14^h_70_^-1^M_{sun}_ with a lower limit M_200c_~6x10^14^h_70_^-1^M_{sun}_, consistent with the expectations for the ACT southern sky survey. These masses are compared to the ACT SZE properties of the sample, specifically, the match-filtered central SZE amplitude {overline}{y_0_}, the central Compton parameter y_0_, and the integrated Compton signal Y_200c_, which we use to derive SZE-mass scaling relations. All SZE estimators correlate with dynamical mass with low intrinsic scatter (<~20%), in agreement with numerical simulations. We explore the effects of various systematic effects on these scaling relations, including the correlation between observables and the influence of dynamically disturbed clusters. Using the three-dimensional information available, we divide the sample into relaxed and disturbed clusters and find that ~50% of the clusters are disturbed. There are hints that disturbed systems might bias the scaling relations, but given the current sample sizes, these differences are not significant; further studies including more clusters are required to assess the impact of these clusters on the scaling relations.
1002. Massive young stellar objects in 30 Doradus
ID:
ivo://CDS.VizieR/J/A+A/636/A54
Title:
Massive young stellar objects in 30 Doradus
Short Name:
J/A+A/636/A54
Date:
21 Oct 2021
Publisher:
CDS
Description:
The process of massive star (M>=8M_{sun}_) formation is still poorly understood. Observations of massive young stellar objects (MYSOs) are challenging due to their rarity, short formation timescale, large distances, and high circumstellar extinction. Here, we present the results of a spectroscopic analysis of a population of MYSOs in the Large Magellanic Cloud (LMC). We took advantage of the spectral resolution and wavelength coverage of X-shooter (300-2500nm), which is mounted on the European Southern Observatory Very Large Telescope, to detect characteristic spectral features in a dozen MYSO candidates near 30 Doradus, the largest starburst region in the Local Group hosting the most massive stars known. The X-shooter spectra are strongly contaminated by nebular emission. We used a scaling method to subtract the nebular contamination from our objects. We detect H{alpha},{beta}, [OI] 630.0nm, CaII infrared triplet, [FeII] 1643.5nm, fluorescent FeII 1687.8nm, H_2_ 2121.8nm, Br{gamma}, and CO bandhead emission in the spectra of multiple candidates. This leads to the spectroscopic confirmation of ten candidates as bona fide MYSOs. We compared our observations with photometric observations from the literature and find all MYSOs to have a strong near-infrared excess. We computed lower limits to the brightness and luminosity of the MYSO candidates, confirming the near-infrared excess and the massive nature of the objects. No clear correlation is seen between the Br_gamma luminosity and metallicity. Combining our sample with other LMC samples results in a combined detection rate of disk features such as fluorescent Fe II and CO bandheads which is consistent with the Galactic rate (40%). Most of our MYSOs show outflow features.
1003. Massive YSOs VLTI observations
ID:
ivo://CDS.VizieR/J/A+A/654/A109
Title:
Massive YSOs VLTI observations
Short Name:
J/A+A/654/A109
Date:
22 Feb 2022
Publisher:
CDS
Description:
Circumstellar discs are essential for high mass star formation, while multiplicity, in particular binarity, appears to be an inevitable outcome since the vast majority of massive stars (>8M_{sun}_) are found in binaries (up to 100%). We spatially resolve and constrain the sizes of the dust and ionised gas emission of the innermost regions towards a sample of MYSOs for the first time, and provide high-mass binary statistics of young stars at 2-300au scales. We observe six MYSOs with VLTI (GRAVITY, AMBER), to resolve and characterise the 2.2um hot dust emission originating from the inner rim of circumstellar discs around MYSOs, and the associated Br{gamma} emission from ionised gas. We fit simple geometrical models to the interferometric observables, and determine the inner radius of the dust emission. We place MYSOs with K-band measurements in a size-luminosity diagram for the first time, and compare our findings to T Tauris and Herbig AeBes. We also compare the observed K-band sizes to the sublimation radius predicted by three different disc scenarios. Lastly, we apply binary geometries to trace close binarity among MYSOs. When the inner sizes of MYSOs are compared to those of lower mass Herbig AeBe and T Tauri stars, they appear to follow a universal trend at which the sizes scale with the square-root of the stellar luminosity. The Br{gamma} emission originates from a similar or somewhat smaller and co-planar area compared to the 2.2um continuum emission. We discuss this new finding with respect to disc-wind or jet origin. Finally, we report an MYSO binary fraction of 17-25% at milli-arcsecond separations (2-300au). The size-luminosity diagram indicates that the inner regions of discs around young stars scale with luminosity independently of the stellar mass. At the targeted scales (2-300au), the MYSO binary fraction is lower than what was previously reported for the more evolved main sequence massive stars, which, if further confirmed, could implicate the predictions from massive binary formation theories. Lastly, we spatially resolve the crucial star/disc interface in a sample of MYSOs, showing that au-scale discs are prominent in high-mass star formation and similar to their low-mass equivalents.
1004. MC cool supergiants spectra
ID:
ivo://CDS.VizieR/J/A+A/618/A137
Title:
MC cool supergiants spectra
Short Name:
J/A+A/618/A137
Date:
21 Oct 2021
Publisher:
CDS
Description:
This atlas composed by more than 1500 spectra of late-type stars (spectral types from G to M) observed simultaneously in the optical and Calcium Triplet spectral ranges. These spectra were obtained as part of a survey to search for cool supergiants in the Magellanic Clouds and taken over four epochs. We provide the spectral and luminosity classification for each spectrum (71% are supergiants, 13% are giants or luminous giants, 4% are Carbon or S~Stars and the remaining 12% are foreground stars of lesser luminosities).
1005. M31 center emission-line point-like sources
ID:
ivo://CDS.VizieR/J/MNRAS/473/4130
Title:
M31 center emission-line point-like sources
Short Name:
J/MNRAS/473/4130
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a detailed description of the wavelength, astrometric and photometric calibration plan for SITELLE, the imaging Fourier transform spectrometer attached to the Canada-France-Hawaii telescope, based on observations of a red (647-685nm) data cube of the central region (11'x11') of the Andromeda galaxy. The first application, presented in this paper, is a radial-velocity catalogue (with uncertainties of ~2-6km/s) of nearly 800 emission-line point-like sources, including ~450 new discoveries. Most of the sources are likely planetary nebulae, although we also detect five novae (having erupted in the first 8 months of 2016) and one new supernova remnant candidate.
1006. M31 CO(2-1) spectra
ID:
ivo://CDS.VizieR/J/A+A/549/A27
Title:
M31 CO(2-1) spectra
Short Name:
J/A+A/549/A27
Date:
21 Oct 2021
Publisher:
CDS
Description:
With IRAM-30m/HERA, we have detected CO(2-1) gas complexes within 30arcsec (100pc) from the center of M31 that amount to a minimum total mass of 4.2x10^4^M_{sun}_ (one third of the positions are detected). Averaging the whole HERA field, we show that there is no additional undetected diffuse component. Moreover, the gas detection is associated with gas lying on the far side of the M31 center as no extinction is observed in the optical, but some emission is present on infrared Spitzer maps. The kinematics is complex. (1) The velocity pattern is mainly redshifted: the dynamical center of the gas differs from the black hole position and the maximum of optical emission, and only the redshifted side is seen in our data. (2) Several velocity components are detected in some lines of sight. Our interpretation is supported by the reanalysis of the effect of dust on a complete planetary nebula sample. Two dust components are detected with respective position angles of 37deg and -66deg. This is compatible with a scenario where the superposition of the (PA=37deg) disk is dominated by the 10kpc ring and the inner 0.7kpc ring detected in infrared data, whose position angle (-66deg) we measured for the first time. The large-scale disk, which dominates the HI data, is steeply inclined (i=77deg), warped and superposed on the line of sight on the less inclined inner ring. The detected CO emission might come from both components.
1007. MC2: redshift analysis of CIZA J2242.8+5301
ID:
ivo://CDS.VizieR/J/ApJ/805/143
Title:
MC2: redshift analysis of CIZA J2242.8+5301
Short Name:
J/ApJ/805/143
Date:
21 Oct 2021
Publisher:
CDS
Description:
X-ray and radio observations of CIZA J2242.8+5301 suggest that it is a major cluster merger. Despite being well studied in the X-ray and radio, little has been presented on the cluster structure and dynamics inferred from its galaxy population. We carried out a deep (i<25) broadband imaging survey of the system with Subaru SuprimeCam (g and i bands) and the Canada-France-Hawaii Telescope (r band), as well as a comprehensive spectroscopic survey of the cluster area (505 redshifts) using Keck DEep Imaging Multi-Object Spectrograph. We use these data to perform a comprehensive galaxy/redshift analysis of the system, which is the first step to a proper understanding of the geometry and dynamics of the merger, as well as using the merger to constrain self-interacting dark matter. We find that the system is dominated by two subclusters of comparable richness with a projected separation of 6.9'_-0.5_^+0.7^ (1.3_-0.10_^+0.13^Mpc). We find that the north and south subclusters have similar redshifts of z~0.188 with a relative line-of-sight (LOS) velocity difference of 69+/-190km/s. We also find that north and south subclusters have velocity dispersions of 1160_-90_^+100^ and 1080_-70_^+100^km/s, respectively. These correspond to masses of 16.1_-3.3_^+4.6^x10^14^ and 13.0_-2.5_^+4.0^x10^14^M_{Sun}_, respectively. While velocity dispersion measurements of merging clusters can be biased, we believe the bias in this system to be minor due to the large projected separation and nearly plane-of-sky merger configuration. We also find that the cDs of the north and south subclusters are very near their subcluster centers, in both projection (55 and 85kpc, respectively) and normalized LOS velocity (|{Delta}v|/{sigma}_v_=0.43+/-0.13 and 0.21+/-0.12 for the north and south, respectively). CIZA J2242.8+5301 is a relatively clean dissociative cluster merger with near 1:1 mass ratio, which makes it an ideal merger for studying merger-associated physical phenomena.
1008. MCS J1206.2-0847 galaxies spectral classification
ID:
ivo://CDS.VizieR/J/A+A/579/A4
Title:
MCS J1206.2-0847 galaxies spectral classification
Short Name:
J/A+A/579/A4
Date:
21 Oct 2021
Publisher:
CDS
Description:
In the effort to understand the link between the structure of galaxy clusters and their galaxy populations, we focus on MACS J1206.2-0847 at z~0.44 and probe its substructure in the projected phase space through the spectrophotometric properties of a large number of galaxies from the CLASH-VLT survey. Our analysis is mainly based on an extensive spectroscopic dataset of 445 member galaxies, mostly acquired with VIMOS@VLT as part of our ESO Large Programme, sampling the cluster out to a radius ~2R200 (4Mpc). We classify 412 galaxies as passive, with strong Hdelta absorption (red and blue galaxies), and with emission lines from weak to very strong. A number of tests for substructure detection are applied to analyze the galaxy distribution in the velocity space, in 2D space, and in 3D projected phase-space. The observational scenario agrees with MACS J1206.2-0847 having WNW-ESE as the direction of the main cluster accretion, traced by passive galaxies and red strong H{delta} galaxies. The red strong H{delta} galaxies, interpreted as poststarburst galaxies, date a likely important event 1-2Gyr before the epoch of observation. The emission line galaxies trace a secondary, ongoing infall where groups are accreted along several directions.
1009. M dwarf flare spectra
ID:
ivo://CDS.VizieR/J/ApJS/207/15
Title:
M dwarf flare spectra
Short Name:
J/ApJS/207/15
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a homogeneous analysis of line and continuum emission from simultaneous high-cadence spectra and photometry covering near-ultraviolet and optical wavelengths for 20 M dwarf flares. These data were obtained to study the white-light continuum components at bluer and redder wavelengths than the Balmer jump. Our goals were to break the degeneracy between emission mechanisms that have been fit to broadband colors of flares and to provide constraints for radiative-hydrodynamic (RHD) flare models that seek to reproduce the white-light flare emission. New model constraints are presented for the time evolution among the hydrogen Balmer lines and between CaII K and the blackbody continuum emission. We calculate Balmer jump flux ratios and compare to the solar-type flare heating predictions from RHD models. The model ratios are too large and the blue-optical ({lambda}=4000-4800{AA}) slopes are too red in both the impulsive and gradual decay phases of all 20 flares. This discrepancy implies that further work is needed to understand the heating at high column mass during dMe flares.
1010. M dwarfs at high spectral-resolution in Y band
ID:
ivo://CDS.VizieR/J/AJ/159/52
Title:
M dwarfs at high spectral-resolution in Y band
Short Name:
J/AJ/159/52
Date:
21 Oct 2021
Publisher:
CDS
Description:
In young Sun-like stars and field M-dwarf stars, chromospheric and coronal magnetic activity indicators such as H{alpha}, X-ray, and radio emission are known to saturate with low Rossby number (Ro<~0.1), defined as the ratio of rotation period to convective turnover time. The mechanism for the saturation is unclear. In this paper, we use photospheric TiI and CaI absorption lines in the Y band to investigate magnetic field strength in M dwarfs for Rossby numbers between 0.01 and 1.0. The equivalent widths of the lines are magnetically enhanced by photospheric spots, a global field, or a combination of the two. The equivalent widths behave qualitatively similar to the chromospheric and coronal indicators: we see increasing equivalent widths (increasing absorption) with decreasing Ro and saturation of the equivalent widths for Ro<~0.1. The majority of M dwarfs in this study are fully convective. The results add to mounting evidence that the magnetic saturation mechanism occurs at or beneath the stellar photosphere.