- ID:
- ivo://CDS.VizieR/J/A+A/507/227
- Title:
- NGC 7129 pre-main sequence stars
- Short Name:
- J/A+A/507/227
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The reflection nebula NGC 7129 has long been known to be a site of recent star formation as shown, e.g., by the presence of deeply embedded protostars and HH objects. However, studies of the stellar population produced in the star formation process have remained rudimentary. A major step forward has been made with recent Spitzer imaging of the region. This study represents the next step towards a systematic assessment of the pre-main sequence population in NGC 7129. Completeness of the pre-main sequence sample is necessary for studying key features that allow the star-forming process to be understood, such as disk evolution, dynamical evolution, and mass function. At a presumed age of ~3Myr, NGC 7129 is in the critical range where disks around young stars disappear.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/625/A100
- Title:
- NGC 1068 SPHERE-VLT images
- Short Name:
- J/A+A/625/A100
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Establishing precisely how stars and interstellar medium distribute within the central 100 pc area around an AGN, down to the pc scale, is key to understanding the late stages of transfer of matter onto the accretion disc. Using adaptive optics-assisted (SPHERE-VLT) near-IR images in the H band, Ks band, and several narrow bands of the Seyfert 2 galaxy NGC 1068, we analysed the radial distribution of brightness in the central r<100pc area down to the pc scale. The median-averaged radial profiles are fitted by a cusp (power law) plus a central point source. A simple radiative transfer model is also used to interpret the data. We find that the fit of radial brightness profiles beyond 10pc is done quite precisely at Ks band by a cusp of exponent -2.0 plus a central point source and by a cusp of exponent -1.2 at H. The difference of exponents between H band and Ks band can be explained by differential extinction, provided that the distribution of dust is itself cuspy, with an exponent -1.0. However, the derived stellar density is found to follow a r^-4^ cusp, which is much steeper than any other cusp, either theoretically predicted around a massive black hole, or observed in the centre of early- and late-type galaxies or in mergers. Introducing a segregation in the stellar population with a central excess of giant stars leads to a somewhat less steep exponent; however, the de-reddened luminosity of the stellar cusp, as well as the mass of dust and gas all appear much too high to be realistic. An alternative scenario, where the Ks-band profile is well fitted by a combination of radiation from a stellar cusp identical to the H-band profile and thermal emission ofwarm/hot dust heated by the central engine appears much more satisfactory. NGC 1068 is shown to satisfy a relationship between half-light radius, cusp luminosity, and exponent that we established using a sample of luminous infrared galaxies (LIRGs) and ultraluminous infrared galaxies ULIRGs. This suggests that the cusp is the remnant of a recent starburst. We identify the central point-like source with the very hot dust at the internal wall of the putative torus and derive an intrinsic luminosity that requires a central extinction A_K_~8, a value consistent with predictions by several torus models. The overall picture revealed by this study is closely consistent with the scheme of a central rather steep stellar cusp, embedded in a diluted medium of warm dust, while a compact and dense structure identified with the putative torus is required to interpret a highly reddened point-like central source of very hot dust.
- ID:
- ivo://CDS.VizieR/J/A+A/565/A4
- Title:
- NGC 891 70-500um images
- Short Name:
- J/A+A/565/A4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the connection between dust and gas in the nearby edge-on spiral galaxy NGC 891, a target of the Very Nearby Galaxies Survey. High resolution Herschel Space Observatory PACS and SPIRE 70, 100, 160, 250, 350, and 500 micron images are combined with JCMT SCUBA 850 micron observations to trace the far-infrared/submillimetre spectral energy distribution (SED). Maps of the HI 21cm line and CO(J=3-2) emission trace the atomic and molecular hydrogen gas, respectively. We fit one-component modified blackbody models to the integrated SED, finding a global dust mass of (8.5+/-2.0)x10^7^M_{sun}_ and an average temperature of 23+/-2K, consistent with results from previous far-infrared experiments. We also fit one-component modified blackbody models to pixel-by-pixel SEDs to produce maps of the dust mass and temperature. A comparison of the dust properties with the gaseous components of the ISM reveals strong spatial correlations between the surface mass densities of dust and the molecular hydrogen and total gas surface densities.
- ID:
- ivo://CDS.VizieR/J/AJ/140/266
- Title:
- NGC 1333 X-ray luminous YSOs properties
- Short Name:
- J/AJ/140/266
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new Chandra X-ray data of the NGC 1333 embedded cluster and combine these data with existing Chandra data, Spitzer photometry, and ground-based spectroscopy of both the NGC 1333 and Serpens cloud core clusters to perform a detailed study of the X-ray properties of two of the nearest embedded clusters to the Sun. We first present new, deeper observations of NGC 1333 with Chandra ACIS-I and combine these with existing Spitzer observations of the region. In NGC 1333, a total of 95 cluster members are detected in X-rays of which 54 were previously identified in the Spitzer data.
- ID:
- ivo://CDS.VizieR/J/A+A/593/A7
- Title:
- NH and AV Towards YSOs in the ONC
- Short Name:
- J/A+A/593/A7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We characterise the relation between the gas and dust content of the interstellar medium towards young stellar objects in the Orion Nebula Cluster. X-ray observations provide estimates of the absorbing equivalent hydrogen column density NH based on spectral fits. Near-infrared extinction values are calculated from intrinsic and observed colour magnitudes (J-H) and (H-Ks) as given by the VISTA Orion A survey. A linear fit of the correlation between column density and extinction values AV yields an estimate of the N_H_/A_V_ ratio. We investigate systematic uncertainties of the results by describing and (if possible) quantifying the influence of circumstellar material as well as the adopted extinction law, X-ray models, and elemental abundances on the NH/AV ratio. Assuming a Galactic extinction law with R_V=3.1 and solar abundances by Anders et al. (1989), we deduce an N_H_/A_V_ ratio of (1.39+/-0.14)*10^21cm^-2^.mag^-1^ for Class III sources in the Orion Nebula Cluster, where the given error does not include systematic uncertainties. This ratio is consistent with similar studies in other star-forming regions and approximately 31% lower than the Galactic value. We find no obvious trends in the spatial distribution of N_H_/A_V_ ratios. Changes in the assumed extinction law and elemental abundances are demonstrated to have a relevant impact on deduced A_V_ and N_H_ values, respectively. Large systematic uncertainties associated with metal abundances in the Orion Nebula Cluster represent the primary limitation for the deduction of a definitive N_H_/A_V_ ratio and the physical interpretation of these results.
- ID:
- ivo://CDS.VizieR/J/AJ/127/131
- Title:
- NICMOS early-type galaxies
- Short Name:
- J/AJ/127/131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Here we report results for two subsamples of early-type galaxies, defined primarily by their morphologies in the F160W band, which were selected from the NICMOS data down to H160AB<24.0. A primary subsample is defined as the 34 galaxies with early-type galaxy morphologies and early-type galaxy spectral energy distributions. The secondary subsample is defined as those 42 objects that have early-type galaxy morphologies with non-early-type galaxy spectral energy distributions.
- ID:
- ivo://CDS.VizieR/J/ApJS/164/307
- Title:
- NICMOS observations of 3CR radio sources
- Short Name:
- J/ApJS/164/307
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present newly acquired images of the near-infrared counterpart of 3CR radio sources. All the sources were selected to have a redshift of less than 0.3 to allow us to obtain the highest spatial resolution. The observations were carried out as a snapshot program using the Near-Infrared Camera and Multiobject Spectrograph (NICMOS) on-board the Hubble Space Telescope (HST). In this paper we describe 69 radio galaxies observed for the first time with NICMOS during HST cycle 13. All the objects presented here are elliptical galaxies. However, each of them has unique characteristics such as close companions, dust lanes, unresolved nuclei, arclike features, globular clusters, and jets clearly visible from the images or with basic galaxy subtraction.
- ID:
- ivo://CDS.VizieR/J/ApJ/819/69
- Title:
- [NII]205um emission in local luminous IR galaxies
- Short Name:
- J/ApJ/819/69
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we present the measurements of the [NII]205{mu}m line for a flux-limited sample of 122 (ultra-)luminous infrared galaxies [(U)LIRGs] and 20 additional normal galaxies, obtained with the Herschel Space Observatory (Herschel). We explore the far-infrared (FIR) color dependence of the [NII]205{mu}m (L_[NII]205{mu}m_) to the total infrared (L_IR_) luminosity ratio, and find that L_[NII]205{mu}m_/L_IR_ only depends modestly on the 70-160{mu}m flux density ratio (f70/f160) when f70/f160<~0.6, whereas such dependence becomes much steeper for f70/f160>0.6. We also investigate the relation between L_[NII]205{mu}m_ and star formation rate (SFR), and show that L_[NII]205{mu}m_ has a nearly linear correlation with SFR, albeit the intercept of such a relation varies somewhat with f60/f100, consistent with our previous conclusion that [NII]205{mu}m emission can serve as an SFR indicator with an accuracy of ~0.4dex, or ~0.2dex if f60/f100 is known independently. Furthermore, together with the Infrared Space Observatory measurements of [NII], we use a total of ~200 galaxies to derive the local [NII]205{mu}m luminosity function (LF) by tying it to the known IR LF with a bivariate method. As a practical application, we also compute the local SFR volume density ({rho}_SFR_) using the newly derived SFR calibrator and LF. The resulting log{rho}_SFR_=-1.96+/-0.11M_{sun}_/yr/Mpc^3^ agrees well with previous studies. Finally, we determine the electron densities (n_e_) of the ionized medium for a subsample of 12 (U)LIRGs with both [NII]205{mu}m and [NII]122{mu}m data, and find that n_e_ is in the range of ~1-100/cm^3^, with a median value of 22/cm^3^.
- ID:
- ivo://CDS.VizieR/J/ApJ/761/22
- Title:
- NIR galaxy cluster candidates in the SPT survey
- Short Name:
- J/ApJ/761/22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of the ground- and space-based optical and near-infrared (NIR) follow-up of 224 galaxy cluster candidates detected with the Sunyaev-Zel'dovich (SZ) effect in the 720deg^2^ of the South Pole Telescope (SPT) survey completed in the 2008 and 2009 observing seasons. We use the optical/NIR data to establish whether each candidate is associated with an overdensity of galaxies and to estimate the cluster redshift. Most photometric redshifts are derived through a combination of three different cluster redshift estimators using red-sequence galaxies, resulting in an accuracy of {Delta}z/(1+z)=0.017, determined through comparison with a subsample of 57 clusters for which we have spectroscopic redshifts. We successfully measure redshifts for 158 systems and present redshift lower limits for the remaining candidates. The redshift distribution of the confirmed clusters extends to z=1.35 with a median of z_med_=0.57. Approximately 18% of the sample with measured redshifts lies at z>0.8. We estimate a lower limit to the purity of this SPT SZ-selected sample by assuming that all unconfirmed clusters are noise fluctuations in the SPT data. We show that the cumulative purity at detection significance {xi}>5 ({xi}>4.5) is >=95% (>=70%). We present the red brightest cluster galaxy (rBCG) positions for the sample and examine the offsets between the SPT candidate position and the rBCG. The radial distribution of offsets is similar to that seen in X-ray-selected cluster samples, providing no evidence that SZ-selected cluster samples include a different fraction of recent mergers from X-ray-selected cluster samples.
- ID:
- ivo://CDS.VizieR/J/A+A/523/A16
- Title:
- NIR imaging of HH 223
- Short Name:
- J/A+A/523/A16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The dark cloud Lynds 723 (L723) is a low-mass star-forming region where one of the few known cases of a quadrupolar CO outflow has been reported. Two recent works have found that the radio continuum source VLA 2, towards the centre of the CO outflow, is actually a multiple system of young stellar objects (YSOs). We imaged a field of 5'x 5' centred on HH 223, which includes the whole region of the quadrupolar CO outflow with narrow-band filters centred on the [FeII] 1.644mum and H_2_ 2.122mum lines, together with off-line H_c_ and K_c_ filters. Our aim is to study L723 in the near-infrared and look for line-emission nebulae associated with the optical and CO outflows.
