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2631. HK photometry in an UCHII region near Sh2-217
ID:
ivo://CDS.VizieR/J/A+A/527/A62
Title:
HK photometry in an UCHII region near Sh2-217
Short Name:
J/A+A/527/A62
Date:
21 Oct 2021
Publisher:
CDS
Description:
We study stars and gas in and around the HII region Sh 2-217 to see if the various physical parameters derived from the data (such as column densities, masses, sizes, and timescales) are consistent with the predictions of a simple model of the collect-and-collapse mechanism. This should indicate whether stars forming in molecular gas at the borders of the HII region could have been triggered by the expansion of the ionized gas. We observed the emission of various molecules and transitions towards Sh 2-217, and obtained both near-infrared photometry in the H and K bands, and near-infrared images in [FeII] and H2 narrow-band filters of the stars in a molecular condensation at the edge of the HII region, where an UC HII region is also located.
2632. HK photometry of rho Oph PMS stars
ID:
ivo://CDS.VizieR/J/A+A/485/155
Title:
HK photometry of rho Oph PMS stars
Short Name:
J/A+A/485/155
Date:
21 Oct 2021
Publisher:
CDS
Description:
Variability is a common characteristic of pre-main-sequence stars (PMS). Near-IR variability surveys of young stellar objects (YSOs) can probe stellar and circumstellar environments and provide information about the dynamics of the ongoing magnetic and accretion processes. Furthermore, variability can be used as a tool to uncover new cluster members in star formation regions. We hope to achieve the deepest near-IR variability study of YSOs targeting the rho Ophiuchi cluster. Fourteen epochs of observations were obtained with the Wide Field Camera (WFCAM) at the UKIRT telescope scheduled in a manner that allowed the study of variability on timescales of days, months, and years. Statistical tools, such as the multi-band cross correlation index and the reduced chi-square, were used to disentangle signals of variability from noise. Variability characteristics are compared to existing models of YSOs in order to relate them to physical processes, and then used to select new candidate members of this star-forming region. Variability in the near-IR is found to be present in 41% of the known population of rho Ophiuchi recovered in our sample. The behaviours shown are several and can be associated with the existence of spots on the stellar surface, variations in circumstellar extinction, or changes in the geometry of an accretion disc. Using variability, a new population of objects has been uncovered, that is believed to be part of the rho Ophiuchi cluster.
2633. HKs photometry in the Arches cluster
ID:
ivo://CDS.VizieR/J/A+A/501/563
Title:
HKs photometry in the Arches cluster
Short Name:
J/A+A/501/563
Date:
21 Oct 2021
Publisher:
CDS
Description:
The massive Arches cluster near the Galactic center should be an ideal laboratory for investigating massive star formation under extreme conditions. But it comes at a high price: the cluster is hidden behind several tens of magnitudes of visual extinction. Severe crowding requires space or AO-assisted instruments to resolve the stellar populations, and even with the best instruments interpreting the data is far from direct. Several investigations using NICMOS and the most advanced AO imagers on the ground revealed an overall top-heavy IMF for the cluster, with a very flat IMF near the center. There are several effects, however, that could potentially bias these results, in particular the strong differential extinction and the problem of transforming the observations into a standard photometric system in the presence of strong reddening. We present new observations obtained with the NAOS-Conica (NACO) AO-imager on the VLT. The problem of photometric transformation is avoided by working in the natural photometric system of NACO, and we use a Bayesian approach to determine masses and reddenings from the broad-band IR colors. A global value of Gamma=-1.1+/-0.2 for the high-mass end (M>10M_{sun}_) of the IMF is obtained, and we conclude that a power law of Salpeter slope cannot be discarded for the Arches cluster. The flattening of the IMF towards the center is confirmed, but is less severe than previously thought. We find Gamma=-0.88+/-0.20, which is incompatible with previous determinations. Within 0.4pc we derive a total mass of ~2.0(+/-0.6)x10^4^M_{sun}_ for the cluster and a central mass density rho=2(+/-0.4)x10^5^M_{sun}_/pc^3^ that confirms Arches as the densest known young massive cluster in the Milky Way.
2634. HLF photometric catalog in GOODS-S v2.0
ID:
ivo://CDS.VizieR/J/ApJS/244/16
Title:
HLF photometric catalog in GOODS-S v2.0
Short Name:
J/ApJS/244/16
Date:
21 Oct 2021
Publisher:
CDS
Description:
This manuscript describes the public release of the Hubble Legacy Fields (HLF) project photometric catalog for the extended GOODS-South region from the Hubble Space Telescope (HST) archival program AR-13252. The analysis is based on the version 2.0 HLF data release that now includes all ultraviolet (UV) imaging, combining three major UV surveys. The HLF data combines over a decade worth of 7475 exposures taken in 2635 orbits totaling 6.3Ms with the HST Advanced Camera for Surveys Wide Field Channel (ACS/WFC) and the Wide Field Camera 3 (WFC3) UVIS/IR Channels in the greater GOODS-S extragalactic field, covering all major observational efforts (e.g., GOODS, GEMS, CANDELS, ERS, UVUDF, and many other programs; see Illingworth+ arXiv:1606.00841). The HLF GOODS-S catalogs include photometry in 13 bandpasses from the UV (WFC3/UVIS F225W, F275W, and F336W filters), optical (ACS/WFC F435W, F606W, F775W, F814W and F850LP filters), to near-infrared (WFC3/IR F098M, F105W, F125W, F140W and F160W filters). Such a data set makes it possible to construct the spectral energy distributions (SEDs) of objects over a wide wavelength range from high-resolution mosaics that are largely contiguous. Here, we describe a photometric analysis of 186474 objects in the HST imaging at wavelengths 0.2-1.6{mu}m. We detect objects from an ultra-deep image combining the PSF-homogenized and noise-equalized F850LP, F125W, F140W, and F160W images, including Gaia astrometric corrections. SEDs were determined by carefully taking the effects of the point-spread function in each observation into account.
2635. H magnitude and radial velocities of A1644
ID:
ivo://CDS.VizieR/J/AJ/122/1289
Title:
H magnitude and radial velocities of A1644
Short Name:
J/AJ/122/1289
Date:
21 Oct 2021
Publisher:
CDS
Description:
We discuss H-band (1.65{mu}m) near-infrared photometry of the central 9h^-2^Mpc^2^ of Abell 1644 (A1644) to a limiting M_H_~M*_H_+3 (throughout this paper H_0_=100h*km/s/Mpc). here are 861 galaxies in the photometric survey region. We also measured radial velocities of 155 galaxies; 141 of these are cluster members within 2.44h^-1^Mpc of the cluster center.
2636. H-magnitudes of spiral galaxies
ID:
ivo://CDS.VizieR/J/ApJS/96/123
Title:
H-magnitudes of spiral galaxies
Short Name:
J/ApJS/96/123
Date:
21 Oct 2021
Publisher:
CDS
Description:
The H-magnitude aperture data published by the Aaronson et al. collaboration (See references) over a 10 year period is collected into a homogeneous data set of 1731 observations of 665 galaxies. Ninety-six percent of these galaxies have isophotal diameters and axial ratios determined by the Third Reference Catalogue of Bright Galaxies (RC3; de Vaucouleurs et al., 1991, Cat. <VII/155>), the most self-consistent set of optical data currently available. The precepts governing the optical data in the RC3 are systematically different from those of the Second Reference Catalogue (de Vaucouleurs, de Vaucouleurs, & Corwin 1976, Cat .<VII/112>), which were used by Aaronson et al. for their original analyses of galaxy peculiar motions. This in turn leads to systematic differences in growth curves and fiducial H-magnitudes, prompting the present recalibration of the near-infrared Tully-Fisher relationship. New optically normalized H-magnitude growth curves are defined for galaxies of types S0 to Im, from which new values of fiducial H-magnitude, H^g^_-0.5_, are measured for the 665 galaxies. A series of internal tests show that these four standard growth curves are defined to an accuracy of 0.05mag over the interval 1.5<=log(A/D_g_)<=-0.2. Comparisons with the Aaronson et al. values of diameters, axial ratios, and fiducial H-magnitudes show the expected differences, given the different definitions of these parameters. The values of H^g^_-0.5_ are assigned quality indices: a quality value of 1 indicates an accuracy of less than 0.2mag, quality 2 indicates an accuracy of 0.2-0.35mag, and quality 3 indicates an accuracy of more than 0.35mag. Revised values of corrected H I velocity widths are also given, based on the new set of axial ratios defined by the RC3.
2637. H narrow-band imaging of XMMU J2235.3-2557
ID:
ivo://CDS.VizieR/J/MNRAS/411/2009
Title:
H narrow-band imaging of XMMU J2235.3-2557
Short Name:
J/MNRAS/411/2009
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the first results of a narrow-band photometric study of the massive galaxy cluster XMMU J2235.3-2557 at z=1.39. We obtained deep H narrow-band imaging with the Near InfraRed Imager and Spectrometer on Gemini North, corresponding to H{alpha} emission at the cluster's redshift. Our sample consists of 82 galaxies within a radius of ~500kpc, 10 of which are spectroscopically confirmed cluster members. 16 galaxies are identified as excess line-emitters.
2638. H narrow-band imaging of XMMU J2235.3-2557
ID:
ivo://CDS.VizieR/J/MNRAS/423/3652
Title:
H narrow-band imaging of XMMU J2235.3-2557
Short Name:
J/MNRAS/423/3652
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of an extended narrow-band H{alpha} study of the massive galaxy cluster XMMU J2235.3-2557 at z=1.39. This paper represents a follow-up study to our previous investigation of star formation in the cluster centre, extending our analysis out to a projected cluster radius of 1.5Mpc. Using the Near InfraRed Imager and Spectrograph on Gemini North Telescope we obtained deep H narrow-band imaging corresponding to the rest-frame wavelength of H{alpha} at the cluster's redshift. We identify a total of 163 potential cluster members in both pointings, excluding stars based on their near-infrared colours derived from VLT/HAWK-I imaging. Of these 163 objects 14 are spectroscopically confirmed cluster members, and 20 per cent are excess line emitters. We find no evidence of star formation activity within a radius of 200 kpc of the brightest cluster galaxy in the cluster core. Dust-corrected star formation rates (SFRs) of excess emitters outside this cluster quenching radius, R_Q_~200kpc, are on average <SFR>=2.7+/-1.0M_{sun}_/yr, but do not show evidence of increasing SFRs towards the extreme 1.5Mpc radius of the cluster. No individual cluster galaxy exceeds an SFR of 6M_{sun}_/yr. Massive galaxies (logM*/M_{sun}_>10.75) all have low specific SFRs (SSFRs, i.e. SFR per unit stellar mass). At fixed stellar mass, galaxies in the cluster centre have lower SSFRs than the rest of the cluster galaxies, which in turn have lower SSFRs than field galaxies at the same redshift by a factor of a few to 10. For the first time we can demonstrate through measurements of individual SFRs that already at very early epochs (at an age of the Universe of ~4.5Gyr) the suppression of star formation is an effect of the cluster environment which persists at fixed galaxy stellar mass.
2639. HOBYS: 46 MDCs found in NGC 6334
ID:
ivo://CDS.VizieR/J/A+A/602/A77
Title:
HOBYS: 46 MDCs found in NGC 6334
Short Name:
J/A+A/602/A77
Date:
21 Oct 2021
Publisher:
CDS
Description:
To constrain models of high-mass star formation, the Herschel-HOBYS key program aims at discovering massive dense cores (MDCs) able to host the high-mass analogs of low-mass prestellar cores, which have been searched for over the past decade. We here focus on NGC 6334, one of the best-studied HOBYS molecular cloud complexes. We used Herschel/PACS and SPIRE 70-500{mu}m images of the NGC 6334 complex complemented with (sub)millimeter and mid-infrared data. We built a complete procedure to extract ~0.1pc dense cores with the getsources software, which simultaneously measures their far-infrared to millimeter fluxes. We carefully estimated the temperatures and masses of these dense cores from their spectral energy distributions (SEDs). We also identified the densest pc-scale cloud structures of NGC 6334, one 2pcx1pc ridge and two 0.8pcx0.8pc hubs, with volume-averaged densities of ~10^5^cm^-3^. A cross-correlation with high-mass star formation signposts suggests a mass threshold of 75M_{sun}_ for MDCs in NGC 6334. MDCs have temperatures of 9.5-40K, masses of 75-1000M_{sun}_, and densities of 1x10^5^-7x10^7^cm^-3^. Their mid-infrared emission is used to separate 6 IR-bright and 10 IR-quiet protostellar MDCs while their 70{mu}m emission strength, with respect to fitted SEDs, helps identify 16 starless MDC candidates. The ability of the latter to host high-mass prestellar cores is investigated here and remains questionable. An increase in mass and density from the starless to the IR-quiet and IR-bright phases suggests that the protostars and MDCs simultaneously grow in mass. The statistical lifetimes of the high-mass prestellar and protostellar core phases, estimated to be 1-7x10^4^yr and at most 3x10^5^yr respectively, suggest a dynamical scenario of high-mass star formation. The present study provides good mass estimates for a statistically significant sample, covering the earliest phases of high-mass star formation. High-mass prestellar cores may not exist in NGC 6334, favoring a scenario presented here, which simultaneously forms clouds, ridges, MDCs, and high-mass protostars.
2640. Hogg 16 peculiar stars
ID:
ivo://CDS.VizieR/J/other/NewA/58.1
Title:
Hogg 16 peculiar stars
Short Name:
J/other/NewA/58.
Date:
21 Oct 2021
Publisher:
CDS
Description:
The study of chemically peculiar (CP) stars in open clusters provides valuable information about their evolutionary status. Their detection can be performed using the Delta-a photometric system, which maps a characteristic flux depression at lambda 5200{AA}. This paper aims at studying the occurrence of CP stars in the earliest stages of evolution of a stellar population by applying this technique to Hogg 16, a very young Galactic open cluster (about 25Myr). We identified several peculiar candidates: two B-type stars with a negative Delta-a index (CD-60 4701, CPD-60 4706) are likely emission-line (Be) stars, even though spectral measurements are necessary for a proper classification of the second one; a third object (CD-60 4703), identified as a Be candidate in literature, appears to be a background B-type supergiant with no significant Delta-a index, which does not rule out the possibility that it is indeed peculiar as the normality line of Delta-a for supergiants has not been studied in detail yet. A fourth object (CD-60 4699) appears to be a magnetic CP star of 8 Msun, but obtained spectral data seem to rule out this hypothesis. Three more magnetic CP star candidates are found in the domain of early F-type stars. One is a probable nonmember and close to the border of significance, but the other two are probably pre-main sequence cluster objects. This is very promising, as it can lead to very strong constraints to the diffusion theory. Finally, we derived the fundamental parameters of Hogg 16 and provide for the first time an estimate of its metal content.