- ID:
- ivo://CDS.VizieR/J/MNRAS/417/114
- Title:
- HST/NICMOS Galactic Center survey catalogue
- Short Name:
- J/MNRAS/417/114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Our Hubble Space Telescope/Near-Infrared Camera and Multi-Object Spectrometer (HST/NICMOS) Paschen {alpha} survey of the Galactic Centre, first introduced by Wang et al. (2010MNRAS.402..895W), provides a uniform, panoramic, high-resolution map of stars and an ionized diffuse gas in the central 416arcmin^2^ of the Galaxy. This survey was carried out with 144 HST orbits using two narrow-band filters at 1.87 and 1.90um in NICMOS Camera 3. In this paper, we describe in detail the data reduction and mosaicking procedures followed, including background level matching and astrometric corrections. We have detected ~570000 near-infrared (near-IR) sources using the 'starfinder' software and are able to quantify photometric uncertainties of the detections.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/534/A10
- Title:
- HST/NICMOS III imaging in Orion Nebula Cluster
- Short Name:
- J/A+A/534/A10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep HST/NICMOS Camera 3 F110W and F160W imaging of a 26'x33', corresponding to 3.1x3.8pc^2^, non-contiguous field towards the Orion Nebula Cluster (ONC). The main aim is to determine the ratio of low-mass stars to brown dwarfs for the cluster as a function of radius out to a radial distance of 1.5pc. The sensitivity of the data outside the nebulous central region is F160W<=21.0mag, significantly deeper than previous studies of the region over a comparable area. We create an extinction limited sample and determine the ratio of low-mass stars (0.08-1M_{sun}_) to brown dwarfs (0.02-0.08M_{sun}_ and 0.03-0.08M_{sun}_) for the cluster as a whole and for several annuli. The ratio found for the cluster within a radius of 1.5pc is R_02_=N(0.08-1M_{sun}_)/N(0.02-0.08M_{sun}_)=1.7+/-0.2, and R_03_=N(0.08-1M_{sun}_)/N(0.03-0.08M_{sun}_)=2.4+/-0.2, after correcting for field stars. The ratio for the central 0.3x0.3pc^2^ region down to 0.03M_{sun}_ was previously found to be R_03_=3.3^+0.8^_-0.7_, suggesting the low-mass content of the cluster is mass segregated. We discuss the implications of a gradient in the ratio of stars to brown dwarfs in the ONC in the context of previous measurements of the cluster and for other nearby star forming regions. We further discuss the current evidence for variations in the low-mass IMF and primordial mass segregation.
- ID:
- ivo://CDS.VizieR/J/ApJ/730/125
- Title:
- HST/NICMOS observations of bright IR galaxies
- Short Name:
- J/ApJ/730/125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new results on the physical nature of infrared-luminous sources at 0.5<z<2.8 as revealed by HST/NICMOS imaging and Infrared Spectrograph mid-infrared spectroscopy. Our sample consists of 134 galaxies selected at 24um with a flux of S(24um)>0.9mJy. We find many (~60%) of our sources to possess an important bulge and/or central point source component, most of which reveal additional underlying structures after subtraction of a best-fit Sersic (or Sersic+PSF) profile. Based on visual inspection of the NIC2 images and their residuals, we estimate that ~80% of all our sources are mergers. We calculate lower and upper limits on the merger fraction to be 62% and 91%, respectively. At z<1.5, we observe objects in early (pre-coalescence) merging stages to be mostly disk and star formation dominated, while we find mergers to be mainly bulge dominated and active galactic nucleus (AGN)-starburst composites during coalescence and then AGN dominated in late stages. This is analogous to what is observed in local ULIRGs. Finally, we observe obscured ({tau}_9.7um_>3.36) quasars to live in faint and compact hosts and show that these are likely high-redshift analogs of local dense-core mergers. We find late-stage mergers to possess predominantly unobscured AGN spectra, but do not observe other morphological classes to carry any specific combination of {tau}_9.7um_ and polycyclic aromatic hydrocarbon (PAH) equivalent width.
- ID:
- ivo://CDS.VizieR/J/ApJ/876/85
- Title:
- HST observations for LMC Cepheids
- Short Name:
- J/ApJ/876/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an improved determination of the Hubble constant from Hubble Space Telescope (HST) observations of 70 long-period Cepheids in the Large Magellanic Cloud (LMC). These were obtained with the same WFC3 photometric system used to measure extragalactic Cepheids in the hosts of SNe Ia. Gyroscopic control of HST was employed to reduce overheads while collecting a large sample of widely separated Cepheids. The Cepheid period-luminosity relation provides a zero-point-independent link with 0.4% precision between the new 1.2% geometric distance to the LMC from detached eclipsing binaries (DEBs) measured by Pietrzynski+ (2019Natur.567..200P) and the luminosity of SNe Ia. Measurements and analysis of the LMC Cepheids were completed prior to knowledge of the new DEB LMC distance. Combined with a refined calibration of the count-rate linearity of WFC3-IR with 0.1% precision, these three improved elements together reduce the overall uncertainty in the geometric calibration of the Cepheid distance ladder based on the LMC from 2.5% to 1.3%. Using only the LMC DEBs to calibrate the ladder, we find H_0_=74.22+/-1.82km/s/Mpc including systematic uncertainties, 3% higher than before for this particular anchor. Combining the LMC DEBs, masers in NGC 4258, and Milky Way parallaxes yields our best estimate: H_0_=74.03+/-1.42km/s/Mpc, including systematics, an uncertainty of 1.91%-15% lower than our best previous result. Removing any one of these anchors changes H0 by less than 0.7%. The difference between H0 measured locally and the value inferred from Planck CMB and {Lambda}CDM is 6.6+/-1.5km/s/Mpc or 4.4{sigma} (P=99.999% for Gaussian errors) in significance, raising the discrepancy beyond a plausible level of chance. We summarize independent tests showing that this discrepancy is not attributable to an error in any one source or measurement, increasing the odds that it results from a cosmological feature beyond {Lambda}CDM.
- ID:
- ivo://CDS.VizieR/J/ApJ/746/88
- Title:
- HST observations of GCs in NGC 1399
- Short Name:
- J/ApJ/746/88
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We combine new Wide Field Camera 3 IR Channel (WFC3/IR) F160W (H_160_) imaging data for NGC 1399, the central galaxy in the Fornax cluster, with archival F475W (g_475_), F606W (V_606_), F814W (I_814_), and F850LP (z _850_) optical data from the Advanced Camera for Surveys (ACS). The purely optical g_475_-I_814_, V_606_-I_814_, and g_475_-z_850_colors of NGC 1399's rich globular cluster (GC) system exhibit clear bimodality, at least for magnitudes I_814_>21.5. The optical-IR I_814_-H_160_ color distribution appears unimodal, and this impression is confirmed by mixture modeling analysis. The V_606_-H_160_ colors show marginal evidence for bimodality, consistent with bimodality in V_606_-I_814_ and unimodality in I_814_-H_160_.
- ID:
- ivo://CDS.VizieR/J/ApJ/742/68
- Title:
- HST observations of low-mass BH host galaxies
- Short Name:
- J/ApJ/742/68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using Hubble Space Telescope observations of 147 host galaxies of low-mass black holes (BHs), we systematically study the structures and scaling relations of these active galaxies. Our sample is selected to have central BHs with virial masses of ~10^5^-10^6^M_{sun}_. The host galaxies have total I-band magnitudes of -23.2<M_I_<-18.8mag and bulge magnitudes of -22.9<M_I_<-16.1mag. Detailed bulge-disk-bar decompositions with GALFIT show that 93% of the galaxies have extended disks, 39% have bars, and 5% have no bulges at all at the limits of our observations. Based on the Sersic index and bulge-to-total ratio, we conclude that the majority of the galaxies with disks are likely to contain pseudobulges and very few of these low-mass BHs live in classical bulges. The fundamental plane of our sample is offset from classical bulges and ellipticals in a way that is consistent with the scaling relations of pseudobulges. The sample has smaller velocity dispersion at fixed luminosity in the Faber-Jackson plane compared with classical bulges and elliptical galaxies. The galaxies without disks are structurally more similar to spheroidals than to classical bulges according to their positions in the fundamental plane, especially the Faber-Jackson projection. Overall, we suggest that BHs with mass <~10^6^M_{sun}_ live in galaxies that have evolved secularly over the majority of their history. A classical bulge is not a prerequisite to host a BH.
- ID:
- ivo://CDS.VizieR/J/AJ/142/187
- Title:
- HST observations of 7 Pop.II variable stars
- Short Name:
- J/AJ/142/187
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new absolute trigonometric parallaxes and proper motions for seven Population II variable stars - five RR Lyr variables: RZ Cep, XZ Cyg, SU Dra, RR Lyr, and UV Oct; and two type 2 Cepheids: VY Pyx and {kappa} Pav. We obtained these results with astrometric data from Fine Guidance Sensors, white-light interferometers on Hubble Space Telescope. We find absolute parallaxes in milliseconds of arc: RZ Cep, 2.12+/-0.16mas; XZ Cyg, 1.67+/-0.17mas; SU Dra, 1.42+/-0.16mas; RR Lyr, 3.77+/-0.13mas; UV Oct, 1.71+/-0.10mas; VY Pyx, 6.44+/-0.23mas; and {kappa} Pav, 5.57+/-0.28mas; an average {sigma}_{pi}_/{pi}=5.4%. With these parallaxes, we compute absolute magnitudes in V and K bandpasses corrected for interstellar extinction and Lutz-Kelker-Hanson bias. Using these RR Lyrae variable star absolute magnitudes, we then derive zero points for M_V_-[Fe/H] and M_K_-[Fe/H]-logP relations. The technique of reduced parallaxes corroborates these results. We employ our new results to determine distances and ages of several Galactic globular clusters and the distance of the Large Magellanic Cloud. The latter is close to that previously derived from Classical Cepheids uncorrected for any metallicity effect, indicating that any such effect is small. We also discuss the somewhat puzzling results obtained for our two type 2 Cepheids.
- ID:
- ivo://CDS.VizieR/J/ApJ/826/32
- Title:
- HST observations of star clusters in NGC 3256
- Short Name:
- J/ApJ/826/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use the Advanced Camera for Surveys on the Hubble Space Telescope to study the rich population of young massive star clusters in the main body of NGC 3256, a merging pair of galaxies with a high star formation rate (SFR) and SFR per unit area ({Sigma}_SFR_). These clusters have luminosity and mass functions that follow power laws, dN/dL{propto}L^{alpha}^ with {alpha}=-2.23+/-0.07, and dN/dM{propto}M^{beta}^ with {beta}=-1.86+/-0.34 for {tau}<10Myr clusters, similar to those found in more quiescent galaxies. The age distribution can be described by dN/d{tau}{propto}{tau}^{gamma}^, with {gamma}~-0.67+/-0.08 for clusters younger than about a few hundred million years, with no obvious dependence on cluster mass. This is consistent with a picture where ~80% of the clusters are disrupted each decade in time. We investigate the claim that galaxies with high {Sigma}_SFR_ form clusters more efficiently than quiescent systems by determining the fraction of stars in bound clusters ({Gamma}) and the CMF/SFR statistic (CMF is the cluster mass function) for NGC 3256 and comparing the results with those for other galaxies. We find that the CMF/SFR statistic for NGC 3256 agrees well with that found for galaxies with {Sigma}_SFR_ and SFRs that are lower by 1-3 orders of magnitude, but that estimates for {Gamma} are only robust when the same sets of assumptions are applied. Currently, {Gamma} values available in the literature have used different sets of assumptions, making it more difficult to compare the results between galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/886/99
- Title:
- HST obs. in the region of 3 young LMC SNIa remnants
- Short Name:
- J/ApJ/886/99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used two methods to search for surviving companions of Type Ia supernova progenitors in three Balmer-dominated supernova remnants in the Large Magellanic Cloud: 0519-69.0, 0505-67.9 (DEM L71), and 0548-70.4. In the first method, we use the Hubble Space Telescope photometric measurements of stars to construct color-magnitude diagrams (CMDs) and compare positions of stars in the CMDs with those expected from theoretical post-impact evolution of surviving main-sequence or helium star companions. No obvious candidates of surviving companions are identified in this photometric search. Future models for surviving red giant companions or with different explosion mechanisms are needed for thorough comparisons with these observations in order to make more definitive conclusions. In the second method, we use Multi Unit Spectroscopic Explorer observations of 0519-69.0 and DEM L71 to carry out spectroscopic analyses of stars in order to use large peculiar radial velocities as diagnostics of surviving companions. We find a star in 0519-69.0 and a star in DEM L71 moving at radial velocities of 182+/-0km/s and 213+/-0km/s, respectively, more than 2.5{sigma} from the mean radial velocity of the underlying stellar population, 264 and 270km/s, respectively. These stars need higher-quality spectra to investigate their abundances and rotation velocities to determine whether they are indeed surviving companions of the supernova progenitors.
- ID:
- ivo://CDS.VizieR/J/ApJ/857/67
- Title:
- HST obs. of Mira candidates in NGC 4258
- Short Name:
- J/ApJ/857/67
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present year-long, near-infrared (NIR) Hubble Space Telescope (HST) WFC3 observations of Mira variables in the water megamaser host galaxy NGC 4258. Miras are asymptotic giant branch variables that can be divided into oxygen- (O-) and carbon- (C-) rich subclasses. Oxygen-rich Miras follow a tight (scatter ~0.14mag) period-luminosity relation (PLR) in the NIR and can be used to measure extragalactic distances. The water megamaser in NGC 4258 gives a geometric distance to the galaxy accurate to 2.6% that can serve to calibrate the Mira PLR. We develop criteria for detecting and classifying O-rich Miras with optical and NIR data as well as NIR data alone. In total, we discover 438 Mira candidates that we classify with high confidence as O-rich. Our most stringent criteria produce a sample of 139 Mira candidates that we use to measure a PLR. We use the OGLE-III sample of O-rich Miras in the Large Magellanic Cloud to obtain a relative distance modulus, {mu}_4258_-{mu}_LMC_=10.95+/-0.01 (statistical) +/-0.06 (systematic) mag, that is statistically consistent with the relative distance determined using Cepheids. These results demonstrate the feasibility of discovering and characterizing Miras using the NIR with the HST and the upcoming James Webb Space Telescope and using those Miras to measure extragalactic distances and determine the Hubble constant.
