- ID:
- ivo://CDS.VizieR/J/A+A/638/A111
- Title:
- HST/ACS photometry of KKH22 and KKH34
- Short Name:
- J/A+A/638/A111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present observations with the Advanced Camera for Surveys on the Hubble Space Telescope of the nearby dwarf spheroidal galaxy KKH 22 = LEDA 2807114 in the vicinity of massive spiral galaxy IC 342. We derived its distance of 3.12+/-0.19Mpc using the Tip of Red Giant Branch method. We also use the 6-m BTA spectroscopy to measure a heliocentric radial velocity of globular cluster in KKH 22 to be +30+/-10km/s. The dSph galaxy KKH 22 has the V-band absolute magnitude of -12.19mag and the central surface brightness {mu}_v,0_=24.1mag/arcsec^2^. Both the velocity and the distance of KKH 22 are consistent with the dSph galaxy being gravitationally bound to IC 342. Another nearby dIr galaxy, KKH 34, with a low heliocentric velocity of +106km/s has the TRGB distance of 7.28+/-0.36Mpc residing in the background respect to the IC 342 group. KKH 34 has surprisinly high negative peculiar velocity of -236+/-26km/s.
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- ID:
- ivo://CDS.VizieR/J/ApJ/738/186
- Title:
- HST and DEIMOS measurements of NGC 2419 stars
- Short Name:
- J/ApJ/738/186
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the analysis of a kinematic data set of stars in the globular cluster NGC 2419, taken with the DEep Imaging Multi-Object Spectrograph at the Keck II telescope. Combined with a reanalysis of deep Hubble Space Telescope and Subaru Telescope imaging data, which provide an accurate luminosity profile of the cluster, we investigate the validity of a large set of dynamical models of the system, which are checked for stability via N-body simulations.
- ID:
- ivo://CDS.VizieR/J/ApJ/499/112
- Title:
- HST CFRS and LDSS redshift surveys. I.
- Short Name:
- J/ApJ/499/112
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze Hubble Space Telescope images of a complete sample of 341 galaxies drawn from the Canada-France Redhsift Survey (CFRS) and Low-Dispersion Survey Spectrograph (LDSS) ground-based redshift surveys. In this, the first paper in the series, each galaxy has been morphologically classified according to a scheme similar to that developed for the Medium Deep Survey. We discuss the reproducibility of these classifications and quantify possible biases that may arise from various redshift-dependent effects. We then discuss automated classifications of the sample and conclude, from several tests, that we can expect an apparent migration with redshift to later Hubble types that corresponds to a misclassification in our adopted machine classification system of ~24%+/-11 of the true "spirals" as "peculiars" at a redshift z~=0.9. After allowing for such biases, the redshift distribution for normal spirals, together with their luminosity function derived as a function of redshift, indicates approximately 1mag of luminosity evolution in B_AB_ by z~=1. The elliptical sample is too small for precise evolutionary constraints. However, we find a substantial increase in the proportion of galaxies with irregular morphology at large redshift from 9%+/-3% for 0.3<=z<=0.5 to 32%+/-12% for 0.7<=z<=0.9. These galaxies also appear to be the dominant cause of the rapid rise with redshift in the blue luminosity density identified in the redshift surveys. Although galaxies with irregular morphology may well comprise a mixture of different physical systems and might not correspond to present-day irregulars, it is clear that the apparently declining abundance and luminosities of our distant "irregulars" holds an important key to understanding recent evolution in the star formation history of normal galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/623/A82
- Title:
- HST/COS and FUSE UV spectra of Mrk 509
- Short Name:
- J/A+A/623/A82
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To elucidate the location, physical conditions, mass outflow rate, and kinetic luminosity of the outflow from the active nucleus of the Seyfert 1 galaxy Mrk 509 we used coordinated ultraviolet and X-ray spectral observations in 2012 to followup our lengthier campaign conducted in 2009. We observed Mrk 509 with the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST) on 2012-09-03 and 2012-10-11 coordinated with X-ray observations using the High Energy Transmission Grating on the Chandra X-ray Observatory. Our far-ultraviolet spectra used grating G140L on COS to cover wavelengths from 920-2000{AA} at a resolving power of 2000, and gratings G130M and G160M to cover 1160-1750{AA} at a resolving power of 15000. We detect variability in the blue-shifted UV absorption lines on timescales spanning 3-12 years. The inferred densities in the absorbing gas are greater than logn[cm^-3^]~3. For ionization parameters ranging over logU=-1.5 to -0.2, we constrain the distances of the absorbers to be closer than 220pc to the active nucleus. The impact on the host galaxy appears to be confined to the nuclear region.
- ID:
- ivo://CDS.VizieR/J/ApJ/804/79
- Title:
- HST/COS observations of QSOs within 600kpc of M31
- Short Name:
- J/ApJ/804/79
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We demonstrate the presence of an extended and massive circumgalactic medium (CGM) around Messier 31 using archival HST Cosmic Origins Spectrograph ultraviolet spectroscopy of 18 QSOs projected within two virial radii of M31 (R_vir_=300kpc). We detect absorption from SiIII at -300<~V_LSR_<~-150km/s toward all three sightlines at R<~0.2R_vir_, 3 of 4 sightlines at 0.8<~R/R_vir_<~1.1, and possibly 1 of 11 at 1.1<R/R_vir_<~1.8. We present several arguments that the gas at these velocities observed in these directions originates from the M31 CGM rather than the Local Group or Milky Way CGM or Magellanic Stream. We show that the dwarf galaxies located in the CGM of M31 have very similar velocities over similar projected distances from M31. We find a non-trivial relationship only at these velocities between the column densities (N) of all the ions and R, whereby N decreases with increasing R. At R<0.8R_vir_, the covering fraction is close to unity for Si III and C IV (f_c_~60%-97% at the 90% confidence level), but drops to f_c_<~10%-20% at R>~R_vir_. We show that the M31 CGM gas is bound, multiphase, predominantly ionized, and is more highly ionized gas at larger R. We estimate using Si II, Si III, and Si IV, a CGM metal mass of >~2x10^6^M_{sun}_ and gas mass of >~3x10^9^(Z_{sun}_/Z)M_{sun}_ within 0.2R_vir_, and possibly a factor of ~10 larger within R_vir_, implying substantial metal and gas masses in the CGM of M31.
- ID:
- ivo://CDS.VizieR/J/ApJ/823/49
- Title:
- HST/COS observations of 7 white dwarfs
- Short Name:
- J/ApJ/823/49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The search for transiting habitable exoplanets has broadened to include several types of stars that are smaller than the Sun in an attempt to increase the observed transit depth and hence the atmospheric signal of the planet. Of all spectral types, white dwarfs (WDs) are the most favorable for this type of investigation. The fraction of WDs that possess close-in rocky planets is unknown, but several large angle stellar surveys have the photometric precision and cadence to discover at least one if they are common. Ultraviolet observations of WDs may allow for detection of molecular oxygen or ozone in the atmosphere of a terrestrial planet. We use archival Hubble Space Telescope data from the Cosmic Origins Spectrograph to search for transiting rocky planets around UV-bright WDs. In the process, we discovered unusual variability in the pulsating WD GD 133, which shows slow sinusoidal variations in the UV. While we detect no planets around our small sample of targets, we do place stringent limits on the possibility of transiting planets, down to sub-lunar radii. We also point out that non-transiting small planets in thermal equilibrium are detectable around hotter WDs through infrared excesses, and identify two candidates.
- ID:
- ivo://CDS.VizieR/J/ApJS/249/15
- Title:
- HST/COS obs. of QSO outflows in 500-1050{AA}. VII.
- Short Name:
- J/ApJS/249/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From Hubble Space Telescope/Cosmic Origins Spectrograph spectra of five quasars, 16 outflows are detected. For 11 outflows, we are able to constrain their distances to the central source (R) and their energetics. In instances of multiple electron number density determinations (used in the calculation of R) for the same outflow, the values are consistent within errors. For the 11 outflows, eight have measurements for R (between 10 and 1000pc), one has a lower limit, another has an upper limit, and the last has a range in R. There are two outflows that have enough kinetic luminosity to be major contributors to active galactic nucleus feedback. The outflowing mass is found primarily in a very high-ionization phase, which is probed using troughs from, e.g., Ne VIII, Na IX, Mg X, and Si XII. Such ions connect the physical conditions of these ultraviolet outflows to the X-ray warm absorber outflows seen in nearby Seyfert galaxies. The ion Cl VII and several new transitions from Ne V have been detected for the first time.
- ID:
- ivo://CDS.VizieR/J/ApJ/871/35
- Title:
- HST/COS spectra of QSOs with SiIV data
- Short Name:
- J/ApJ/871/35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Every quasar (quasi-stellar object; QSO) spectrum contains absorption-line signatures from the interstellar medium, disk-halo interface, and circumgalactic medium (CGM) of the Milky Way (MW). We analyze Hubble Space Telescope/Cosmic Origins Spectrograph (COS) spectra of 132 QSOs to study the significance and origin of SiIV absorption at |v_LSR_|<=100km/s in the Galactic halo. The gas in the north predominantly falls in at -50<~v_LSR_<~0km/s, whereas in the south, no such pattern is observed. The SiIV column density has an average and a standard deviation of <N_SiIV_>=(3.8+/-1.4)x10^13^cm^-2^. At |b|>~30{deg}, N_SiIV_ does not significantly correlate with b, which cannot be explained by a commonly adopted flat-slab geometry. We propose a two-component model to reconstruct the N_SiIV_-b distribution: a plane-parallel component N_DH_^{perp}^ to account for the MW's disk-halo interface and a global component N_G_ to reproduce the weak dependence on b. We find N_DH_^{perp}^=1.3_-0.7_^+4.7^x10^12^cm^-2^ and N_G_=3.4+/-0.3)x10^13^cm^-2^ on the basis of Bayesian analyses and block bootstrapping. The global component is most likely to have a Galactic origin, although its exact location is uncertain. If it were associated with the MW's CGM, we would find M_gas,all_>~ 4.7x10^9^M_{sun}_(C_f_/1)(R/75kpc)^2^(f_SiIV_/0.3)^-1^(Z/0.3Z_{sun}_)^-1^ for the cool gas at all velocities in the Galactic halo. Our analyses show that there is likely a considerable amount of gas at |v_LSR_|<=100km/s hidden in the MW's CGM.
- ID:
- ivo://CDS.VizieR/J/ApJS/230/6
- Title:
- HST -COS & -STIS absorption-line spectroscopy. II.
- Short Name:
- J/ApJS/230/6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present basic data and modeling for a survey of the cool, photoionized circumgalactic medium (CGM) of low-redshift galaxies using far-UV QSO absorption-line probes. This survey consists of "targeted" and "serendipitous" CGM subsamples, originally described in Stocke+ (Paper I, 2013ApJ...763..148S). The targeted subsample probes low-luminosity, late-type galaxies at z<0.02 with small impact parameters (<{rho}>=71kpc), and the serendipitous subsample probes higher luminosity galaxies at z<~0.2 with larger impact parameters (<{rho}>=222kpc). Hubble Space Telescope and FUSE UV spectroscopy of the absorbers and basic data for the associated galaxies, derived from ground-based imaging and spectroscopy, are presented. We find broad agreement with the COS-Halos results, but our sample shows no evidence for changing ionization parameter or hydrogen density with distance from the CGM host galaxy, probably because the COS-Halos survey probes the CGM at smaller impact parameters. We find at least two passive galaxies with HI and metal-line absorption, confirming the intriguing COS-Halos result that galaxies sometimes have cool gas halos despite no on-going star formation. Using a new methodology for fitting HI absorption complexes, we confirm the CGM cool gas mass of Paper I, but this value is significantly smaller than that found by the COS-Halos survey. We trace much of this difference to the specific values of the low-z metagalactic ionization rate assumed. After accounting for this difference, a best-value for the CGM cool gas mass is found by combining the results of both surveys to obtain log(M/M_{sun}_)=10.5+/-0.3, or ~30% of the total baryon reservoir of an L>=L^*^, star-forming galaxy.
- ID:
- ivo://CDS.VizieR/J/ApJ/817/111
- Title:
- HST/COS survey of z<0.9 AGNs. I.
- Short Name:
- J/ApJ/817/111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use high-quality, medium-resolution Hubble Space Telescope/Cosmic Origins Spectrograph (HST/COS) observations of 82 UV-bright active galactic nuclei (AGNs) at redshifts z_AGN_<0.85 to construct the largest survey of the low-redshift intergalactic medium (IGM) to date: 5138 individual extragalactic absorption lines in HI and 25 different metal-ion species grouped into 2611 distinct redshift systems at z_abs_<0.75 covering total redshift pathlengths {Delta}z_HI_=21.7 and {Delta}z_OVI_=14.5. Our semi-automated line-finding and measurement technique renders the catalog as objectively defined as possible. The cumulative column density distribution of HI systems can be parametrized d N(>N)/dz=C_14_(N/10^14^/cm2)^-({beta}-1)^, with C_14_=25+/-1 and {beta}=1.65+/-0.02. This distribution is seen to evolve both in amplitude, C_14_{propto}(1+z)^2.3+/-0.1^, and slope {beta}(z)=1.75-0.31 z for z<=0.47. We observe metal lines in 418 systems, and find that the fraction of IGM absorbers detected in metals is strongly dependent on N_H1_. The distribution of OVI absorbers appears to evolve in the same sense as the Ly{alpha} forest. We calculate contributions to {Omega}_b_ from different components of the low-z IGM and determine the Ly{alpha} decrement as a function of redshift. IGM absorbers are analyzed via a two-point correlation function in velocity space. We find substantial clustering of HI absorbers on scales of {Delta}v=50-300km/s with no significant clustering at {Delta}v>~1000km/s. Splitting the sample into strong and weak absorbers, we see that most of the clustering occurs in strong, N_HI_>~10^13.5^/cm2, metal-bearing IGM systems.
