- ID:
- ivo://CDS.VizieR/J/A+A/618/A122
- Title:
- Cetus dSph stellar chemo-kinematics
- Short Name:
- J/A+A/618/A122
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Cetus is an isolated, dwarf spheroidal (dSph) galaxy at a distance of 755kpc. In order to quantify its stellar chemo-kinematical properties, we observed individual red giants branch stars in Cetus with the Very Large Telescope (VLT) FORS2 instrument, in Mask eXchange Unit (MXU) configuration. The kinematic analysis shows that Cetus is a mainly pressure-supported ({sigma}_v_=11.0^+1.6^_-1.3_km/s), dark-matter-dominated system (M_1/2_/L_V_=23.9^+9.7^_-8.9_M_{sun}_/L_{sun}_) with no significant signs of internal rotation. We find Cetus to be a metal-poor system with a significant metallicity spread (median [Fe/H]=-1.71dex, median-absolute-deviation =0.49dex), as expected for its stellar mass. We report the presence of a mild metallicity gradient compatible with those found in other dSphs of the same luminosity; we trace the presence of a stellar population gradient also in the spatial distribution of stars in different evolutionary phases in ancillary photometric data. There are tentative indications of two chemo-kinematically distinct sub-populations, with the more metal-poor stars showing a hotter kinematics than the metal-richer ones. Our results add Cetus to the growing scatter in stellar-dark matter halo properties in low-mass galactic systems. The presence of a metallicity gradient akin to those found in similar systems inhabiting different environments may hint at metallicity gradients in Local Group early-type dwarfs being driven by internal mechanisms.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/220/9
- Title:
- CfAIR2: NIR light curves of Type Ia SNe
- Short Name:
- J/ApJS/220/9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CfAIR2 is a large, homogeneously reduced set of near-infrared (NIR) light curves (LCs) for Type Ia supernovae (SNe Ia) obtained with the 1.3m Peters Automated InfraRed Imaging TELescope. This data set includes 4637 measurements of 94 SNe Ia and 4 additional SNe Iax observed from 2005 to 2011 at the Fred Lawrence Whipple Observatory on Mount Hopkins, Arizona. CfAIR2 includes JHKs photometric measurements for 88 normal and 6 spectroscopically peculiar SN Ia in the nearby universe, with a median redshift of z~0.021 for the normal SN Ia. CfAIR2 data span the range from -13 days to +127 days from B-band maximum. More than half of the LCs begin before the time of maximum, and the coverage typically contains ~13-18 epochs of observation, depending on the filter. We present extensive tests that verify the fidelity of the CfAIR2 data pipeline, including comparison to the excellent data of the Carnegie Supernova Project. CfAIR2 contributes to a firm local anchor for SN cosmology studies in the NIR. Because SN Ia are more nearly standard candles in the NIR and are less vulnerable to the vexing problems of extinction by dust, CfAIR2 will help the SN cosmology community develop more precise and accurate extragalactic distance probes to improve our knowledge of cosmological parameters, including dark energy and its potential time variation.
- ID:
- ivo://CDS.VizieR/J/ApJS/200/12
- Title:
- CfA4: light curves for 94 type Ia SNe
- Short Name:
- J/ApJS/200/12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present multi-band optical photometry of 94 spectroscopically confirmed Type Ia supernovae (SNe Ia) in the redshift range 0.0055-0.073, obtained between 2006 and 2011. There are a total of 5522 light-curve points. We show that our natural-system SN photometry has a precision of <~0.03mag in BVr'i', <~0.06mag in u', and <~0.07mag in U for points brighter than 17.5mag and estimate that it has a systematic uncertainty of 0.014, 0.010, 0.012, 0.014, 0.046, and 0.073mag in BVr'i'u'U, respectively. Comparisons of our standard-system photometry with published SN Ia light curves and comparison stars reveal mean agreement across samples in the range of ~0.00-0.03mag. The current sample of low-z SNe Ia is now sufficiently large to remove most of the statistical sampling error from the dark-energy error budget.
- ID:
- ivo://CDS.VizieR/J/ApJ/765/28
- Title:
- CFHTLS galaxies with faint tidal features
- Short Name:
- J/ApJ/765/28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of the detectability of faint tidal features in galaxies from the wide-field component of the Canada-France-Hawaii Telescope Legacy Survey. Our sample consists of 1781 luminous (M_r'_<-19.3mag) galaxies in the magnitude range 15.5mag<r'<17mag and in the redshift range 0.04<z<0.2. Although we have classified tidal features according to their morphology (e.g., streams, shells, and tails), we do not attempt to interpret them in terms of their physical origin (e.g., major versus minor merger debris). Instead, we provide a catalog that is intended to provide raw material for future investigations which will probe the nature of low surface brightness substructure around galaxies. We find that around 12% of the galaxies in our sample show clear tidal features at the highest confidence level. This fraction rises to about 18% if we include systems with convincing, albeit weaker tidal features, and to 26% if we include systems with more marginal features that may or may not be tidal in origin. These proportions are a strong function of rest-frame color and of stellar mass. Linear features, shells, and fans are much more likely to occur in massive galaxies with stellar masses >10^10.5^M_{sun}_, and red galaxies are twice as likely to show tidal features than are blue galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/749/38
- Title:
- CFHTLS-SL2S-ARCS strong lens candidates
- Short Name:
- J/ApJ/749/38
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the Strong Lensing Legacy Survey-ARCS (SARCS) sample compiled from the final T0006 data release of the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) covering a total non-overlapping area of 159 deg^2^. We adopt a semi-automatic method to find gravitational arcs in the survey that makes use of an arc-finding algorithm. The candidate list is pruned by visual inspection and ranking to form the final SARCS sample. This list also includes some serendipitously discovered lens candidates which the automated algorithm did not detect. The SARCS sample consists of 127 lens candidates which span arc radii ~2"-18" within the unmasked area of ~150 deg^2^. Within the sample, 54 systems are promising lenses among which, we find 12 giant arcs (length-to-width ratio >= 8). We also find two radial arc candidates in SL2SJ141447+544704. From our sample, we detect a systematic alignment of the giant arcs with the major axis of the baryonic component of the putative lens in concordance with previous studies. This alignment is also observed for all arcs in the sample and does not vary significantly with increasing arc radius. The mean values of the photometric redshift distributions of lenses corresponding to the giant arcs and all arcs sample are at z~0.6.
- ID:
- ivo://CDS.VizieR/J/ApJ/720/1674
- Title:
- CFHT M33 extended sources catalog
- Short Name:
- J/ApJ/720/1674
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of 2990 extended sources in a 1x1{deg} area centered on M33 using the MegaCam camera on the 3.6m Canada-France-Hawaii Telescope. The catalog includes 599 new candidate stellar clusters, 204 previously confirmed clusters, 1969 likely background galaxies, and 218 unknown extended objects. We present ugriz integrated magnitudes of the candidates and confirmed star clusters (SCs) as well as the full width at half maximum, ellipticity, and stellarity. Based on the properties of the confirmed SCs, we select a sub-sample of highly probable clusters composed of 246 objects. The integrated photometry of the complete cluster catalog reveals a wide range of colors of -0.4<(g-r)<1.5 and -1.0<(r-i)<1.0 with no obvious cluster subpopulations. Comparisons with models of simple stellar populations suggest a large range of ages some as old as ~10Gyr.
- ID:
- ivo://CDS.VizieR/J/ApJ/872/202
- Title:
- CFHT ugi photometry of globular clusters in M85
- Short Name:
- J/ApJ/872/202
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We survey globular clusters (GCs) in M85 using ugi-band images of a 1{deg}x1{deg} field obtained with the MegaCam at the 3.6m Canada-France-Hawaii Telescope. We identify 1318 GC candidates with 20.0mag<g_0_<23.5mag in the entire survey region. Their radial number density profile is well fit by a Sersic profile with n=2.58_-0.33_^+0.43^ and effective radius R_e,GCS_=4.14' (=22kpc), showing that the candidates at R<20' are mostly genuine GCs in M85. We estimate the total number of GCs, N(total)=1216_-50_^+82^, and the specific frequency, S_N_=1.41_-0.06_^+0.10^. The overall color distribution of the GCs in M85 is bimodal, but the GCs in the central region at R<2' do not show a bimodal distribution clearly. The radial number density profile and surface number density map of the blue GCs (BGCs) show more extended structures than those of the red GCs (RGCs). The spatial distributions of both BGCs and RGCs are elongated, similar to that of the galaxy stellar light. The number fraction of the RGCs in the central region is much smaller compared to those in other early-type galaxies of similar luminosity. The mean (g-i)_0_ color of the RGCs in M85 is about 0.1mag bluer than typical values for other Virgo early-type galaxies of similar luminosity, indicating that a significant fraction of the RGCs in M85 may be younger than typical GCs. These results indicate that M85 might have undergone a major wet merger recently.
- ID:
- ivo://CDS.VizieR/J/ApJS/109/367
- Title:
- 4C 23.56 field deep imaging
- Short Name:
- J/ApJS/109/367
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep infrared and optical imaging of a 1.25arcmin^2^ field centered on the giant (~0.5Mpc) high-redshift (z=2.479) ultra-steep-spectrum radio source 4C 23.56. The optical/infrared continuum morphology of the host galaxy is asymmetric, with strong color gradients and an enormous biconical emission-line nebula. The morphology of 4C 23.56 is best described by a dusty galaxy illuminated by a beam from an active galactic nucleus that is scattered into our line of sight. We determine the K' band number counts in the field to a limit of K'=22.5mag and find a marginally significant excess of objects with K'=19-21mag, compared to other K' band surveys. Spectral energy distributions (SEDs) of 117 objects in the field are constructed from aperture photometry in five bands (U', NB, V, I, and K'). From the SEDS we distinguish three subsets of objects as possible candidates for z~2.48 companions: emission-line galaxies, very red galaxies, and flat-spectrum star-forming galaxies. The field has nine candidate objects with line emission in a narrow band centered on the redshifted Ly{alpha} line, compared to an expected number of at most three foreground [O II] emitters that could mimic Ly{alpha} alpha sources. We find a high density of faint, very red objects with I-K'>4mag in the field, including two with I-K'>6mag.
- ID:
- ivo://CDS.VizieR/J/ApJ/602/816
- Title:
- Chamaeleon I star-forming region census
- Short Name:
- J/ApJ/602/816
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- I present a new census of the members of the Chamaeleon I star-forming region. Optical spectroscopy has been obtained for 179 objects that have been previously identified as possible members of the cluster, that lack either accurate spectral types or clear evidence of membership, and that are optically visible (I<~18). I have used these spectroscopic data and all other available constraints to evaluate the spectral classifications and membership status of a total sample of 288 candidate members of Chamaeleon I that have appeared in published studies of the cluster. The latest census of Chamaeleon I now contains 158 members, eight of which are later than M6 and thus are likely to be brown dwarfs. I find that many of the objects identified as members of Chamaeleon I in recent surveys are actually field stars. Meanwhile, seven of nine candidates discovered by Carpenter and coworkers are confirmed as members, one of which is the coolest known member of Chamaeleon I at a spectral type of M8 (~0.03M_{sun}_). I have estimated extinctions, luminosities, and effective temperatures for the members and used these data to construct an H-R diagram for the cluster. Chamaeleon I has a median age of ~2Myr according to evolutionary models and hence is similar in age to IC 348 and is slightly older than Taurus (~1Myr). The measurement of an initial mass function for Chamaeleon I from this census is not possible because of the disparate methods with which the known members were originally selected and must await an unbiased, magnitude-limited survey of the cluster.
- ID:
- ivo://CDS.VizieR/J/ApJS/178/339
- Title:
- ChaMP extended stellar survey (ChESS)
- Short Name:
- J/ApJS/178/339
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 348 X-ray-emitting stars identified from correlating the Extended Chandra Multiwavelength Project (ChaMP), a wide-area serendipitous survey based on archival X-ray images, with the Sloan Digital Sky Survey (SDSS-DR6). We use morphological star/galaxy separation, matching to an SDSS quasar catalog, an optical color-magnitude cut, and X-ray data-quality tests to create our catalog, the ChaMP Extended Stellar Survey (ChESS), from a sample of 2121 matched ChaMP/SDSS sources. Our cuts retain 92% of the spectroscopically confirmed stars in the original sample while excluding 99.6% of the 684 spectroscopically confirmed extragalactic sources. Fewer than 3% of the sources in our final catalog are previously identified stellar X-ray emitters. For 42 catalog members, spectroscopic classifications are available in the literature. We present new spectral classifications and H{alpha} measurements for an additional 79 stars. The catalog is dominated by main-sequence stars; we estimate the fraction of giants in ChESS is ~10%. We identify seven giant stars (including a possible Cepheid and an RR Lyrae star) as ChaMP sources, as well as three cataclysmic variables. Future papers will present analyses of source variability and comparisons of this catalog to models of stellar activity in the Galactic disk.
