- ID:
- ivo://CDS.VizieR/J/ApJS/237/18
- Title:
- Cr, Co, and Ni abundances for metal-poor red giants
- Short Name:
- J/ApJS/237/18
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present measurements of the abundances of chromium, cobalt, and nickel in 4113 red giants, including 2277 stars in globular clusters (GCs), 1820 stars in the Milky Way's dwarf satellite galaxies, and 16 field stars. We measured the abundances from mostly archival Keck/DEIMOS medium-resolution spectroscopy with a resolving power of R~6500 and a wavelength range of approximately 6500-9000{AA}. The abundances were determined by fitting spectral regions that contain absorption lines of the elements under consideration. We used estimates of temperature, surface gravity, and metallicity that we previously determined from the same spectra. We estimated systematic error by examining the dispersion of abundances within mono- metallic GCs. The median uncertainties for [Cr/Fe], [Co/Fe], and [Ni/Fe] are 0.20, 0.20, and 0.13, respectively. Finally, we validated our estimations of uncertainty through duplicate measurements, and we evaluated the accuracy and precision of our measurements through comparison to high-resolution spectroscopic measurements of the same stars.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/900/140
- Title:
- CSP-II: sp. obs. of the 03fg-like SN Ia LSQ14fmg
- Short Name:
- J/ApJ/900/140
- Date:
- 02 Feb 2022 11:26:50
- Publisher:
- CDS
- Description:
- The Type Ia supernova (SN Ia) LSQ14fmg exhibits exaggerated properties that may help to reveal the origin of the "super-Chandrasekhar" (or 03fg-like) group. The optical spectrum is typical of a 03fg-like SNIa, but the light curves are unlike those of any SNe Ia observed. The light curves of LSQ14fmg rise extremely slowly. At -23 rest-frame days relative to B-band maximum, LSQ14fmg is already brighter than M_V_=-19mag before host extinction correction. The observed color curves show a flat evolution from the earliest observation to approximately 1 week after maximum. The near-infrared light curves peak brighter than -20.5mag in the J and H bands, far more luminous than any 03fg-like SNe Ia with near-infrared observations. At 1 month past maximum, the optical light curves decline rapidly. The early, slow rise and flat color evolution are interpreted to result from an additional excess flux from a power source other than the radioactive decay of the synthesized 56Ni. The excess flux matches the interaction with a typical superwind of an asymptotic giant branch (AGB) star in density structure, mass-loss rate, and duration. The rapid decline starting at around 1 month past B-band maximum may be an indication of rapid cooling by active carbon monoxide (CO) formation, which requires a low-temperature and high-density environment. These peculiarities point to an AGB progenitor near the end of its evolution and the core degenerate scenario as the likely explosion mechanism for LSQ14fmg.
- ID:
- ivo://CDS.VizieR/J/ApJ/898/161
- Title:
- 500days of ASASSN-18pg multiwavelength obs.
- Short Name:
- J/ApJ/898/161
- Date:
- 16 Mar 2022 00:55:51
- Publisher:
- CDS
- Description:
- We present nearly 500 days of observations of the tidal disruption event (TDE) ASASSN-18pg, spanning from 54 days before peak light to 441 days after peak light. Our data set includes X-ray, UV, and optical photometry, optical spectroscopy, radio observations, and the first published spectropolarimetric observations of a TDE. ASASSN-18pg was discovered on 2018 July 11 by the All-Sky Automated Survey for Supernovae (ASAS-SN) at a distance of d=78.6Mpc; with a peak UV magnitude of m~14, it is both one of the nearest and brightest TDEs discovered to-date. The photometric data allow us to track both the rise to peak and the long-term evolution of the TDE. ASASSN-18pg peaked at a luminosity of L~2.4x10^44^erg/s, and its late-time evolution is shallower than a flux {propto}t^-5/3^ power-law model, similar to what has been seen in other TDEs. ASASSN-18pg exhibited Balmer lines and spectroscopic features consistent with Bowen fluorescence prior to peak, which remained detectable for roughly 225days after peak. Analysis of the two-component H{alpha} profile indicates that, if they are the result of reprocessing of emission from the accretion disk, the different spectroscopic lines may be coming from regions between ~10 and ~60 lt-days from the black hole. No X-ray emission is detected from the TDE, and there is no evidence of a jet or strong outflow detected in the radio. Our spectropolarimetric observations indicate that the projected emission region is likely not significantly aspherical, with the projected emission region having an axis ratio of >~0.65.
- ID:
- ivo://CDS.VizieR/J/ApJ/688/597
- Title:
- Debris disks in NGC 2232
- Short Name:
- J/ApJ/688/597
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe Spitzer IRAC and MIPS observations of the nearby 25Myr old open cluster NGC 2232. Combining these data with ROSAT All-Sky Survey observations, proper motions, and optical photometry/spectroscopy, we construct a list of highly probable cluster members. We identify one A-type star, HD 45435, that has definite excess emission at 4.5-24um indicative of debris from terrestrial planet formation. We also identify 2-4 late-type stars with possible 8um excesses and 8 early-type stars with definite 24um excesses. Constraints on the dust luminosity and temperature suggest that the detected excesses are produced by debris disks. From our sample of B and A stars, stellar rotation appears to be correlated with 24um excess, a result that would be expected if massive primordial disks evolve into massive debris disks. To explore the evolution of the frequency and magnitude of debris around A-type stars, we combine our results with data for other young clusters.
- ID:
- ivo://CDS.VizieR/J/ApJ/858/77
- Title:
- DEIMOS 10K spectroscopic survey in COSMOS field
- Short Name:
- J/ApJ/858/77
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of 10718 objects in the COSMOS field, observed through multi-slit spectroscopy with the Deep Imaging Multi-Object Spectrograph (DEIMOS) on the Keck II telescope in the wavelength range ~5500-9800{AA}. The catalog contains 6617 objects with high-quality spectra (two or more spectral features), and 1798 objects with a single spectroscopic feature confirmed by the photometric redshift. For 2024 typically faint objects, we could not obtain reliable redshifts. The objects have been selected from a variety of input catalogs based on multi-wavelength observations in the field, and thus have a diverse selection function, which enables the study of the diversity in the galaxy population. The magnitude distribution of our objects is peaked at I_AB_~23 and K_AB_~21, with a secondary peak at K_AB_~24. We sample a broad redshift distribution in the range 0<z<6, with one peak at z~1, and another one around z~4. We have identified 13 redshift spikes at z>0.65 with chance probabilities <4x10^-4^, some of which are clearly related to protocluster structures of sizes >10Mpc. An object-to-object comparison with a multitude of other spectroscopic samples in the same field shows that our DEIMOS sample is among the best in terms of fraction of spectroscopic failures and relative redshift accuracy. We have determined the fraction of spectroscopic blends to about 0.8% in our sample. This is likely a lower limit and at any rate well below the most pessimistic expectations. Interestingly, we find evidence for strong lensing of Ly{alpha} background emitters within the slits of 12 of our target galaxies, increasing their apparent density by about a factor of 4.
- ID:
- ivo://CDS.VizieR/J/AJ/156/216
- Title:
- Differential photometry & RVs of HATS-59
- Short Name:
- J/AJ/156/216
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the first discovery of a multi-planetary system by the HATSouth network, HATS-59b,c, a planetary system with an inner transiting hot Jupiter and an outer cold massive giant planet, which was detected via radial velocity. The inner transiting planet, HATS-59b, is on an eccentric orbit with e=0.129+/-0.049, orbiting a V=13.951+/-0.030 mag solar-like star (M_*_=1.038+/-0.039 M_{sun}_ and R_*_=1.036+/-0.067 R_{sun}_) with a period of 5.416081+/-0.000016 days. The outer companion, HATS-59c is on a circular orbit with msini=12.70+/-0.87 M_J_ and a period of 1422+/-14 days. The inner planet has a mass of 0.806+/-0.069 M_J_ and a radius of 1.126+/-0.077 R_J_, yielding a density of 0.70+/-0.16 g/cm^3^. Unlike most planetary systems that include only a single hot Jupiter, HATS-59b,c includes, in addition to the transiting hot Jupiter, a massive outer companion. The architecture of this system is valuable for understanding planet migration.
- ID:
- ivo://CDS.VizieR/J/AJ/158/182
- Title:
- Discoveries from the NEOWISE proper motion survey
- Short Name:
- J/AJ/158/182
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present low-resolution near-infrared spectra of discoveries from an all-sky proper motion search conducted using multi-epoch data from the Wide-field Infrared Survey Explorer. Using the data from NEOWISE, along with the AllWISE catalog, Schneider et al. (2016, J/ApJ/817/112) conducted an all-sky proper motion survey to search for nearby objects with high proper motions. Here, we present a follow-up spectroscopic survey of 65 of their discoveries, which focused primarily on potentially nearby objects (d<25 pc), candidate late-type brown dwarfs (>=L7), and subdwarf candidates. We found 31 new M dwarfs, 18 new L dwarfs, and 11 new T dwarfs. Of these, 13 are subdwarfs, including one new sdL1 and two new sdL7s. Eleven of these discoveries, with spectral types ranging from M7 to T7 (including one subdwarf) are predicted to be within 25 pc, adding to the number of known objects in the solar neighborhood. We also discovered three new early-type T subdwarf candidates, one sdT1, one sdT2, and one sdT3, which would increase the number of known early-type T subdwarfs from two to five.
- ID:
- ivo://CDS.VizieR/J/ApJ/779/L6
- Title:
- 3D kinematic observations of stars in Galactic Centre
- Short Name:
- J/ApJ/779/L6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present three-dimensional (3D) kinematic observations of stars within the central 0.5pc of the Milky Way (MW) nuclear star cluster (NSC) using adaptive optics imaging and spectroscopy from the Keck telescopes. Recent observations have shown that the cluster has a shallower surface density profile than expected for a dynamically relaxed cusp, leading to important implications for its formation and evolution. However, the true 3D profile of the cluster is unknown due to the difficulty in de-projecting the stellar number counts. Here, we use spherical Jeans modeling of individual proper motions and radial velocities to constrain, for the first time, the de-projected spatial density profile, cluster velocity anisotropy, black hole mass (M_BH_), and distance to the Galactic center (R_0_) simultaneously. We find that the inner stellar density profile of the late-type stars, {rho}(r){prop.to}r^-{gamma}^, have a power law slope {gamma}=0.05_-0.60^+0.29^, much more shallow than the frequently assumed Bahcall-Wolf slope of {gamma}=7/4. The measured slope will significantly affect dynamical predictions involving the cluster, such as the dynamical friction time scale. The cluster core must be larger than 0.5 pc, which disfavors some scenarios for its origin. Our measurement of M_BH_=5.76_-1.26_^+1.76^x10^6^M_{sun}_ and R_0_=8.92_-0.55_^+0.58^kpc is consistent with that derived from stellar orbits within 1" of Sgr A*. When combined with the orbit of S0-2, the uncertainty on R_0_ is reduced by 30% (8.46_-0.38_^+0.42^kpc). We suggest that the MW NSC can be used in the future in combination with stellar orbits to significantly improve constraints on R_0_.
- ID:
- ivo://CDS.VizieR/J/AJ/159/46
- Title:
- Elemental abundances of 416 stars in 5 dSphs of M31
- Short Name:
- J/AJ/159/46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep spectroscopy from Keck/DEIMOS (DEep Imaging Multi-Object Spectrograph) of Andromeda I, III, V, VII, and X, all of which are dwarf spheroidal satellites (dSphs) of M31. The sample includes 256 spectroscopic members across all five dSphs. We confirm previous measurements of the velocity dispersions and dynamical masses, and we provide upper limits on bulk rotation. Our measurements confirm that M31 satellites obey the same relation between stellar mass and stellar metallicity as Milky Way (MW) satellites and other dwarf galaxies in the Local Group. The metallicity distributions show trends with stellar mass that are similar to those of MW satellites, including evidence in massive satellites for external influence, like pre-enrichment or gas accretion. We present the first measurements of individual element ratios, like [Si/Fe], in the M31 system, as well as measurements of the average [{alpha}/Fe] ratio. The trends of [{alpha}/Fe] with [Fe/H] also follow the same galaxy mass-dependent patterns as MW satellites. Less massive galaxies have more steeply declining slopes of [{alpha}/Fe] that begin at lower [Fe/H]. Finally, we compare the chemical evolution of M31 satellites to M31's Giant Stellar Stream and smooth halo. The properties of the M31 system support the theoretical prediction that the inner halo is composed primarily of massive galaxies that were accreted early. As a result, the inner halo exhibits higher [Fe/H] and [{alpha}/Fe] than surviving satellite galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/871/258
- Title:
- ELQS in SDSS. III. The full ELQS quasar catalog
- Short Name:
- J/ApJ/871/258
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have designed the Extremely Luminous Quasar Survey (ELQS) to provide a highly complete census of unobscured UV-bright quasars during the cosmic noon, z=2.8-5.0. Here we report the discovery of 70 new quasars in the ELQS South Galactic Cap (ELQS-S) quasar sample, doubling the number of known extremely luminous quasars in 4237.3deg^2^ of the Sloan Digital Sky Survey footprint. These observations conclude the ELQS and we present the properties of the full ELQS quasar catalog, containing 407 quasars over 11838.5deg^2^. Our novel ELQS quasar selection strategy resulted in unprecedented completeness at the bright end and allowed us to discover 109 new quasars in total. This marks an increase of ~36% (109/298) in the known population at these redshifts and magnitudes, while we further are able to retain a selection efficiency of ~80%. On the basis of 166 quasars from the full ELQS quasar catalog, which adhere to the uniform criteria of the Two Micron All Sky Survey point source catalog, we measure the bright-end quasar luminosity function (QLF) and extend it one magnitude brighter than previous studies. Assuming a single power law with exponential density evolution for the functional form of the QLF, we retrieve the best-fit parameters from a maximum likelihood analysis. We find a steep bright-end slope of {beta}~-4.1, and we can constrain the bright-end slope to {beta}<=-3.4 with 99% confidence. The density is well modeled by the exponential redshift evolution, resulting in a moderate decrease with redshift ({gamma}~-0.4).