- ID:
- ivo://CDS.VizieR/J/ApJ/831/L3
- Title:
- NIR spectra of 10 PNe in LMC and SMC
- Short Name:
- J/ApJ/831/L3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present near-infrared spectra of 10 planetary nebulae (PNe) in the Large and Small Magellanic Clouds (LMC and SMC), acquired with the FIRE and GNIRS spectrometers on the 6.5 m Baade and 8.1 m Gemini South Telescopes, respectively. We detect Se and/or Kr emission lines in eight of these objects, the first detections of n-capture elements in Magellanic Cloud PNe. Our abundance analysis shows large s-process enrichments of Kr (0.6-1.3 dex) in the six PNe in which it was detected, and Se is enriched by 0.5-0.9 dex in five objects. We also estimate upper limits to Rb and Cd abundances in these objects. Our abundance results for the LMC are consistent with the hypothesis that PNe with 2-3 M_{\sun}_ progenitors dominate the bright end of the PN luminosity function in young gas-rich galaxies. We find no significant correlations between s-process enrichments and other elemental abundances, central star temperature, or progenitor mass, though this is likely due to our small sample size. We determine S abundances from our spectra and find that [S/H] agrees with [Ar/H] to within 0.2 dex for most objects, but is lower than [O/H] by 0.2-0.4 dex in some PNe, possibly due to O enrichment via third dredge-up. Our results demonstrate that n-capture elements can be detected in PNe belonging to nearby galaxies with ground-based telescopes, allowing s-process enrichments to be studied in PN populations with well-determined distances.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/812/66
- Title:
- NIR spectra of 5 red quasars at 0.5<z<0.9
- Short Name:
- J/ApJ/812/66
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Red quasars are thought to be an intermediate population between merger-driven star-forming galaxies in dust-enshrouded phase and normal quasars. If so, they are expected to have high accretion ratios, but their intrinsic dust extinction hampers reliable determination of Eddington ratios. Here, we compare the accretion rates of 16 red quasars at z~0.7 to those of normal type 1 quasars at the same redshift range. The red quasars are selected by their red colors in optical through near-infrared (NIR) and radio detection. The accretion rates of the red quasars are derived from the P{beta} line in NIR spectra, which is obtained by the SpeX on the Infrared Telescope Facility in order to avoid the effects of dust extinction. We find that the measured Eddington ratios (L_bol_/L_Edd_~=0.69) of red quasars are significantly higher than those of normal type 1 quasars, which is consistent with a scenario in which red quasars are the intermediate population and the black holes of red quasars grow very rapidly during such a stage.
- ID:
- ivo://CDS.VizieR/J/ApJ/806/L35
- Title:
- NIR spectroscopy of COSMOS FIR galaxies
- Short Name:
- J/ApJ/806/L35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used FMOS on Subaru to obtain near-infrared spectroscopy of 123 far-infrared-selected galaxies in COSMOS and the key rest-frame optical emission lines. This is the largest sample of infrared galaxies with near-infrared spectroscopy at these redshifts. The far-infrared selection results in a sample of galaxies that are massive systems that span a range of metallicities in comparison with previous optically selected surveys, and thus has a higher active galactic nucleus (AGN) fraction and better samples the AGN branch. We establish the presence of AGNs and starbursts in this sample of (U)LIRGs selected as Herschel-PACS and Spitzer-MIPS detections in two redshift bins (z~0.7 and z~1.5) and test the redshift dependence of diagnostics used to separate AGNs from star formation dominated galaxies. In addition, we construct a low-redshift (z~0.1) comparison sample of infrared-selected galaxies and find that the evolution from z~1.5 to today is consistent with an evolving AGN selection line and a range of ISM conditions and metallicities from the models of Kewley et al. (2013ApJ...774L..10K). We find that a large fraction of (U)LIRGs are BPT-selected AGNs using their new redshift-dependent classification line. We compare the position of known X-ray-detected AGNs (67 in total) with the BPT selection and find that the new classification line accurately selects most of these objects (>70%). Furthermore, we identify 35 new (likely obscured) AGNs not selected as such by their X-ray emission. Our results have direct implications for AGN selection at higher redshift with either current (MOSFIRE, KMOS) or future (PFS, MOONS) spectroscopic efforts with near-infrared spectral coverage.
- ID:
- ivo://CDS.VizieR/J/ApJ/734/82
- Title:
- NIR spectroscopy of five dwarf galaxies
- Short Name:
- J/ApJ/734/82
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present near-infrared (NIR) spectroscopic observations of five blue compact dwarf (BCD) galaxies, II Zw 40, Mrk 71, Mrk 930, Mrk 996, and SBS 0335-052E. The NIR spectra which cover the 0.90-2.40um wavelength range show hydrogen, molecular hydrogen, helium, sulfur, and iron emission lines. The NIR data for all BCDs have been supplemented by optical spectra.
- ID:
- ivo://CDS.VizieR/J/AJ/143/149
- Title:
- NIR spectroscopy of Galactic Wolf-Rayet stars. II.
- Short Name:
- J/AJ/143/149
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We are continuing a J, K and narrowband imaging survey of 300{deg}^2^ of the plane of the Galaxy, searching for new Wolf-Rayet (W-R) stars. Our survey spans 150{deg} in Galactic longitude and reaches 1{deg} above and below the Galactic plane. The survey has a useful limiting magnitude of K=15 over most of the observed Galactic plane, and K=14 (due to severe crowding) within a few degrees of the Galactic center. Thousands of emission-line candidates have been detected. In spectrographic follow-ups of 146 relatively bright W-R star candidates, we have re-examined 11 previously known WC and WN stars and discovered 71 new W-R stars, 17 of type WN and 54 of type WC. Our latest image analysis pipeline now picks out W-R stars with a 57% success rate. Star subtype assignments have been confirmed with the K-band spectra and distances approximated using the method of spectroscopic parallax. Some of the new W-R stars are among the most distant known in our Galaxy. The distribution of these new W-R stars is beginning to trace the locations of massive stars along the distant spiral arms of the Milky Way.
- ID:
- ivo://CDS.VizieR/J/MNRAS/452/2858
- Title:
- NIR spectroscopy of Galactic WR stars. III
- Short Name:
- J/MNRAS/452/2858
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A new method of image subtraction is applied to images from a J, K, and narrow-band imaging survey of 300 deg2 of the plane of the Galaxy, searching for new Wolf-Rayet (WR) stars. Our survey spans 150{deg} in Galactic longitude and reaches b=+/-1{deg} with respect to the Galactic plane. The survey has a useful limiting magnitude of K=15 over most of the observed Galactic plane, and K=14 (due to severe crowding) within a few degrees of the Galactic Centre. The new image subtraction method described here (better than aperture or even point-spread-function photometry in very crowded fields) detected several thousand emission-line candidates. In 2011 and 2012 June and July, we spectroscopically followed up on 333 candidates with MDM-TIFKAM and Infrared Telescope Facility (IRTF)-SpeX, discovering 89 emission-line sources. These include 49 WR stars, 43 of them previously unidentified, including the most distant known Galactic WR stars, more than doubling the number on the far side of the Milky Way. We also demonstrate our survey's ability to detect very faint planetary nebulae and other NIR emission objects.
- ID:
- ivo://CDS.VizieR/J/AJ/154/112
- Title:
- NIR spectroscopy of new L and T dwarf candidates
- Short Name:
- J/AJ/154/112
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the final results from a targeted search for brown dwarfs with unusual near-infrared colors. From a positional cross-match of the Sloan Digital Sky Survey (SDSS), 2-Micron All-Sky Survey (2MASS), and Wide-Field Infrared Survey Explorer (WISE) catalogs, we have identified 144 candidate peculiar L and T dwarfs. Spectroscopy confirms that 20 of the objects are peculiar or are candidate binaries. Of the 420 objects in our full sample 9 are young (<~200Myr; 2.1%) and another 8 (1.9%) are unusually red, with no signatures of youth. With a spectroscopic J-K_s_ color of 2.58+/-0.11mag, one of the new objects, the L6 dwarf 2MASS J03530419+0418193, is among the reddest field dwarfs currently known and is one of the reddest objects with no signatures of youth known to date. We have also discovered another potentially very-low-gravity object, the L1 dwarf 2MASS J00133470+1109403, and independently identified the young L7 dwarf 2MASS J00440332+0228112, which was first reported by Schneider and collaborators. Our results confirm that signatures of low gravity are no longer discernible in low to moderate resolution spectra of objects older than ~200Myr. The 1.9% of unusually red L dwarfs that do not show other signatures of youth could be slightly older, up to ~400Myr. In this case a red J-K_s_ color may be more diagnostic of moderate youth than individual spectral features. However, its is also possible that these objects are relatively metal-rich, and thus have enhanced atmospheric dust content.
- ID:
- ivo://CDS.VizieR/J/A+A/585/A143
- Title:
- NIR spectroscopy of the Sun and HD20010
- Short Name:
- J/A+A/585/A143
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Effective temperature, surface gravity, and metallicity are basic spectroscopic stellar parameters necessary to characterize a star or a planetary system. Reliable atmospheric parameters for FGK stars have been obtained mostly from methods that rely on high resolution and high signal-to-noise optical spectroscopy. The advent of a new generation of high resolution near-infrared (NIR) spectrographs opens the possibility of using classic spectroscopic methods with high resolution and high signal-to-noise in the NIR spectral window. We compile a new iron line list in the NIR from a solar spectrum to derive precise stellar atmospheric parameters, comparable to the ones already obtained from high resolution optical spectra. The spectral range covers 10000{AA} to 25000{AA}, which is equivalent to the Y,J,H, and K-bands. Our spectroscopic analysis is based on the iron excitation and ionization balance done in local thermodynamic equilibrium. We use a high resolution and high signal-to-noise ratio spectrum of the Sun from the Kitt Peak telescope as a starting point to compile the iron line list. The oscillator strengths (loggf) of the iron lines were calibrated for the Sun. The abundance analysis was done using the MOOG code after measuring equivalent widths of 357 solar iron lines.
- ID:
- ivo://CDS.VizieR/J/ApJ/817/55
- Title:
- NIR spectroscopy of 1.5<z<3.5 broad-band QSOs
- Short Name:
- J/ApJ/817/55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the rest-frame optical properties of 74 luminous (L_bol_=10^46.2-48.2^erg/s), 1.5<z<3.5 broad-line quasars with near-IR (JHK) slit spectroscopy. Systemic redshifts based on the peak of the [OIII]{lambda}5007 line reveal that redshift estimates from the rest-frame UV broad emission lines (mostly MgII) are intrinsically uncertain by ~200km/s (measurement errors accounted for). The overall full-width-at-half-maximum of the narrow [OIII] line is ~1000km/s on average. A significant fraction of the total [OIII] flux (~40%) is in a blueshifted wing component with a median velocity offset of ~700km/s, indicative of ionized outflows within a few kpc from the nucleus; we do not find evidence of significant [OIII] flux beyond ~10kpc in our slit spectroscopy. The [OIII] line is noticeably more asymmetric and weaker than that in typical less luminous low-z quasars. However, when matched in quasar continuum luminosity, low-z quasars have similar [OIII] profiles and strengths as these high-z systems. Therefore the exceptionally large width and blueshifted wing, and the relatively weak strength of [OIII] in high-z luminous quasars are mostly a luminosity effect rather than redshift evolution. The H{beta}-[OIII] region of these high-z quasars displays a similar spectral diversity and Eigenvector 1 correlations with anti-correlated [OIII] and optical FeII strengths, as seen in low-z quasars; but the average broad H{beta} width is larger by 25% than typical low-z quasars, indicating more massive black holes in these high-z systems. These results highlight the importance of understanding [OIII] in the general context of quasar parameter space in order to understand quasar feedback in the form of [OIII] outflows. The calibrated one-dimensional near-IR spectra are made publicly available, along with a composite spectrum.
- ID:
- ivo://CDS.VizieR/J/A+A/605/L9
- Title:
- NIR spectrum of exoplanet HIP 65426b
- Short Name:
- J/A+A/605/L9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The SHINE program is a high-contrast near-infrared survey of 600 young, nearby stars aimed at searching for and characterizing new planetary systems using VLT/SPHERE's unprecedented high-contrast and high-angular-resolution imaging capabilities. It is also intended to place statistical constraints on the rate, mass and orbital distributions of the giant planet population at large orbits as a function of the stellar host mass and age to test planet-formation theories. We used the IRDIS dual-band imager and the IFS integral field spectrograph of SPHERE to acquire high-contrast coronagraphic differential near-infrared images and spectra of the young A2 star HIP 65426. It is a member of the ~17Myr old Lower Centaurus-Crux association. At a separation of 830 mas (92au projected) from the star, we detect a faint red companion. Multi-epoch observations confirm that it shares common proper motion with HIP 65426. Spectro-photometric measurements extracted with IFS and IRDIS between 0.95 and 2.2{mu}m indicate a warm, dusty atmosphere characteristic of young low-surface-gravity L5-L7 dwarfs. Hot-start evolutionary models predict a luminosity consistent with a 6-12M_Jup_, T_eff_=1300-1600K and R=1.5+/-0.1R_Jup_ giant planet. Finally, the comparison with Exo-REM and PHOENIX BT-Settl synthetic atmosphere models gives consistent effective temperatures but with slightly higher surface gravity solutions of log(g)=4.0-5.0 with smaller radii (1.0-1.3R_Jup_). Given its physical and spectral properties, HIP 65426 b occupies a rather unique placement in terms of age, mass, and spectral-type among the currently known imaged planets. It represents a particularly interesting case to study the presence of clouds as a function of particle size, composition, and location in the atmosphere, to search for signatures of non-equilibrium chemistry, and finally to test the theory of planet formation and evolution.
