- ID:
- ivo://CDS.VizieR/J/ApJ/891/171
- Title:
- COCONUTS. I. Spectra of a WD and T4 comoving syst.
- Short Name:
- J/ApJ/891/171
- Date:
- 17 Jan 2022 13:06:37
- Publisher:
- CDS
- Description:
- We present the first discovery from the COol Companions ON Ultrawide orbiTS (COCONUTS) program, a large-scale survey for wide-orbit planetary and substellar companions. We have discovered a comoving system COCONUTS-1, composed of a hydrogen-dominated white dwarf (PSOJ058.9855+45.4184; d=31.5pc) and a T4 companion (PSOJ058.9869+45.4296) at a 40.6" (1280au) projected separation. We derive physical properties for COCONUTS-1B from (1) its near-infrared spectrum using cloudless Sonora atmospheric models, and (2) its luminosity and the white dwarf's age (7.3_-1.6_^+2.8^Gyr) using Sonora evolutionary models. The two methods give consistent temperatures and radii, but atmospheric models infer a lower surface gravity and therefore an unphysically young age. Assuming evolutionary model parameters (T_eff_=1255_-8_^+6^K, logg=5.44_-0.03_^+0.02^dex, R=0.789_-0.005_^+0.011^R_Jup_), we find that cloudless model atmospheres have brighter Y- and J-band fluxes than the data, suggesting that condensate clouds have not fully dispersed around 1300K. The W2 flux (4.6{mu}m) of COCONUTS-1B is fainter than models, suggesting non-equilibrium mixing of CO. To investigate the gravity dependence of the L/T transition, we compile all 60 known L6-T6 benchmarks and derive a homogeneous set of temperatures, surface gravities, and masses. As is well known, young, low-gravity late-L dwarfs have significantly fainter, redder near-infrared photometry and ~200-300K cooler temperatures than old, high-gravity objects. Our sample now reveals such gravity dependence becomes weaker for T dwarfs, with young objects having comparable near-infrared photometry and ~100K cooler temperatures compared to old objects. Finally, we find that young objects have a larger amplitude J-band brightening than old objects, and also brighten at H band as they cross the L/T transition.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+AS/93/121
- Title:
- CO emission from a sample of IRAS sources
- Short Name:
- J/A+AS/93/121
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The first results from a survey of circumstellar CO(1-0) emission are presented. The sources were selected from the IRAS point source catalog according to the IRAS color criteria described in van der Veen and Habing (1988A&A...194..125V). The sources have good quality fluxes at 12, 25, and 60 microns, flux densities larger than 20Jy at 25{mu}m, and are situated more than 5{deg} away from the Galactic plane. The survey is undertaken to study the relationship between mass loss rates, dust properties, and the evolution along the AGB. The sample consists of 787 sources and contains both oxygen and carbon-rich stars, including Mira variables, OH/IR objects, protoplanetary nebulae, planetary nebulae, and 60-micron excess sources. So far, 519 objects, situated on both the northern and the southern sky, have been observed; 163 sources were found to have circumstellar CO emission, and in 58 of these CO emission has not previously been detected.
- ID:
- ivo://CDS.VizieR/J/ApJ/606/L73
- Title:
- CO emission of 5 Herbig Ae stars
- Short Name:
- J/ApJ/606/L73
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore the high-resolution ({Lambda}/{Delta}{Lambda}=25000;{Delta}v=12km/s) M-band (4.7-5.1{mu}m) spectra of several disk-dominated Herbig Ae (HAe) systems: AB Aur, MWC 758, MWC 480, HD 163296, and VV Ser.
- ID:
- ivo://CDS.VizieR/J/ApJS/141/157
- Title:
- CO (J=1-0) data of cold IRAS sources
- Short Name:
- J/ApJS/141/157
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We conducted a large-scale survey for the cold infrared sources along the northern Galactic plane in the CO (J=1-0) line. There are 1912 IRAS sources selected on the basis of their color indices over the 12, 25, and 60{mu}m wave bands and their association with regions of recent star formation. A quick single-point survey was made toward all of the sources, which results in a detection of 1331 sources with significant CO emission above the detection limit of 0.7K, inferring a CO detection rate of 70%. Located over a wide range of the Galactocentric distances, the CO sources show high concentration toward the spiral arms. Among the detected sources, there are 351 sources found to have high-velocity CO wing emission. A search for the latest catalog of high-velocity CO flows (HVFs) from young stellar objects indicates that 289 sources are beyond the present lists of HVFs. These high-velocity wing sources provide us with a comprehensive database for the study of HVFs from young stellar objects. Using the known outflow sources as an effective indicator, we found that the detection rate for high-velocity wings during the quick survey is 62%, moderately sensitive in searching for new outflow sources. The CO detection rate of the IRAS sources, combined with the ratio of high-velocity wing, suggests that 41% of the CO sources are undergoing the HVF phase. In this paper, the CO spectra are presented along with the preliminary statistics of the data.
- ID:
- ivo://CDS.VizieR/J/A+A/504/543
- Title:
- ^12^C^16^O lines in Arcturus IR spectrum
- Short Name:
- J/A+A/504/543
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the infrared spectrum of Arcturus to clarify the nature of the cool component of its atmosphere, referred to as the CO-mosphere, and its relationship to the warm molecular envelope or the MOLsphere in cooler M (super)giant stars.
- ID:
- ivo://CDS.VizieR/II/84
- Title:
- 13-color photometry of 1380 bright stars
- Short Name:
- II/84
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalogue contains observations of essentially all stars brighter than fifth visual magnitude north of declination -20 degrees and brighter than fourth visual magnitude south of declination -20 degrees, in the 13-color medium-narrow-band photometric system.
- ID:
- ivo://CDS.VizieR/J/A+A/578/A29
- Title:
- Column density maps in 4 IRDCs
- Short Name:
- J/A+A/578/A29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyse column density and temperature maps derived from Herschel dust continuum observations of a sample of prominent, massive infrared dark clouds (IRDCs) i.e. G11.11-0.12, G18.82-0.28, G28.37+0.07, and G28.53-0.25. We disentangle the velocity structure of the clouds using ^13^CO 1->0 and ^12^CO 3->2 data, showing that these IRDCs are the densest regions in massive giant molecular clouds (GMCs) and not isolated features. The probability distribution function (PDF) of column densities for all clouds have a power-law distribution over all (high) column densities, regardless of the evolutionary stage of the cloud: G11.11-0.12, G18.82-0.28, and G28.37+0.07 contain (proto)-stars, while G28.53-0.25 shows no signs of star formation. This is in contrast to the purely log-normal PDFs reported for near and/or mid-IR extinction maps. We only find a log-normal distribution for lower column densities, if we perform PDFs of the column density maps of the whole GMC in which the IRDCs are embedded. By comparing the PDF slope and the radial column density profile of three of our clouds, we attribute the power law to the effect of large-scale gravitational collapse and to local free-fall collapse of pre- and protostellar cores for the highest column densities. A significant impact on the cloud properties from radiative feedback is unlikely because the clouds are mostly devoid of star formation. Independent from the PDF analysis, we find infall signatures in the spectral profiles of ^12^CO for G28.37+0.07 and G11.11-0.12, supporting the scenario of gravitational collapse. Our results are in line with earlier interpretations that see massive IRDCs as the densest regions within GMCs, which may be the progenitors of massive stars or clusters. At least some of the IRDCs are probably the same features as ridges (high column density regions with N>10^23^cm^-2^ over small areas), which were defined for nearby IR-bright GMCs. Because IRDCs are only confined to the densest (gravity dominated) cloud regions, the PDF constructed from this kind of a clipped image does not represent the (turbulence dominated) low column density regime of the cloud.
- ID:
- ivo://CDS.VizieR/J/A+A/510/A5
- Title:
- CO(2-1) maps of IRAS 00117+6412
- Short Name:
- J/A+A/510/A5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Our main aim is to study the influence of the initial conditions of a cloud in the intermediate/high-mass star formation process. We observed with the VLA, PdBI, and SMA the centimeter and millimeter continuum, N_2_H^+^ (1-0), and CO (2-1) emission associated with a dusty cloud harboring a nascent cluster with intermediate-mass protostars.
- ID:
- ivo://CDS.VizieR/J/AJ/156/68
- Title:
- Comet C/2017 E4 composition with iSHELL at NASA/IRTF
- Short Name:
- J/AJ/156/68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In 2017 April, we acquired comprehensive high-resolution spectra of newly discovered comet C/2017 E4 (Lovejoy) as it approached perihelion, and before its disintegration. We detected many cometary emission lines in the range (2.8-5.3) {mu}m, in four customized instrument settings (L1-c, L3, Lp1-c, and M1) of iSHELL - the new near-IR high-resolution immersion echelle spectrograph at NASA/IRTF (Maunakea, Hawaii). We identified 12 molecular species: nine primary volatiles (H_2_O, HCN, NH_3_, CO, C_2_H_2_, C_2_H_6_, CH_4_, CH_3_OH, H_2_CO) and three product species (CN, NH_2_, OH). We detected 85 H_2_O emission lines from 12 water vibrational bands across L1-c and M1 settings. The many detected water emission lines enabled retrieval of accurate measures for ortho- and para-H_2_O independently, thereby reducing systematic uncertainty in the derived ortho-para ratio and nuclear spin temperature. Excitation analyses and emission profile analyses were performed for all species, and molecular abundance ratios relative to water are compared with values found for other Oort Cloud comets in our infrared database. Abundance ratios are consistent for most species, with the exception of underabundant methanol and overabundant ammonia in E4.
- ID:
- ivo://CDS.VizieR/J/MNRAS/441/224
- Title:
- Compact FIR-bright sources in M33
- Short Name:
- J/MNRAS/441/224
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a multiwavelength study of a sample of far-infrared (FIR) sources detected on the Herschel broad-band maps of the nearby galaxy M33. We perform source photometry on the FIR maps as well as mid-infrared (MIR), H{alpha}, far-ultraviolet and integrated Hi and CO line emission maps. By fitting MIR/FIR dust emission spectra, the source dust masses, temperatures and luminosities are inferred. The sources are classified based on their H{alpha} morphology (sub-structured versus not-substructured) and on whether they have a significant CO detection (S/N>3{sigma}). We find that the sources have dust masses in the range 10^2^-10^4^M_{sun}_ and that they present significant differences in their inferred dust/star formation/gas parameters depending on their H{alpha} morphology and CO detection classification. The results suggests differences in the evolutionary states or in the number of embedded HII regions between the sub-samples. The source background-subtracted dust emission seems to be predominantly powered by local star formation, as indicated by a strong correlation between the dust luminosity and the dust-corrected H{alpha} luminosity and the fact that the extrapolated young stellar luminosity is high enough to account for the observed dust emission. Finally, we do not find a strong correlation between the dust-corrected H{alpha} luminosity and the dust mass of the sources, consistent with previous results on the breakdown of simple scaling relations at sub-kpc scales. However, the scatter in the relation is significantly reduced by correcting the H{alpha} luminosity for the age of the young stellar populations in the star-forming regions.
