- ID:
- ivo://CDS.VizieR/J/ApJ/764/102
- Title:
- First quadrant IRDCs in CS(2-1) with Mopra
- Short Name:
- J/ApJ/764/102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Infrared dark clouds (IRDCs) are believed to host the earliest stages of high-mass star and cluster formation. Because O stars typically travel short distances over their lifetimes, if IRDCs host the earliest stages of high-mass star formation then these cold, dense molecular clouds should be located in or near the spiral arms in the Galaxy. The Galactic distribution of a large sample of IRDCs should therefore provide information on Galactic structure. Moreover, determination of distances enables mass and luminosity calculations. We have observed a large sample of IRDC candidates in the first Galactic quadrant in the dense gas tracer CS(2-1) using the Mopra telescope in order to determine kinematic distances from the molecular line velocities. We find that the IRDCs are concentrated around a Galactocentric distance of ~4.5kpc, agreeing with the results of Simon et al. (2006, J/ApJ/653/1325). This distribution is consistent with the location of the Scutum-Centaurus spiral arm. The group of IRDCs near the Sun in the first quadrant detected in ^13^CO(1-0) in Simon et al. is not detected in the CS data. This discrepancy arises from the differences in the critical densities between the ^13^CO(1-0) and CS(2-1) lines. We determine that the Midcourse Space Experiment selected IRDCs are not a homogeneous population, and ^13^CO(1-0) traces a population of IRDCs with lower column densities and lower 1.1 mm flux densities in addition to more dense IRDCs detected in CS. Masses of the first quadrant IRDCs are calculated from ^13^CO(1-0) maps. We find a strong peak in the Galactocentric IRDC mass surface density distribution at R_Gal_~4.5kpc.
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- ID:
- ivo://CDS.VizieR/J/A+A/642/A216
- Title:
- Five Herbig-Haro objects SOFIA/FIFI-LS images
- Short Name:
- J/A+A/642/A216
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present SOFIA/FIFI-LS observations of five prototypical, low-mass Class I outflows (HH111, SVS13, HH26, HH34, HH30) in the far-infrared [OI]63um and [OI]145um transitions. Spectroscopic [OI]63um,145um maps enable us to study the spatial extent of warm, low-excitation atomic gas within outflows driven by Class I protostars. These [OI] maps may potentially allow us to measure the mass-loss rates (dM/dt_jet_) of this warm component of the atomic jet. A fundamental tracer of warm (i.e. T~500-1500K), low-excitation atomic gas is the [OI]63um emission line, which is predicted to be the main coolant of dense dissociative J-type shocks caused by decelerated wind or jet shocks associated with protostellar outflows. Under these conditions, the [O I]63um line can be directly connected to the instantaneous mass ejection rate.Thus, by utilising spectroscopic [OI]63um maps, we wish to determine the atomic mass flux rate dM/dt_jet_ ejected from our target outflows. Strong [OI]63um emission is detected at the driving sources HH111IRS, HH34IRS, SVS13, as well as at the bow shock region, HH7. The detection of the [OI]63um line at HH26A and HH8/HH10 can be attributed to jet deflection regions. The far-infrared counterpart of the optical jet is detected in [OI]63um only for HH111, but not for HH34. We interpret the [OI]63um emission at HH111IRS, HH34IRS, and SVS13 to be coming primarily from a decelerated wind shock, whereas multiple internal shocks within the HH111 jet may cause most of the [O I]63um emission seen there. At HH30, no [O I]63um,145um was detected. The [OI]145um line detection is at noise level almost everywhere in our obtained maps. The observed outflow rates of our Class I sample are to the order of dM/dt_jet_~10^-6^M_{sun}_/yr, if proper shock conditions prevail. Independent calculations connecting the [OI]63um line luminosity and observable jet parameters with the mass-loss rate are consistent with the applied shock model and lead to similar mass-loss rates. Wediscuss applicability and caveats of both methods. High-quality spectroscopic [OI]63um maps of protostellar outflows at the jet driving source potentially allow a clear determination of the mass ejection rate.
- ID:
- ivo://CDS.VizieR/J/ApJ/727/91
- Title:
- Fluorescence excitation models in comets
- Short Name:
- J/ApJ/727/91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Ammonia is a major reservoir of nitrogen atoms in cometary materials. However, detections of ammonia in comets are rare, with several achieved at radio wavelengths. A few more detections were obtained through near-infrared observations (around the 3um wavelength region), but moderate relative velocity shifts are required to separate emission lines of cometary ammonia from telluric absorption lines in the 3um wavelength region. On the other hand, the amidogen radical (NH_2_, a photodissociation product of ammonia in the coma) also shows rovibrational emission lines in the 3um wavelength region. Thus, gas production rates for ammonia can be determined from the rovibrational emission lines of ammonia (directly) and amidogen radical (indirectly) simultaneously in the near-infrared. In this article, we present new fluorescence excitation models for cometary ammonia and amidogen radical in the near-infrared, and we apply these models to the near-infrared high-dispersion spectra of comet C/2004 Q2 (Machholz) to determine the mixing ratio of ammonia to water in the comet. Based on direct detection of NH_3_ lines, the mixing ratio of NH_3_/H_2_O is 0.46%+/-0.03% in C/2004 Q2 (Machholz), in agreement with other results. The mixing ratio of ammonia determined from the NH_2_ observations (0.31%-0.79%) is consistent but has relatively larger error, owing to uncertainty in the photodissociation rates of ammonia. At the present level of accuracy, we confirm that NH_3_ could be the sole parent of NH_2_ in this comet.
- ID:
- ivo://CDS.VizieR/J/ApJS/220/12
- Title:
- FMOS-COSMOS survey III. 0.7<z<2.5 galaxies
- Short Name:
- J/ApJS/220/12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a spectroscopic survey of galaxies in the COSMOS field using the Fiber Multi-object Spectrograph (FMOS), a near-infrared instrument on the Subaru Telescope. Our survey is specifically designed to detect the H{alpha} emission line that falls within the H-band (1.6-1.8{mu}m) spectroscopic window from star-forming galaxies with 1.4<z<1.7 and M_stellar_>~10^10^M_{sun}_. With the high multiplex capability of FMOS, it is now feasible to construct samples of over 1000 galaxies having spectroscopic redshifts at epochs that were previously challenging. The high-resolution mode (R~2600) effectively separates H{alpha} and [NII]{lambda}6585, thus enabling studies of the gas-phase metallicity and photoionization state of the interstellar medium. The primary aim of our program is to establish how star formation depends on stellar mass and environment, both recognized as drivers of galaxy evolution at lower redshifts. In addition to the main galaxy sample, our target selection places priority on those detected in the far-infrared by Herschel/PACS to assess the level of obscured star formation and investigate, in detail, outliers from the star formation rate (SFR)--stellar mass relation. Galaxies with H{alpha} detections are followed up with FMOS observations at shorter wavelengths using the J-long (1.11-1.35{mu}m) grating to detect H{beta} and [OIII]{lambda}5008 which provides an assessment of the extinction required to measure SFRs not hampered by dust, and an indication of embedded active galactic nuclei. With 460 redshifts measured from 1153 spectra, we assess the performance of the instrument with respect to achieving our goals, discuss inherent biases in the sample, and detail the emission-line properties. Our higher-level data products, including catalogs and spectra, are available to the community.
- ID:
- ivo://CDS.VizieR/J/ApJ/874/82
- Title:
- Follow-up photometry & spectroscopy of PTF14jg
- Short Name:
- J/ApJ/874/82
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the outbursting source PTF 14jg, which, prior to the onset of its late 2013 eruption, was a faint, unstudied, and virtually uncataloged star. The salient features of the PTF 14jg outburst are (i) projected location near the W4 HII region and radial velocity consistent with physical association; (ii) a light curve that underwent an ~6-7mag optical (R-band) through mid-infrared (L-band) brightening on a timescale of a few months, peaked and then faded by ~3mag, but plateaued still >3.5mag above quiescence by ~8 months post-peak, lasting to at least 4yr after eruption; (iii) strong outflow signatures with velocities reaching -530km/s; (iv) a low-gravity and broad (~100-150km/s FWHM) optical absorption-line spectrum that systematically changes its spectral type with wavelength; (v) lithium; and (vi) ultraviolet and infrared excess. We tentatively identify the outburst as exhibiting characteristics of a young star FU Ori event. However, the burst would be unusually hot, with an absorption spectrum exhibiting high-excitation (~11000-15000K) lines in the optical and no evidence of CO in the near-infrared, in addition to exhibiting an unusual light curve. We thus also consider alternative scenarios-including various forms of novae, nuclear-burning instabilities, massive star events, and mergers-finding them all inferior to the atypically hot FU Ori star classification. The source eventually may be interpreted as a new category of young star outburst with a larger amplitude and shorter rise time than most FU Ori-like events.
- ID:
- ivo://CDS.VizieR/J/A+A/650/A173
- Title:
- Four Herbig-Haro objects SOFIA/FIFI-LS images
- Short Name:
- J/A+A/650/A173
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We present SOFIA/FIFI-LS observations of three Class 0 and one Class I outflows (Cep E, HH 1, HH 212, and L1551 IRS5) in the far-infrared [OI]63um and [OI]145um transitions. Spectroscopic [OI]63um maps enable us to infer the spatial extent of warm (T~500-1200K), low-excitation atomic gas within these protostellar outflows. Our main goal is to determine mass-loss rates from the obtained [OI]63um maps and compare these with accretion rates from other studies. The far-infrared [OI]63um emission line is predicted to be the main coolant of dense, dissociative J-shocks caused by decelerated wind or jet shocks. If proper shock conditions prevail, the instantaneous mass-ejection rate is directly connected to the [OI]63um luminosity. In order to unravel evolutionary trends we analyse a set of 14 Class 0/I outflow sources that have been spatially resolved in the [OI]63um emission. We compare these data with a sample of 74 Class 0/I/II outflow sources that have been observed with Herschel (WISH, DIGIT, WILL, GASPS surveys) without spatially resolving the [OI]63um line.
- ID:
- ivo://CDS.VizieR/J/A+A/603/A58
- Title:
- Full spectrum of Proxima Centauri
- Short Name:
- J/A+A/603/A58
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The discovery of Proxima b, a terrestrial temperate planet, presents the opportunity of studying a potentially habitable world in optimal conditions. A key aspect to model its habitability is to understand the radiation environment of the planet in the full spectral domain. We characterize the X-rays to mid-IR radiative properties of Proxima with the goal of providing the top-of-atmosphere fluxes on the planet. We also aim at constraining the fundamental properties of the star, namely its mass, radius, effective temperature and luminosity. We employ observations from a large number of facilities and make use of different methodologies to piece together the full spectral energy distribution of Proxima. In the high-energy domain, we pay particular attention to the contribution by rotational modulation, activity cycle, and flares so that the data provided are representative of the overall radiation dose received by the atmosphere of the planet.
- ID:
- ivo://CDS.VizieR/J/A+A/646/A102
- Title:
- FU Ori multi-band interferometric observations
- Short Name:
- J/A+A/646/A102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- FU Orionis is the archetypal FUor star, a subclass of young stellar object (YSO) that undergo rapid brightening events, often gaining 4-6 magnitudes on timescales of days. This brightening is often associated with a massive increase in accretion; one of the most ubiquitous processes in astrophysics from planets and stars to super-massive black holes. We present multi-band interferometric observations of the FU Ori circumstellar environment, including the first J-band interferometric observations of a YSO. We investigate the morphology and temperature gradient of the inner-most regions of the accretion disk around FU Orionis. We aim to characterise the heating mechanisms of the disk and comment on potential outburst triggering processes. Methods. Recent upgrades to the MIRC-X instrument at the CHARA array allowed the first dual-band J and H observations of YSOs. Using baselines up to 331m, we present high angular resolution data of a YSO covering the near-infrared bands J, H, and K. The unprecedented spectral range of the data allows us to apply temperature gradient models to the innermost regions of FU Ori. We spatially resolve the innermost astronomical unit of the disk and determine the exponent of the temperature gradient of the inner disk to T{prop.to}r^-0.74+/-0.02^. This agrees with theoretical work that predicts T{prop.to}r^-0.75^ for actively accreting, steady state disks, a value only obtainable through viscous heating within the disk. We find a disk which extends down to the stellar surface at 0.015+/-0.007au where the temperature is found to be 5800+/-700K indicating boundary layer accretion. We find a disk inclined at 32+/-4{deg} with a minor-axis position angle of 34+/-11{deg}.
- ID:
- ivo://CDS.VizieR/J/MNRAS/487/2771
- Title:
- Gaia-DR2 distance to the W3 Complex
- Short Name:
- J/MNRAS/487/2771
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Perseus Arm is the closest Galactic spiral arm from the Sun, offering an excellent opportunity to study in detail its stellar population. However, its distance has been controversial with discrepancies by a factor of two. Kinematic distances are in the range 3.9-4.2kpc as compared to 1.9-2.3kpc from spectrophotometric and trigonometric parallaxes, reinforcing previous claims that this arm exhibits peculiar velocities. We used the astrometric information of a sample of 31 OB stars from the star-forming W3Complex to identify another 37 W3 members and to derive its distance from their Gaia-DR2 parallaxes with improved accuracy. The Gaia-DR2 distance to the W3Complex, 2.14^+0.08^_-0.07_kpc, coincides with the previous stellar distances of ~2kpc. The Gaia-DR2 parallaxes tentatively show differential distances for different parts of the W3 Complex: W3 Main, located to the NE direction, is at 2.30^+0.19^_-0.16_kpc, the W3 Cluster (IC1795), in the central region of the complex, is at 2.17^+0.12^_-0.11_kpc, and W3(OH) is at 2.00^+0.29^_-0.23_kpc to the SW direction. The W3 Cluster is the oldest region, indicating that it triggered the formation of the other two star-forming regions located at the edges of an expanding shell around the cluster.
- ID:
- ivo://CDS.VizieR/J/AJ/160/108
- Title:
- Gaia-Kepler stellar properties catalog. II. Planets
- Short Name:
- J/AJ/160/108
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Studies of exoplanet demographics require large samples and precise constraints on exoplanet host stars. Using the homogeneous Kepler stellar properties derived using the Gaia Data Release 2 by Berger et al., we recompute Kepler planet radii and incident fluxes and investigate their distributions with stellar mass and age. We measure the stellar mass dependence of the planet radius valley to be dlogR_p/d_logM_{star}_=0.26_-0.16_^+0.21^, consistent with the slope predicted by a planet mass dependence on stellar mass (0.24-0.35) and core-powered mass loss (0.33). We also find the first evidence of a stellar age dependence of the planet populations straddling the radius valley. Specifically, we determine that the fraction of super-Earths (1-1.8{R_{Earth}_) to sub-Neptunes (1.8-3.5R_{Earth}_) increases from 0.61{+/-}0.09 at young ages (<1Gyr) to 1.00{+/-}0.10 at old ages (>1Gyr), consistent with the prediction by core-powered mass loss that the mechanism shaping the radius valley operates over Gyr timescales. Additionally, we find a tentative decrease in the radii of relatively cool (Fp<150{F}_{Earth}_) sub-Neptunes over Gyr timescales, which suggests that these planets may possess H/He envelopes instead of higher mean molecular weight atmospheres. We confirm the existence of planets within the hot sub-Neptunian "desert" (2.2R_{Earth}_<Rp<3.8R_{Earth}_, Fp>650F_{Earth}_) and show that these planets are preferentially orbiting more evolved stars compared to other planets at similar incident fluxes. In addition, we identify candidates for cool (Fp<20F_{Earth}_) inflated Jupiters, present a revised list of habitable zone candidates, and find that the ages of single and multiple transiting planet systems are statistically indistinguishable.
