- ID:
- ivo://CDS.VizieR/J/A+A/651/A59
- Title:
- Dense warm ionized medium in the inner Galaxy
- Short Name:
- J/A+A/651/A59
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Ionized interstellar gas is an important component of the interstellar medium and its lifecycle. The recent evidence for a widely distributed highly ionized warm interstellar gas with a density intermediate between the warm ionized medium (WIM) and compact HII regions suggests that there is a major gap in our understanding of the interstellar gas. Our goal is to investigate the properties of the dense warm ionized medium in the Milky Way using spectrally resolved SOFIA GREAT [NII] 205um fine-structure lines and Green Bank Telescope hydrogen radio recombination lines (RRL) data, supplemented by spectrally unresolved Herschel PACS [NII] 122um data, and spectrally resolved ^12^CO. We observed eight lines of sight (LOS) in the 20{deg}<l<30{deg}region in the Galactic plane. We spectrally unresolved Herschel PACS [NII] 122um data, and spectrally resolved ^12^CO. Methods. We observed eight lines of sight (LOS) in the 20{deg}<l<30{deg}region in the Galactic plane. We analyzed spectrally resolved lines of [NII] at 205um and RRL observations, along with the spectrally unresolved Herschel PACS 122um emission, using excitation and radiative transfer models to determine the physical parameters of the dense warm ionized medium. We derived the kinetic temperature, as well as the thermal and turbulent velocity dispersions from the [NII] and RRL linewidths. The regions with [NII] 205um emission are characterized by electron densities, n(e)~10-35cm^-3^, temperatures range from 3400 to 8500K, and nitrogen column densities N(N^+^)~7x10^16^ to 3x10^17^cm^-2^. The ionized hydrogen column densities range from 6x10^20^ to 1.7x10^21^cm^-2^ and the fractional nitrogen ion abundance x(N^+^)~1.1x10^-4^ to 3.0x10^-4^, implying an enhanced nitrogen abundance at a distance ~4.3kpc from the Galactic Center. The [NII] 205um emission lines coincide with CO emission, although often with an offset in velocity, which suggests that the dense warm ionized gas is located in, or near, star-forming regions, which themselves are associated with molecular gas. These dense ionized regions are found to contribute >~50% of the observed [CII] intensity along these LOS. The kinetic temperatures we derive are too low to explain the presence of N^+^ resulting from electron collisional ionization and/or proton charge transfer of atomic nitrogen. Rather, these regions most likely are ionized by extreme ultraviolet (EUV) radiation from nearby star-forming regions or as a result of EUV leakage through a clumpy and porous interstellar medium.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/835/217
- Title:
- Density distributions for mm-wave line ratios
- Short Name:
- J/ApJ/835/217
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore the use of mm-wave emission line ratios to trace molecular gas density when observations integrate over a wide range of volume densities within a single telescope beam. For observations targeting external galaxies, this case is unavoidable. Using a framework similar to that of Krumholz & Thompson (2007ApJ...669..289K), we model emission for a set of common extragalactic lines from lognormal and power law density distributions. We consider the median density of gas that produces emission and the ability to predict density variations from observed line ratios. We emphasize line ratio variations because these do not require us to know the absolute abundance of our tracers. Patterns of line ratio variations have the potential to illuminate the high-end shape of the density distribution, and to capture changes in the dense gas fraction and median volume density. Our results with and without a high-density power law tail differ appreciably; we highlight better knowledge of the probability density function (PDF) shape as an important area. We also show the implications of sub-beam density distributions for isotopologue studies targeting dense gas tracers. Differential excitation often implies a significant correction to the naive case. We provide tabulated versions of many of our results, which can be used to interpret changes in mm-wave line ratios in terms of adjustments to the underlying density distributions.
- ID:
- ivo://CDS.VizieR/J/A+A/421/595
- Title:
- Deprojecting spiral galaxies method
- Short Name:
- J/A+A/421/595
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use two new methods developed recently (Barbera et al., 2004, Cat. <J/A+A/415/849>), as well as information obtained from the literature, to calculate the orientation parameters of the spiral galaxies in the Ohio State University Bright Spiral Galaxy Survey (OSUBSGS). We compare the results of these methods with data from the literature, and find in general good agreement. We provide a homogeneous set of mean orientation parameters which can be used to approximately deproject the disks of the galaxies and facilitate a number of statistical studies of galaxy properties.
- ID:
- ivo://CDS.VizieR/J/A+A/415/849
- Title:
- Deprojection of spiral galaxies
- Short Name:
- J/A+A/415/849
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present two methods that can be used to deproject spirals, based on Fourier analysis of their images, and discuss their potential and restrictions. Our methods perform particularly well for galaxies more inclined than 50 degrees or for non-barred galaxies more inclined than 35 degrees. They are fast and straightforward to use, and thus ideal for large samples of galaxies. Moreover, they are very robust for low resolutions and thus are appropriate for samples of cosmological interest. The relevant software is available from us upon request. We use these methods to determine the values of the position and inclination angles for a sample of 81 spiral galaxies contained in the Frei et al. (1996AJ....111..174F) sample. We compare our results with the values found in the literature, based on other methods. We find statistically very good agreement.
- ID:
- ivo://CDS.VizieR/J/AJ/81/807
- Title:
- Deprojection of the r^1/4^ law tables
- Short Name:
- J/AJ/81/807
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A spherical galaxy with reduced surface brightness, J=B({alpha})/B_e_, obeying the r^1/4^ law, logJ=-3.3307 ({alpha}^1/4^-1), where {alpha} is the reduced radius, {alpha}=r/r_e_ (r_e_ is the effective radius), is deprojected to find the corresponding space density, mass, mean density, force, potential, escape velocity, and potential energy at each point in the galaxy. Numerical tabulations to five significant figures are given for 124 points in the range 10^-6^<=R/r_e_<=260. In addition the projected surface brightness B({alpha}) and integrated luminosity within {alpha} are tabulated for the range 10^-6^<={alpha}=r/r_e_<=260. Conversion factors to cgs units and to M_{sun}_, pc, km/s, L_{sun}_ units are given. Asymptotic expansions for the space density {rho}(s) in the ranges s=<10^-4^ and s>=10^-1^ are derived, and it is demonstrated that the projection of the expansion for s<=10^-1^ is almost indistinguishable from the r^1/4^ law itself, apart from a small excess of luminosity in the central regions. Formulae and numerical tables of the luminosity distribution are given for use in galaxy photometry. Relations between the total galactic mass M_T_, the effective radius r_e_, the velocity dispersion {sigma}_v_, the central density {rho}_c_ and the mass M_N_ and radius R_N_ of the nucleus are derived. Here the "nucleus" is defined as the region within which stars having a velocity equal to the mean velocity dispersion in space, {sigma}_v_.
- ID:
- ivo://CDS.VizieR/J/AJ/160/84
- Title:
- Depth-of-search & completness for 213 exoplanets
- Short Name:
- J/AJ/160/84
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Identifying which systems are more likely to host an imageable planet can play an important role in the construction of an optimized target list for future direct imaging missions, such as the planned Coronagraph Instrument (CGI) technology demonstration for the Nancy Grace Roman Space Telescope. For single-planet systems, the presence of an already detected exoplanet can severely restrict the target's stable region and should therefore be considered when searching for unknown companions. To do so, we first analyze the performance and robustness of several two-planet stability criteria by comparing them with long-term numerical simulations. We then derive the necessary formulation for the computation of (a, R) analytic stability maps, which can be used in conjunction with depth-of-search grids in order to define the stable-imageable region of a system. The dynamically stable completeness (i.e., the expected number of imageable and stable planets) can then be calculated via convolution with the selected occurrence grid, obtaining a metric that can be directly compared for imaging prioritization. Applying this procedure to all the currently known single-planet systems within a distance of 50pc, we construct a ranked target list based on the CGI's predicted performance and SAG13 occurrence rates. Finally, we evaluate the importance of considering the radial velocity data from past Doppler surveys in order to rule out entire regions of our parameter space where, if a planet existed, it would have certainly been detected by previous RV observations.
- ID:
- ivo://CDS.VizieR/J/ApJS/119/277
- Title:
- -3.5<=DE<=8.5, 11.5<RA<13.5 redshift survey
- Short Name:
- J/ApJS/119/277
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We compile 1113 redshifts (648 new measurements, 465 from the literature) for Zwicky catalog galaxies (Cat. <VII/4>) in the region (-3.5{deg}<={delta}<=8.5{deg}, 11.5h<={alpha}<=13.5h). We include redshifts for 114 component objects in 78 Zwicky catalog multiplets. The redshift survey in this region is 99.5% complete to the Zwicky catalog limit, m_Zw_=15.7. It is 99.9% complete to m_Zw_=15.5, the CfA Redshift Survey (CfA2) magnitude limit. The survey region is adjacent to the northern portion of CfA2, overlaps the northernmost slice of the Las Campanas Redshift Survey (Cat. <VII/203>), includes the southern extent of the Virgo Cluster, and is roughly centered on the QSO 3C 273. As in other portions of the Zwicky catalog, bright and faint galaxies trace the same large-scale structure.
- ID:
- ivo://CDS.VizieR/J/MNRAS/489/5301
- Title:
- DES Y3 substellar LT and M catalogs
- Short Name:
- J/MNRAS/489/5301
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we present a catalogue of 11745 brown dwarfs with spectral types ranging from L0 to T9, photometrically classified using data from the Dark Energy Survey (DES) year 3 release matched to the Vista Hemisphere Survey (VHS) DR3 and Wide-field Infrared Survey Explorer (WISE) data, covering ~2400deg^2^ up to i_AB_=22. The classification method follows the same photo-type method previously applied to SDSS-UKIDSS-WISE data. The most significant difference comes from the use of DES data instead of SDSS, which allow us to classify almost an order of magnitude more brown dwarfs than any previous search and reaching distances beyond 400 parsecs for the earliest types. Next, we also present and validate the GalmodBD simulation, which produces brown dwarf number counts as a function of structural parameters with realistic photometric properties of a given survey. We use this simulation to estimate the completeness and purity of our photometric LT catalogue down to i_AB_=22, as well as to compare to the observed number of LT types. We put constraints on the thin disk scale height for the early L (L0-L3) population to be around 450 parsecs, in agreement with previous findings. For completeness, we also publish in a separate table a catalogue of 20863 M dwarfs that passed our colour cut with spectral types greater than M6. Both the LT and the late M catalogues are found at https://des.ncsa.illinois.edu/releases/other/y3-mlt.
- ID:
- ivo://CDS.VizieR/J/A+A/622/A114
- Title:
- Detached eclipsing binaries MITSuME photometry
- Short Name:
- J/A+A/622/A114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of the combined photometric and spectroscopic analysis of three detached eclipsing binaries (DEBs), the secondary components of which are not visible or are very hard to identify in the optical spectra - ASAS J052743-0359.7, ASAS J065134-2211.5, and ASAS J073507-0905.7. The first one is the known visual binary ADS~4022, and we found that it is a quadruple system composed of two spectroscopic binaries, one of which shows eclipses.
- ID:
- ivo://CDS.VizieR/J/ApJ/872/85
- Title:
- Detached eclipsing binaries with Gaia parallaxes
- Short Name:
- J/ApJ/872/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using a sample of 81 Galactic, detached eclipsing binary stars we investigated the global zero-point shift of their parallaxes with the Gaia Data Release 2 (DR2) parallaxes. The stars in the sample lay in a distance range of 0.04-2kpc from the Sun. The photometric parallaxes {omega}_Phot_ of the eclipsing binaries were determined by applying a number of empirical surface brightness-color (SBC) relations calibrated on optical-infrared colors. For each SBC relation we calculated the individual differences d{varpi}_i_=({varpi}_Gaia_-{varpi}_Phot_)_i_ and then we calculated unweighted and weighted means. As the sample covers the whole sky we interpret the weighted means as the global shifts of the Gaia DR2 parallaxes with respect to our eclipsing binary sample. Depending on the choice of the SBC relation the shifts vary from -0.094 to -0.025mas. The weighted mean of the zero-point shift from all colors and calibrations used is d{omega}=-0.054+/-0.024mas. However, the SBC relations based on (B-K) and (V-K) colors, which are the least reddening dependent and have the lowest intrinsic dispersions, give a zero-point shift of d{omega}=-0.031+/-0.011mas in full agreement with results obtained by Lindegren+ (2018A&A...616A...2L) and Arenou+ (2018A&A...616A..17A). Our result confirms the global shift of Gaia DR2 parallaxes of d{omega}=-0.029mas reported by the Gaia team, but we do not confirm the larger zero-point shift reported by a number of follow-up papers.