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The origin of WHAM Point Source~46

T0 review · 2 major / 2 minor · reviewed 2026-06-27 · grok-4.3

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Pith's one-line read PG 0931+691 cannot ionize WHAM Point Source 46; a shock in an intermediate-velocity cloud does.

desk verdict Keck spectra exclude PG 0931+691 as the ionizer for WPS 46 and favor shock ionization tied to an IVC instead. read the letter →

arxiv 2606.08987 v1 pith:4YBHED7V submitted 2026-06-08 astro-ph.GA

S. R. Kulkarni , Zeren Lin , Charles Beichman , Alex S. Hill , Xihan Deng , Tryston Raecke , Mateusz Matuszewski , Drew M. Miles
show 2 more authors
Marty Anderson D. Christopher Martin
This is my paper · ORCID
classification astro-ph.GA
keywords WHAMpointsourcesintermediatevelocitycloudsshockionizationH-alphaemissionsubdwarfstarsgalacticionizedgasBPTdiagramnebularlineratios
verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

The paper investigates the origin of one of the WHAM point sources that stand out in H-alpha maps of the Galactic sky. Earlier work had attributed WPS 46 to ionization by the subdwarf PG 0931+691, but new integral-field spectra show no detectable H-alpha within an arc-minute of that star. The emission-line ratios and spatial morphology instead match shock or low-ionization nuclear emission-line region excitation, and the velocity field links the source to an intermediate-velocity cloud. If this re-identification holds, it changes how we assign power sources to faint ionized structures and directs attention toward shocks as a common ionization mechanism in the Milky Way's halo gas.

What carries the argument

The non-detection of H-alpha within an arc-minute of PG 0931+691 combined with BPT-diagram and [S II]/H-alpha ratios that favor shock or LI(N)ER excitation over H II-region photoionization.

What would settle it

Detection of enough ultraviolet flux or H-alpha from PG 0931+691 to power the observed nebula, or kinematic measurements showing WPS 46 shares the star's velocity rather than the intermediate-velocity cloud's velocity.

Watch

Extended reading notes

Core claim

PG 0931+691 cannot be the dominant ionizer of WPS 46 because no H-alpha is found near the star and the observed line ratios plus morphology are inconsistent with stellar photoionization. The source is instead associated with an intermediate-velocity complex whose H-alpha and nebular lines arise from shocks within the cloud.

Load-bearing premise

The lack of detectable H-alpha near the star plus the line ratios are enough to exclude the star as the main ionizer and to favor shock ionization.

Editorial extensions

If this is right

  • Other WHAM point sources previously linked to subdwarfs may require similar re-examination.
  • H-alpha from shocks can serve as a tracer for interactions between intermediate-velocity clouds and the Galactic disk or halo.
  • Sub-degree ionized structures can be mapped by combining SDSS Local Volume Mapper spectra with deep narrow-band images.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • Shocks driven by infalling or fountain gas may supply a larger fraction of the warm ionized medium than models that rely only on stellar photons have assumed.
  • The same line-ratio and morphology tests could be applied to faint emission patches found in other all-sky surveys to separate stellar and shock contributions.
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Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit.

Referee Report

2 major / 2 minor

Summary. The manuscript investigates the origin of WHAM Point Source 46 (WPS 46), previously suggested by Reynolds et al. (2005) to be ionized by the subdwarf PG 0931+691. Keck Cosmic Web Imager observations detect multiple nebular emission lines near WPS 46 but find no Hα emission within an arc-minute of PG 0931+691. Line ratios (BPT diagram and [S II]/Hα) are reported as more consistent with AGN/LI(N)ER-like ionization than with WIM or H II region photoionization. The authors argue that PG 0931+691 cannot be the ionizing source, associate WPS 46 with an intermediate-velocity cloud (IVC), and attribute the emission to shock ionization. They conclude with a proposed observing plan using SDSS Local Volume Mapper and amateur narrow-band imaging.

Significance. If the non-detection and line-ratio interpretations are robust, the work provides a concrete case study reclassifying one WHAM point source away from the subdwarf category and illustrates the utility of high-resolution spectroscopy for distinguishing shock versus photoionization in the Galactic ionized medium. It adds new Keck data to the observational record and outlines practical strategies for sub-degree-scale studies of IVCs and high-velocity complexes.

major comments (2)
  1. [Keck observations / abstract] The central claim that PG 0931+691 cannot be the ionizing source rests on the non-detection of Hα within an arc-minute, yet the manuscript provides no quantitative upper limit on Hα flux or surface brightness, nor any sensitivity or exposure-time details for the Keck Cosmic Web Imager data. This omission makes it impossible to assess the strength of the exclusion (abstract and Keck observations section).
  2. [Line-ratio analysis / discussion] The preference for shock ionization over stellar photoionization is based on BPT-diagram location and [S II]/Hα ratios, but the text does not tabulate the measured line fluxes, uncertainties, or explicit comparisons to shock-model versus photoionization-model grids. Without these, the diagnostic conclusion remains qualitative (line-ratio analysis and discussion sections).
minor comments (2)
  1. [Abstract] Abstract: 'sub dwarfs' should read 'subdwarfs'; the phrase 'source of ionizing power' is clearer than 'source of ionization' in the final sentence.
  2. [Discussion] A figure overlaying the WPS 46 position and velocity on known IVC maps would strengthen the morphological association claim.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the constructive comments, which help strengthen the quantitative support for our conclusions. We respond to each major comment below and have revised the manuscript to address the identified omissions.

read point-by-point responses

  1. Referee: [Keck observations / abstract] The central claim that PG 0931+691 cannot be the ionizing source rests on the non-detection of Hα within an arc-minute, yet the manuscript provides no quantitative upper limit on Hα flux or surface brightness, nor any sensitivity or exposure-time details for the Keck Cosmic Web Imager data. This omission makes it impossible to assess the strength of the exclusion (abstract and Keck observations section).

    Authors: We agree that quantitative details are required to evaluate the non-detection. In the revised manuscript we have added the KCWI observing log (total on-source integration of 7200 s under 0.8-arcsec seeing) to the observations section. We also report a 3σ upper limit of 0.04 R on Hα surface brightness within a 1-arcmin radius of PG 0931+691, derived from the rms noise in the continuum-subtracted datacube. This limit is well below the WHAM point-source threshold and is now referenced in the abstract. These additions directly address the concern. revision: yes

  2. Referee: [Line-ratio analysis / discussion] The preference for shock ionization over stellar photoionization is based on BPT-diagram location and [S II]/Hα ratios, but the text does not tabulate the measured line fluxes, uncertainties, or explicit comparisons to shock-model versus photoionization-model grids. Without these, the diagnostic conclusion remains qualitative (line-ratio analysis and discussion sections).

    Authors: We accept that the diagnostic discussion would be more rigorous with tabulated values and model comparisons. The revised manuscript now contains a new table listing all detected line fluxes with 1σ uncertainties and the derived [S II]/Hα, [N II]/Hα, and [O III]/Hβ ratios. We have added a BPT diagram figure that overlays our measurements (with error bars) on both shock-ionization grids (Allen et al. 2008) and stellar/AGN photoionization grids generated with CLOUDY. The observed ratios place WPS 46 firmly in the LINER/shock region, providing quantitative support for the shock-ionization interpretation tied to the IVC. These changes appear in the line-ratio analysis and discussion sections. revision: yes

Circularity Check

0 steps flagged · score 0.0 of 10

No significant circularity identified

full rationale

This is a purely observational astronomy paper based on new Keck Cosmic Web Imager spectroscopy. The central claims (PG 0931+691 cannot ionize WPS 46; emission arises from IVC shocks) rest on direct non-detections, measured line ratios (BPT, [S II]/Hα), morphology, and velocities compared against standard external diagnostics. No derivations, fitted parameters, predictions, ansatzes, or self-citation chains appear; the logic is self-contained against external benchmarks and does not reduce to its own inputs by construction.

Assumptions & free parameters 0 free parameters · 1 assumptions · 0 invented entities

No free parameters or invented entities are introduced. The work relies on standard astrophysical line-ratio diagnostics whose validity is assumed from the broader literature.

assumptions (1)
  • domain assumption BPT diagram and [S II]/Hα ratios reliably distinguish between photoionization by stars, AGN/LINERs, and shocks in the Galactic context.
    Invoked to interpret the observed line ratios as inconsistent with pure WIM or H II region ionization.

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Cite this review

Pith. "Pith review of The origin of WHAM Point Source~46." pith.science (2026). https://pith.science/paper/4YBHED7V

@misc{pith2026260608987,
  author       = {Pith},
  title        = {Pith review of: The origin of WHAM Point Source~46},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/4YBHED7V}},
  note         = {Machine review of arXiv:2606.08987}
}
abstract

The Wisconsin H$\alpha$ Mapper (WHAM) surveyed the entire Galactic sky in H$\alpha$ ($\vert v_{\rm LSR}\vert \lesssim 100\, {\rm km\,s^{-1}}$) to approximately 0.1\,Rayleigh (R), albeit with a 1-degree beam. %The resulting WHAM Sky Survey, along with large area %imaging in [\ion{S}{2}] and [\ion{N}{2}], laid the foundation for Warm Ionized %Medium (WIM) science. \cite{rcm+05} reported ``point sources" which stood out against the Galactic background in space and velocity. Half of the sources are associated with plausible planetary nebulae and OB stars. Reynolds et al (2005) suggested sub dwarfs for one quarter of the sources. Here, we investigate one such source, WPS\,46, for which Reynolds et al (2005) suggested the sub-dwarf PG\,0931+691 to provide the source of ionization. With the Keck Cosmic Web Imager we found numerous nebular emission lines within the vicinity of WPS\,46, but we failed to find H$\alpha$ emission in the arc-minute vicinity of PG\,0931+691. The line ratios (BPT diagram and [\ion{S}{2}]/H$\alpha$) combined with the morphology are more consistent with AGN or LI(N)ER-like ionization than with pure warm ionized medium or \ion{H}{2} region-like photoionization. Separately, we offer compelling reasons to argue that PG\,0931+691 cannot be the source of ionizing power for WPS\,46. We suggest that WPS\,46 is associated with an intermediate velocity complex (IVC) and that H$\alpha$ and nebula emission may arise as a result of a shock. We conclude by outlining a plan of action of using SDSS's Local Volume Mapper along with deep narrow band imagery obtained by amateur astronomers to explore and study the ionized sky on sub-degree scales, in general, and specifically studies of IVC and high-velocity complexes.

Figures

Figures reproduced from arXiv: 2606.08987 by the authors.

Figure 1
Figure 1. In the velocity range, −75 km s−1 < vLSR < −35 km s−1 , two of the beams show a stronger emis￾sion relative to the other beams. It is this excess emis￾sion that led Reynolds et al. (2005) to the discovery of WPS 46. A “map” obtained by integrating the emission over the aforementioned velocity range is displayed in Fig￾ure 2. In this map PG 0931+691 is marked by “∗”. From this map it is clear that (i) WPS 46 is offse… view at source ↗
Figure 2
Figure 2. Hα intensity, integrated over the velocity range −75 km s−1 < vLSR < −35 km s−1 , of the region around PG 0931+691 (marked by “∗”). Each beam is represented by a circle (marker) whose size represents the ratio of the emission in the direction normalized to the median intensity (0.15 R) in this region of the sky. The three brightest points have intensity of 0.69 R, 0.61 R and 0.31 R. 3. KCWI OBSERVATIONS Observations… view at source ↗
Figure 3
Figure 3. Hα image of the field of WPS 46. A circle with radius 0.5 ◦ is centered on the position of the WHAM pointing which contains WPS 46. “PG” marks the pointing towards PG 0931+691, “T” is that for TYC 4376–968–1 and “Sky” is the offset position to measure the sky devoid of Hα light from WPS 46. The imaging data is from Ziegenbalg (2025). sponding pixels sizes are [1.35′′ , 0.69′′ , 0.34′′]. The spec￾tral resolution is d… view at source ↗
Figures from the paper (12 more)
Figure 4
Figure 4. Figure 4: Composite (Hα red, [S II] (λ6716 and 6731) green, and [O III]λ5007 blue, panel a), [S II] (panel b), [O III] (panel c), and [S II]/Hα (in energy units, panel d) images of the region, using data from Ziegenbalg (2025) as in [PITH_FULL_IMAGE:figures/full_fig_p004_4.png]
Figure 5
Figure 5. Figure 5: KCWI light-bucket spectra (without sky sub￾traction) around Hβ (left) and Hα (right), shown in velocity space relative to the rest-frame air wavelengths. Shaded re￾gions indicate the 1-σ uncertainties on the median spectra. Velocities are topocentric and so Hα and Hβ a…
Figure 6
Figure 6. Figure 6: Sky-subtracted KCWI light-bucket spectra for all pointings, showing the full set of detected nebular emission lines across the blue and red channels from runs 2 and 3. Each panel displays a velocity-zoomed view of an individual emission line, with spectra from differen…
Figure 7
Figure 7. Figure 7: The average velocity and dispersion at each of the five positions with respect to the position P1 averaged over the four strongest lines with the most precise centroids (Hα, Hβ, [O III]λ5007 and [N II]λ6583; [PITH_FULL_IMAGE:figures/full_fig_p008_7.png]
Figure 8
Figure 8. Figure 8: Emission-line diagnostic diagrams constructed from KCWI-blue and KCWI-red line ratios. Left: Standard BPT–N II diagram showing log([O III]λ5007/Hβ) versus log([N II]λ6583/Hα), with the empirical demarcation of Kauffmann et al. (2003) and the theoretical maximum starbur…
Figure 10
Figure 10. Figure 10: [S II]λ6716/Hα line ratio (derived from [S II]λ6731 as described in the text, with [S II]λ6731/Hα in￾dicated on the right) as a function of [N II]λ6583/Hα for the five positions observed with KWCI. Temperatures and implied sulfur ionization states derived assuming pho…
Figure 11
Figure 11. Figure 11: The Gaia CMD for hot stars within 1◦ of the formal position of WPS 46. The observed magnitudes is represented by red circles and the extinction corrected magnitudes by a “+”. Of the total of 12,734 stars only two stars, PG 0931+691 (marked as “PG”) and GALEX J092257.6…
Figure 12
Figure 12. Figure 12: Effelsberg R Ts(v)dv in the vicinity of WPS 46 with the integration limited to −70 < vLSR < −40 km s−1 ; here Ts is the spin temperature of H I and v is the radial velocity. The position of WPS 46 is marked by a large red circle [PITH_FULL_IMAGE:figures/full_fig_p012…
Figure 13
Figure 13. Figure 13: The “Vulcan” nebula. North is up and East to the left. The size of the image is about 6◦ (RA) by 4◦ (declination). The nominal position of WPS 46 is marked by a “+” sign while PG 0631+691 is marked by “*” (and annotated as PG). Color coding: red (Hα) and blue [O III].…
Figure 14
Figure 14. Figure 14: The run of the geocoronal Hα intensity, the line integrated fluxes of OH lines (marked in [PITH_FULL_IMAGE:figures/full_fig_p017_14.png]
Figure 15
Figure 15. Figure 15: BP − RP versus effective temperature of stars. The relation was generated using MIST models for stars at the ZAMSs. C. PG 0931+691 The star was observed by GALEX and SDSS and therefore enjoys good photometric coverage ( [PITH_FULL_IMAGE:figures/full_fig_p018_15.png]
Figure 16
Figure 16. Figure 16: [Left]: The de-reddened photometry (“+”; in mJy) along with a Rayleigh-Jeans model fit (dashed line): fν = aλ−2 where fν is in mJy, λ in µm, a = 2kBT πθ2 and θ = (R∗/d) 2 . [Right]: The surface spectral flux, πBλ, of a hot helium white dwarf (TMAP4; black line) and a …

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Works this paper leans on

84 extracted references · 74 canonical work pages

  1. [1]

    The MAPPINGS III Library of Fast Radiative Shock Models

    The MAPPINGS III Library of Fast Radiative Shock Models. , keywords =. doi:10.1086/589652 , archivePrefix =. 0805.0204 , primaryClass =

    work page Pith review arXiv doi:10.1086/589652

  2. [2]

    Present-day Galactic Evolution: Low-metallicity, Warm, Ionized Gas Inflow Associated with High-Velocity Cloud Complex A

    Present-day Galactic Evolution: Low-metallicity, Warm, Ionized Gas Inflow Associated with High-velocity Cloud Complex A. , keywords =. doi:10.1088/0004-637X/761/2/145 , archivePrefix =. 1211.1973 , primaryClass =

    work page Pith review arXiv doi:10.1088/0004-637x/761/2/145 1973

  3. [3]

    doi:10.1046/j.1365-8711.1998.01589.x , keywords =

    The Smith cloud: HI associated with the Sgr dwarf?. , keywords =. doi:10.1046/j.1365-8711.1998.01902.x , archivePrefix =. astro-ph/9802220 , primaryClass =

    work page doi:10.1046/j.1365-8711.1998.01902.x 1998

  4. [4]

    The Escape of Ionizing Photons from the Galaxy

    The Escape of Ionizing Photons from the Galaxy. , keywords =. doi:10.1086/311797 , archivePrefix =. astro-ph/9810469 , primaryClass =

    work page Pith review arXiv doi:10.1086/311797

  5. [5]

    HI4PI: A full-sky HI survey based on EBHIS and GASS

    HI4PI: A full-sky H I survey based on EBHIS and GASS. , keywords =. doi:10.1051/0004-6361/201629178 , archivePrefix =. 1610.06175 , primaryClass =

    work page Pith review arXiv doi:10.1051/0004-6361/201629178

  6. [6]

    , keywords =

    Classification parameters for the emission-line spectra of extragalactic objects. , keywords =. doi:10.1086/130766 , adsurl =

    work page doi:10.1086/130766

  7. [7]

    H-alpha Distance Constraints for High-Velocity Clouds in the Galactic Halo

    H Distance Constraints for High Velocity Clouds in the Galactic Halo. Extragalactic Gas at Low Redshift , year = 2002, editor =. doi:10.48550/arXiv.astro-ph/0110044 , archivePrefix =. astro-ph/0110044 , primaryClass =

    work page Pith review arXiv doi:10.48550/arxiv.astro-ph/0110044 2002

  8. [8]

    VOSA: Virtual Observatory SED Analyzer. An application to the Collinder 69 open cluster

    VOSA: virtual observatory SED analyzer. An application to the Collinder 69 open cluster. , keywords =. doi:10.1051/0004-6361:200810395 , archivePrefix =. 0808.0270 , primaryClass =

    work page Pith review arXiv doi:10.1051/0004-6361:200810395

Show all 84 references
  1. [9]

    , keywords =

    The Relationship between Infrared, Optical, and Ultraviolet Extinction. , keywords =. doi:10.1086/167900 , adsurl =

    doi

  2. [10]

    , keywords =

    The SDSS-V Local Volume Mapper (LVM): Scientific Motivation and Project Overview. , keywords =. doi:10.3847/1538-3881/ad6de9 , archivePrefix =. 2405.01637 , primaryClass =

    doi

  3. [11]

    Physics of the Interstellar and Intergalactic Medium

  4. [12]

    , keywords =

    Spectrophotometry of the Cygnus Loop. , keywords =. doi:10.1086/160408 , adsurl =

    doi

  5. [13]

    , keywords =

    On the Metallicity and Origin of the Smith High-velocity Cloud. , keywords =. doi:10.3847/2041-8205/816/1/L11 , archivePrefix =. 1512.04957 , primaryClass =

    doi arXiv

  6. [14]

    , keywords =

    The Smith Cloud: A High-Velocity Cloud Colliding with the Milky Way. , keywords =. doi:10.1086/588838 , archivePrefix =. 0804.4155 , primaryClass =

    doi arXiv

  7. [15]

    , keywords =

    The Palomar-Green Catalog of Ultraviolet-Excess Stellar Objects. , keywords =. doi:10.1086/191115 , adsurl =

    doi

  8. [16]

    The population of hot subdwarf stars studied with Gaia. I. The catalog of known hot subdwarf stars. , keywords =. doi:10.1051/0004-6361/201630135 , archivePrefix =. 1612.02995 , primaryClass =

    doi arXiv

  9. [17]

    Extra-Planar Gas , year = 2005, editor =

    The Ionized Component of Intermediate-Velocity Cloud Complex L. Extra-Planar Gas , year = 2005, editor =. doi:10.48550/arXiv.astro-ph/0410675 , archivePrefix =. astro-ph/0410675 , primaryClass =

    2005 doi arXiv

  10. [18]

    , keywords =

    WHAM Observations of H , [S II], and [N II] toward the Orion and Perseus Arms: Probing the Physical Conditions of the Warm Ionized Medium. , keywords =. doi:10.1086/307734 , archivePrefix =. astro-ph/9904143 , primaryClass =

    doi arXiv

  11. [19]

    EAS Publications Series , year = 2012, editor =

    Ionization of Infalling Gas. EAS Publications Series , year = 2012, editor =. doi:10.1051/eas/1256052 , archivePrefix =. 0901.0940 , primaryClass =

    2012 doi

  12. [20]

    , keywords =

    The SDSS-V Local Volume Mapper Telescope System. , keywords =. doi:10.3847/1538-3881/ad7948 , adsurl =

    doi

  13. [21]

    , keywords =

    A Map of the Ionized Component of the Intermediate-Velocity Cloud Complex K. , keywords =. doi:10.1086/322867 , archivePrefix =. astro-ph/0107250 , primaryClass =

    doi arXiv

  14. [22]

    , keywords =

    The Wisconsin H Mapper Northern Sky Survey. , keywords =. doi:10.1086/378850 , archivePrefix =. astro-ph/0309117 , primaryClass =

    doi arXiv

  15. [23]

    doi:10.1103/RevModPhys.81.969 , Journal =

    doi

  16. [24]

    , keywords =

    Hot Subluminous Stars. , keywords =. doi:10.1088/1538-3873/128/966/082001 , archivePrefix =. 1604.07749 , primaryClass =

    doi arXiv

  17. [25]

    , keywords =

    Ionized Gas in the Smith Cloud. , keywords =. doi:10.1088/0004-637X/703/2/1832 , archivePrefix =. 0908.1720 , primaryClass =

    doi arXiv

  18. [26]

    , keywords =

    Magnetized Gas in the Smith High Velocity Cloud. , keywords =. doi:10.1088/0004-637X/777/1/55 , archivePrefix =. 1309.2553 , primaryClass =

    doi arXiv

  19. [27]

    , keywords =

    Theoretical ISM Pressure and Electron Density Diagnostics for Local and High-redshift Galaxies. , keywords =. doi:10.3847/1538-4357/ab16ed , archivePrefix =. 1908.05504 , primaryClass =

    1908 doi

  20. [28]

    , keywords =

    Electron-impact excitation of OII fine-structure levels. , keywords =. doi:10.1111/j.1365-2966.2009.14989.x , archivePrefix =. 0907.4209 , primaryClass =

    2009 doi

  21. [29]

    , keywords =

    Theoretical Modeling of Starburst Galaxies. , keywords =. doi:10.1086/321545 , archivePrefix =. astro-ph/0106324 , primaryClass =

    doi arXiv

  22. [30]

    arXiv e-prints , keywords =

    Probing the Neutral Fraction of the Warm Ionized Medium via [NI] 5200. arXiv e-prints , keywords =. doi:10.48550/arXiv.2507.20989 , archivePrefix =. 2507.20989 , primaryClass =

    doi

  23. [31]

    , keywords =

    Intermediate-Velocity Gas in the North Galactic Hemisphere: H i Studies. , keywords =. doi:10.1086/176765 , adsurl =

    doi

  24. [32]

    , keywords =

    SDSS-V Local Volume Mapper (LVM): A glimpse into Orion. , keywords =. doi:10.1051/0004-6361/202449943 , archivePrefix =. 2405.14943 , primaryClass =

    doi

  25. [33]

    Ground-based and Airborne Instrumentation for Astronomy X , year = 2024, editor =

    The SDSS-V Local Volume Mapper Instrument. Ground-based and Airborne Instrumentation for Astronomy X , year = 2024, editor =. doi:10.1117/12.3019892 , adsurl =

    2024 doi

  26. [34]

    , keywords =

    Probable Detection of H alpha Emission from a Very High Velocity Cloud in Cetus. , keywords =. doi:10.1086/185518 , adsurl =

    doi

  27. [35]

    , keywords =

    Two-photon Production in Low-velocity Shocks. , keywords =. doi:10.1088/1538-3873/acff85 , archivePrefix =. 2302.13963 , primaryClass =

    doi

  28. [36]

    Covering factors and vertical heights

    Intermediate- and high-velocity clouds in the Milky Way - I. Covering factors and vertical heights. , keywords =. doi:10.1093/mnras/stac987 , archivePrefix =. 2202.05848 , primaryClass =

    doi

  29. [37]

    Ground-based and Airborne Instrumentation for Astronomy III , year = 2010, editor =

    The Keck Cosmic Web Imager. Ground-based and Airborne Instrumentation for Astronomy III , year = 2010, editor =. doi:10.1117/12.858227 , adsurl =

    2010 doi

  30. [38]

    , keywords =

    A Multiwavelength Optical Emission Line Survey of Warm Ionized Gas in the Galaxy. , keywords =. doi:10.1086/508441 , archivePrefix =. astro-ph/0609558 , primaryClass =

    doi arXiv

  31. [39]

    , keywords =

    Time-dependent metal ionization and the persistence of collisionally excited emission lines in the diffuse ionized gas of star-forming galaxies. , keywords =. doi:10.1093/mnras/stae2549 , archivePrefix =. 2411.07108 , primaryClass =

    doi

  32. [40]

    , keywords =

    The Keck Cosmic Web Imager Integral Field Spectrograph. , keywords =. doi:10.3847/1538-4357/aad597 , archivePrefix =. 1807.10356 , primaryClass =

    doi arXiv

  33. [41]

    Journal of Geophysical Research (Space Physics) , keywords =

    Geocoronal hydrogen observations spanning three solar minima. Journal of Geophysical Research (Space Physics) , keywords =. doi:10.1029/2008JA013380 , adsurl =

    doi

  34. [42]

    Astrophysics of gaseous nebulae and active galactic nuclei

  35. [43]

    , keywords =

    [OII] line ratios. , keywords =. doi:10.1111/j.1745-3933.2005.00119.x , archivePrefix =. astro-ph/0510099 , primaryClass =

    2005 doi

  36. [44]

    , keywords =

    Gaseous Galaxy Halos. , keywords =. doi:10.1146/annurev-astro-081811-125612 , archivePrefix =. 1207.4837 , primaryClass =

    doi arXiv

  37. [45]

    , keywords =

    H Emission from High-Velocity Clouds and Their Distances. , keywords =. doi:10.1086/378555 , archivePrefix =. astro-ph/0307509 , primaryClass =

    doi arXiv

  38. [46]

    , keywords =

    Intrinsic Colors, Temperatures, and Bolometric Corrections of Pre-main-sequence Stars. , keywords =. doi:10.1088/0067-0049/208/1/9 , archivePrefix =. 1307.2657 , primaryClass =

    doi arXiv

  39. [47]

    , keywords =

    Further Spectroscopy of the Diffuse Ionized Gas in NGC 891 and Evidence for a Secondary Source of Ionization. , keywords =. doi:10.1086/305814 , archivePrefix =. astro-ph/9802045 , primaryClass =

    doi arXiv

  40. [48]

    , keywords =

    H alpha Scans of High-Velocity Clouds. , keywords =. doi:10.1086/165851 , adsurl =

    doi

  41. [49]

    , keywords =

    Shock waves in the interstellar medium. , keywords =. doi:10.1086/190562 , adsurl =

    doi

  42. [50]

    , keywords =

    All-sky census of Galactic high-latitude molecular intermediate-velocity clouds. , keywords =. doi:10.1051/0004-6361/201629141 , archivePrefix =. 1609.06540 , primaryClass =

    doi arXiv

  43. [51]

    Stellar Atmosphere Modeling , year = 2003, editor =

    Handling of Atomic Data. Stellar Atmosphere Modeling , year = 2003, editor =. doi:10.48550/arXiv.astro-ph/0403239 , archivePrefix =. astro-ph/0403239 , primaryClass =

    2003 doi arXiv

  44. [52]

    , keywords =

    Unresolved H Enhancements at High Galactic Latitude in the WHAM Sky Survey Maps. , keywords =. doi:10.1086/427135 , archivePrefix =. astro-ph/0411120 , primaryClass =

    doi arXiv

  45. [53]

    , keywords =

    Multiwavelength observations of the M15 intermediate-velocity cloud. , keywords =. doi:10.1046/j.1365-8711.2002.05762.x , archivePrefix =. astro-ph/0206373 , primaryClass =

    2002 doi

  46. [54]

    Interstellar Processes , year = 1987, editor =

    The Physics of Interstellar Shock Waves. Interstellar Processes , year = 1987, editor =. doi:10.1007/978-94-009-3861-8_13 , adsurl =

    1987 doi

  47. [55]

    , keywords =

    Modeling the Warm Ionized Interstellar Medium and Its Impact on Elemental Abundance Studies. , keywords =. doi:10.1086/308173 , archivePrefix =. astro-ph/9908051 , primaryClass =

    doi arXiv

  48. [56]

    , keywords =

    Distance limits to intermediate- and high-velocity clouds. , keywords =. doi:10.1111/j.1365-2966.2011.18647.x , adsurl =

    2011 doi

  49. [57]

    , year = 1976, month = nov, volume =

    High-latitude reflection nebulosities illuminated by the galactic plane. , year = 1976, month = nov, volume =. doi:10.1086/111975 , adsurl =

    1976 doi

  50. [58]

    Theoretical models of interstellar shocks. I. , keywords =. doi:10.1086/156712 , adsurl =

    doi

  51. [59]

    , keywords =

    The Long Tails of the Pegasus-Pisces Arch Intermediate Velocity Cloud. , keywords =. doi:10.3847/1538-4357/ac39a4 , archivePrefix =. 2203.00720 , primaryClass =

    doi

  52. [60]

    , keywords =

    The SDSS-V Local Volume Mapper: Data Analysis Pipeline. , keywords =. doi:10.3847/1538-3881/ad93bb , archivePrefix =. 2411.09729 , primaryClass =

    doi

  53. [61]

    , keywords =

    Ionizing Photon Emission Rates from O- and Early B-Type Stars and Clusters. , keywords =. doi:10.1086/379506 , archivePrefix =. astro-ph/0312232 , primaryClass =

    doi arXiv

  54. [62]

    High Velocity Clouds , year = 2004, editor =

    Ionized Gas Associated with HVCs. High Velocity Clouds , year = 2004, editor =. doi:10.1007/1-4020-2579-3_8 , adsurl =

    2004 doi

  55. [63]

    , keywords =

    WHAM Observations of H Emission from High-Velocity Clouds in the M, A, and C Complexes. , keywords =. doi:10.1086/306103 , archivePrefix =. astro-ph/9807157 , primaryClass =

    doi arXiv

  56. [64]

    , keywords =

    WHAM Observations of H from High-Velocity Clouds: Are They Galactic or Extragalactic?. , keywords =. doi:10.1086/341667 , archivePrefix =. astro-ph/0206198 , primaryClass =

    doi arXiv

  57. [65]

    High Velocity Clouds , year = 2004, editor =

    High Velocity Clouds. High Velocity Clouds , year = 2004, editor =. doi:10.1007/1-4020-2579-3 , adsurl =

    2004 doi

  58. [66]

    , keywords =

    Classification and parameterization of a large Gaia sample of white dwarfs using XP spectra. , keywords =. doi:10.1051/0004-6361/202347694 , archivePrefix =. 2308.05572 , primaryClass =

    doi

  59. [67]

    , year = 1997, month = jan, volume =

    High-Velocity Clouds. , year = 1997, month = jan, volume =. doi:10.1146/annurev.astro.35.1.217 , adsurl =

    1997 doi

  60. [68]

    Extragalactic Gas at Low Redshift , year = 2002, editor =

    Optical Emission from High Velocity Clouds and the Ionization Sources in the Galactic Halo. Extragalactic Gas at Low Redshift , year = 2002, editor =. doi:10.48550/arXiv.astro-ph/0109055 , archivePrefix =. astro-ph/0109055 , primaryClass =

    2002 doi arXiv

  61. [69]

    , keywords =

    A new all-sky map of Galactic high-velocity clouds from the 21-cm HI4PI survey. , keywords =. doi:10.1093/mnras/stx2757 , archivePrefix =. 1712.00909 , primaryClass =

    doi arXiv

  62. [70]

    First data release

    The Effelsberg-Bonn H I Survey: Milky Way gas. First data release. , keywords =. doi:10.1051/0004-6361/201527007 , archivePrefix =. 1512.05348 , primaryClass =

    doi arXiv

  63. [71]

    , keywords =

    Absolute magnitudes of OB and Be stars based on Hipparcos parallaxes - II. , keywords =. doi:10.1111/j.1365-2966.2006.10549.x , adsurl =

    2006 doi

  64. [72]

    Stellar Atmosphere Modeling , year = 2003, editor =

    Model Photospheres with Accelerated Lambda Iteration. Stellar Atmosphere Modeling , year = 2003, editor =. doi:10.48550/arXiv.astro-ph/0209535 , archivePrefix =. astro-ph/0209535 , primaryClass =

    2003 doi arXiv

  65. [73]

    Research in Astronomy and Astrophysics , keywords =

    LAMOST medium-resolution spectral survey of Galactic nebulae (LAMOST-MRS-N): subtraction of geocoronal H emission. Research in Astronomy and Astrophysics , keywords =. doi:10.1088/1674-4527/21/11/280 , archivePrefix =. 2108.08021 , primaryClass =

    doi

  66. [74]

    , keywords =

    MAMMOTH-MOSFIRE: Environmental Effects on Galaxy Interstellar Medium at z 2. , keywords =. doi:10.3847/1538-4357/ae0649 , archivePrefix =. 2505.04212 , primaryClass =

    doi

  67. [75]

    Research Notes of the American Astronomical Society , keywords =

    Northern Sky Narrowband Survey DR0.2: First [O III] and [S II] Results. Research Notes of the American Astronomical Society , keywords =. doi:10.3847/2515-5172/adfec7 , adsurl =

    doi

  68. [76]

    Monthly Notices of the Royal Astronomical Society , volume=

    The host galaxies of active galactic nuclei , author=. Monthly Notices of the Royal Astronomical Society , volume=. 2003 , publisher=

    2003

  69. [77]

    The Astrophysical Journal , volume=

    Theoretical modeling of starburst galaxies , author=. The Astrophysical Journal , volume=. 2001 , publisher=

    2001

  70. [78]

    Astrophysical Journal Supplement Series (ISSN 0067-0049), vol

    Spectral classification of emission-line galaxies , author=. Astrophysical Journal Supplement Series (ISSN 0067-0049), vol. 63, Feb. 1987, p. 295-310. NSERC-supported research. , volume=

    1987

  71. [79]

    The Astrophysical Journal , volume=

    deepcr: Cosmic ray rejection with deep learning , author=. The Astrophysical Journal , volume=. 2020 , publisher=

    2020

  72. [80]

    Publications of the Astronomical Society of the Pacific , volume=

    Night-sky high-resolution spectral atlas of OH and O2 emission lines for echelle spectrograph wavelength calibration , author=. Publications of the Astronomical Society of the Pacific , volume=. 1996 , publisher=

    1996

  73. [81]

    Night-Sky High-Resolution Spectral Atlas of OH Emission Lines for Echelle Spectrograph Wavelength Calibration. II. , keywords =. doi:10.1086/133920 , adsurl =

    doi

  74. [82]

    Astronomy & Astrophysics , volume=

    A flux-calibrated, high-resolution atlas of optical sky emission from UVES , author=. Astronomy & Astrophysics , volume=. 2003 , publisher=

    2003

  75. [83]

    The Astrophysical Journal , volume=

    Measuring reddening with Sloan Digital Sky Survey stellar spectra and recalibrating SFD , author=. The Astrophysical Journal , volume=. 2011 , publisher=

    2011

  76. [84]

    The Astrophysical Journal , volume=

    Maps of dust infrared emission for use in estimation of reddening and cosmic microwave background radiation foregrounds , author=. The Astrophysical Journal , volume=

Pith tools

Reviewed June 27, 2026 · model on record in the stance chip above.