J/AJ/170/342ivo://CDS.VizieR/J/AJ/170/342CDSYoungblood A.France K.Koskinen T.Mason J.P.Redfield S.Wood B.E.,Bourrier V.dos Santos L.Johns-Krull C.King G.W.Linsky J.L.,Peacock S.2026-08-19T14:33:11Z2026-08-19T14:40:29ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frinterstellar-mediumh-i-line-emissionspectroscopyultraviolet-astronomyvisible-astronomyultraviolet-sourcesx-ray-sourcesObtaining a complete census of gas in the local interstellar medium (LISM; <100pc) is challenging given the limited available tracers of the warm, partially ionized medium. Medium- to high-resolution UV absorption spectroscopy toward individual nearby stars is the primary method used, and incomplete spatial sampling of this complex medium makes a global map of the material difficult. Using HI column density measurements derived from HI Ly{alpha} spectroscopy toward 164 stars inside 100pc, we have generated 2D spatially interpolated N(HI) maps for different distance shells. Based on the area-weighted sky averages, we find that sight lines inside 10pc typically have log_10_(N(HI)/cm^-2^)~17.9. For greater distance shells, log_10_(N(HI)/cm^-2^) increases to 18.3 (10-20pc), then to 18.4 (20-70pc), and finally to 18.6 (70-100pc). This last increase is likely associated with the detection of the Local Bubble boundary, thus making the plateau of column density from 20 to 70pc notable and suggestive of the rarity of warm LISM material beyond ~10-20pc. We estimate that the uncertainties associated with N(HI) values inferred from the interpolated sky maps are approximately inversely correlated with the number of samples in each distance shell, and are in the range of 0.20-0.48dex, compared to the 0.01-0.30dex typically determined from direct Ly{alpha} observations. We discuss the impact of these uncertainties on interstellar medium corrections of extreme-UV and Ly{alpha} observations for nearby stars. Denser spatial sampling of the sky via UV absorption spectroscopy of nearby stars is required to improve the accuracy of these N(HI) estimates.2025AJ....170..342Yhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/170/342CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/203A : Second Extreme Ultra-Violet Explorer Catalog (2EUVE, 1997)III/135A : Henry Draper Catalogue and Extension (Cannon+ 1918-1924; ADC 1989)IV/39 : TESS Input Catalog version 8.2 (TIC v8.2) (Paegert+, 2021)IX/35 : Second EUVE Catalogues (Bowyer+, 1996-99)J/MNRAS/274/1165 : The 2RE Source Catalogue (Pye+ 1995)J/A+A/510/A54 : NaI and CaII interstellar absorption (Welsh+, 2010)J/A+A/615/A117 : 55 Cnc geocoronal emission lines template (Bourrier+, 2018)J/ApJ/886/19 : Lya obs. of low-mass stars Ross 825 & 1044 (Schneider+, 2019)J/A+A/634/L4 : HST/STIS FUV spectra of K2-18 (dos Santos+, 2020)J/A+A/661/A147 : Gal. interstellar dust Gaia-2MASS 3D maps (Lallement+, 2022)J/AJ/164/106 : Parameters for 130 sight lines within 100pc (Linsky+, 2022)J/ApJ/946/98 : HST/COS obs. of main-sequence FGKM dwarfs (Cruz Aguirre+, 2023)J/ApJS/272/30 : Habitable Worlds Observatory (HWO): 164 targets (Harada+, 2024)J/AJ/170/26 : Predicted detections of exoplanets using CHES & HWO (Bao+, 2025)J/AJ/170/147 : Mass-separation constraints for HWO target syst (Painter+, 2025)J/PASP/137/J4402 : HWO Target Stars & Systems 2025 list (TSS25) (Tuchow+, 2025)J/AJ/170/293 : HWO: UV & X-ray catalog from archival data (Peacock+, 2025)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/170/342https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/170/342http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/170/342https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/170/342https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/170/342http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/170/342GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/170/342/tablea1 (Target list and N(HI) values)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/170/342/tablea1?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/170/342/tablea1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/170/342/tablea1?GETtext/xml+votable180.050000true217.4315-62.68210.0055555555555555566/311 798 1032 1036 1504 1875 1890 2127 2472 2737 3005 4444 4591 4651 5413 5420 5534 6219 6241 6256 7264 7516 7610 7763 8205 8790 9459 9835 10386 10731 10999 11044 11126 11856 12451 12592 12644 12983 13264 13301 13688 13743 13778 14266 14293 14534 14825 14858 14931 16220 16472 16834 17253 17425 17790 18147 18450 18496 18666 18726 18785 18800 19970 20178 20327-20328 20701 20940 20981 21941 22289 22300 22309 22616 22626 22645 22708-22709 22813 22818 23191 23230 23531 23538-23540 24151 24160 24227 24587 24924 25427 25444 26538 27462 27568 27574 27787 28026 28151 28400 28548 28696 28955 29196 30543 30833 31191 31216 31751 31781 32335 32491 32848 33717 33813 33849 33966 34181 34446 36614 36658 36664 36693 36697 37654 38067 38095 38456 38461 38464 39165 39693 40250 40784 40892 41591 41763 42101 42290 42459 42652 44669 44816 44921 45382 45472 45530 45564 45669 46128 46429 46566 46632 46922 47347 47589 48163 48274 48572 48652https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/170/342?format=asciiX-rayEUVUVOpticalRadiodefaultJ/AJ/170/342/tablea1Target list and N(HI) valuesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar name (1)meta.id;meta.maincharGLON[2.21/358.28] Galactic longitude (1)degpos.galactic.lonGLAT[-84.1/89.58] Galactic latitude (1)degpos.galactic.latDist[1.3/98.26] Distance (1)pcpos.distancefloat[NHI][17.34/19.53] Log of column density (2)log(cm**-2)phys.columnDensityfloate_[NHI][0/0.66] Uncertainty in log10 (NHI) (2)log(cm**-2)stat.error;phys.columnDensityfloate_[NHI]adj[0.1/0.66] Adjusted uncertainty in log10 (NHI) (3)log(cm**-2)stat.error;phys.columnDensityfloatnHI[2e-3/0.21] Average volume densitycm**-3phys.densityfloate_nHI[0/0.1] Uncertainty in nHIcm**-3stat.error;phys.densitydoublee_nHIadj[7e-4/0.14] Adjusted uncertainty in nHIcm**-3stat.error;phys.densityfloatInstInstrument/Grating (5)meta.id;instrcharRef[1/51] Column density reference (4)meta.ref;phys.columnDensityint_RA.icrsRight ascension (ICRS) (computed by VizieR, not part of the original data. The format may include more digits than the original data because of internal accuracy requirements in VizieR and across other CDS services)degpos.eq.raindexed_DE.icrsDeclination (ICRS) (computed by VizieR, not part of the original data. The format may include more digits than the original data because of internal accuracy requirements in VizieR and across other CDS services)degpos.eq.decindexed