J/ApJ/526/788ivo://CDS.VizieR/J/ApJ/526/788doi:10.26093/cds/vizier.15260788CDSLee C.W.Myers P.C.Tafalla M.2013-03-06T06:17:55Z2000-03-26T10:00:12ZCDS support team

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

cds-question@unistra.frinterstellar-mediumradio-sourcesmolecular-cloudsWe present the first results of a survey of 220 starless cores selected primarily by their optical obscuration and observed in CS (2-1), N_2_H^+^ (1-0), and C^18^O (1-0) using the Northeast Radio Observatory Corporation (NEROC) Haystack 37 m telescope. We have detected 163 out of 196 sources observed in CS, 72 out of 142 in N_2_H^+^, and 30 out of 30 in C18O. In total, 69 sources were detected in both CS and N_2_H^+^. The isolated component of the N_2_H^+^ (1-0) spectrum (F_1_F = 0,1-1,2) usually shows a weak symmetric profile that is optically thin. In contrast, a significant fraction of the CS spectra show non-Gaussian shapes, which we interpret as arising from a combination of self-absorption due to lower excitation gas in the core front and kinematics in the core. The distribution of the normalized velocity difference ({delta}V_CS_) between the CS and N_2_H^+^ peaks appears significantly skewed to the blue (V_CS_ < 0), as was found in a similar study of dense cores with embedded young stellar objects (YSOs). The incidence of sources with blue asymmetry tends to increase as the total optical depth or the integrated intensity of the N_2_H^+^ line increases.1999ApJ...526..788Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/526/788CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/288/601 : Dense molecular cores (Zinchenko+ 1994)J/A+AS/111/95 : Studies of dense molecular cores (Zinchenko+, 1995)J/A+AS/118/191 : Multitransition CS-study towards H2O masers (Juvela, 1996)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/526/788https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/526/788http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/526/788https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/526/788https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/526/788http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/526/788GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/526/788/table1 (Starless Cores Observed in CS, N_2_H^+^, and C^18^O)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/526/788/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/526/788/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/526/788/table1?GETtext/xml+votable180.050000true0.84759967.3130330.005555555555555556Cone search capability for table J/ApJ/526/788/table2 (Parameters of starless cores observed in both CS and N_2_H^+^)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/526/788/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/526/788/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/526/788/table2?GETtext/xml+votable180.050000true36.55735675.4509260.0055555555555555565/3869 6/1031 1037 1039 1048 1050 1052 1054 1067 1068 1074 1075 1080 1114 1117 1126 1129 1136 1170 1290 1542 1825 1935 1937 1959 1968 3038 3755 3849 3898 12964 13997 14002 14199 14270 14317 14319 14333 14347 14350 14351 14369 14371 14654 14663 14686 14708 14710 15408 15411 15426 15433 15541 15543 15556 15582 15590 15630 15633 15643 15649 15851 15964 15965 16129 16197 16198 22205 22829 23549 23560 23561 23739 23970 24300 24308 24515 29112 29247 29347 29350 29354 29362 29366 29367 29374 29375 29377 29551 29560 29562 29566 29597 29646 29653 29657 29661 29668 29682 29683 30219 30228 30234 30344 30346 30349 30355 30574 30575 30609 30621 30623 30664 30666 30670 30743 30748 30792 30793 30798 30820 31257 31263 32011 32068 32092 42970 42981 42992 42993https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/526/788?format=asciiRadiodefaultJ/ApJ/526/788/table1Starless Cores Observed in CS, N_2_H^+^, and C^18^OrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameSource namemeta.id;meta.maincharf_RAB1950[cd] Indicates source position obtained elsewhere (1)meta.codecharRAB1950Right Ascension (B1950) from Lee+ (1999ApJS..123..233L)pos.eq.ra;meta.mainDEB1950Declination (B1950) from Lee+ (1999)pos.eq.dec;meta.mainVCS? Velocity of CSkm/sphys.velocfloatnullablef_VCS[ND] Indicates object was not detected in CSmeta.codechare_VCS? Error in VCSkm/sstat.errorfloatnullableVN2H? Velocity of N_2_Hkm/sphys.velocfloatnullablef_VN2H[ND] Indicates object was not detected in N_2_H^+^meta.codechare_VN2H? Error in VN2Hkm/sstat.errorfloatnullableVC18O? Velocity of C^18^Okm/sphys.velocfloatnullablee_VC18O? Error in VC18Okm/sstat.errorfloatnullable_RA.icrsRight ascension (ICRS) (computed by VizieR, not part of the original data)pos.eq.ranullableindexed_DE.icrsDeclination (ICRS) (computed by VizieR, not part of the original data)pos.eq.decnullableindexedJ/ApJ/526/788/table2Parameters of starless cores observed in both CS and N_2_H^+^n_DCS[h] Note on DCS (3)meta.notecharVN2H? Velocity of N_2_Hkm/sphys.velocfloatnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameSource namemeta.id;meta.maincharf_RAB1950[fg] Indicates source position obtained elsewhere (1)meta.codecharRAB1950Right Ascension (B1950) from Lee+ (1999ApJS..123..233L)pos.eq.ra;meta.mainDEB1950Declination (B1950) from Lee+ (1999)pos.eq.dec;meta.mainVCS? Velocity of CSkm/sphys.velocfloatnullablee_VCS? 1{sigma} error in VCSkm/sstat.errorfloatnullablee_VN2H? 1{sigma} error in VN2Hkm/sstat.errorfloatnullableVC18O? Velocity of C^18^Okm/sphys.velocfloatnullablee_VC18O? 1{sigma} error in VC18Okm/sstat.errorfloatnullableFWHM? FWHM of N_2_Hkm/sphys.angSizefloatnullablee_FWHM? 1{sigma} error in FWHMkm/sstat.error;phys.angSizefloatnullableTau? Optical depth of N_2_Hkm/sphys.absorption.opticalDepthfloatnullablee_Tau? 1{sigma} error in Taukm/sstat.errorfloatnullablef_Tau[e] Indicates values are difficult to ensure because S/N < 5meta.codecharDCS? Normalized velocity difference of CS (2)km/sphys.veloc;arith.difffloatnullablee_DCS? 1{sigma} error in DCSkm/sstat.errorfloatnullable_RA.icrsRight ascension (ICRS) (computed by VizieR, not part of the original data)pos.eq.ranullableindexed_DE.icrsDeclination (ICRS) (computed by VizieR, not part of the original data)pos.eq.decnullableindexed