{"work":{"id":"60d83241-bfac-42f1-9f2b-4731c6cac2e7","openalex_id":"https://openalex.org/W2143675579","doi":"10.1086/318388","arxiv_id":"astro-ph/0009217","raw_key":null,"title":"The Milky Way in Molecular Clouds: A New Complete CO Survey","authors":[{"given":"T. M.","family":"Dame","sequence":"first","affiliation":[]},{"given":"Dap","family":"Hartmann","sequence":"additional","affiliation":[]},{"given":"P.","family":"Thaddeus","sequence":"additional","affiliation":[]}],"authors_text":"Dame, T","year":2000,"venue":"astro-ph","abstract":"New large-scale CO surveys of the first and second Galactic quadrants and the nearby molecular cloud complexes in Orion and Taurus, obtained with the CfA 1.2 m telescope, have been combined with 31 other surveys obtained over the past two decades with that instrument and a similar telescope on Cerro Tololo in Chile, to produce a new composite CO survey of the entire Milky Way. The survey consists of 488,000 spectra that Nyquist or beamwidth (1/8-deg) sample the entire Galactic plane over a strip 4-10 deg wide in latitude, and beamwidth or 1/4-deg sample nearly all large local clouds at higher latitudes.\n  A map of molecular column density predicted from complete and unbiased far-infrared and 21 cm surveys of the Galaxy was used both to determine the completeness of the present survey and to extrapolate it to the entire sky at |b| < 32 deg. The close agreement of the observed and predicted maps implies that only ~2% of the total CO emission at |b| < 32 deg lies outside our current sampling. Taking into account this small amount of unobserved emission, the mean molecular column density decreases from ~3 E20 cm-2 at |b| = 5 deg to ~0.1 E20 cm-2 at |b| = 30 deg.\n  The ratio of the predicted molecular column density map to the observed CO intensity map provides a calibration of the CO-to-H2 mass conversion factor X = N(H2)/Wco. Out of the Galactic plane (|b| > 5 deg), X shows little systematic variation with latitude from a mean value of 1.8 +/- 0.3 E20 cm-2 K-1 km-1 s. Given the large sky area and large quantity of CO data analyzed, we conclude that this is the most reliable measurement to date of the mean X value in the solar neighborhood.","external_url":"https://arxiv.org/abs/astro-ph/0009217","cited_by_count":1820,"metadata_source":"pith","metadata_fetched_at":"2026-07-09T10:46:11.504548+00:00","pith_arxiv_id":"astro-ph/0009217","created_at":"2026-05-08T17:33:47.697508+00:00","updated_at":"2026-07-11T11:50:26.030339+00:00","title_quality_ok":true,"display_title":"M., Hartmann, D., & Thaddeus, P","render_title":"M., Hartmann, D., & Thaddeus, P"},"hub":{"state":{"work_id":"60d83241-bfac-42f1-9f2b-4731c6cac2e7","tier":"hub","tier_reason":"10+ Pith inbound or 1,000+ external citations","pith_inbound_count":33,"external_cited_by_count":1820,"distinct_field_count":4,"first_pith_cited_at":"2024-04-21T04:00:03+00:00","last_pith_cited_at":"2026-07-08T14:21:18+00:00","author_build_status":"not_needed","summary_status":"needed","contexts_status":"needed","graph_status":"needed","ask_index_status":"not_needed","reader_status":"not_needed","recognition_status":"not_needed","updated_at":"2026-08-23T10:49:33.751005+00:00","tier_text":"hub"},"tier":"hub","role_counts":[{"context_role":"dataset","n":2},{"context_role":"background","n":1}],"polarity_counts":[{"context_polarity":"use_dataset","n":2},{"context_polarity":"background","n":1}],"runs":{},"summary":{},"graph":{},"authors":[]}}