分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： Based on the accurate color excess $E_{\rm G_{BP},G_{RP}}$ of more than 4 million stars and $E_{\rm NUV,G_{BP}}$ of more than 1 million stars from \citet{2021ApJS..254...38S}, the distance and the extinction of the molecular clouds in the MBM catalog at $|b|>20^{\circ}$ are studied in combination with the distance measurement of \emph{Gaia}/EDR3. The distance as well as the color excess is determined for 66 molecular clouds. The color excess ratio $E_{\rm G_{BP},G_{RP}}/E_{\rm NUV,G_{BP}}$ is derived for 39 of them, which is obviously larger and implies more small particles at smaller extinction. In addition, the scale height of the dust disk is found to be about 100 pc and becomes large at the anticenter direction due to the disk flaring.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： The three-dimensional extinction and structure are studied for the Taurus, Orion, Perseus and California molecular clouds based on the LAMOST spectroscopy. Stellar color excess is calculated with the intrinsic color index derived from the atmospheric parameters in the LAMOST DR8 catalog and the observed color index in the Gaia EDR3 and the 2MASS PSC. In combination with the distance from the Gaia EDR3 parallax, the three-dimensional dust extinction maps are retrieved in the color excesses $E_{\rm{G_{BP},G_{RP}}}$ and $E_{\rm{J,K_{S}}}$ with an uncertainty of $\sim$0.03mag and $\sim$0.07mag respectively. The extinction maps successfully separate the clouds that overlap in the sky area and manifest the structure of the individual cloud. Meanwhile, a bow-like structure is found with a distance range from 175pc to 250pc, half of which is a part of the Per-Tau Shell in similar coordinates and distance while the other half is not. Three low-extinction rings are additionally discovered and briefly discussed.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： Extinction in ultraviolet is much more significant than in optical or infrared, which can be very informative to precisely measure the extinction and understand the dust properties in the low extinction areas. The high Galactic latitude sky is such an area, important for studying the extragalactic sky and the universe. Based on the stellar parameters measured by the LAMOST and GALAH spectroscopy and the ultraviolet photomery by the \emph{GALEX} space telescope, the extinction of 1,244,504 stars in the \emph{GALEX}/NUV band and 56,123 stars in the \emph{GALEX}/FUV band are calculated precisely. \textbf{The error of color excess is 0.009, 0.128 and 0.454 mag for $E_{\rm G_{BP}, G_{RP}}$, $E_{\rm NUV,G_{BP}}$ and $E_{\rm FUV,G_{BP}}$ respectively.} They delineates the \emph{GALEX}/NUV extinction map of about a third of the sky mainly at the high Galactic latitude area with an angular resolution of $\sim 0.4\,\, \rm deg$. The mean color excess ratio in the entire sky areas is derived to be 3.25, 2.95 and -0.37 for $E_{{\rm NUV,G_{BP}}} / E_{{\rm G_{BP},G_{RP}}}$, $E_{{\rm FUV,G_{BP}}} / E_{{\rm G_{BP},G_{RP}}}$ and $E_{{\rm FUV,NUV}} / E_{{\rm G_{BP},G_{RP}}}$ respectively, which is in general agreement with the previous works, and their changes with the Galactic latitude and the interstellar extinction are discussed.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： The three-dimensional extinction and structure are studied for the Taurus, Orion, Perseus and California molecular clouds based on the LAMOST spectroscopy. Stellar color excess is calculated with the intrinsic color index derived from the atmospheric parameters in the LAMOST DR8 catalog and the observed color index in the Gaia EDR3 and the 2MASS PSC. In combination with the distance from the Gaia EDR3 parallax, the three-dimensional dust extinction maps are retrieved in the color excesses $E_{\rm{G_{BP},G_{RP}}}$ and $E_{\rm{J,K_{S}}}$ with an uncertainty of $\sim$0.03mag and $\sim$0.07mag respectively. The extinction maps successfully separate the clouds that overlap in the sky area and manifest the structure of the individual cloud. Meanwhile, a bow-like structure is found with a distance range from 175pc to 250pc, half of which is a part of the Per-Tau Shell in similar coordinates and distance while the other half is not. Three low-extinction rings are additionally discovered and briefly discussed.
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