<p>We use various analytical techniques to study Young Stellar Objects (YSOs) in an area of approximately <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(10~^{\prime }\times 10~^{\prime }\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>10</mn> <mmultiscripts> <mspace width="3.33333pt" /> <mrow /> <mo>′</mo> </mmultiscripts> <mo>×</mo> <mn>10</mn> <mmultiscripts> <mspace width="3.33333pt" /> <mrow /> <mo>′</mo> </mmultiscripts> </mrow> </math></EquationSource> </InlineEquation> in the IRAS 18456-0223 star-forming region. We use archival optical (<i>Gaia DR3</i>) and infrared (<i>2MASS</i>, <i>UKIDSS</i>, <i>Spitzer</i>, <i>WISE</i>, and <i>Herschel</i>) data and our optical spectroscopy of three bright stars for this purpose. We identify 89 YSOs (80 class II and 9 class I), based on their infrared properties. Our multiwavelength SED fits of select YSOs show that they have masses <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(\sim 0.1\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo>∼</mo> <mn>0.1</mn> </mrow> </math></EquationSource> </InlineEquation>–7.2&#xa0;<InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(M_\odot \)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>M</mi> <mo>⊙</mo> </msub> </math></EquationSource> </InlineEquation> and are upto 4&#xa0;Myr old. Our Minimum Spanning Tree (MST) analysis shows that these YSOs, situated at around 600 pc, form clusters with radial extent of order <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(0.5\,\textrm{pc}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>0.5</mn> <mspace width="0.166667em" /> <mtext>pc</mtext> </mrow> </math></EquationSource> </InlineEquation> and mean surface densities <InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(\sim 60\,\textrm{pc}^{-2}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo>∼</mo> <mn>60</mn> <mspace width="0.166667em" /> <msup> <mtext>pc</mtext> <mrow> <mo>-</mo> <mn>2</mn> </mrow> </msup> </mrow> </math></EquationSource> </InlineEquation>. We compare <i>UKIDSS</i> and <i>2MASS</i> data of the YSOs and find that some of them show variability. We constructed maps based on <i>Herschel</i> data which reveal multiple column density peaks (<InlineEquation ID="IEq6"> <EquationSource Format="TEX">\(N_{\mathrm{H_2}}\sim 10^{22}\,\textrm{cm}^{-2}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>N</mi> <msub> <mi mathvariant="normal">H</mi> <mn>2</mn> </msub> </msub> <mo>∼</mo> <msup> <mn>10</mn> <mn>22</mn> </msup> <mspace width="0.166667em" /> <msup> <mtext>cm</mtext> <mrow> <mo>-</mo> <mn>2</mn> </mrow> </msup> </mrow> </math></EquationSource> </InlineEquation>) embedded in cold (<InlineEquation ID="IEq7"> <EquationSource Format="TEX">\(T_d \sim 10{-}13\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>T</mi> <mi>d</mi> </msub> <mo>∼</mo> <mn>10</mn> <mo>-</mo> <mn>13</mn> </mrow> </math></EquationSource> </InlineEquation>&#xa0;K) filaments. Our near-infrared extinction map exhibits several high-<InlineEquation ID="IEq8"> <EquationSource Format="TEX">\(A_V\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>A</mi> <mi>V</mi> </msub> </math></EquationSource> </InlineEquation> peaks, some of which coincide with the sub-mm column density maxima. Using our optical spectra of three bright sources, we show that they are of A-K type. One star shows the Li I 6707&#xa0;Å&#xa0; line, indicating its youth.</p>

错误:搜索内容不能为空,请输入英文关键词
错误:关键词超出字数限制,请精简
高级检索

Stellar contents and star formation in IRAS 18456-0223

  • Nilesh Pandey,
  • U. S. Kamath

摘要

We use various analytical techniques to study Young Stellar Objects (YSOs) in an area of approximately \(10~^{\prime }\times 10~^{\prime }\) 10 × 10 in the IRAS 18456-0223 star-forming region. We use archival optical (Gaia DR3) and infrared (2MASS, UKIDSS, Spitzer, WISE, and Herschel) data and our optical spectroscopy of three bright stars for this purpose. We identify 89 YSOs (80 class II and 9 class I), based on their infrared properties. Our multiwavelength SED fits of select YSOs show that they have masses \(\sim 0.1\) 0.1 –7.2  \(M_\odot \) M and are upto 4 Myr old. Our Minimum Spanning Tree (MST) analysis shows that these YSOs, situated at around 600 pc, form clusters with radial extent of order \(0.5\,\textrm{pc}\) 0.5 pc and mean surface densities \(\sim 60\,\textrm{pc}^{-2}\) 60 pc - 2 . We compare UKIDSS and 2MASS data of the YSOs and find that some of them show variability. We constructed maps based on Herschel data which reveal multiple column density peaks ( \(N_{\mathrm{H_2}}\sim 10^{22}\,\textrm{cm}^{-2}\) N H 2 10 22 cm - 2 ) embedded in cold ( \(T_d \sim 10{-}13\) T d 10 - 13  K) filaments. Our near-infrared extinction map exhibits several high- \(A_V\) A V peaks, some of which coincide with the sub-mm column density maxima. Using our optical spectra of three bright sources, we show that they are of A-K type. One star shows the Li I 6707 Å  line, indicating its youth.