Hostname: page-component-848d4c4894-8kt4b Total loading time: 0 Render date: 2024-07-05T01:07:48.577Z Has data issue: false hasContentIssue false
  • English
  • Français

Infrared study of the star-forming region associated with the UC HII regions G45.07+0.13 and G45.12+0.13

Published online by Cambridge University Press:  26 May 2022

N. Azatyan Open the ORCID record for N. Azatyan [Opens in a new window] ,
E. Nikoghosyan Open the ORCID record for E. Nikoghosyan [Opens in a new window] ,
H. Harutyunian ,
D. Baghdasaryan  and
D. Andreasyan
N. Azatyan*
Affiliation:
Byurakan Astrophysical Observatory, 0213, Aragatsotn Province, Byurakan, Armenia
E. Nikoghosyan
Affiliation:
Byurakan Astrophysical Observatory, 0213, Aragatsotn Province, Byurakan, Armenia
H. Harutyunian
Affiliation:
Byurakan Astrophysical Observatory, 0213, Aragatsotn Province, Byurakan, Armenia
D. Baghdasaryan
Affiliation:
Byurakan Astrophysical Observatory, 0213, Aragatsotn Province, Byurakan, Armenia
D. Andreasyan
Affiliation:
Byurakan Astrophysical Observatory, 0213, Aragatsotn Province, Byurakan, Armenia
*
Corresponding author: N. Azatyan, email: nayazatyan@bao.sci.am.
Get access Rights & Permissions [Opens in a new window]

Abstract

Ultra-compact H ii (UC HII) regions are an important phase in the formation and early evolution of massive stars and a key component of the interstellar medium (ISM). The main objectives of this work are to study the young stellar population associated with the G45.07+0.13 and G45.12+0.13 UC HII regions, as well as the ISM in which they are embedded. We determined the distribution of the hydrogen column density (N( $\mathrm{H}_2$ )) and dust temperature ( $T_d$ ) in the molecular cloud using Modified blackbody fitting on Herschel images obtained in four bands: 160, 250, 350, and $500\,\unicode{x03BC}\mathrm{m}$ . We used near-, mid-, and far-infrared photometric data to identify and classify the young stellar objects (YSOs). Their main parameters were determined by the radiation transfer models. We also constructed a colour-magnitude diagram and K luminosity functions (KLFs) to compare the parameters of stellar objects with the results of the radiative transfer models. We found that N( $\mathrm{H}_2$ ) varies from ${\sim}3.0 \times 10^{23}$ to $5.5 \times 10^{23}\,\mathrm{cm}^{-2}$ within the G45.07+0.13 and G45.12+0.13 regions, respectively. The maximum $T_d$ value is 35 K in G45.12+0.13 and 42 K in G45.07+0.13. $T_d$ then drops significantly from the centre to the periphery, reaching about 18–20 K at distances of ${\sim}2.6$ and ${\sim}3.7\,\mathrm{pc}$ from InfraRed Astronomical Satellite (IRAS) 19110+1045 (G45.07+0.13) and IRAS 19111+1048 (G45.12+0.13), respectively. The gas plus dust mass value included in G45.12+0.13 is ${\sim}3.4 \times 10^5\,\mathrm{M}_\odot$ and ${\sim}1.7 \times 10^5\,\mathrm{M}_\odot$ in G45.07+0.13. The UC HII regions are connected through a cold ( $T_d = 19\,\mathrm{K}$ ) bridge. The radial surface density distribution of the identified 518 YSOs exhibits dense clusters in the vicinity of both IRAS sources. The parameters of YSOs in the IRAS clusters (124 objects) and 394 non-cluster objects surrounding them show some differences. About 75% of the YSOs belonging to the IRAS clusters have an evolutionary age greater than $10^6$ yr. Their slope $\alpha$ of the KLF agrees well with a Salpeter-type initial mass function (IMF) ( $\gamma = 1.35$ ) for a high mass range (O–F stars, $\beta \sim 2$ ) at 1 Myr. The non-cluster objects are uniformly distributed in the molecular cloud, 80% of which are located to the right of the 0.1 Myr isochrone. The slope $\alpha$ of the KLF of non-cluster objects is $0.55\,\pm\,0.09$ , corresponding better to a Salpeter-type IMF for low-mass objects (G–M stars, $\beta \sim 1$ ). Our results show that two dense stellar clusters are embedded in these two physically connected UC HII regions. The clusters include several high- and intermediate-mass zero-age main sequence stellar objects. Based on the small age spread of the stellar objects, we suggest that the clusters originate from a single triggering shock. The extended emission observed in both UC HII regions is likely due to the stellar clusters.

Keywords

stars: pre-main sequencestars: luminosity functioninfrared: starsradiative transferinterstellar medium (ISM), nebulae
Type
Research Article
Information
Publications of the Astronomical Society of Australia , Volume 39 , 2022 , e024
Check for updates
Copyright
© The Author(s), 2022. Published by Cambridge University Press on behalf of the Astronomical Society of Australia

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Allen, L., et al. 2007, Protostars and Planets V, 361Google Scholar
Allen, L. E., et al. 2004, ApJS, 154, 363Google Scholar
Argon, A. L., Reid, M. J., & Menten, K. M. 2000, ApJS, 129, 159Google Scholar
Azatyan, N. M. 2019, A&A, 622, A38Google Scholar
Azatyan, N. M., Nikoghosyan, E. H., & Khachatryan, K. G. 2016, Ap, 59, 339Google Scholar
Balog, Z., et al. 2004, AJ, 128, 2942Google Scholar
Battersby, C., et al. 2011, A&A, 535, A128Google Scholar
Bessell, M. S., & Brett, J. M. 1988, PASP, 100, 1134Google Scholar
Blum, R. D., & McGregor, P. J. 2008, AJ, 135, 1708Google Scholar
Breen, S. L., et al. 2019, MNRAS, 484, 5072Google Scholar
Carey, S. J., et al. 2009, PASP, 121, 76Google Scholar
Carpenter, J. M. 2001, AJ, 121, 2851Google Scholar
Caulet, A., Gruendl, R. A., & Chu, Y. H. 2008, ApJ, 678, 200Google Scholar
Cesaroni, R., et al. 2015, A&A, 581, A124Google Scholar
Churchwell, E. 2002, ARA&A, 40, 27Google Scholar
Churchwell, E., Sievers, A., & Thum, C. 2010, A&A, 513, A9Google Scholar
Churchwell, E., Walmsley, C. M., & Wood, D. O. S. 1992, A&A, 253, 541Google Scholar
Churchwell, E., et al. 2009, PASP, 121, 213Google Scholar
de la Fuente, E., et al. 2020a, MNRAS, 492, 895Google Scholar
de la Fuente, E., et al. 2020b, MNRAS, 497, 4436Google Scholar
Egan, M. P., et al. 2003, VizieR Online Data Catalog, 5114Google Scholar
Ellsworth-Bowers, T. P., et al. 2015, ApJ, 799, 29Google Scholar
Elmegreen, B. G., & Lada, C. J. 1977, ApJ, 214, 725Google Scholar
Fazio, G. G., et al. 2004, ApJS, 154, 10Google Scholar
Fish, V. L., Reid, M. J., Wilner, D. J., & Churchwell, E. 2003, ApJ, 587, 701Google Scholar
Flaherty, K. M., et al. 2007, ApJ, 663, 1069Google Scholar
Garay, G., & Lizano, S. 1999, PASP, 111, 1049Google Scholar
Griffin, M. J., et al. 2010, A&A, 518, L3Google Scholar
Gutermuth, R. A., et al. 2008, ApJ, 674, 336Google Scholar
Han, X. H., et al. 2015, A&A, 576, A131Google Scholar
Hartmann, L. 2009, Accretion Processes in Star Formation (2nd edn.; Cambridge University Press)Google Scholar
Hartmann, L., et al. 2005, ApJ, 629, 881Google Scholar
Hernández, J., et al. 2005, AJ, 129, 856Google Scholar
Hernández-Hernández, V., et al. 2019, AJ, 158, 18Google Scholar
Hernández-Hernández, V., Zapata, L., Kurtz, S., & Garay, G. 2014, ApJ, 786, 38Google Scholar
Hildebrand, R. H. 1983, QJRAS, 24, 267Google Scholar
Hofner, P., & Churchwell, E. 1996, A&AS, 120, 283CrossRefGoogle Scholar
Hunter, T. R., Phillips, T. G., & Menten, K. M. 1997, ApJ, 478, 283Google Scholar
Jose, J., et al. 2012, MNRAS, 424, 2486Google Scholar
Kauffmann, J., Bertoldi, F., Bourke, T. L., Evans, N. J., I., & Lee, C. W. 2008, A&A, 487, 993Google Scholar
Kenyon, S. J., Gomez, M., Marzke, R. O., & Hartmann, L. 1994, AJ, 108, 251Google Scholar
Keto, E. 2007, ApJ, 666, 976Google Scholar
Koenig, X. P., et al. 2012, ApJ, 744, 130Google Scholar
Könyves, V., et al. 2015, A&A, 584, A91Google Scholar
Kroupa, P. 2002, Sci, 295, 82Google Scholar
Kurtz, S., Churchwell, E., & Wood, D. O. S. 1994, ApJS, 91, 659Google Scholar
Lada, C. J. 1987, in IAU Symposium, Vol. 115, Star Forming Regions, ed. Peimbert, M., & Jugaku, J., 1CrossRefGoogle Scholar
Lada, C. J., & Adams, F. C. 1992, ApJ, 393, 278Google Scholar
Lada, C. J., Alves, J., & Lada, E. A. 1996, AJ, 111, 1964Google Scholar
Lada, C. J., & Lada, E. A. 2003, ARA&A, 41, 57Google Scholar
Lada, C. J., Young, E. T., & Greene, T. P. 1993, ApJ, 408, 471Google Scholar
Lada, C. J., et al. 2006, AJ, 131, 1574Google Scholar
Lada, E. A., & Lada, C. J. 1995, AJ, 109, 1682CrossRefGoogle Scholar
Liu, M., et al. 2019, ApJ, 874, 16Google Scholar
López-Chico, T., & Salas, L. 2007, RMxAA, 43, 155Google Scholar
Lucas, P. W., et al. 2008, MNRAS, 391, 136Google Scholar
Maddox, N., et al. 2017, MNRAS, 470, 2314Google Scholar
Mateen, M., Hofner, P., & Araya, E. 2006, ApJS, 167, 239Google Scholar
McKee, C. F., & Ostriker, E. C. 2007, ARA&A, 45, 565Google Scholar
McKee, C. F., & Tan, J. C. 2003, ApJ, 585, 850Google Scholar
Megeath, S. T., et al. 1996, A&A, 307, 775Google Scholar
Megeath, S. T., et al. 2004, ApJS, 154, 367Google Scholar
Meyer, M. R., Calvet, N., & Hillenbrand, L. A. 1997, AJ, 114, 288Google Scholar
Miller, G. E., & Scalo, J. M. 1979, ApJS, 41, 513Google Scholar
Molinari, S., et al. 2016, A&A, 591, A149Google Scholar
Muzerolle, J., et al. 2004, ApJS, 154, 379Google Scholar
Neugebauer, G., et al. 1984, ApJ, 278, L1Google Scholar
Paron, S., Cichowolski, S., & Ortega, M. E. 2009, A&A, 506, 789Google Scholar
Persi, P., & Tapia, M. 2019, MNRAS, 485, 784Google Scholar
Peters, T., et al. 2010, ApJ, 711, 1017Google Scholar
Pezzuto, S., et al. 2021, A&A, 645, A55Google Scholar
Pilbratt, G. L., et al. 2010, A&A, 518, L1Google Scholar
Poglitsch, A., et al. 2010, A&A, 518, L2Google Scholar
Price, S. D., Egan, M. P., Carey, S. J., Mizuno, D. R., & Kuchar, T. A. 2001, AJ, 121, 2819Google Scholar
Qiu, K., et al. 2008, ApJ, 685, 1005Google Scholar
Rieke, G. H., & Lebofsky, M. J. 1985, ApJ, 288, 618Google Scholar
Rivera-Ingraham, A., et al. 2010, ApJ, 723, 915Google Scholar
Robitaille, T. P., Whitney, B. A., Indebetouw, R., & Wood, K. 2007, ApJS, 169, 328Google Scholar
Robitaille, T. P., Whitney, B. A., Indebetouw, R., Wood, K., & Denzmore, P. 2006, ApJS, 167, 256Google Scholar
Robitaille, T. P., et al. 2008, AJ, 136, 2413Google Scholar
Roy, A., et al. 2014, A&A, 562, A138Google Scholar
Salpeter, E. E. 1955, ApJ, 121, 161Google Scholar
Sánchez-Portal, M., et al. 2014, ExA, 37, 453CrossRefGoogle Scholar
Scalo, J. M. 1986, FCPh, 11, 1Google Scholar
Schlegel, D. J., Finkbeiner, D. P., & Davis, M. 1998, ApJ, 500, 525CrossRefGoogle Scholar
Siess, L., Dufour, E., & Forestini, M. 2000, A&A, 358, 593Google Scholar
Simon, R., Jackson, J. M., Clemens, D. P., Bania, T. M., & Heyer, M. H. 2001, ApJ, 551, 747Google Scholar
Solin, O., Ukkonen, E., & Haikala, L. 2012, A&A, 542, A3Google Scholar
Stern, D., et al. 2005, ApJ, 631, 163Google Scholar
Vig, S., Ghosh, S. K., Kulkarni, V. K., Ojha, D. K., & Verma, R. P. 2006, ApJ, 637, 400Google Scholar
Williams, J. P., & McKee, C. F. 1997, ApJ,, 476, 166Google Scholar
Wood, D. O. S., & Churchwell, E. 1989, ApJS, 69, 831Google Scholar
Wright, E. L., et al. 2010, AJ, 140, 1868Google Scholar
Wu, Y. W., et al. 2019, ApJ, 874, 94Google Scholar
Zinnecker, H., McCaughrean, M. J., & Wilking, B. A. 1993, in Protostars and Planets III, ed. Levy, E. H., & Lunine, J. I., 429Google Scholar
Zinnecker, H., & Yorke, H. W. 2007, ARA&A, 45, 481Google Scholar