The infrared dust bubble N22: an expanding HII region and the star formation around it

Aims. To increase the observational samples of star formation around expanding Hii regions, we analyzed the interstellar medium and star formation around N22. Methods. We used data extracted from the seven large-scale surveys from infrared to radio wavelengths. In addition we used the JCMT observations of the J = 3-2 line of 12CO emission data released on CADC and the 12CO J = 2-1 and J =3-2 lines observed by the KOSMA 3 m telescope. We performed a multiwavelength study of bubble N22. Results. A molecular shell composed of several clumps agrees very well with the border of N22, suggesting that its expansion is collecting the surrounding material. The high integrated 12CO line intensity ratio (ranging from 0.7 to 1.14) implies that shocks have driven into the molecular clouds. We identify eleven possible O-type stars inside the Hii region, five of which are located in projection inside the cavity of the 20 cm radio continuum emission and are probably the exciting-star candidates of N22. Twenty-nine YSOs (young stellar objects) are distributed close to the dense cores of N22. We conclude that star formation is indeed active around N22; the formation of most of YSOs may have been triggered by the expanding of the Hii region. After comparing the dynamical age of N22 and the fragmentation time of the molecular shell, we suggest that radiation-driven compression of pre-existing dense clumps may be ongoing.Comment: accepted in A&A 30/05/2012. arXiv admin note: text overlap with arXiv:1010.5430 by other author

Understanding the chemistry of the young stellar object G29.862-0.0044

In previous works, we have investigated the star-forming region G29.96$-$0.02 where the massive young stellar object (MYSO) G29.862$-$0.0044 (hereafter G29) is embedded in a hot molecular core. In one of them, of multiwavelength nature, using data from the Atacama Submillimeter Telescope Experiment (ASTE), data from the Atacama Large Millimeter Array (ALMA), and photometric data from NIRI-Gemini, G29 was investigated at different spatial scales. However, the intriguing morphology of G29 in the near-infrared, together with the distribution of the associated molecular gas, reveals that the star-formation scenario is far from being understood. This work incorporates the analysis of the emission of several molecular lines acquired with ALMA that were not previously examined (eg.,~CH$_{3}$OH, HC$_{3}$N, H$_{ 2}$CO, C$^{34}$S, H$_{2}$CS) as well as a new determination of the temperature of the region. Additionally, we present the progress of results obtained through new observations in the near-infrared, in this case spectroscopic, using NIFS-Gemini, and in radio continnum obtained with the Karl G. Jansky Very Large Array (JVLA). This research allows us to carry out a detailed chemical study of the region, which will contribute to the understanding of the physical processes involved in the high-mass star formation.Comment: accepted to be published in Bolet\'in de la Asociaci\'on Argentina de Astronom\'i

Understanding the chemistry of the young stellar object G29.862—0.0044

En trabajos previos, hemos investigado la región de formación estelar G29.96—0.02 donde se encuentra el objeto estelar joven masivo (MYSO, por sus siglas en inglés) G29.862—0.0044 (de ahora en adelante G29) embebido en un núcleo molecular caliente. En uno de ellos, de carácter multiespectral, que incluyó datos obtenidos con el Atacama Submillimeter Telescope Experiment (ASTE), Atacama Large Millimeter Array (ALMA) y NIRI-Gemini, se investigó a G29 en distintas escalas espaciales. Sin embargo, su intrigante morfología revelada en el infrarrojo cercano junto con la distribución del gas molecular de su entorno, hacen que el escenario en el cual dicha fuente evoluciona esté muy lejos de ser comprendido. Este trabajo incorpora el análisis de la emisión de varias líneas moleculares adquiridas con ALMA, que no habían sido previamente examinadas (ej.: CH₃OH, HC₃N, H₂CO, C³⁴S, H₂CS) y se presenta una nueva determinación de la temperatura. Adicionalmente, se presenta un resultado preliminar obtenido de observaciones espectroscópicas realizadas con el instrumento NIFS en Gemini y en continuo de radio obtenidas con el Karl G. Jansky Very Large Array (JVLA). Esta investigación permitrá llevar a cabo un minucioso estudio químico de la región, que contribuirá a avanzar en la comprensión de los procesos físicos involucrados en la formación estelar de alta masa.In previous works, we have investigated the star-forming region G29.96—0.02 where the massive young stellar object (MYSO) G29.862—0.0044 (hereafter G29) is embedded in a hot molecular core. In one of them, of multiwavelength nature, using data from the Atacama Submillimeter Telescope Experiment (ASTE), data from the Atacama Large Millimeter Array (ALMA), and photometric data from NIRI-Gemini, G29 was investigated at different spatial scales. However, the intriguing morphology of G29 in the near-infrared, together with the distribution of the associated molecular gas, reveals that the star-formation scenario is far from being understood. This work incorporates the analysis of the emission of several molecular lines acquired with ALMA that were not previously examined (eg., CH₃OH, HC₃N, H₂CO, C³⁴S, H₂CS) as well as a new determination of the temperature of the region. Additionally, we present the progress of results obtained through new observations in the near-infrared, in this case spectroscopic, using NIFS-Gemini, and in radio continnum obtained with the Karl G. Jansky Very Large Array (JVLA). This research allows us to carry out a detailed chemical study of the region, which will contribute to the understanding of the physical processes involved in the high-mass star formation.Asociación Argentina de Astronomí

Efecto de la ablacion peduncular en la maduracion gonadal de Pleoticus muelleri bate (decapoda, solenoceridae). I. interaccion entre muda y desarrollo ovarico

The objective of this study was to compare the ovary development of ablated and non-ablated females of Pleoticus muelleri and to evaluate the influence of eyestalk ablation on molting frequency. The females (7-22 g weight) were maintained under culture conditions with 12: 12 fotoperiod, 15-17ºC temperature and 31%0 salinity. They were fed on fresh squid, prawn and clam. The ovaries and digestive glands were weighed and fixed for histological examination at 4,9, 15,20, 40, and 50 days. Gonad index varied between 0.925 and 3.747 (control) and 1.457 and 5.035 (ablated). The digestive gland index ranged from 2.059 to 4.520 (control) and 3.471 to 4.471 (ablated). The intermolt duration was 21.7 :j: 3.9 and 23.2 :j: 2.4 for the control and ablated respectively. At the end of the experiment the ovaries of ablated females were mature and those of the control were in primary vitellogenesis. It was concluded that the eyestalk ablation in P. muelleri resulted in precocious maturation of the ovary without changes in the molting frequency. The ovary index was size-independent. Ablation had no effect on the relative weight of digestive gland.Este trabalho teve como objetivo comparar o grau de desenvolvimento ovariano de remeas ablacionadas e intactas de Pleoticus muelleri e avaliar a influência da ablação sobre a freqüência da muda. As femeas, de 7 a 22 g de peso, foram mantidas em condições de cultivo com fotoperíodo de 12:12, temperatura entre 15 e 17ºC, salinidade de 31 e alimentadas com lula, camarão e bivalvos frescos. Foram pesados e fixados os ovários e hepatopâncreas, realizando um controle histológico nos 4; 9; 15; 20; 40 e 50 dias. O índice gonadossomático variou entre 0,925 e 3,747 (controle) e entre 1,457 e 5,035 (ablacionados). Determinou-se valores de índice hepatopancreático entre 2,059 a 4,520 (controle) e de 3,471 a 4,471 (ablacionados). A duração média da intermuda foi 21,7 :j: 3,9 e 23,2 :j: 2,4 dias para o grupo controle e ablacionados, respectivamente. Ao finalizar o experimento a análise histológica demostrou que os ovários das femeas ablacionadas encontravam-se totalmente amadurecidos e os do controle em vitelogênese primária. Conclui-se que a ablação peduncular acelera a maturação ovariana de P. muelleri, sem modificar a freqüência da muda. O índice ovariano é independente do tamanho no intervalo de peso estudado e a ablação não apresentou efeito sobre o peso relativo dos hepatopâncreas