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| Content Provider | Springer Nature Link |
|---|---|
| Author | Kantharia, N. G. Anantharamaiah, K. R. |
| Copyright Year | 2001 |
| Abstract | We present the results of a search for carbon recombination lines in the Galaxy at 34.5 MHz (C575α) made using the dipole array at Gauribidanur near Bangalore. Observations made towards 32 directions resulted in detections of lines, in absorption at nine positions. Followup observations at 328 MHz (C272α) using the Ooty Radio Telescope detected these lines in emission. A VLA D-array observation of one of the positions at 330 MHz yielded no detection implying a lower limit of 10′ for the angular size of the line forming region.The longitude-velocity distribution of the observed carbon lines indicate that the line forming regions are located mainly between 4 kpc and 7 kpc from the Galactic centre. Combining our results with published carbon recombination line data near 76 MHz (Erickson, McConnell & Anantharamaiah 1995), we obtain constraintson the physical parameters of the line forming regions. We find thatif the angular size of the line forming regions is ≥ 4°, then the range of parameters that fit the data are:T $_{ e }$=20–40 K,n $_{ e }$ ∼ 0.1–0.3 cm$^{−3}$ and pathlengths ∼ 0.07–0.9 pc which may correspond to thin photodissociated regions around molecular clouds. On the other hand, if the line forming regions are ∼ 2° in extent, then warmer gas (T $_{ e }$ ∼ 60–300 K) with lower electron densities (n $_{ e }$ ∼ 0.03–0.05 cm$^{−3}$) extending over several tens of parsecs along the line of sight and possibly associated with atomic HI gas can fit the data. Based on the range of derived parameters, we suggest that the carbon line regions are most likely associated with photo-dissociation regions. |
| Starting Page | 51 |
| Ending Page | 80 |
| Page Count | 30 |
| File Format | |
| ISSN | 02506335 |
| Journal | Journal of Astrophysics and Astronomy |
| Volume Number | 22 |
| Issue Number | 1 |
| Language | English |
| Publisher | Springer India |
| Publisher Date | 2001-01-01 |
| Publisher Institution | Indian Academy of Sciences |
| Publisher Place | New Delhi |
| Access Restriction | One Nation One Subscription (ONOS) |
| Subject Keyword | Interstellar medium: clouds, lines, line profiles, radio lines Astronomy Astrophysics |
| Content Type | Text |
| Resource Type | Article |
| Subject | Astronomy and Astrophysics Space and Planetary Science |
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