Interacting system NGC 7805/6 (Arp 112) and its tidal dwarf galaxy candidate
Abstract
We present results from our Giant Metrewave Radio Telescope (GMRT) HI, Himalayan Chandra Telescope (HCT) Hα, 1 m Sampurnanand Telescope (ST) and 1.3 m Devasthal Fast Optical Telescope (DFOT) deep optical observations of the NGC 7805/6 (Arp 112) system to test KUG 2359+311's tidal dwarf galaxy (TDG) candidacy and explore the properties of the interacting system. Our GMRT H I map shows no H I detection associated with KUG 2359+311, nor any H I tail or bridge-like structure connecting KUG 2359+311 to the NGC 7805/6 system. Our HCT Hα image, on the other hand, displays strong detections in KUG 2359+311, with net SFR ∼ 0.035 ± 0.009 M⊙ yr-1. The Hα data constrain the redshift of KUG 2359+311 to 0.00 ≤ z ≤ 0.043, compared to the redshift of NGC 7806 of ∼ 0.015. TDGs detected to date have all been H I rich, and displayed H I, ionised gas and stellar tidal debris trails (bridges or tails) linking them to their parent systems. However, neither our H I data nor our optical imaging, while three magnitudes deeper than SDSS, reveals a tidal trail connecting KUG 2359+311 to NGC 7805/6. Lack of H I, presence of an old stellar population, ongoing star formation and reasonably high SFR compared to normal dwarf galaxies suggest that KUG 2359+311 may not be an Arp 112 TDG. It is most likely a case of a regular gas-rich dwarf galaxy undergoing a morphological transformation after having lost its entire gas content to an interaction with the Arp 112 system. Redshift and metallicity from future spectroscopic observations of KUG 2359+311 would help clarify the nature of this enigmatic structure.
- Publication:
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Research in Astronomy and Astrophysics
- Pub Date:
- March 2021
- DOI:
- 10.1088/1674-4527/21/2/43
- arXiv:
- arXiv:2011.06368
- Bibcode:
- 2021RAA....21...43F
- Keywords:
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- galaxies: dwarf;
- galaxies: interactions;
- galaxies: spiral;
- galaxies: star formation;
- galaxies: peculiar;
- radio lines: galaxies;
- Astrophysics - Astrophysics of Galaxies;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- Accepted in RAA