We present the results of observations of the very low surface brightness ( VLSB ) dwarf galaxy SDSS J092609.45+334304.1 with extreme parameters which indicate its unevolved status .
Namely , its value of O/H , derived as an average of that in two adjacent H ii regions at the NE edge of the disc , corresponds to the parameter 12+ \log ( O/H ) =7.12 \pm 0.02 , which is amongst two lowest known .
The total HI flux measurement obtained with the Nançay Radio Telescope and the photometric results imply that the galaxy ratio M ( HI ) /L _ { B } \sim 3.0 , is among the top known in the Local Volume .
The galaxy is situated in the region of a nearby underdense region known as the Lynx-Cancer void , where other , unevolved galaxies , including DDO 68 , HS 0832+3542 and SAO 0822+3545 , are known to be present .
The total mass of this almost edge-on VLSB galaxy is \sim 8.3 times larger than its baryonic mass , implying the dynamical dominance of Dark Matter ( DM ) halo .
The ( u - g ) , ( g - r ) colours of outer parts of this galaxy are consistent with the ages of its main stellar population of 1–3 Gyr .
Thanks to the galaxy isolation , the small effect of current or recent star formation ( SF ) , its proximity and rather large HI flux ( \sim 2.5 Jy \cdot km s ^ { -1 } ) , this VLSB dwarf is a good laboratory for the detailed study of DM halo properties through HI kinematics and the star formation processes in very metal-poor low surface density environment .
This finding , along with the discovery of other unusual dwarf galaxies in this void , provides evidence for the relation between galaxy evolution and its very low-density environment for the baryonic mass range of 10 ^ { 8 } to 10 ^ { 9 } M _ { \odot } .
This relation seems to be consistent with that expected in the \Lambda CDM models of galaxy and structure formation .