KK 242, a faint companion to the isolated Scd galaxy NGC 6503. (arXiv:2111.14691v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Karachentsev_I/0/1/0/all/0/1">Igor D. Karachentsev</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cannon_J/0/1/0/all/0/1">John M. Cannon</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fuson_J/0/1/0/all/0/1">Jackson Fuson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Inoue_J/0/1/0/all/0/1">John L. Inoue</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tully_R/0/1/0/all/0/1">R. Brent Tully</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Anand_G/0/1/0/all/0/1">Gagandeep S. Anand</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kaisin_S/0/1/0/all/0/1">Serafim S. Kaisin</a>
Using Hubble Space Telescope imaging of the resolved stellar population of
KK~242 = NGC6503-d1 = PGC~4689184, we measure the distance to the galaxy to be
$6.46pm0.32$ Mpc and find that KK~242 is a satellite of the low-mass spiral
galaxy NGC~6503 located on the edge of the Local Void. Observations with the
Karl G. Jansky Very Large Array show signs of a very faint HI-signal at the
position of KK~242 within a velocity range of $V_{hel} = -80pm10$
km,s$^{-1}$. This velocity range is severely contaminated by HI emission from
the Milky Way and from NGC6503. The dwarf galaxy is classified as the
transition type, dIrr/dSph, with a total HI-mass of $< 10^6 M_{odot}$ and a
star formation rate SFR(H$alpha$) = –4.82 dex ($M{odot}$/yr). Being at a
projected separation of 31 kpc with a radial velocity difference of — 105
km,s$^{-1}$ relative to NGC~6503, KK~242 gives an estimate of the halo mass of
the spiral galaxy to be $log(M/M_{odot}$) = 11.6. Besides NGC~6503, there are
8 more detached low-luminosity spiral galaxies in the Local Volume: M~33,
NGC~2403, NGC~7793, NGC~1313, NGC~4236, NGC~5068, NGC~4656 and NGC~7640, from
whose small satellites we have estimated the average total mass of the host
galaxies and their average total mass-to-K-band-luminosity $langle
M_T/M_{odot}rangle = (3.46pm0.84)times 10^{11}$ and $(58pm19)
M_{odot}/L_{odot}$, respectively.
Using Hubble Space Telescope imaging of the resolved stellar population of
KK~242 = NGC6503-d1 = PGC~4689184, we measure the distance to the galaxy to be
$6.46pm0.32$ Mpc and find that KK~242 is a satellite of the low-mass spiral
galaxy NGC~6503 located on the edge of the Local Void. Observations with the
Karl G. Jansky Very Large Array show signs of a very faint HI-signal at the
position of KK~242 within a velocity range of $V_{hel} = -80pm10$
km,s$^{-1}$. This velocity range is severely contaminated by HI emission from
the Milky Way and from NGC6503. The dwarf galaxy is classified as the
transition type, dIrr/dSph, with a total HI-mass of $< 10^6 M_{odot}$ and a
star formation rate SFR(H$alpha$) = –4.82 dex ($M{odot}$/yr). Being at a
projected separation of 31 kpc with a radial velocity difference of — 105
km,s$^{-1}$ relative to NGC~6503, KK~242 gives an estimate of the halo mass of
the spiral galaxy to be $log(M/M_{odot}$) = 11.6. Besides NGC~6503, there are
8 more detached low-luminosity spiral galaxies in the Local Volume: M~33,
NGC~2403, NGC~7793, NGC~1313, NGC~4236, NGC~5068, NGC~4656 and NGC~7640, from
whose small satellites we have estimated the average total mass of the host
galaxies and their average total mass-to-K-band-luminosity $langle
M_T/M_{odot}rangle = (3.46pm0.84)times 10^{11}$ and $(58pm19)
M_{odot}/L_{odot}$, respectively.
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