KK 242, a faint companion to the isolated Scd galaxy NGC 6503

Abstract

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 $6.46\pm 0.32$ 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 $V_{hel}=-80\pm 10$ 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 $⟨M_T/M_{\odot }⟩=(3.46\pm 0.84)\times 10^{11}$ and $(58\pm 19)M_{\odot }/L_{\odot }$, respectively.

Accepted for publication in the Astronomical Journal

References in corpus (19)

• The GALEX Ultraviolet Atlas of Nearby Galaxies
• Updated Nearby Galaxy Catalog
• The Panchromatic Hubble Andromeda Treasury X. Ultraviolet to Infrared Photometry of 117 Million Equidistant Stars
• Galaxy Groups within 3500 km s${}^{-1}$
• Tip of the Red Giant Branch Distances. I. Optimization of a Maximum Likelihood Algorithm
• GHASP : An Halpha kinematic survey of spiral and irregular galaxies - VI. New Halpha data cubes for 108 galaxies
• First results from the MADCASH Survey: A Faint Dwarf Galaxy Companion to the Low Mass Spiral Galaxy NGC 2403 at 3.2 Mpc
• The Extragalactic Distance Database: The Color-Magnitude Diagrams and Tip of the Red Giant Branch Distances Catalog
• AUTO-MULTITHRESH: A General Purpose Automasking Algorithm
• Infrared Tip of the Red Giant Branch and Distances to the Maffei/IC 342 Group
• Dynamical evidence for a morphology-dependent relation between the stellar and halo masses of galaxies
• Bright galaxy sample in the Kilo-Degree Survey Data Release 4: selection, photometric redshifts, and physical properties
• Orbital masses of nearby luminous galaxies
• The dependence of the galaxy stellar-to-halo mass relation on galaxy morphology
• Aperture Synthesis Observations of the Nearby Spiral NGC 6503: Modeling the Thin and Thick HI Disks
• SHIELD: Neutral Gas Kinematics and Dynamics
• SHIELD: Comparing Gas and Star Formation in Low Mass Galaxies
• Discovery of New Dwarf Galaxy near The Isolated Spiral Galaxy NGC 6503
• Star Formation in Nearby Dwarf Galaxies