Visible spectroscopy in the neighborhood of 2003 EL61

TL;DR

This study used visible spectroscopy to analyze five trans-neptunian objects near 2003 EL61, confirming two as members of its group based on spectral similarity, while identifying others as non-members or potential members.

Contribution

It provides new spectral data for five TNOs, confirming the association of two objects with the 2003 EL61 group and identifying spectral characteristics of potential members.

Findings

Confirmed 1995 SM55 and 2003 OP32 as 2003 EL61 group members.

Identified 2003 UZ117 as a possible group member based on spectral data.

Determined 2004 SB60 and 2005 UQ513 are interlopers with different surface compositions.

Abstract

Context: The recent discovery of a group of trans-neptunian objects (TNOs) in a narrow region of the orbital parameter space and with surfaces composed of almost pure water ice, being 2003 EL61 its largest member, promises new and interesting results about the formation and evolution of the trans-neptunian belt (TNb) and the outer Solar System. Aims: The aim of this paper is to obtain information of the surface properties of two members of this group ((24835) 1995 SM55, (120178) 2003 OP32) and three potential members (2003 UZ117, (120347) 2004 SB60 and 2005 UQ513) and to use that in order to confirm or reject their association. Methods: We obtained visible spectra of five TNOs using the 3.58m Telescopio Nazionale Galileo at the ''Roque de los Muchachos Observatory'' (La Palma, Spain) Results: The spectra of the five TNOs are featureless within the uncertainties and with colors from slightly blue to red (-2< S'<18%/0.1microns). No signatures of any absorption are found. Conclusions: We confirm the association of 1995 SM55 and 2003 OP32 with the group of 2003 EL61 as their spectra are almost identical to that of 2003 EL61. Only one of the three candidates, 2003 UZ117, can be considered as a possible member of the EL61-group, as its visible spectrum is compatible with a spectrum of a surface composed of almost pure water ice and no complex organics. The other two, 2004 SB60 and 2005 UQ513 are red and must be considered as interlopers.