Gomez's Hamburger (IRAS 18059-3211): A pre main-sequence A-type star

TL;DR

Gomez's Hamburger is a young star with a Keplerian disk, confirmed through high-resolution CO observations, challenging previous post-AGB classifications and providing insights into early stellar disk formation.

Contribution

This study provides the first high-resolution CO maps of Gomez's Hamburger, confirming its nature as a pre-main-sequence star with a rotating disk, rather than an evolved post-AGB object.

Findings

The CO gas forms a Keplerian rotating disk.

The central mass is approximately 4 solar masses.

The object is likely a transitional pre-MS star.

Abstract

We study the nature of Gomez's Hamburger (IRAS 18059-3211), a nebula that has been proposed to be a post-AGB object. Such a classification is not confirmed; instead, we argue that it will be a key object in the study of disks rotating around young stars. We present high resolution SMA maps of CO J=2--1 in Gomez's Hamburger. The data are analyzed by means of a code that simulates the emission of a nebula showing a variety of physical conditions and kinematics. Our observations clearly show that the CO emitting gas in Gomez's Hamburger forms a spectacular disk in keplerian rotation. Model calculations undoubtly confirm this result. The central (mainly stellar) mass is found to be high, ~ 4 Mo for a distance of 500 pc. The mass and (relatively low) luminosity of the source are, independent of the assumed distance, very different from those possible in evolved stars. Gomez's Hamburger is probably a transitional object between the pre-MS and MS phases, still showing interstellar material around the central star or stellar system.