Discovery of A Binary System in IRAM 04191+1522

TL;DR

This study reveals a binary system in the Class 0 protostar IRAM 04191+1522 through high-resolution submillimeter observations, showing how core rotation influences fragmentation during star formation.

Contribution

First detection of a binary system in IRAM 04191+1522 using high-resolution SMA imaging, highlighting the role of core rotation in fragmentation.

Findings

Two distinct sources separated by 7.8 arcseconds identified.

The secondary source has an extremely low bolometric luminosity.

Rotational energy in dense cores influences binary formation.

Abstract

We present high angular resolution observations of the Class 0 protostar IRAM04191+1522, using the Submillimeter Array (SMA). The SMA 1.3 mm continuum images reveal within IRAM04191+1522 two distinct sources with an angular separation of 7.8\,$\pm$\,0.2$"$. The two continuum sources are located in the southeast-northwest direction, with total gas masses of about 0.011 M_sun and about 0.005 M_sun, respectively. The southeastern source, associated with an infrared source seen in the Spitzer images, is the well-known Class 0 protostar with a bolometric luminosity of about 0.08 L_sun. The newly-discovered northwestern continuum source is not visible in the Spitzer images at wavelengths from 3.6 to 70 micron, and has an extremely low bolometric luminosity (< 0.03 L_sun). Complementary IRAM N2H+(1-0) data that probe the dense gas in the common envelope suggest that the two sources were formed through the rotational fragmentation of an elongated dense core. Furthermore, comparisons between IRAM04191+1522 and other protostars suggest that most cores with binary systems formed therein have ratios of rotational energy to gravitational energy $\beta_{\rm rot}$ > 1%. This is consistent with theoretical simulations and indicates that the level of rotational energy in a dense core plays an important role in the fragmentation process.