The Carina High-contrast Imaging Project for massive Stars (CHIPS): II. O stars in Trumpler~14

Abstract

Most massive stars belong to multiple systems, yet the formation process leading to such high multiplicity remains insufficiently understood. To help constrain the different formation scenarios that exist, insights on the low-mass end of the companion mass function of such stars is crucial. However, this is a challenging endeavour as (sub-)solar mass companions at angular separations ($\rho$) below 1" (corresponding to 1000-3000 au in nearby young open clusters and OB associations) are difficult to detect due to the large brightness contrast with the central star. With the Carina High-contrast Imaging Project of massive Stars (CHIPS), we aim to obtain statistically significant constraints on the presence and properties of low-mass companions around massive stars at a previously unreachable observing window ($\Delta \mathrm{mag}\gtrsim 10$ at $\rho \lesssim$ 1"). In this second paper in the series, we focus on the Trumpler 14 cluster, which harbours some of the youngest and most massive O-type stars in the Milky Way. We obtained VLT-SPHERE observations of seven O-type objects in Trumpler 14 using the IRDIFS_EXT mode. These allow us to search for companions at separations larger than 0."15 (approx. 360 au) and down to magnitude contrast $>10\mathrm{mag}$ in the near-infrared. We used angular and spectral differential imaging along with PSF fitting to detect sources and measure their flux relative to that of the central object. We detected 211 sources with near-infrared magnitude contrast in the range of 2 to 12. The closest companion, at only 0."26, is characterised as a 1.4M${}_{\odot }$ stars with an age of 0.6Myr, in excellent agreement with previous age estimates for Tr 14. The mass function peaks at about 0.4M${}_{\odot }$ and presents a dearth of stars in the 0.5 to 0.8M${}_{\odot }$ mass range compared to previous estimates of the initial mass function in Tr 14.

14 pages, 10 figures. Accepted in A&A 22/11/2021

References in corpus (10)

• Southern Massive Stars at High Angular Resolution: Observational Campaign and Companion Detection
• Star formation through gravitational collapse and competitive accretion
• Circumventing the radiation pressure barrier in the formation of massive stars via disk accretion
• VIP: Vortex Image Processing package for high-contrast direct imaging
• SPHERE IRDIS and IFS astrometric strategy and calibration
• The young massive SMC cluster NGC 330 seen by MUSE. I. Observations and stellar content
• Testing the role of environmental effects on the initial mass function of low-mass stars
• A close encounter of the massive kind
• System IMF of the 25 Ori Group from Planetary-Mass Objects to Intermediate/High-Mass Stars
• A High Angular Resolution Survey of Massive Stars in Cygnus OB2: $JHK$ Adaptive Optics Results from the Gemini Near-InfraRed Imager

Cited by in corpus (6)

• The multiplicity of massive stars in the Scorpius OB1 association through high-contrast imaging
• Probing the low-mass end of the companion mass function for O-type stars
• The population of young low-mass stars in Trumpler 14
• The onset of stellar multiplicity in massive star formation: A search for low-mass companions of massive young stellar objects with $L^{\prime }$-band adaptive optics imaging
• Gaia-ESO Survey: massive stars in the Carina Nebula. II. The spectroscopic analysis of the O-star population
• Low-mass stellar and substellar candidate companions around massive stars in Sco OB1 and M17