Carina High-contrast Imaging Project for massive Stars (CHIPS)

Rainot, A.; Reggiani, Maddalena; Sana, H.; Bodensteiner, J.; Gomez-Gonzalez, C. A.; Absil, Olivier; Christiaens, Valentin; Delorme, P.; Almeida, L. A.; Caballero-Nieves, S. M.; Kratter, Kaitlin M.; Lacour, S.; Bouquin, J.-B. Le; Pueyo, Laurent; Zinnecker, H.

doi:10.1051/0004-6361/201936448

Cited by 15 publications

(16 citation statements)

References 63 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Once we identified the true physical objects on our images, we extracted position and flux for each source. As described by Rainot et al (2020), we adopted two different techniques based on the radial separations of the sources. For all IFS sources and all IRDIS source within 2 , we used a negative fake companion approach, implemented in VIP (see Sect.…”

Section: Source Characterizationmentioning

confidence: 99%

“…Therefore, for point-like objects beyond this separation, the use of ADI and SDI techniques is not necessarily needed to derive precise astrometry and photometry. Following Rainot et al (2020), we adopted a standard PSF-fitting technique as described in Bodensteiner et al (2020), which is based on the photutils 3 python package along with an effective PSF model developed by Anderson & King (2000).…”

Section: Sources Beyondmentioning

confidence: 99%

“…To identify which of the detected sources could be bound companions, we estimated on a statistical base the probability of chance alignment association. Following Rainot et al (2020), we defined the probability of spurious association (P spur (ρ i |Σ(K i ))) as the probability that at least one object is found by chance at an angular separation from the central star ρ smaller or equal than that of the ith companion (i.e., ρ ≤ ρ i ), given the local source density Σ of stars at least as bright as i (K ≤ K i ). To compute P spur , we first evaluated the local field density Σ(K i ) = N obj (K ≤ K i )/(πr 2 ) of objects at least as bright as the companion i in a πr 2 surface.…”

Section: Spurious Association Probabilitiesmentioning

confidence: 99%

“…Similarly to what was done by Rainot et al (2020) for QZ Car, we used the low-resolution IFS spectrum of all IFS detections to constrain their stellar parameters. To do so, we used both the ATLAS9 LTE atmosphere models (Castelli & Kurucz 2003), covering the 3500−50 000 K temperature range, and the LTE PHOENIX models (2300−12 000 K, Husser et al 2013) for T < 3500 K. To each age value in the pre-main sequence (PMS) A122, page 7 of 14 A&A 660, A122 (2022) Table 4.…”

Section: Spectral Fittingmentioning

confidence: 99%

“…In this regard, the first paper of the Carina High-contrast Imaging Project of massive Stars (CHIPS, Rainot et al 2020) represents a proof of concept that the extreme AO, implemented at the VLT through the Spectro-Polarimetric High-contrast Exoplanet REsearch instrument (SPHERE, Beuzit et al 2019), provides the necessary spatial resolution and dynamics to look for the faintest companions to nearby massive stars.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Probing the low-mass end of the companion mass function for O-type stars

Reggiani

Rainot

Sana

et al. 2022

A&A

Self Cite

View full text Add to dashboard Cite

Context. Past observations of O-type stars in the Galaxy have shown that almost all massive stars are part of a binary or higher-order multiple system. Given the wide range of separations at which these companions are found, several observational techniques have been adopted to characterize them. Despite the recent advancements in interferometric and adaptive optics observations, contrasts greater than 4 in the H band have never been reached between 100 and 1000 mas. Aims. Using new adaptive optics (AO) assisted coronagraphic observations, we aim to study the multiplicity properties of a sample of 18 dwarf (or sub-giant) O stars in the galactic field and in OB associations to probe the existence of stellar companions in the angular separation range from 0.″15 to 6″ down to very low mass ratios. Methods. We used VLT/SPHERE to observe simultaneously with the IRDIS and IFS sub-systems 18 O-type stars within 6 kpc and ages between 1 and 5 Myr. The IFS YJH band observations have allowed us to probe the presence of sub-solar companions in a 1.7″ × 1.7″ field-of-view down to magnitude limits of ΔH = 10 at 0.″4. In the wider 12″ × 12″ IRDIS field-of-view, we reached contrasts of ΔK = 12 at 1″, enabling us to look for even fainter companions at larger angular separations and to probe the source density of the surrounding portion of the sky. Results. This paper presents five newly discovered intermediate (< 1″) separation companions, three of which are smaller than 0.2 M⊙. If confirmed by future analyses of proper motions, these new detections represent the lowest-mass companions ever found around O-type stars. Additionally, 29 other sources are found in the IRDIS field-of-view with spurious association probabilities smaller than 5%. Assuming that all sources detected within 1″ are physically bound companions, the observed (uncorrected for bias) fraction of companions for O-type stars between 150 and 900 mas is 0.39 ± 0.15, whereas it increases to 1.6 ± 0.3 in the separation range from 0.″9 to 6″. Conclusions. These findings clearly support the notion that massive stars form almost exclusively in multiple systems, serving as proof of concept that supports the application of larger AO-assisted coronagraphic surveys as a crucial step in placing constraints on the multiplicity properties of massive star companions in regions of the parameter space that have previously gone unexplored. These results also demonstrate that the companion mass function is populated down to the lowest stellar masses.

show abstract

Section: Source Characterizationmentioning

confidence: 99%

Section: Sources Beyondmentioning

confidence: 99%

Section: Spurious Association Probabilitiesmentioning

confidence: 99%

Section: Spectral Fittingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Probing the low-mass end of the companion mass function for O-type stars

Reggiani

Rainot

Sana

et al. 2022

A&A

Self Cite

View full text Add to dashboard Cite

show abstract

Spectroscopy of Massive Stars

Bodensteiner

2022

Observational Imprints of Binary Evolution on B- And Be-Star Populations

View full text Add to dashboard Cite

Carina High-contrast Imaging Project for massive Stars (CHIPS)

Rainot

Reggiani²,

Sana³

et al. 2022

A&A

Self Cite

View full text Add to dashboard Cite

Context. 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 into 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 (ρ) 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. Aims. 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 in a previously unreachable observing window (Δmag ≳ 10 at ρ ≲ 1″). In the second paper of 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. Methods. We obtained VLT-SPHERE observations of seven O-type objects in Trumpler 14 using IRDIFS_EXT mode. These provide us with a 12″ × 12″ field of view (approximately ((3 × 3)×104 au) centred on each O star and allow us to search for companions at separations larger than 0″.15 (approx. 360 au) and down to magnitude contrast > 10 mag in the near-infrared. We used angular and spectral differential imaging along with Point Spread Function (PSF) fitting to detect sources and measure their flux relative to that of the central object. We then used grids of ATLAS9 and PHOENIX Local Thermodynamic Equilibrium (LTE) atmosphere models combined with (pre-)main-sequence evolutionary tracks to estimate the mass of the detected candidate companions. Results. We detected 211 sources with near-infrared magnitude contrast in the range of 2–12. Given the large surface number density of stars in Trumpler 14, one cannot reliably distinguish between cluster members and genuine companions for most of the detected sources. The closest companion, at only 0″.26, is characterised as a 1.4 M⊙ star with an age of 0.6 Myr, in excellent agreement with previous age estimates for Tr 14. The mass function peaks at about 0.4 M⊙ and presents a dearth of stars in the 0.5–0.8 M⊙ mass range compared to previous estimates of the initial mass function in Tr 14. While statistically significant, part of these differences may result from contamination of the K-band fluxes by circumstellar material. Conclusions. SPHERE is clearly suitable to probe the low-mass end of the mass function in the vicinity of massive stars. Follow-up SPHERE observations to obtain the full Y to K spectral energy distribution would allow for better constraints on the masses of the detected sources, and to confirm (or invalidate) the curious mass function that we derived for low-mass stars in the vicinity of the O-type objects in Trumpler 14.

show abstract

Carina High-contrast Imaging Project for massive Stars (CHIPS)

Cited by 15 publications

References 63 publications

Probing the low-mass end of the companion mass function for O-type stars

Probing the low-mass end of the companion mass function for O-type stars

Spectroscopy of Massive Stars

Carina High-contrast Imaging Project for massive Stars (CHIPS)

Contact Info

Product

Resources

About