A <scp>TGAS</scp>/<i>Gaia</i><scp>DR1</scp> parallactic distance to the σ Orionis cluster

Caballero, J. A.

doi:10.1002/asna.201713312

Cited by 8 publications

(10 citation statements)

References 93 publications

(162 reference statements)

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“…This is consistent with Hipparcos and encompasses most of the previous estimates. It is also in line with recently published estimations using interferometric observations (Schaefer et al 2016) and TGAS data (Caballero 2017).…”

Section: Target Region: the σ Orionis Clustersupporting

confidence: 93%

A deep staring campaign in the σ Orionis cluster

Elliott

Scholz

Jayawardhana

et al. 2017

A&A

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Context. The young star cluster near σ Orionis is one of the primary environments to study the properties of young brown dwarfs down to masses comparable to those of giant planets. Aims. Deep optical imaging is used to study time-domain properties of young brown dwarfs over typical rotational timescales and to search for new substellar and planetary-mass cluster members. Methods. We used the Visible Multi Object Spectrograph (VIMOS) at the Very Large Telescope (VLT) to monitor a 24 × 16 field in the I-band. We stared at the same area over a total integration time of 21 hours, spanning three observing nights. Using the individual images from this run we investigated the photometric time series of nine substellar cluster members with masses from 10 to 60 M Jup . The deep stacked image shows cluster members down to ≈5 M Jup . We searched for new planetary-mass objects by combining our deep I-band photometry with public J-band magnitudes and by examining the nearby environment of known very low mass members for possible companions. Results. We find two brown dwarfs, with significantly variable, aperiodic light curves, both with masses around 50 M Jup , one of which was previously unknown to be variable. The physical mechanism responsible for the observed variability is likely to be different for the two objects. The variability of the first object, a single-lined spectroscopic binary, is most likely linked to its accretion disc; the second may be caused by variable extinction by large grains. We find five new candidate members from the colour-magnitude diagram and three from a search for companions within 2000 au. We rule all eight sources out as potential members based on non-stellar shape and/or infrared colours. The I-band photometry is made available as a public dataset. Conclusions. We present two variable brown dwarfs. One is consistent with ongoing accretion, the other exhibits apparent transient variability without the presence of an accretion disc. Our analysis confirms the existing census of substellar cluster members down to ≈7 M Jup . The zero result from our companion search agrees with the low occurrence rate of wide companions to brown dwarfs found in other works.

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Section: Target Region: the σ Orionis Clustersupporting

confidence: 93%

A deep staring campaign in the σ Orionis cluster

Elliott

Scholz

Jayawardhana

et al. 2017

A&A

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“…In Figure 26 we plot the TTS in the V-J CMDs for each of these two groups, together with the early type stars found within each overdensity. We assumed a distance of 390 pc, consistent with the latest determinations for the σ Ori cluster (Schaefer et al 2016;Hernández et al 2014;Caballero 2017), which is generally assumed to be part of the OB1b region. There are 231 TTS in these two (Figure 17).…”

Section: The Pms Population In Orion Ob1bmentioning

confidence: 99%

The CIDA Variability Survey of Orion OB1. II. Demographics of the Young, Low-mass Stellar Populations^*

et al. 2019

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We present results of our large scale, optical, multi-epoch photometric survey of ∼ 180 square degrees across the Orion OB1 association, complemented with extensive follow up spectroscopy. Our focus is mapping and characterizing in an uniform way the off-cloud, low-mass, pre-main sequence populations. We report 2064, mostly K and M-type, confirmed T Tauri members. Most (59%) are located in the OB1a subassociation, 27% are projected onto the OB1b subassociation, and the remaining 14% are located within the confines of the A and B molecular clouds. There is significant structure in the spatial distribution of the young stars. We characterize two new clusterings of T Tauri stars, the HD 35762 and HR 1833 groups, both located in the OB1a subassociation, not far form the 25 Ori cluster. We also confirm two stellar overdensities in OB1b, I and II, containing a total of 231 T Tauri stars. A ∼ 2 deg wide halo of young stars surrounds the Orion Nebula Cluster; the north and south parts corresponding to the low-mass populations of NGC 1977 and NGC 1980, respectively. There is indication of two populations of young stars in the OB1b region, located at two different distances, which may be due to the OB1a subassociation overlapping on front of OB1b. The various groups and regions can be ordered in an age sequence that agrees with the long standing picture of star formation starting in Orion OB1a some 10-15 Myr ago.We use the strength of the Hα line in emission, combined with characteristics of IR excesses and optical variability, to define a new type of T Tauri star, the C/W class, stars we propose may be nearing the end of their accretion phase, in an evolutionary state between that of Classical T Tauri and Weak-lined T Tauri stars. The evolution of the ensemble-wide equivalent width of the Li Iλ6707 line shows the depletion of Li with a timescale of 8.5 Myr. The decline of the accretion fraction, from ∼ 2 − 10 Myr, implies an accretion e-folding timescale of 2.1 Myr, consistent with previous studies. Finally, we use the median amplitude of the V -band variability in each type of star, to show the decline of stellar activity, from the accreting Classical T Tauri stars to the population of least active field dwarfs.

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“…Although the membership in cluster of many stars and brown dwarfs in the almost 10‐year‐old Mayrit catalog has been confirmed or refuted in newer astrometric (Caballero 2010, 2017), X‐rays (Caballero et al 2010; López‐Santiago & Caballero 2008), and spectroscopic surveys (Caballero et al 2008b, 2012; Hernández et al 2014; Koenig et al 2015; Maxted et al 2008; Sacco et al 2008), it is still the most comprehensive catalog of cluster members and member candidates in σ Orionis. The Mayrit catalog is complete down to (and slightly beyond) the cluster substellar boundary at J ∼ 14.5 mag (Caballero et al 2007), where the UKIDSS quality image is still good enough for multiplicity studies. An exhaustive analysis of multiplicity of much fainter brown dwarfs and planetary‐mass objects in σ Orionis would require a new deeper dataset, such as VIRCAM (Peña Ramírez et al 2012; V. J. S. Béjar, in prep.)…”

Section: Analysis and Resultsmentioning

confidence: 99%

“… b References—Ste86: Stephenson 1986; GC93: Gray & Corbally 1993; Wo96: Wolk 1996; Sh04: Sherry et al 2004; Fr06: Franciosini et al 2006; Ca07b: Caballero 2007b; He07: Hernández et al 2007; Ca08: Caballero et al 2008b; GH08: González Hernández et al 2008; LSC08; López‐Santiago & Caballero 2008; Ma08: Maxted et al 2008; Sa08: Sacco et al 2008; Lo09: Lodieu et al 2009; Ca10a: Caballero 2010; Ca10b: Caballero et al 2010; Ca12: Caballero et al 2012; Ca14: Caballero 2014; He14: Hernández et al 2014; Ca17: Caballero 2017. …”

Section: Analysis and Resultsmentioning

confidence: 99%

Wide σ Orionis binaries resolved by UKIDSS

Caballero

Novalbos²,

Tobal³

et al. 2017

Astron Nachr

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In spite of its importance for the study of star formation at all mass domains, the nearby young Orionis cluster still lacks a comprehensive survey for multiplicity. We try to fill that observational gap by looking for wide resolved binaries with angular separations between 0.4 and 4.0 arcsec. We search for companions to 331 cataloged cluster stellar members and candidates in public K-band UKIDSS images outside the innermost 1 arcmin, which is affected by the glare of the bright, eponymous Ori multiple system, and investigate their cluster membership with color-magnitude diagrams and previous knowledge of youth features. Of the 18 identified pairs, 10 have very low individual probabilities of chance alignment (< 1%) and are considered here as physical pairs. Four of them are new, while the other six had been discovered previously but never investigated homogeneously and in detail. Projected physical separations and magnitude differences of the 10 probably bound pairs range from 180 to 1220 au, and from 0.0 to 3.4 mag in K, respectively. Besides, we identify two cluster stars with elongated point spread functions. We determine the minimum frequency of wide multiplicity in the interval of projected physical separations s = 160-1600 au in Orionis at 3.0 +1.2 −1.1 %. We discover a new Lindroos system, find that massive and X-ray stars tend to be in pairs or trios, conclude that multiplicity truncates circumstellar disks and enhances X-ray emission, and ascribe a reported lithium depletion in a young star to unresolved binarity in spectra of moderate resolution. When accounting for all known multiples, including spectroscopic binaries, the minimum frequency of multiplicity increases to about 10%, which implies that of the order of 80-100 unknown multiple systems still await discovery in Orionis.

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A TGAS/GaiaDR1 parallactic distance to the σ Orionis cluster

Cited by 8 publications

References 93 publications

A deep staring campaign in the σ Orionis cluster

A deep staring campaign in the σ Orionis cluster

The CIDA Variability Survey of Orion OB1. II. Demographics of the Young, Low-mass Stellar Populations^*

Wide σ Orionis binaries resolved by UKIDSS

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A TGAS/GaiaDR1 parallactic distance to the σ Orionis cluster

Cited by 8 publications

References 93 publications

A deep staring campaign in the σ Orionis cluster

A deep staring campaign in the σ Orionis cluster

The CIDA Variability Survey of Orion OB1. II. Demographics of the Young, Low-mass Stellar Populations*

Wide σ Orionis binaries resolved by UKIDSS

Contact Info

Product

Resources

About

The CIDA Variability Survey of Orion OB1. II. Demographics of the Young, Low-mass Stellar Populations^*