The η Chamaeleontis Cluster: A Remarkable New Nearby Young Open Cluster

Mamajek, Eric E.; Lawson, W. A.; Feigelson, E. D.

doi:10.1086/312005

Cited by 179 publications

(231 citation statements)

References 16 publications

Supporting

Mentioning

223

Contrasting

Order By: Relevance

“…Proper motion and parallax information from H has been used to assess the origin of the star formation in the clouds and their relation to other neighbouring associations (Sartori et al 2003). X-ray observations during the past two decades, combined with H astrometry, have shown that the young stars observed towards the Chamaeleon sky area can be grouped into several distinct associations: the Chamaeleon dark cloud complex itself, and the foreground (at around 100 pc) Chamaeleontis ( Cha) and η Chamaeleontis (η Cha) young associations (Feigelson et al 2003;Mamajek et al 1999). The observations have shown that these two associations are older than the Chamaeleon star-forming complex (∼15−20 Myr), but it is unclear whether there is a relation between the two, or whether they are somehow related to the dark clouds.…”

Section: Introductionmentioning

confidence: 99%

Proper motions of young stars in Chamaeleon

Martí

Jiménez-Esteban

Bayo

et al. 2013

A&A

View full text Add to dashboard Cite

Context. The study of the motion of the members of a given open cluster or stellar association provides key information about their formation and early evolution. The Chamaeleon cloud complex constitutes one of the closest and best studied low-mass star-forming regions in the Galaxy. Aims. We want to provide further evidence of the origin of the proposed stellar members of Chamaeleon and to identify interlopers from the foreground Cha and η Cha associations. Methods. We have compiled lists of spectroscopically confirmed members of Chamaeleon I and II, Cha and η Cha, and of background objects in the same line of sight. Using Virtual Observatory tools, we cross-match these lists with the UCAC3 catalogue to get the proper motions of the objects. In the vector point diagram, we identify the different moving groups, and use this information to study the membership of proposed candidate members of the associations from the literature. For those objects with available radial velocities, we compute their Galactic space velocities. We look for correlations between the known properties of the objects and their proper motions. Results. The members of the dark clouds exhibit clearly different proper motions from those of the foreground associations and of the background stars. The data suggest that Chamaeleon II could have different dynamical properties from Chamaeleon I. Although the two foreground clusters and η Chamaeleontis constitute two different proper motion groups, they have similar spatial motions, which are different from the spatial motion of Chamaeleon I. On the other hand, the space motions of the Chamaeleon II stars look more similar to those of the foreground clusters than to the Chamaeleon I stars, but the numbers are low. We find no correlations between the proper motions and the properties of the objects in either of the clouds. Conclusions. On the basis of proper motion, Chamaeleon I and II constitute two physical entities unrelated to the foreground and η Chamaeleontis clusters, but with the available data it is unclear to what extent the stellar populations in both clouds are physically connected to each other.

show abstract

Section: Introductionmentioning

confidence: 99%

Proper motions of young stars in Chamaeleon

Martí

Jiménez-Esteban

Bayo

et al. 2013

A&A

View full text Add to dashboard Cite

show abstract

“…Because of their youth ( < ∼ a few ×10 7 yr), they are supposed to be distributed within ∼10 pc of their birthplaces. Nonetheless, many so-called "isolated TTSs", separated from the molecular clouds by more than a few tens of pc, are found, for example, south of the Taurus and η Cha clusters (Mamajek et al 1999), even though many of those south of Taurus were later reported to be active binaries (Torres et al 2002). Recent studies suggest that such isolation is likely caused by in situ star formation in small clouds and their subsequent rapid dissipation (e.g., Mizuno et al 1998;Tachihara et al 2001).…”

Section: Introduction: the Cepheus-cassiopeia Star-forming Regionmentioning

confidence: 99%

Search for new T Tauri stars in the Cepheus-Cassiopeia region

Tachihara¹,

Neuhäuser²,

Kun

et al. 2005

A&A

View full text Add to dashboard Cite

Abstract. The Cepheus-Cassiopeia star-forming region has been searched for new T Tauri stars (TTSs) based on the ROSAT all sky survey (RASS). Optical spectroscopic observations were carried out toward 45 GSC stellar counterparts of RASS sources looking for the Li absorption line (6708 Å), a sign of youth. The detection of this line resulted in finding 11 to 16 new TTSs in this region. Using follow-up optical photometric observations and evolutionary models these Li-rich stars are revealed to be young low-mass stars. The most of the young stars are separated from the 13 CO molecular clouds by ∼10 pc, significantly more than in Chamaeleon. A group of the new TTSs are isolated from the CO clouds and distributed inside the previously determined CO void. Possible formation scenarios including the interaction with the supernova shock for the isolated TTSs are discussed.Key words. ISM: clouds -ISM: molecules -stars: formation -stars: late-type -stars: pre-main sequence -X-rays: stars Introduction: The Cepheus-Cassiopeia star-forming regionLarge-scale X-ray surveys are a powerful method to search for T Tauri stars (TTSs) that are widely spread over starforming regions (SFRs). Spectroscopic follow-up observations towards the X-ray sources found by the ROSAT X-ray satellite have been carried out in nearby SFRs such as Taurus ), Chamaeleon (Alcalá et al. 1995), and Lupus (Wichmann et al. 1997, most of which are thought to belong to the Gould belt. These surveys found a large number of T Tauri stars (see Neuhäuser 1997 for a review). One of the interesting results of the X-ray selected TTS surveys is that a large number of TTSs have been found far away from the molecular clouds. Because of their youth ( < ∼ a few ×10 7 yr), they are supposed to be distributed within ∼10 pc of their birthplaces. Nonetheless, many so-called "isolated TTSs", separated from the molecular clouds by more than a few tens of pc, are found, for example, south of the Taurus and η Cha clusters (Mamajek et al. 1999), even though many of those south of Taurus were later reported to be active binaries (Torres et al. 2002). Recent studies suggest that such isolation is likely caused by in situ star formation in small clouds and their subsequent rapid dissipation (e.g., Mizuno et al. 1998;Tachihara et al. 2001).Cepheus-Cassiopeia (Cep-Cas) is a nearby SFR located at l ∼ 100 • -140 • and b ∼ 5 • -25 • . The region has been surveyed extensively for molecular clouds in 12 CO by Grenier et al. (1989) who found a total molecular mass of ∼10 5 M . They reported that the cloud distribution shows a CO void which contains an excess of soft X-rays and radio continuum, suggesting a hot bubble created by a supernova. A distance estimation to several dark clouds have been carried out by measuring the colour excess or utilizing star counts (Kun & Prusti 1993;Kun et al. 1994;Kun 1998;Obayashi et al. 1998). Yonekura et al. (1997) surveyed the region in 13 CO and detected 188 distinct molecular clouds. They obtained different radial velocities suggesting that layers at d...

show abstract

“…INTRODUCTION Several groups of young stars within 100 pc of the Sun have recently received much attention as suitable laboratories for detailed studies of star and planet formation. Many of these groups, such as the TW Hydrae association at ∼55 pc (Kastner et al 1997) and the h Chamaeleontis cluster at ∼97 pc (Mamajek, Lawson, & Feigelson 1999), are far from any obvious parent molecular clouds. Thus, their nature, origin, and age are still matters of debate.…”

mentioning

confidence: 99%

Protoplanetary Disks in the Nearest Star-Forming Cloud: Mid-Infrared Imaging and Optical Spectroscopy of MBM 12 Members

Jayawardhana

Wolk

Barrado

et al. 2001

The Astrophysical Journal

View full text Add to dashboard Cite

The recent identification of several groups of young stars within 100 pc of the Sun has generated widespread interest. Given their proximity and possible age differences, these systems are ideally suited for detailed studies of star and planet formation. Here we report on the first investigation of protoplanetary disks in one such group, the high-latitude cloud MBM 12 at a distance of ∼65 pc. We present mid-infrared observations of the eight candidate pre-main-sequence (PMS) members and the two main-sequence (MS) stars in the same line of sight, which may or may not be associated with the group. We have also derived Ha and Li line widths from mediumresolution optical spectra. We report the discovery of significant mid-infrared excess from six PMS stars-LkHa 262, LkHa 263, LkHa 264, E02553ϩ2018, RX J0258.3ϩ1947, and S18-presumably due to optically thick circumstellar disks. Our flux measurements for the other two PMS stars and the two MS stars are consistent with photospheric emission, allowing us to rule out dusty inner disks. The disks we have found in MBM 12 represent the nearest known sample of very young protoplanetary systems and thus are prime targets for high-resolution imaging at infrared and millimeter wavelengths.

show abstract

The η Chamaeleontis Cluster: A Remarkable New Nearby Young Open Cluster

Cited by 179 publications

References 16 publications

Proper motions of young stars in Chamaeleon

Proper motions of young stars in Chamaeleon

Search for new T Tauri stars in the Cepheus-Cassiopeia region

Protoplanetary Disks in the Nearest Star-Forming Cloud: Mid-Infrared Imaging and Optical Spectroscopy of MBM 12 Members

Contact Info

Product

Resources

About