A deep imaging survey of the Pleiades with ROSAT

Stauffer, J. R.; Caillault, J. P.; Gagné, Marc; Prosser, Charles F.; Hartmann, L.

doi:10.1086/191951

Cited by 190 publications

(254 citation statements)

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“…These spectra were best fitted with a column density of N H ¼ 3:6 Â 10 20 cm À2 , in agreement with the reddening to the cluster and previous column density estimates (Caillault & Helfand 1985;Stauffer et al 1994; Paper I). For three stars (HII 1094, HII 1124, and HII 1355), singletemperature models yielded 2 > 2:0.…”

Section: Variability Hardness Ratios and Spectrasupporting

confidence: 85%

“…Therefore, current models do not predict X-ray emission from late B-to A-type stars. However, Paper I, Huélamo et al (2001), Stauffer et al (1994), Caillault et al (1994), Berghöfer & Schmitt (1994, Schmitt et al (1993), Micela et al (1990), Pallavicini, Tagliaferri, & Stella (1990), Caillault & Zoonematkermani (1989), and Schmitt et al (1985) have all recorded X-ray emission from a small percentage of the observed B and A stars using the Einstein, ROSAT, and Chandra satellites. Micela et al (1996), Stauffer et al (1994), Schmitt et al (1993), Grillo et al (1992), Caillault & Helfand (1985), and Golub et al (1983) have proposed that this X-ray emission from some early-type stars could be explained as emission from previously unknown latetype companions.…”

Section: Are B-and A-type Stars Intrinsic X-ray Sources?mentioning

confidence: 99%

“…In this study, Simon et al (1995) concluded that the remaining five must have late-type companions. Stauffer et al (1994) performed a ROSAT survey of the Pleiades showing inconclusive results on this subject. Finally, in Einstein and ROSAT studies of B6-A3 stars in the Orion Nebula, Caillault & Zoonematkermani (1989) and Stauffer et al (1994) proposed that the X-ray emission from these stars could be attributed to T Tauri stars.…”

Section: Introductionmentioning

confidence: 99%

“…Stauffer et al (1994) performed a ROSAT survey of the Pleiades showing inconclusive results on this subject. Finally, in Einstein and ROSAT studies of B6-A3 stars in the Orion Nebula, Caillault & Zoonematkermani (1989) and Stauffer et al (1994) proposed that the X-ray emission from these stars could be attributed to T Tauri stars. As Caillault & Zoonematkermani (1989) also suggested, the current models for X-ray emission may need to be revised since none of these studies could prove or disprove the late-type companion hypothesis.…”

Section: Introductionmentioning

confidence: 99%

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ChandraObservations of the Pleiades Open Cluster: X‐Ray Emission from Late B‐ to Early F‐Type Binaries

Daniel

Linsky

Gagné

2002

ApJ

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We present the analysis of a 38.4 and 23.6 ks observation of the core of the Pleiades open cluster. The Advanced CCD Imaging Spectrometer on board the Chandra X-Ray Observatory detected 99 X-ray sources in a 17 0 Â 17 0 region, including 18 of 23 Pleiades members. Five candidate Pleiades members have also been detected, confirming their cluster membership. Fifty-seven sources have no optical or near-infrared counterparts to limiting magnitudes V ¼ 22:5 and J ¼ 14:5. The unidentified X-ray sources are probably background active galactic nuclei and not stars. The Chandra field of view contains seven intermediate-mass cluster members. Five of these, HII 980 (B6+G), HII 956 (A7+F6), HII 1284 (A9+K), HII 1338 (F3+F6), and HII 1122 (F4+K), are detected in this study. All but HII 1284 have high X-ray luminosity and soft X-ray spectra. HII 1284 has X-ray properties comparable to nonflaring K-type stars. Since all five stars are visual or spectroscopic binaries with X-ray properties similar to F-G stars, the late-type binary companions are probably producing the observed coronal X-ray emission. Strengthening this conclusion is the nondetection by Chandra of two A stars, HII 1362 (A7, no known companion) and HII 1375 (A0+A SB) with X-ray luminosity upper limits 27-54 times smaller than HII 980 and HII 956, the B6-A7 stars with cooler companions. Despite the low number statistics, the Chandra data appear to confirm the expectation that late B and A stars are not strong intrinsic X-ray sources. The ACIS spectra and hardness ratios suggest a gradual increase in coronal temperature with decreasing mass from F4 to K. M stars appear to have somewhat cooler coronae than active K stars.

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Section: Variability Hardness Ratios and Spectrasupporting

confidence: 85%

Section: Are B-and A-type Stars Intrinsic X-ray Sources?mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

ChandraObservations of the Pleiades Open Cluster: X‐Ray Emission from Late B‐ to Early F‐Type Binaries

Daniel

Linsky

Gagné

2002

ApJ

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“…4, right panel) shows a dynamical range of three orders of magnitude. The cluster members are distributed in a sequence of values that goes from ρ Ophiuchi A+B and ρ Ophiuchi C (L X /L bol = 2×10 −6 and 4×10 −5 , respectively) to cooler objects which ratios peak at around 10 −3 , a value found among the most active and young coronae (Caillault & Helfand 1985;Micela et al 1985;Stauffer et al 1994). The origin of this value is debated but it could be a limit to the efficiency in the production of X-rays in dynamo driven coronae of active stars (Charbonneau & MacGregor 1992) or a breaking of magnetic loops in fast rotating stars (Jardine & Unruh 1999).…”

Section: X-ray Luminositiesmentioning

confidence: 99%

First stars of theρOphiuchi dark cloud

Pillitteri

Wolk

Chen

et al. 2016

A&A

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Star formation in molecular clouds can be triggered by the dynamical action of winds from massive stars. Furthermore, X-ray and UV fluxes from massive stars can influence the life time of surrounding circumstellar disks. We present the results of a 53 ks XMMNewton observation centered on the ρ Ophiuchi A+B binary system. ρ Ophiuchi lies in the center of a ring of dust, likely formed by the action of its winds. This region is different from the dense core of the cloud (L1688 Core F) where star formation is at work. X-rays are detected from ρ Ophiuchi as well as a group of surrounding X-ray sources. We detected 89 X-ray sources, 47 of them have at least one counterpart in 2MASS+All-WISE catalogs. Based on IR and X-ray properties, we can distinguish between young stellar objects (YSOs) belonging to the cloud and background objects. Among the cloud members, we detect three debris-disk objects and 22 disk-less − Class III young stars. We show that these stars have ages in 5−10 Myr, and are significantly older than the YSOs in L1688. We speculate that they are the result of an early burst of star formation in the cloud. An X-ray energy of ≥5 × 10 44 erg has been injected into the surrounding medium over the past 5 Myr, we discuss the effects of such energy budget in relation to the cloud properties and dynamics.

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Stellar X‐ray surveys and Galaxy structure

Micela

2003

Astron Nachr

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Abstract. Soft X-ray surveys are very effective to study low-mass stellar populations in our Galaxy. Indeed stellar X-ray counts well complement optical stellar counts since they allow us to study spatial distributions and densities of main sequence stars as function of age. This capability is due to the strong dependence of X-ray luminosity on stellar age, especially during the main sequence life. As a consequence X-ray surveys oversample young stars, detectable at large distances, permitting to study the spatial characteristics of these populations and the stellar birthrate in the solar neighborhood in the last billion year. In this context both low and high latitude X-ray surveys play an important role, since low-latitude surveys allow us to determine the stellar density as a function of age on the Plane, while high latitude surveys constrain the scale heights of the different populations. The comparison of the results at various latitudes can constrain the recent star formation history in the solar neighborhood. I will discuss which improvements the Chandra and XMM-Newton surveys can provide in our knowledge of stellar populations, and some preliminary results from new ongoing surveys.

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A deep imaging survey of the Pleiades with ROSAT

Cited by 190 publications

References 1 publication

ChandraObservations of the Pleiades Open Cluster: X‐Ray Emission from Late B‐ to Early F‐Type Binaries

ChandraObservations of the Pleiades Open Cluster: X‐Ray Emission from Late B‐ to Early F‐Type Binaries

First stars of theρOphiuchi dark cloud

Stellar X‐ray surveys and Galaxy structure

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