<i>Infrared Space Observatory</i>Photometric Search of Main‐Sequence Stars for Vega‐Type Systems

Fajardo-Acosta, S. B.; Stencel, R. E.; Backman, D. E.; Thakur, N.

doi:10.1086/307458

Cited by 31 publications

(31 citation statements)

References 22 publications

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“…From a survey of 38 main-sequence stars using IRAS and ISOPHOT data Fajardo-Acosta et al (1999) found no star with a significant excess at 12 µm, and a fraction of ∼14% excess stars at 20 µm. It is difficult to interpret this fraction since the ISOPHOT data used in their study were inconclusive, and the 20 µm detections needed confirmation.…”

Section: Discussionmentioning

confidence: 99%

A 25 micron search for Vega-like disks around main-sequence stars with ISO

Laureijs¹,

Muizon²,

Leech³

et al. 2002

A&A

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Abstract. We present an ISO 25 µm photometric survey of a sample of 81 nearby main-sequence stars in order to determine the incidence of "warm" dust disks. All stars were detected by ISO. We used an empirical relation to estimate the photospheric flux of the stars at 25 µm. We find 5 stars (6%) with excess above the photospheric flux which we attribute to a Vega-like disk. These stars show disk temperatures not warmer than 120 K. Our study indicates that warm disks are relatively rare. Not a single star in our sample older than 400 Myr has a warm disk. We find an upper limit of M disk = 2 × 10 −5 M⊕ for the mass of the disks which we did not detect.

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Section: Discussionmentioning

confidence: 99%

A 25 micron search for Vega-like disks around main-sequence stars with ISO

Laureijs¹,

Muizon²,

Leech³

et al. 2002

A&A

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“…We compiled a total of 113 Southern Hemisphere Vega-like candidate stars from the literature, based on their infrared or submillimetric excess emission (Backman & Paresce 1993;Sylvester et al 1996;Mannings & Barlow 1998;Fajardo-Acosta et al 1999;Sylvester & Mannings 2000;Habing et al 2001;Laureijs et al 2002;Sheret et al 2004). This compilation also includes G dwarfs with infrared excess recently detected by Spitzer (Beichman et al 2005(Beichman et al , 2006aBryden et al 2006;Su et al 2006;Trilling et al 2008).…”

Section: The Samplementioning

confidence: 99%

Spectroscopic metallicities of Vega-like stars

Saffe¹,

Gómez²,

Pintado³

et al. 2008

A&A

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Aims. We aim to determine the metallicities of 113 Southern Hemisphere Vega-like candidate stars in relation to the giant exoplanet host group and field stars. Methods. We applied two spectroscopic methods of abundance determinations: equivalent width measurements together with the ATLAS9 model atmospheres and the WIDTH9 program, and a comparison of observed spectra with a grid of synthetic spectra. Results. For the Vega-like group, the metallicities are indistinguishable from those of field stars not known to be associated with planets or disks. This result is quite different from the metallicities of giant exoplanet host stars, which are metal-rich in comparison to field stars.

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“…Using ISOPHOT data from the Infrared Space Observatory (ISO; Kessler et al 1996) Fajardo-Acosta et al (1999 confirmed the infrared excess of HD 110411 and report a tentative detection of HD 192640 (only at 20 µm).…”

Section: Results Of Infrared Measurements From the Literaturementioning

confidence: 99%

“…Furthermore, the ISO satellite brought a flood of new data for group members. Fajardo-Acosta et al (1999) presented data for three λ Bootis stars, namely HD 11413, HD 110411 and HD 192640. In Sect. 2, we summarize the current literature status on the λ Bootis phenomenon focusing especially on circumstellar dust and gas.…”

Section: Introductionmentioning

confidence: 99%

A study of λ Bootis type stars in the wavelength region beyond 7000 Å

Paunzen

Kamp

Weiß

et al. 2003

A&A

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Abstract. The group of λ Bootis type stars comprises late B-to early F-type, Population I objects which are basically metal weak, in particular the Fe group elements, but with the clear exception of C, N, O and S. One of the theories to explain the abundance pattern of these stars involves circumstellar or interstellar matter around the objects. Hence, we have compiled all available data from the literature of well established members of the λ Bootis group redward of 7000 Å in order to find evidence for matter around these objects. Furthermore, we present unpublished ISO as well as submillimeter continuum and CO (2-1) line measurements to complete the data set. In total, measurements for 34 (26 with data redward of 20 µm) well established λ Bootis stars are available. There is evidence for an infrared excesses in six stars (HD 31295, HD 74873, HD 110411, HD 125162, HD 198160/1 and HD 210111) and two are doubtful cases (HD 11413 and HD 192640) resulting in a percentage of 23% (excluding the two doubtful cases). Dust models for these objects show fractional dust luminosities comparable to the Vega-type stars and slightly higher dust temperatures. ISO-SWS spectroscopy for HD 125162 and HD 192640 resulted in the detection of pure stellar H  lines ruling out an active accretion disk (as found for several Herbig Ae/Be stars) around these objects. The submillimeter measurements gave only upper limits for the line and continuum fluxes.Key words. stars: chemically peculiar -stars: early-type IntroductionThe group of λ Bootis stars comprise of true Population I, late B to early F-type stars, with moderate to extreme (up to a factor 100) surface underabundances of most Fe-peak elements and solar abundances of lighter elements (C, N, O, and S). Tables 2 and 3 are only available in electronic form at http://www.edpsciences.org gas is accreted by the star. Hence, a circumstellar disk or shell should exist around λ Bootis stars which manifests itself in an infrared (IR hereafter) excess.The first near-infrared data for well established λ Bootis stars was already published by Oke (1967). He lists spectrophotometry for HD 31295, HD 125162 and HD 192640 up to 10870 Å. Data for wavelengths beyond 10 µm became available with the launch of the IRAS-satellite. The IR excesses detected for Vega, Eridani, α Piscis Austrini and β Pictoris (Aumann et al. 1984) have been interpreted as due to cold circumstellar disks or shells around these stars. Later, the disk of β Pictoris was directly imaged in the IR revealing a solar system-sized dust disk extending to at least 1100 AU (Smith & Terrile 1984). A simple model of this system indicates a central star (spectral type: A5V), encircled by an ionized gaseous inner disk and an outer dust disk. Aumann (1985) established the group of Vega-like stars containing main-sequence (MS hereafter) stars also showing an infrared excess (defined by the IRAS colors at 12 and 60 µm: [12]-[60] > 1 mag) similar to the prototype Vega. Many Vega-like stars are in fact much cooler than Vega (A0 V) itself.Ar...

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Infrared Space ObservatoryPhotometric Search of Main‐Sequence Stars for Vega‐Type Systems

Cited by 31 publications

References 22 publications

A 25 micron search for Vega-like disks around main-sequence stars with ISO

A 25 micron search for Vega-like disks around main-sequence stars with ISO

Spectroscopic metallicities of Vega-like stars

A study of λ Bootis type stars in the wavelength region beyond 7000 Å

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