We investigated the environment of the infrared dust bubble N68 and searched for evidence of triggered star formation in its surroundings. We performed a multiwavelength study of the nebula with data taken from severa...We investigated the environment of the infrared dust bubble N68 and searched for evidence of triggered star formation in its surroundings. We performed a multiwavelength study of the nebula with data taken from several large-scale surveys： GLIMPSE, MIPSGAL, IRAS, NVSS, GRS and JCMT. We analyzed the spectral pro- file and the distribution of the molecular gas （13CO J -- 1 - 0 and J -- 3 - 2）, and the dust in the environment of N68. The position-velocity diagram clearly shows that N68 may be expanding outward. We used two three-color images of the mid-infrared emis- sion to explore the physical environment, and one color-color diagram to investigate the distribution of young stellar objects （YSOs）. We found that the 24 p^m emission is surrounded by the 8.0 ~m emission. Morphologically, the 1.4 GHz continuum strongly correlates with the 24 gm emission, and the 13CO J -- 1 - 0 and J -- 3 - 2 emissions correlate well with the 8.0 p^m emission. We investigated two compact cores located in the shell of N68. The spectral intensity ratios of 13CO J -- 3 - 2 to J = 1 - 0 range from 5 to 0.3. In addition, YSOs, masers, IRAS and UC HII regions are distributed in the shell of the bubble. The active region may be triggered by the expansion of the bubble N68.展开更多
We present the optical to mid-infrared SEDs of 11 debris disk candidates from Spitzer SWIRE fields. All the candidates are selected from SWIRE 24 μm sources matched with both the SDSS star catalog and the 2MASS point...We present the optical to mid-infrared SEDs of 11 debris disk candidates from Spitzer SWIRE fields. All the candidates are selected from SWIRE 24 μm sources matched with both the SDSS star catalog and the 2MASS point source catalog. They show an excess in the mid-infrared at 24 μm （Ks-[24]vega 〉 0.44）, indicating the presence of a circumstellar dust disk. The observed optical spectra show that they are all late-type main-sequence stars covering the spectral types of FGKM. Their fractional luminosities are well above 5× 10-5, even up to the high fractional luminosity of 1×10-3. The high galactic latitudes of SWIRE fields indicate that most of these candidates could belong to the oldest stars in the thick disk. Our results indicate that high fractional luminosity debris disks could exist in old solar-like star systems, though they are still quite rare. Their discovery at high galactic latitudes also provides an exellent opportunity for further study of the properties and evolution of debris disks in regions of the Galaxy with low densities of ISM, called ISM poor environments.展开更多
The Infrared Space Observatory （ISO） Short-Wavelength Spectrometer （SWS） spectra of 10 Be stars are presented. It can be seen that the Be stars show a diversity in their ISO SWS01 spectral classifications by Kraem...The Infrared Space Observatory （ISO） Short-Wavelength Spectrometer （SWS） spectra of 10 Be stars are presented. It can be seen that the Be stars show a diversity in their ISO SWS01 spectral classifications by Kraemer et al., from naked stars, stars associated with dust, stars with warm dust shells, stars with cool dust shells to very red sources. In addition, the Brα/HI（14-6） line flux ratio derived for the sample stars is compared with that of P Cyg, and it is found that the line ratio of Be stars which were investigated show not only lower values as suggested by Waters et al., but also larger values. Therefore, the line ratio cannot be used to judge whether a star is a Be star or not.展开更多
This study presents the results of an infrared search of young stellar objects (YSOs) associated with cores with high optical extinction and no associated infrared IRAS source. Four hundred YSO candidates were identif...This study presents the results of an infrared search of young stellar objects (YSOs) associated with cores with high optical extinction and no associated infrared IRAS source. Four hundred YSO candidates were identified in the WISE photometric catalog based on the infrared excess attributed to the circumstellar materials and proto-planetary disks. One-hundred and forty-nine cores do not have YSO candidates. Whereas, 32 cores harbor only Class I candidates and 107 cores have Class II candidates. Ninety-one cores that were previously identified as starless cores, were found to contain YSOs. The ratio of the number of starless cores to the number of star-forming cores suggests that the typical timescale from molecular cloud core formation to the birth of a star is in the range of 0.5 - 1.4 Myr.展开更多
Recent submillimeter dust thermal emission observations have unveiled a significant number of inter-arm massive molecular clouds in M31.However,the effectiveness of this technique is limited to its sensitivity,making ...Recent submillimeter dust thermal emission observations have unveiled a significant number of inter-arm massive molecular clouds in M31.However,the effectiveness of this technique is limited to its sensitivity,making it challenging to study more distant galaxies.This study introduces an alternative approach,utilizing optical extinctions derived from space-based telescopes,with a focus on the forthcoming China Space Station Telescope(CSST).We first demonstrate the capability of this method by constructing dust extinction maps for 17 inter-arm massive molecular clouds in M31 using the Panchromatic Hubble Andromeda Treasury data.Our analysis reveals that inter-arm massive molecular clouds with an optical extinction(A_(V)) greater than 1.6 mag exhibit a notable A_(V) excess,facilitating their identification.The majority of these inter-arm massive molecular clouds show an A_(V) around 1 mag,aligning with measurements from our JCMT data.Further validation using a mock CSST RGB star catalog confirms the method's effectiveness.We show that the derived A_(V)values using CSST z and y photometries align more closely with the input values.Molecular clouds with A_(V)> 1.6 mag can also be identified using the CSST mock data.We thus claim that future CSST observation clouds provide an effective way for the detection of inter-arm massive molecular clouds with significant optical extinction in nearby galaxies.展开更多
We present a study of the pre-protostellar core (PPC) L1498. A series of self-consistent, three-dimensional continuum radiative transfer models are constructed. The outputs of these models are convolved with appropria...We present a study of the pre-protostellar core (PPC) L1498. A series of self-consistent, three-dimensional continuum radiative transfer models are constructed. The outputs of these models are convolved with appropriate telescope beam responses, including the effect of beam chopping to simulate SCUBA observations. The simulated observations are compared with existing observational data. An automated search is conducted in the multi-dimensional parameter space to identify the best-fit model. Grids of models are constructed in the vicinity of the best fit in order to understand the sensitivity/uncertainty of the results. We find that the source is well fit by a prolate spheroid of cutoff (and thus approximately outer) radius rcut = 0.073 ± 0.005 pc, axis ratio q = 2.0 ± 0.2, a central luminosity L* -3 Lsun, and an optical depth in the visible of τv = 20 ± 5. We find that the PPC is illuminated by two external radiation fields: a uniform ISRF of strength sISRF= 0.5 ± 0.25 and a local plane-parallel radiation field sPPRF = 1.0 ± 0.5. Both of these radiation fields are locally attenuated, with τISRF = 1.0 ± 0.25, and τPPRF = 1.25 ± 0.75, consistent with the fact that L1498 is embedded in a larger cloud. Most interestingly, the density fall-off at the outer edge is extremely steep, having a power law of m > 10. This is effectively a “sharp edge” to the PPC, and together with the constant density interior, is interpreted as potential signs of a pressure-confined core.展开更多
The chemical classification of IRAS 17515-2407 has been debated for a longtime. Up to now there are two contenders, oxygen-rich or carbon-rich. We believe that IRAS17515-2407 is an oxygen-rich source: because (ⅰ) it ...The chemical classification of IRAS 17515-2407 has been debated for a longtime. Up to now there are two contenders, oxygen-rich or carbon-rich. We believe that IRAS17515-2407 is an oxygen-rich source: because (ⅰ) it shows the silicate self-absorbed emission; (ⅱ)in the near infrared-IRAS diagram it is located in the oxygen-rich object region and (ⅲ)particularly, it has detected SiO maser emission.展开更多
We collected almost all Highly Processed Data Products （HPDP） of ISO SWS01 spectra for the Galactic visual carbon stars,infrared carbon stars,extreme carbon stars and carbon-rich proto-planetary nebulae （PPNs）.Tho...We collected almost all Highly Processed Data Products （HPDP） of ISO SWS01 spectra for the Galactic visual carbon stars,infrared carbon stars,extreme carbon stars and carbon-rich proto-planetary nebulae （PPNs）.Those infrared spectra are primarily analyzed and discussed.It is shown that either spectral shapes/peaks,or main molecular/dust features are evidenced to change in the sequence of visual carbon stars,infrared carbon stars,extreme carbon stars and carbon-rich PPNs.Statistically,in this sequence,continua are gradually changed from blue to red and locations of spectral peaks of continua are also gradually changed from short wavelengths to long wavelengths.In addition,in this sequence,intensities of main molecular/dust features are also gradually changed from prominent in the short wavelengths to prominent in the long wavelengths.Furthermore,from 2MASS and IRAS photometric data,the sequence is also proved.Results in this paper strongly support the previous suggestion for the evolution sequence of carbon-rich objects in our Galaxy,that is the sequence of visual carbon stars → infrared carbon stars → extreme carbon stars → carbon-rich PPNs.展开更多
We report variation of K-band infrared(IR) emission in the vicinity of the G025.65+1.05 water and methanol maser source. New observational data were obtained with the 2.5 m telescope at the Caucasian Mountain Observat...We report variation of K-band infrared(IR) emission in the vicinity of the G025.65+1.05 water and methanol maser source. New observational data were obtained with the 2.5 m telescope at the Caucasian Mountain Observatory(CMO) of Moscow State University on 2017–09–21 during a strong water maser flare. We found that the IR source situated close to the maser position had decreased brightness in comparison to archive data. This source is associated with a massive young stellar object(MYSO) corresponding to the compact IR source IRAS 18316–0602(RAFGL 7009 S). A similar decrease in K-brightness of the IR source close to the maser position was observed in March 2011 when the water maser experienced a period of increased activity. The dips in MYSO brightness can be related to the maser flare phases. Maser flares that are concurrent with dips in the IR emission can be explained if the lower IR radiation field enables a more efficient sink for the pumping cycle by allowing IR photons to escape the maser region.展开更多
系外行星直接成像探测能够获取系外行星更全面的物理信息,是未来搜寻系外生命的关键技术之一.针对近期地基望远镜高对比度成像观测数据,对新发现的多星候选体进行系统展示.前期,结合地基系外行星高对比度成像设备观测能力,从已发表文献...系外行星直接成像探测能够获取系外行星更全面的物理信息,是未来搜寻系外生命的关键技术之一.针对近期地基望远镜高对比度成像观测数据,对新发现的多星候选体进行系统展示.前期,结合地基系外行星高对比度成像设备观测能力,从已发表文献整理的Gaia星表恒星数据中筛选,得到约1000个观测目标.这些目标分布于不同的年轻星团中.近期,使用Palomar天文台Hale望远镜对上述观测目标中的42个目标在K波段开展了高对比度成像观测.这些目标恒星在可见光波段为7.5-14.2019年经过两轮观测,发现了6个多星系统候选体,这些目标在Gaia Data Release 2星表和Gaia early Data Release 3星表中难以确认是单星还是多星系统.展开更多
Debris disks around stars are considered as components of planetary systems.Constraining the dust properties of these disks can give crucial information to formation and evolution of planetary systems.As an all-sky su...Debris disks around stars are considered as components of planetary systems.Constraining the dust properties of these disks can give crucial information to formation and evolution of planetary systems.As an all-sky survey,InfRared Astronomical Satellite(IRAS)gave great contribution to the debris disk searching which discovered the first debris disk host star(Vega).The IRAS-detected debris disk sample published by Rhee(Rhee et al.2007)contains 146 stars with detailed information of dust properties.While the dust properties of 45 of them still cannot be determined due to the limitations with the IRAS database(have IRAS detection at 60μm only).Therefore,using more sensitivity data of Wide-.field Infrared Survey Explorer(WISE),we can better characterize the sample stars:for the stars with IRAS detection at 60μm only,we refit the excessive flux densities and obtain the dust temperatures and fractional luminosities;while for the remaining stars with multi-bands IRAS detections,the dust properties are revised which show that the dust temperatures were overestimated in the high temperature band before.Moreover,we identify 17 stars with excesses at the WISE 22μm which have smaller distribution of distance from Earth and higher fractional luminosities than the other stars without mid-infrared excess emission.Among them,15 stars can be found in previous works.展开更多
We have collected a catalog of 1095 debris disks with properties and classification(resolved,planet,gas)information.From the catalog,we defined a less biased sample with 612 objects and presented the distributions of ...We have collected a catalog of 1095 debris disks with properties and classification(resolved,planet,gas)information.From the catalog,we defined a less biased sample with 612 objects and presented the distributions of their stellar and disk properties to search for correlations between disks and stars.We found debris disks were widely distributed from B to M-type stars while planets were mostly found around solar-type stars,gases were easier to detect around early-type stars and resolved disks were mostly distributed from A to G-type stars.The fractional luminosity dropped off with stellar age and planets were mostly found around old stars while gas-detected disks were much younger.The dust temperature of both one-belt systems and cold components in two-belt systems increased with distance while decreasing with stellar age.In addition,we defined a less biased planet sample with 211 stars with debris disks but no planets and 35 stars with debris disks and planets and found the stars with debris disks and planets had higher metallicities than stars with debris disks but no planets.Among the 35 stars with debris disks and planets,we found the stars with disks and cool Jupiters were widely distributed with age from 10 Myr to 10 Gyr and metallicity from-1.56 to 0.28 while the other three groups tended to be old(>4Gyr)and metal-rich(>-0.3).In addition,the eccentricities of cool Jupiters are distributed from 0 to 0.932,wider than the other three types of planets(<0.3).展开更多
基金supported by the Young Researcher Grant of the National Astronomical Observatories,Chinese Academy of Sciences (Grant No. O835032002)
文摘We investigated the environment of the infrared dust bubble N68 and searched for evidence of triggered star formation in its surroundings. We performed a multiwavelength study of the nebula with data taken from several large-scale surveys： GLIMPSE, MIPSGAL, IRAS, NVSS, GRS and JCMT. We analyzed the spectral pro- file and the distribution of the molecular gas （13CO J -- 1 - 0 and J -- 3 - 2）, and the dust in the environment of N68. The position-velocity diagram clearly shows that N68 may be expanding outward. We used two three-color images of the mid-infrared emis- sion to explore the physical environment, and one color-color diagram to investigate the distribution of young stellar objects （YSOs）. We found that the 24 p^m emission is surrounded by the 8.0 ~m emission. Morphologically, the 1.4 GHz continuum strongly correlates with the 24 gm emission, and the 13CO J -- 1 - 0 and J -- 3 - 2 emissions correlate well with the 8.0 p^m emission. We investigated two compact cores located in the shell of N68. The spectral intensity ratios of 13CO J -- 3 - 2 to J = 1 - 0 range from 5 to 0.3. In addition, YSOs, masers, IRAS and UC HII regions are distributed in the shell of the bubble. The active region may be triggered by the expansion of the bubble N68.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11173030, 11078017, 10833006, 10978014 and 10773014)partly supported by the China Ministry of Science and Technology under the State Key Development Program for Basic Research (2007CB815400 and 2012CB821800)S. Wolf was supported by the German Research Foundation (DFG) through the Emmy Noether grant WO 857/2
文摘We present the optical to mid-infrared SEDs of 11 debris disk candidates from Spitzer SWIRE fields. All the candidates are selected from SWIRE 24 μm sources matched with both the SDSS star catalog and the 2MASS point source catalog. They show an excess in the mid-infrared at 24 μm （Ks-[24]vega 〉 0.44）, indicating the presence of a circumstellar dust disk. The observed optical spectra show that they are all late-type main-sequence stars covering the spectral types of FGKM. Their fractional luminosities are well above 5× 10-5, even up to the high fractional luminosity of 1×10-3. The high galactic latitudes of SWIRE fields indicate that most of these candidates could belong to the oldest stars in the thick disk. Our results indicate that high fractional luminosity debris disks could exist in old solar-like star systems, though they are still quite rare. Their discovery at high galactic latitudes also provides an exellent opportunity for further study of the properties and evolution of debris disks in regions of the Galaxy with low densities of ISM, called ISM poor environments.
基金This publication makes use of observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherlands and the UK) with the participation of ISAS and NASAsupported by the National Natural Science Foundation of China (10503011 and 10778702)the Natural Science Foundation of Yunnan University (2008YB036)
文摘The Infrared Space Observatory （ISO） Short-Wavelength Spectrometer （SWS） spectra of 10 Be stars are presented. It can be seen that the Be stars show a diversity in their ISO SWS01 spectral classifications by Kraemer et al., from naked stars, stars associated with dust, stars with warm dust shells, stars with cool dust shells to very red sources. In addition, the Brα/HI（14-6） line flux ratio derived for the sample stars is compared with that of P Cyg, and it is found that the line ratio of Be stars which were investigated show not only lower values as suggested by Waters et al., but also larger values. Therefore, the line ratio cannot be used to judge whether a star is a Be star or not.
文摘This study presents the results of an infrared search of young stellar objects (YSOs) associated with cores with high optical extinction and no associated infrared IRAS source. Four hundred YSO candidates were identified in the WISE photometric catalog based on the infrared excess attributed to the circumstellar materials and proto-planetary disks. One-hundred and forty-nine cores do not have YSO candidates. Whereas, 32 cores harbor only Class I candidates and 107 cores have Class II candidates. Ninety-one cores that were previously identified as starless cores, were found to contain YSOs. The ratio of the number of starless cores to the number of star-forming cores suggests that the typical timescale from molecular cloud core formation to the birth of a star is in the range of 0.5 - 1.4 Myr.
基金supported by the National Natural Science Foundation of China Nos.11988101,12373012,and 12041302supported by CMS-CSST-2021A08 and CMS-CSST-2021-B02support from NSFC with grant No.12203064。
文摘Recent submillimeter dust thermal emission observations have unveiled a significant number of inter-arm massive molecular clouds in M31.However,the effectiveness of this technique is limited to its sensitivity,making it challenging to study more distant galaxies.This study introduces an alternative approach,utilizing optical extinctions derived from space-based telescopes,with a focus on the forthcoming China Space Station Telescope(CSST).We first demonstrate the capability of this method by constructing dust extinction maps for 17 inter-arm massive molecular clouds in M31 using the Panchromatic Hubble Andromeda Treasury data.Our analysis reveals that inter-arm massive molecular clouds with an optical extinction(A_(V)) greater than 1.6 mag exhibit a notable A_(V) excess,facilitating their identification.The majority of these inter-arm massive molecular clouds show an A_(V) around 1 mag,aligning with measurements from our JCMT data.Further validation using a mock CSST RGB star catalog confirms the method's effectiveness.We show that the derived A_(V)values using CSST z and y photometries align more closely with the input values.Molecular clouds with A_(V)> 1.6 mag can also be identified using the CSST mock data.We thus claim that future CSST observation clouds provide an effective way for the detection of inter-arm massive molecular clouds with significant optical extinction in nearby galaxies.
文摘We present a study of the pre-protostellar core (PPC) L1498. A series of self-consistent, three-dimensional continuum radiative transfer models are constructed. The outputs of these models are convolved with appropriate telescope beam responses, including the effect of beam chopping to simulate SCUBA observations. The simulated observations are compared with existing observational data. An automated search is conducted in the multi-dimensional parameter space to identify the best-fit model. Grids of models are constructed in the vicinity of the best fit in order to understand the sensitivity/uncertainty of the results. We find that the source is well fit by a prolate spheroid of cutoff (and thus approximately outer) radius rcut = 0.073 ± 0.005 pc, axis ratio q = 2.0 ± 0.2, a central luminosity L* -3 Lsun, and an optical depth in the visible of τv = 20 ± 5. We find that the PPC is illuminated by two external radiation fields: a uniform ISRF of strength sISRF= 0.5 ± 0.25 and a local plane-parallel radiation field sPPRF = 1.0 ± 0.5. Both of these radiation fields are locally attenuated, with τISRF = 1.0 ± 0.25, and τPPRF = 1.25 ± 0.75, consistent with the fact that L1498 is embedded in a larger cloud. Most interestingly, the density fall-off at the outer edge is extremely steep, having a power law of m > 10. This is effectively a “sharp edge” to the PPC, and together with the constant density interior, is interpreted as potential signs of a pressure-confined core.
基金Supported by the National Natural Science Foundation of China
文摘The chemical classification of IRAS 17515-2407 has been debated for a longtime. Up to now there are two contenders, oxygen-rich or carbon-rich. We believe that IRAS17515-2407 is an oxygen-rich source: because (ⅰ) it shows the silicate self-absorbed emission; (ⅱ)in the near infrared-IRAS diagram it is located in the oxygen-rich object region and (ⅲ)particularly, it has detected SiO maser emission.
基金supported by grants from the National Natural Science Foundation of China (Nos. 10503011,10533050 and 10803023)the Natural Science Foundation Project of CQ CSTC (2008BB0153)and the Chinese Academy of Sciences
文摘We collected almost all Highly Processed Data Products （HPDP） of ISO SWS01 spectra for the Galactic visual carbon stars,infrared carbon stars,extreme carbon stars and carbon-rich proto-planetary nebulae （PPNs）.Those infrared spectra are primarily analyzed and discussed.It is shown that either spectral shapes/peaks,or main molecular/dust features are evidenced to change in the sequence of visual carbon stars,infrared carbon stars,extreme carbon stars and carbon-rich PPNs.Statistically,in this sequence,continua are gradually changed from blue to red and locations of spectral peaks of continua are also gradually changed from short wavelengths to long wavelengths.In addition,in this sequence,intensities of main molecular/dust features are also gradually changed from prominent in the short wavelengths to prominent in the long wavelengths.Furthermore,from 2MASS and IRAS photometric data,the sequence is also proved.Results in this paper strongly support the previous suggestion for the evolution sequence of carbon-rich objects in our Galaxy,that is the sequence of visual carbon stars → infrared carbon stars → extreme carbon stars → carbon-rich PPNs.
基金supported by the Russian ScienceFoundation (Grant 18-12-00193)supported by Russian Foundation for Basic Research(Grant 18-32-00314)
文摘We report variation of K-band infrared(IR) emission in the vicinity of the G025.65+1.05 water and methanol maser source. New observational data were obtained with the 2.5 m telescope at the Caucasian Mountain Observatory(CMO) of Moscow State University on 2017–09–21 during a strong water maser flare. We found that the IR source situated close to the maser position had decreased brightness in comparison to archive data. This source is associated with a massive young stellar object(MYSO) corresponding to the compact IR source IRAS 18316–0602(RAFGL 7009 S). A similar decrease in K-brightness of the IR source close to the maser position was observed in March 2011 when the water maser experienced a period of increased activity. The dips in MYSO brightness can be related to the maser flare phases. Maser flares that are concurrent with dips in the IR emission can be explained if the lower IR radiation field enables a more efficient sink for the pumping cycle by allowing IR photons to escape the maser region.
文摘系外行星直接成像探测能够获取系外行星更全面的物理信息,是未来搜寻系外生命的关键技术之一.针对近期地基望远镜高对比度成像观测数据,对新发现的多星候选体进行系统展示.前期,结合地基系外行星高对比度成像设备观测能力,从已发表文献整理的Gaia星表恒星数据中筛选,得到约1000个观测目标.这些目标分布于不同的年轻星团中.近期,使用Palomar天文台Hale望远镜对上述观测目标中的42个目标在K波段开展了高对比度成像观测.这些目标恒星在可见光波段为7.5-14.2019年经过两轮观测,发现了6个多星系统候选体,这些目标在Gaia Data Release 2星表和Gaia early Data Release 3星表中难以确认是单星还是多星系统.
基金supported by the National Natural Science Foundation of China(Grant No.U1631109)based on the sample of Rhee and makes use of data products from many telescopes:WISE(a joint project of the University of California,Los Angeles+1 种基金the Jet Propulsion Laboratory/California Institute of Technology)Hipparcos(the primary result of the Hipparcos space astrometry mission,undertaken by the European Space Agency)and 2MASS(a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology)。
文摘Debris disks around stars are considered as components of planetary systems.Constraining the dust properties of these disks can give crucial information to formation and evolution of planetary systems.As an all-sky survey,InfRared Astronomical Satellite(IRAS)gave great contribution to the debris disk searching which discovered the first debris disk host star(Vega).The IRAS-detected debris disk sample published by Rhee(Rhee et al.2007)contains 146 stars with detailed information of dust properties.While the dust properties of 45 of them still cannot be determined due to the limitations with the IRAS database(have IRAS detection at 60μm only).Therefore,using more sensitivity data of Wide-.field Infrared Survey Explorer(WISE),we can better characterize the sample stars:for the stars with IRAS detection at 60μm only,we refit the excessive flux densities and obtain the dust temperatures and fractional luminosities;while for the remaining stars with multi-bands IRAS detections,the dust properties are revised which show that the dust temperatures were overestimated in the high temperature band before.Moreover,we identify 17 stars with excesses at the WISE 22μm which have smaller distribution of distance from Earth and higher fractional luminosities than the other stars without mid-infrared excess emission.Among them,15 stars can be found in previous works.
基金supported in part by the National Natural Science Foundation of China(NSFC,Nos.U1631109,11703093 and U2031120)supported in part by the Special Natural Science Fund of Guizhou University(Grant No.201911A)the First-class Physics Promotion Programme(2019)of Guizhou University。
文摘We have collected a catalog of 1095 debris disks with properties and classification(resolved,planet,gas)information.From the catalog,we defined a less biased sample with 612 objects and presented the distributions of their stellar and disk properties to search for correlations between disks and stars.We found debris disks were widely distributed from B to M-type stars while planets were mostly found around solar-type stars,gases were easier to detect around early-type stars and resolved disks were mostly distributed from A to G-type stars.The fractional luminosity dropped off with stellar age and planets were mostly found around old stars while gas-detected disks were much younger.The dust temperature of both one-belt systems and cold components in two-belt systems increased with distance while decreasing with stellar age.In addition,we defined a less biased planet sample with 211 stars with debris disks but no planets and 35 stars with debris disks and planets and found the stars with debris disks and planets had higher metallicities than stars with debris disks but no planets.Among the 35 stars with debris disks and planets,we found the stars with disks and cool Jupiters were widely distributed with age from 10 Myr to 10 Gyr and metallicity from-1.56 to 0.28 while the other three groups tended to be old(>4Gyr)and metal-rich(>-0.3).In addition,the eccentricities of cool Jupiters are distributed from 0 to 0.932,wider than the other three types of planets(<0.3).
