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Article

Physical Properties of Radio Stars Based on LAMOST Spectral Survey

by
Liyun Zhang
1,*,
Yao Cheng
1,
Xianming L. Han
1,2,
Qingfeng Pi
3,
Prabhakar Misra
4,
Baoda Li
1 and
Zhongzhong Zhu
1
1
Department of Physics and Astronomy, College of Physics, Guizhou University, Guiyang 550025, China
2
Department of Physics and Astronomy, Butler University, Indianapolis, IN 46208, USA
3
School of Pharmacy, Guizhou University of Traditional Chinese Medicine, Guiyang 550025, China
4
Department of Physics & Astronomy, Howard University, Washington, DC 20059, USA
*
Author to whom correspondence should be addressed.
Universe 2022, 8(7), 384; https://doi.org/10.3390/universe8070384
Submission received: 31 May 2022 / Revised: 5 July 2022 / Accepted: 6 July 2022 / Published: 19 July 2022
(This article belongs to the Special Issue Stellar Multi-Band Observational Studies in the Era of Big Data)
Browse Figures
Review Reports Versions Notes

Abstract

:
Radio emission has been detected for all types of stars in the Hertzsprung Russell diagram. Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) low and medium-resolution spectroscopic surveys provide a good opportunity to obtain the spectroscopic properties of radio stars. We cross-matched big data from the LAMOST DR7 low resolution spectral survey with a catalogue of radio stars, and obtained 449 stellar spectra of 258 stars. We detected 185 spectra with H α emission. There are a total of 108 objects with repeated low resolution spectral observations, of which 63 show variations in the H α line over a long time, about several months. We cross-matched LAMOST DR7 medium resolution spectra with the radio star catalogue. We obtained 1319 LAMOST medium-resolution spectra of the 156 radio stars and then calculated their equivalent widths ( E W s ) of the H α line. Among them, 93 radio stars with H α emission were found from the LAMOST medium resolution spectra, and 63 objects showed short and long-term variabilities, especially on a short time scale of approximately 20 min. Finally, we estimated the minimal detectable radio flux of the FAST telescope and provided a scientific plan for studying radio stars.

1. Introduction

Radio waves have been detected in all types of stars across the Hertzsprung–Russell (HR) diagram [1,2]. Radio stars are defined as stars with continuum radiation at the radio wavelength. Radio emission has been detected from the accretion disks of young stellar objects [3], star–planet interactions between host stars with extra-solar planets [4], magnetic activity in T Tau stars [5], ultracool dwarfs [6], low-mass [7] and RS CVn stars [8], and binary interactions in eclipsing binary systems [9]. Thermal or non-thermal physical processes explain such detection. The most direct probes of physical non-thermal processes are stellar magnetic field activities or shock, wind–wind interaction, jets, stellar pulsation, particle acceleration, and energy release on stars. Thermal radio emissions include mass transport, stellar wind outflows, and circumstellar disk emission [2]. Bai et al. (2012) [10] used a 25 m radio telescope in Urumqi, China and made continuum and polarization observations on two RS CVn binaries, V772 Her and Beta Per. They detected two radio flares and determined their polarization fractions. The detection of radio emissions from nearby stars is one of the earlier scientific projects of the Five-Hundred-Meter Aperture Spherical Radio Telescope (FAST) [11,12]. Observations of radio stars can both enrich our understanding of their physical parameters and active phenomena and promote the development of stellar theory in the radio domain with cm wavelengths.
Wendker [13,14] released an updated catalogue of 3699 single radio stars and binary systems. The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) has recently offered stellar parameters from low and medium-resolution spectra [15,16,17], which are extremely useful for studying the chromospheric activity of solar-like stars and other chromospheric active stars in the H α and C a Ⅱ IRT lines [18,19,20,21,22]. Zhang et al. (2017) [23] analyzed 147 spectra of 89 active radio stars in the catalogue of radio stars using the LAMOST low resolution survey DR2. They found that 28 stars exhibited long-term variation of chromospheric activity among 36 objects. Gizis et al. (2002) [24] and Lee et al. (2010) [25] found that approximately 30% of low mass stars showed variations in the H α emission in short time scales of minutes to hours. In this study, we determined the nature of the physical parameters and optical properties of radio stars using LAMOST, particularly the time series of medium-resolution spectra. The relationship between the optical and radio wavelengths of nearby radio stars should be determined in the future.
The remainder of this paper is organized as follows. Based on the LAMOST low and medium resolution spectral surveys, we provide updated parameters of radio stars in Section 2. Then, we analyze the spectroscopic properties and variations in the H α line in Section 3. Finally, we discuss the variation in the H α line and provide an observational plan of the FAST telescope in Section 4.

2. Data

LAMOST is a reflecting Schmidt optical telescope with an effective aperture of 4 m and a field view of approximately 5 square degrees which is operated by the National Astronomical Observatories of China (NAOC); it is designed for low- and medium-resolution spectroscopic surveys [26,27]. In 2018, it was used to obtain a time series of the medium-resolution spectral survey [28]. More than 9.16 million LAMOST stellar spectra with a signal-to-noise ratios (SNR) above 10, and 6.20 million stellar parameters, were published on 30 June 2019 from the low resolution LAMOST DR7 [15,17]. There are two observational modes for the surveys of the LAMOST medium resolution spectra, namely, non-time domain and time-domain modes. A total of 0.67 million spectra of 0.51 million stars with an SNR of above 10 have been reported, and 0.51 million stellar parameters have been published as non time-domain data under the medium resolution. In addition, there are 1.61 million spectra of 0.29 million objects with SNR above 10. In total, 2.28 million spectra with an SNR above 10 and 0.81 million stellar parameters have been published. A standard reduction process was used to obtain the stellar parameters (e.g., the effective temperature, surface gravity, and metallicity) [15,29].
The LAMOST low- and medium-resolution spectra provide useful information for studying the chromospheric activity and parameters of radio stars. We cross-matched the LAMOST DR7 catalogue with the radio stars which were detected at least once and those with upper limits [13,14]. We obtained 449 stellar spectra of 258 radio stars with an SNR greater than about 10. We have listed the parameters of all the spectra of the radio stars in Table 1 and the repeated observations in Table 2. We have listed the LAMOST name (first column), number of radio stars (second column), other names (third column), observational HJD date (fourth column), exposure time (fifth column), spectral type (sixth column), and SNR using an R filter (seventh column). In addition, we cross-matched the radio stars with the medium spectra of LAMOST DR7. We obtained 1319 stellar spectra of 156 radio stars with an SNR above 10. In Table 3, we have listed the LAMOST name (first column), radio star number (second column), other names (third column), HJD (fourth column), exposure time (fifth column), and SNR (sixth column). We have listed only those parameters important for radio stars.

3. Spectroscopic Analyses

3.1. LAMOST Low-Resolution Spectroscopic Analyses

For the LAMOST low resolution spectra, we obtained the continuum using the two sides of different chromospheric active indicators based on the Hammer program, which was published in 2007 [30,31]. The regions of these two sides of these indicators are listed in previously published papers [31,32]. We used a similar method to reduce the spectra from the LAMOST survey [15]. This method has previously been used to reduce the SDSS spectra by other astronomers [33]. The published LAMOST radial velocity was used to revise the spectrum and determine the position of the H α line. We calculated the equivalent widths (EWs) in the H α , H β , H γ , H δ , and C a Ⅱ H&K and IRT lines using the integration method within the region of ±10 Å around the core of the spectral lines. Simultaneously, we used the Gaussian function to fit the H α line and obtained the H α EW. The EW difference between the two methods is the uncertainty of the H α EW. We listed the EWs (eighth column) and heights (ninth column) of H α . Using the EWs of the H α indicator, we determined the behavior of the absorption or emission (10th column). For the OBAFGK stars, we used the criterion of EW 0 Å. If the EW value of the H α line was above 0 Å and simultaneously larger than the errors and the value of the height of the H α line was three times larger than the standard error [34], we considered the behavior of the H α line to be emission. However, the EW must be larger than 0.75 Å, because there are numerous molecular lines for M-type stars [23,31]. We have listed the EW of H β in the 11th column of Table 1 and the radio intensities at 4.8 GHz and 23 GHz in the 12th and 13th columns of Table 1. The printed versions of the tables include other values of all active chromospheric active indicators, and will be made available in the online database at the CDS. Among the 150 radio stars with single spectra, 77 radio stars had emissions. Several examples of radio stars with single spectra are plotted in the left-hand panels in Figure 1. There are obvious emissions of the H α , H β , H γ , H δ , H8, C a Ⅱ H&K and IRT lines. In addition, there are 299 spectra of 108 objects with repeated observations of radio stars. Similar to Table 1, we list the parameters of the radio stars with repeated spectra in Table 2. The amplitude of the H α EW variability is three times larger than the error, and we considered the radio star as a variable [23]. Among them, 69 objects show a long time variation in their H α intensity. We plotted two examples and marked different chromospheric activity indicators in the right panels of Figure 1. In the small window of the right panel, the details of the H α variation are clearly presented.

3.2. LAMOST Medium-Resolution Spectroscopic Analyses

For the total coadd spectra from LAMOST medium-resolution spectra, cosmic rays have been reduced. To discuss the variation in the H α line of the radio star on a short time scale of approximately 20 min, we used the single exposure spectra. However, there are cosmic rays in these single spectra of the DR7 released data of the LAMOST. First, we needed to detect and remove the cosmic rays from the single exposure spectra. We calculated the ratio of the data above the mean of the surrounding wavelengths. If there were typical values five times or higher than the standard deviation of the background, we considered the points as cosmic rays and removed them for numerous runs. The detected cosmic rays were replaced by the average value of the neighboring pixels. Multiple detection passes are required to detect and replace cosmic ray events. As there are many repeated observations for LAMOST medium spectra, we reduced the cosmic rays using the cross-judgement method. In Figure 2, we provide several examples of the observed medium-resolution LAMOST spectra with cosmic rays (left) and the results of our reduction with no cosmic rays (right). We obtained the continuum spectra of the radio stars by 5- or 6-order polynomial function fitting and normalised spectra after normalisation. We plotted the observed (right panel) and normalised (left panel) LAMOST spectra, as shown in Figure 3. The methods used for obtaining the E W s and their uncertainties were similar to those reported by Zhang et al. (2020) [21].

3.3. Comparison between Low-Resolution and Medium-Resolution LAMOST Spectra

By cross-matching the LAMOST low- and medium-resolution catalogue of radio stars, we found 102 objects with both low and medium resolution spectroscopic observations. Figure 4 shows several examples of FP Tau, FX Tau, DL Tau, and DM +25 1065 with two spectral observational modes. In Figure 4, it can be seen that there is a single peak emission of the low-resolution spectra. However, there are two or more peaks in the medium-resolution spectra because of the higher resolution of 7500. These emissions are caused by the substructures of the stellar disk, different regions of the chromospheric active region, or different components of binaries. Medium-resolution spectra are extremely important for investigating the details of spectroscopic binaries and special physical phenomena.

3.4. Short-Term and Long-Term Scale Variations of the H α Line

The time domain medium-resolution observations were made using the LAMOST telescope. These can be used to discuss the H α variations of radio stars over short time scale of approximately 20 min. There are 1319 spectra of 156 objects with repeated observations. There are 93 objects with H α emission. Among them, the emission intensities of 29 active objects are stable on a short time scale. We have plotted several examples (HBC 20, DK Tau, GO Tau and GG Tau) of radio stars with stable H α emissions in Figure 5, where the continuum spectra are shown in the left panel and the H α EW values are shown in the right panel. The H α emissions of 63 objects show short and long time scale variations, especially short time scale of approximately 20 min. It is interesting to note that there are short time variations of 20 min in CY Tau, BP Tau, Hubble 4, HBC 230, and V590 Mon. We have plotted examples of the LAMOST medium resolution spectra of radio stars in the left panel of Figure 6. The variation in the H α EW is shown in the right panel of Figure 6. We can observe the increase and decay phases of the H α variation. Similar to Figure 6, we show examples with obvious long-term variations in the EW of the H α line in Figure 7. More data on the H α intensity are required to detect the chromospheric activity cycle in the future.

4. Discussion and Conclusions

We have investigated the H α behavior of the detected radio stars and discussed the properties of short and long-term variations. We have additionally considered the radio stars in the observational region of the FAST.

4.1. Behavior of the H α Line and Variation

We detected 449 low-resolution spectra for 258 objects. There were 185 objects with emissions above the continuum of the H α line. There were 108 objects with the repeated observations, with 63 objects exhibiting long-term variations. We additionally obtained 1319 LAMOST medium-resolution spectra of 156 radio stars. Comparing the low- and medium-resolution LAMOST spectra, the medium-resolution spectra show more detailed behaviour. There are 93 radio stars with medium-resolution spectra with H α emissions. Among them, 63 objects exhibited short- and long-term variability, particularly at a short time scale of approximately 20 min. The properties of H α emission and spectral line variation of the radio stars are due to different physical mechanisms, including photo-star disks, stellar activity, and binary systems. For our data, we have provided the possible mechanism in the last columns of Table 1 and Table 3. The cause of the H α emission cannot be ascertained in the present paper, as we need more data to confirm it.
Most of our objects are young stars (such as FP Tau, FW Tau, DH Tau, HBC 230, etcetera). For young objects, the H α emission can be explained by strong stellar winds, circumstellar discs, and outflow activity [35,36,37]. For solar-like and cool dwarf stars (such as UX Com,...), the short and long-term variations are due to magnetic phenomena. The short term variations can be explained by chromospheric activity of plages or flares, prominence, post-flare loops, and other chromospheric activity phenomena [38]. Several of our objects are eclipsing binaries, such as AC Cnc, DM +16 516), in which case the variations are caused by the activity of the two components or their interactions [39]. The chromospheric variation might be explained by orbital phase modulation of chromospheric emission [39] or chromospheric activity longitudes [40]. Long-term chromospheric variation was found on RX J0437.4+1851A and JH 56, which was explained by stellar H α activity evolution [41]. As data from the time series LAMOST medium-resolution survey accumulated, we were able to detect the chromospheric activity cycles. There is an obvious EW decrease for CY Tau and an EW increase for BP Tau in the short time scales in Figure 6. If the intensity of the H α emission shows a rapid increase followed by a gradual decrease, the phenomenon might be due to a flare event [42]. We expect to search for flare events with rise and decay in the future.
There were numerous objects (FP Tau, FX Tau, FQ Tau, DM +25 1065,...) observed in the low and medium-resolution spectral surveys. The medium-resolution spectra are more detailed than the low resolution spectra. We can see self-absorption in the H α emission of early stars in Figure 4, which might be caused by accretion and outflow regions of circumstellar discs [43]. While we were able to confirm that the disks were more complex [37], we need more spectral data on the complete orbital phases to determine the disk structure. Meng et al. (2021) [44] identified two emissions from the primary and secondary components of eclipsing binary 2MASS J04100497+2931023 using the LAMOST medium spectra. This binary with both blended emissions and double H α emissions might be caused by the two components of the active binaries [45]. The medium LAMOST spectral survey only started a few years ago, and thus the data for each object are insufficient. Here, we provide the complex and detailed theoretical mechanism and discuss the relationship between the optical and radio radiation.

4.2. Observational Plan of Radio Stars Using FAST

Wendker [13,14] published an updated catalogue of 3699 radio stars or binary systems. Owing to its excellent radio detection capability, we anticipate using the FAST telescope to observe radio stars, especially the nearby radio stars, in the future. Our project is dedicated to revealing the nature of radio emissions. Based on the latitude coverage of the sky from −14.6 to 65.6 Dec for FAST, we plotted the distribution of the radio stars in Figure 8, where the red points are within the observation region of FAST.
The formula for the minimal detection flux density of the radio telescope is as follows:
S m i n = 2 K T s y s η A Δ η p t
where K is the Boltzmann constant, K = 1.38 × 10 − 23 erg/k, T s y s is the telescope system temperature, T s y s = 27 k. η is the aperture efficiency of the telescope, η m i n = 0.55. A is the effective aperture area of the radio telescope (the effective aperture area of FAST is 300 m in diameter), η p is a fixed value, η p = 2, Δ bandwidth is 500 MHz, t is the sampling time, and we take t = 1 s. Based on these parameters [46], we can estimate the minimal detectable radio flux ( S m i n ∼ 60 μ Jy) of the FAST telescope.
We compared the flux of radio stars at 1.4 GHz with the minimal radio observational flux of FAST. We show the observational ability of FAST in Figure 9, where the horizontal axis is the number of radio stars in descending order of declination and the vertical axis is the intensity of the radio stars. For data points, the magenta five-pointed stars represent the real value of the radio flux, the green circles represent the upper limit of the radio flux, and the red line represents our estimated limit of the radio flux of FAST. It can be seen that FAST can theoretically detect the flux for the samples of radio stars above the limited line. In addition, the detection frequency band of the FAST telescope is limited to [47] (70 MHz∼3 GHz), and the limitation of the observation sky is Dec: −14.5∼65.6. We were thus able to obtain samples from the yellow region, as shown in Figure 9. The horizontal axis represents the serial number according to the size of the declination of the radio stars. The red dots in Figure 9 are above the detection limit of FAST, and are thus easy to detect. For the green points, the maximum possible value of the radio stars is above the detection limit of FAST, and we thus need to use FAST to conduct further validation checks. We have listed these in Table 4, as they are likely to be detected by FAST.
We have selected several interesting candidates from among the radio stars, such as the active stars from the LAMOST survey [21], ultracool dwarfs [48], and host stars with an extra-solar planet [49]. We intend to trace them over 4–6 h using FAST [28] and then attempt to detect their possible radio radiations. We might detect flare events and star–planet and binary interactions [9]. In the future the study of radio stars will be able to use both FAST and the upcoming SKA platform [50]. We intend to study non-thermal radio emission due to shock acceleration from the wind collision region of massive stars, the high energy emission process of young stellar objects [51,52], the generation and dissipation of kG-strength magnetic fields of ultra-cool dwarfs [53,54,55], and stellar and planetary magnetosphere interactions [56]. FIn the future, we will analyze the relationship between radio radiation and stellar physical parameters, as radio and optical emissions are required to determine the relationship between chromospheric and coronal emissions. The use of the FAST, SKA, and LAMOST platforms has the potential to unlock a great deal of new science concerning radio stars.

Author Contributions

Conceptualization, L.Z.; software, Y.C., B.L. and Z.Z.; investigation, Q.P.; writing—review and editing, L.Z., X.L.H. and P.M. All authors have read and agreed to the published version of the manuscript.

Funding

This research is funded by the Joint Fund of Astronomy of the NSFC and CAS Grant Nos. 11963002 and U1931132, and the China Manned Space Project, No. CMS-CSST-2021-B07. This research is also funded by the Cultivation Project for FAST Scientific Payoff Grant No. 2021.

Conflicts of Interest

The authors declare no conflict of interest.

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Universe 08 00384 g001 550
Figure 1. Examples of the low resolution LAMOST spectra of several radio stars with single (left) and repeated (right) observations. We marked several important spectral lines with obvious emissions in the Ca Ⅱ H&K, H δ , H γ , H β , H α , and Ca Ⅱ IRT lines. There are obvious variations in the H α line in the small panels.
Figure 1. Examples of the low resolution LAMOST spectra of several radio stars with single (left) and repeated (right) observations. We marked several important spectral lines with obvious emissions in the Ca Ⅱ H&K, H δ , H γ , H β , H α , and Ca Ⅱ IRT lines. There are obvious variations in the H α line in the small panels.
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Figure 2. Observed medium-resolution LAMOST spectra with cosmic rays (left) and reduction spectra with no cosmic rays (right). The red lines are cosmic rays in the observed spectra.
Figure 2. Observed medium-resolution LAMOST spectra with cosmic rays (left) and reduction spectra with no cosmic rays (right). The red lines are cosmic rays in the observed spectra.
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Figure 3. Observed medium-resolution LAMOST spectra (left) and its normalised spectrum (right).
Figure 3. Observed medium-resolution LAMOST spectra (left) and its normalised spectrum (right).
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Figure 4. LAMOST spectra of radio stars with both low (left) and medium (right) resolution observations. We marked several important spectral lines with obvious emissions in the C a Ⅱ H&K, H δ , H γ , H β , H α , and C a Ⅱ IRT lines. Detailed behavior of the H α line is shown in the small panels. The right panel shows the detailed behavior of LAMOST medium-resolution spectra, and different colors represent the different observations.
Figure 4. LAMOST spectra of radio stars with both low (left) and medium (right) resolution observations. We marked several important spectral lines with obvious emissions in the C a Ⅱ H&K, H δ , H γ , H β , H α , and C a Ⅱ IRT lines. Detailed behavior of the H α line is shown in the small panels. The right panel shows the detailed behavior of LAMOST medium-resolution spectra, and different colors represent the different observations.
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Figure 5. Examples of radio stars with stable H α emissions and EWs.
Figure 5. Examples of radio stars with stable H α emissions and EWs.
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Figure 6. Medium resolution LAMOST spectra of radio stars with repeated observations on short time scale (left). The short-term variation of EW is shown on the (right).
Figure 6. Medium resolution LAMOST spectra of radio stars with repeated observations on short time scale (left). The short-term variation of EW is shown on the (right).
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Figure 7. Medium resolution LAMOST spectra of radio stars with repeated observations over a long time scale of several months (left). There are obvious long-term variations in the EWs of H α , as shown in the (right) panel.
Figure 7. Medium resolution LAMOST spectra of radio stars with repeated observations over a long time scale of several months (left). There are obvious long-term variations in the EWs of H α , as shown in the (right) panel.
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Figure 8. Position distribution of radio stars; red points are within the observational field of the FAST telescope.
Figure 8. Position distribution of radio stars; red points are within the observational field of the FAST telescope.
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Figure 9. Distribution of the radio flux of radio stars in the 1.4 GHz frequency; the red line is the detection limit of the FAST telescope.
Figure 9. Distribution of the radio flux of radio stars in the 1.4 GHz frequency; the red line is the detection limit of the FAST telescope.
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Table
Table 1. Parameters of radio stars observed in LAMOST low resolution spectral survey along with their H α properties.
Table 1. Parameters of radio stars observed in LAMOST low resolution spectral survey along with their H α properties.
LAMOST NameRadio No.Other NameHJDExposureSpSNRH α H α HeightEmissionH β 4.8 GHz23 GHzMechanism
---ds--Å Åmjymjy
J035721.13+125815.7476RX J0357.3+125858522.800691800F9261−0.712 ± 0.0155a−1.404 ± 0.040--disk
J040519.59+200928.1508RX J0405.3+200957437.784031800G9576−0.329 ± 0.0038a−0.888 ± 0.032<0.8-disk
J040540.36+224812.0512DM +22 63057397.922221800-8−1.802 ± 0.2653a−0.736 ± 0.156--disk
J040651.35+254128.2523DRX J0406.8+254156972.069441800M03464.674 ± 0.3468e2.785 ± 0.117--disk
J040909.90+290130.2539RX J0409.1+290156967.097221800G8539−0.015 ± 0.0012a−0.678 ± 0.024<0.29-disk
J041327.22+281624.6566DHBC 36656967.097221800M03281.936 ± 0.05810e1.440 ± 0.0414.82<14disk
J041412.87+281209.9570DHD 28344756967.097221800K47931.504 ± 0.0475e0.651 ± 0.0253.8–2924–42binary
J041430.60+285129.8575LkCa 256682.818751800M0901.677 ± 0.02023e1.893 ± 0.122<0.65<12disk
J041447.98+275234.6581HBC 36856967.097221800M25562.057 ± 0.05212e1.770 ± 0.062<0.6<14disk
J041551.37+310035.7589RX J0415.8+310056981.054171800G3234−0.830 ± 0.0157a−1.592 ± 0.047<0.20-disk
J041926.27+282613.9654DV819 Tau56682.781251800K71422.856 ± 0.06823e1.622 ± 0.054<0.2434.magnetic
J041929.78+214513.9659LP 358-68557397.922221800M32374.381 ± 0.10642e6.516 ± 0.331<0.5-disk
042049.82+300915.5668RX J0420.8+300956682.818751800M0541.821 ± 0.0658e1.083 ± 0.104--disk
J042155.63+275506.0681DDE Tau56682.781251800M114224.035 ± 10.4535e38.107 ± 1.336<0.5836.disk
J042158.91+281803.2683DDM +27 65757377.956251800G4482−0.295 ± 0.0049a−1.309 ± 0.0430.33–3.29<15disk
J042203.15+282538.7686HBC 38256682.818751800M11774.021 ± 0.16615e3.089 ± 0.139<0.65<12disk
J042159.64+193207.2688DT Tau57409.863891800K3408−6.043 ± 6.2140a19.578 ± 0.899--disk
..........................................
We only listed the radio intensities of 4.8 and 23 GHz with the most radio observations. For many stars there are no flux values at 4.8 and 23 GHz, as their intensities are at 1.4, 8.6 GHz, or other radio wavelengths. All of the radio intensities of radio stars in all of the radio wavelengths can be downloaded from the internet (https://cdsarc.cds.unistra.fr/viz-bin/cat/VIII/99 (accessed on 30 May 2022)) [13,14].
Table
Table 2. Radio stars with repeated spectra from low resolution LAMOST survey DR7 and their H α variation in long time scales (several months).
Table 2. Radio stars with repeated spectra from low resolution LAMOST survey DR7 and their H α variation in long time scales (several months).
LAMOST NameRadio No.Other NameHJDExposure TimeSpSNRH α H α HeightEmissionLong VariationH β 4.8 GHz23 GHz
---ds--Å Åmjymjy
J042929.70+261652.8891FW Tau56625.940283000M67910.915 ± 0.77229e60v10.725 ± 1.724-<15
J042929.71+261653.2891FW Tau56284.956251200M6338.945 ± 0.71218e60v5.373 ± 0.791-<15
J043001.13+351724.7901DHBC 39056570.156251800M1856.583 ± 0.52212e61v1.791 ± 0.1780.5<15
J043001.13+351724.7901DHBC 39056325.81251200A2V177.942 ± 0.75414e61v−1.042 ± 0.0750.5<15
J043019.15+351745.4908DHBC 39156570.156251800G53360.519 ± 0.0122e62v−1.151 ± 0.0354.2<18
J043016.55+243928.5915V587 Tau57377.956251800G281−1.412 ± 0.0648a63n−1.839 ± 0.094-<20
J043016.54+243928.5915V587 Tau56284.927781200G237−1.399 ± 0.0458a63n−1.914 ± 0.072-<20
J043029.61+242645.0917DFX Tau57425.772921800M12687.538 ± 1.5114e64v4.505 ± 0.165-20.
J043029.61+242644.9917DFX Tau56284.956251200M11115.482 ± 0.5337e64v2.655 ± 0.124-20
J043029.61+242644.9917DFX Tau56284.927781200M11005.768 ± 0.5807e64v2.520 ± 0.116-20
J043051.38+244222.1926ZZ Tau56284.956251200M3495.989 ± 0.45312e65v14.064 ± 3.309-<20
J043051.38+244222.1926ZZ Tau56284.927781200M3436.535 ± 0.45914e65v11.374 ± 1.381-<20
J043123.81+241052.7937V927 Tau56284.927781200M4684.540 ± 0.3409e66v4.722 ± 0.519-<20
J043123.81+241052.7937V927 Tau56284.956251200M4794.159 ± 0.2639e66v3.783 ± 0.423-<20
J043123.81+241052.9937V927 Tau58512.841671800M4316.208 ± 0.51411e66v5.119 ± 1.486-<20
J043130.42+203537.9941RX J0431.4+203556608.01253000M22104.534 ± 0.27911e67v13.380 ± 0.584--
J043130.42+203537.9941RX J0431.4+203557060.770834500M22103.556 ± 0.2178e67v9.458 ± 0.561--
J043150.56+242418.0952DHK Tau56284.927781200M23413.623 ± 3.4336e68v11.754 ± 1.1641.4041–110
J043150.57+242417.3952DHK Tau56239.109031800M15118.194 ± 6.1806e68v20.532 ± 2.073<0.6-
J043150.56+242418.0952DHK Tau56284.956251200M14014.022 ± 3.5306e68v16.709 ± 2.4581.4041–110
J043150.57+242417.7952DHK Tau58487.859034500M219413.960 ± 3.4177e68v9.764 ± 0.387<0.6<11
J043157.80+182136.2959DV710 Tau56332.792361200M16719.860 ± 5.9049e69v13.506 ± 1.059<0.660–71
J043157.79+182137.9959DV710 Tau57437.832641800M124717.614 ± 4.8737e69v13.950 ± 0.458<0.660–71
J043215.40+242859.7962DV806 Tau58512.841671800EM4615.250 ± 6.1654e70v18.243 ± 9.525-124
..........................................
We list several parameters of radio stars with repeated observations. All parameters are available in the online journal.
Table
Table 3. Radio stars with LAMOST medium-resolution spectra and their H α variations in short time scale (about 20 min).
Table 3. Radio stars with LAMOST medium-resolution spectra and their H α variations in short time scale (about 20 min).
LAMOST NameRadio No.Other NameHJDExposure TimeSNRH α EmissionShort VariationMechanism
---ds-Å
J042929.70+261652.7891FW Tau58466.912512003616.891 ± 0.189yydisk
J042929.70+261652.7891FW Tau58467.0263912003616.939 ± 0.125yydisk
J042929.70+261652.7891FW Tau58467.0104212003618.176 ± 0.167yydisk
J042929.70+261652.7891FW Tau58466.9291712003617.299 ± 0.090yydisk
J042929.70+261652.7891FW Tau58466.9451412003617.308 ± 0.184yydisk
J042929.70+261652.7891FW Tau58466.9937512003617.108 ± 0.191yydisk
J042929.70+261652.7891FW Tau58466.9777812003616.720 ± 0.149yydisk
J042929.70+261652.7891FW Tau58466.9611112003617.030 ± 0.233yydisk
J042941.56+263258.2895DDH Tau58143.7930612004436.716 ± 0.754yydisk
J042941.56+263258.2895DDH Tau58143.8097212004435.127 ± 0.719yydisk
J042941.56+263258.2895DDH Tau58143.8256912004434.032 ± 0.683yydisk
J043049.21+211410.1927RX J0430.8+211358416.070141200799−0.530 ± 0.134nndisk
J043049.21+211410.1927RX J0430.8+211358502.836111200327−0.747 ± 0.113nndisk
J043049.21+211410.1927RX J0430.8+211358416.054171200799−0.664 ± 0.105nndisk
J043049.21+211410.1927RX J0430.8+211358502.872221200327−0.890 ± 0.138nndisk
J043049.21+211410.1927RX J0430.8+211358502.888891200327−0.859 ± 0.117nndisk
J043049.21+211410.1927RX J0430.8+211358502.856251200327−0.783 ± 0.109nndisk
J043049.21+211410.1927RX J0430.8+211358416.086811200799−0.649 ± 0.108nndisk
J043049.21+211410.1927RX J0430.8+211358416.102781200799−0.668 ± 0.106nndisk
J043049.21+211410.1927RX J0430.8+211358416.118751200799−0.562 ± 0.137nndisk
J043049.21+211410.1927RX J0430.8+211358416.135421200799−0.531 ± 0.136nndisk
J043049.21+211410.1927RX J0430.8+211358416.151391200799−0.527 ± 0.135nndisk
J043049.21+211410.1927RX J0430.8+211358416.167361200799−0.530 ± 0.141nndisk
J034548.28+322411.8402DHBC 2058417.11319120034411.558 ± 0.0512yndisk
J034548.28+322411.8402DHBC 2058417.03194120034411.686 ± 0.0522yndisk
J034548.28+322411.8402DHBC 2058417.04861120034411.693 ± 0.0525yndisk
J034548.28+322411.8402DHBC 2058417.06458120034411.683 ± 0.0534yndisk
J034548.28+322411.8402DHBC 2058417.08056120034411.665 ± 0.0521yndisk
J034548.28+322411.8402DHBC 2058417.09722120034411.569 ± 0.0517yndisk
J034548.28+322411.8402DHBC 2058417.12917120034411.506 ± 0.0496yndisk
..............................
There may be multiple mechanisms for Ha line on radio stars, which are from the published paper [13,14] and our data. The cause of the Ha emission can not be ascertained, and needs more data prior to confirmation. Here, we list several parameters of radio stars. All parameters are available in the online journal.
Table
Table 4. Radio stars expected to be observed by FAST in the 1.4 GHz band.
Table 4. Radio stars expected to be observed by FAST in the 1.4 GHz band.
Star Name S v (mJy)RaDecStar Name S v (mJy)RaDec
V 711 Tau5603 34 13.151+00 25 33.09RS CVn0.813 08 17.891+36 12 01.23
V 711 Tau6403 34 13.151+00 25 33.09BH CVn4.0213 32 33.923+37 26 16.49
V 711 Tau7003 34 13.151+00 25 33.09BH CVn913 32 33.923+37 26 16.49
V 711 Tau10003 34 13.151+00 25 33.09XTE J2012+3813.520 10 47.86+38 01 56.5
V 711 Tau13503 34 13.151+00 25 33.09SAO 612241.6709 00 17.091+38 02 29.99
BI Cet2.1701 20 16.665+00 27 15.9812 ALF(2) CVn0.8512 53 40.181+38 35 03.42
GSC2.4221 35 07.444+01 23 42.26BM CVn1.0613 19 17.318+39 08 31.80
YZ CMi1.3207 42 03.870+03 40 48.50SAO 640907.114 19 02.311+39 12 53.99
V 1343 Aql65019 09 21.282+04 53 54.27SAO 64090914 19 02.311+39 12 53.99
DM +00 198<0.701 10 27.453+00 48 52.39HD 276968<0.604 49 11.948+43 13 43.30
EC 95<618 27 25.5+01 10 42.HD 30650<0.604 47 58.294+43 29 39.34
YZ CMi<14007 42 03.870+03 40 48.50DM +43 3571<120 18 46.720+43 41 43.33
HD 219188<0.623 11 27.893+04 43 29.1968 Cyg<0.621 16 35.169+43 44 05.51
47 RHO Leo<0.610 30 10.762+09 33 52.22HD 4142<0.600 41 38.936+47 35 25.64
HD 39680<0.605 51 54.528+13 50 48.09V 819 Cyg<0.619 51 32.365+47 40 36.45
HR 2222<0.606 12 18.204+13 52 03.46HD 20218<0.603 13 53.308+47 56 47.84
T Tau2.804 19 04.209+19 25 05.67V 1016 Cyg1719 55 19.835+39 41 29.59
AD Leo14010 16 53.863+20 07 19.20MWC 3496820 30 56.836+40 29 20.81
PS Ser0.9315 41 46.963+22 29 48.17Algol10003 04 54.343+40 45 52.16
FK Com1.7513 28 24.780+24 28 25.39V 1521 Cyg14,68020 30 37.62+40 47 12.85
DH Leo1.0809 57 13.283+24 47 36.76Cyg OB2-94.820 31 22.958+41 04 50.39
MS Ser2.2615 56 38.067+25 42 45.42Tycho 3429 16091.809 37 54.550+48 49 48.87
SAO 1461942.2615 56 38.067+25 42 45.42MWC 8412004 15 39.18+55 52 46.1
V 340 Gem6.507 18 28.136+26 15 16.80SAO 290701.3114 14 22.905+56 59 18.20
V 340 Gem9.907 18 28.136+26 15 16.8054 Cam1.0207 58 32.107+57 24 50.89
Gliese 171.2101904 33 41.765+27 02 01.03NOV Mon 7530006 20 11.176−00 19 10.80
17 SIG CrB4.716 12 48.306+33 59 02.91HD 201910<0.621 09 27.402+40 58 47.05
17 SIG CrB6.816 12 48.306+33 59 02.91HR 6146<0.7316 26 59.860+41 59 26.35
53 Ari<0.603 04 36.481+17 41 18.52DM +49 2596<0.6417 09 06.804+49 01 35.37
HD 248434<0.605 48 42.+21 32HD 216534<0.622 50 47.943+49 35 55.19
HD 214930<0.622 39 02.017+23 35 06.44AM Her<0.2418 14 58.75+49 50 54.9
RU Cnc<0.6408 34 33.729+23 44 12.58HD 14220<0.602 16 14.755+52 19 55.07
ST LMi<0.6411 02 58.0+25 22 42MWC 84<204 15 39.18+55 52 46.1
UX Ari5403 23 33.027+28 32 32.43NOV Mon 7530006 20 11.176−00 19 10.80
UX Ari6303 23 33.027+28 32 32.43AZ Psc1.2822 56 18.789−00 35 03.43
75 SIG Gem3.607 40 11.390+29 00 22.34AY Cet2.5501 14 03.832−02 45 46.70
HD 721466.508 29 13.865+29 29 23.06M 2-93217 02 52.588−10 04 31.16
LB 10117511 16 24.07+30 08 17.946 KSI Per<0.603 55 42.806+35 38 56.45
J1408+30543.314 05 53.56+31 09 00.0HD 37737<0.605 39 08.716+36 10 36.86
66 ALF Gem0.7607 31 24.725+31 59 59.20XTE J2012+381<120 10 47.86+38 01 56.5
Tycho 2553 3161.0714 24 34.273+32 05 41.05HD 192281<0.620 10 46.724+40 07 01.21
GJ 11085.908 05 45.95+32 57 59.2HR 1500<0.604 40 44.928+40 41 40.18
T CrB<0.715 57 24.520+26 03 38.7022 LAM Cep<0.622 09 48.513+59 10 02.39
ZZ Boo<0.6713 53 51.821+26 09 46.07LSI +60 141<0.601 04 53.3+60 17 05.
Ross 868<0.717 17 53.+26 32 48.SAO 20610<0.623 22 18.396+60 52 59.33
HD 39478<0.605 41 00.576+26 44 51.93HD 16429<0.602 36 53.641+61 04 05.33
5 ALF CrB<0.6715 32 34.146+26 52 54.42DM -02 1885<0.606 58 15.991−03 02 43.49
WY Cnc<0.6708 58 58.0+26 53 14.DM -02 3312<0.611 13 38.617−03 11 56.90
Pollux<0.6707 42 15.512+28 08 55.29DM -05 4318<0.616 31 47.917−06 01 58.63
UX Com<0.5512 59 08.9+28 54 02.HD 125924<0.614 20 03.717−08 01 15.93
HD 195907<0.620 31 03.680+31 29 08.83DM -08 4675<0.618 38 04.177−08 45 58.28
HD 201345<0.621 05 51.711+33 11 40.14HD 220172<0.623 19 15.073−10 02 08.25
HR 1712<0.605 12 59.774+34 15 25.3213 ZET Oph<0.616 34 24.137−10 28 02.81
GX 17+2<0.218 13 10.920−14 03 14.44DM -10 4493<0.617 23 30.808−10 57 01.17
G 165-82.5113 29 27.46+29 32 02.4
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MDPI and ACS Style

Zhang, L.; Cheng, Y.; Han, X.L.; Pi, Q.; Misra, P.; Li, B.; Zhu, Z. Physical Properties of Radio Stars Based on LAMOST Spectral Survey. Universe 2022, 8, 384. https://doi.org/10.3390/universe8070384

AMA Style

Zhang L, Cheng Y, Han XL, Pi Q, Misra P, Li B, Zhu Z. Physical Properties of Radio Stars Based on LAMOST Spectral Survey. Universe. 2022; 8(7):384. https://doi.org/10.3390/universe8070384

Chicago/Turabian Style

Zhang, Liyun, Yao Cheng, Xianming L. Han, Qingfeng Pi, Prabhakar Misra, Baoda Li, and Zhongzhong Zhu. 2022. "Physical Properties of Radio Stars Based on LAMOST Spectral Survey" Universe 8, no. 7: 384. https://doi.org/10.3390/universe8070384

APA Style

Zhang, L., Cheng, Y., Han, X. L., Pi, Q., Misra, P., Li, B., & Zhu, Z. (2022). Physical Properties of Radio Stars Based on LAMOST Spectral Survey. Universe, 8(7), 384. https://doi.org/10.3390/universe8070384

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